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Publisher: Elsevier   (Total: 3183 journals)

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Showing 1 - 200 of 3183 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 38, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 26, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 102, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 40, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 7)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 436, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 28, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 5, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 312, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
Acta Psychologica     Hybrid Journal   (Followers: 26, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 18, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 11, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 183, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 12, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 17, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 29, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 34, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 26, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 15)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 13)
Advances in Digestive Medicine     Open Access   (Followers: 12)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 43, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 29, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 51, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 65, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 21, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 10, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 7, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 25)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 3, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 9, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 14, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 8, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 24)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 5)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 5, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 67)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 1, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 421, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 37, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 53, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 384, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 475, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 44, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 8, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 12)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 10, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 53, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 58, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 63, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 46, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 12)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 37, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 36, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 50)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 255, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 32, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 28, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 66, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 24, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 5, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 209, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 223, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 6, SJR: 0.937, CiteScore: 2)
Animal Reproduction Science     Hybrid Journal   (Followers: 7, SJR: 0.704, CiteScore: 2)

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Similar Journals
Journal Cover
Algal Research
Journal Prestige (SJR): 1.142
Citation Impact (citeScore): 4
Number of Followers: 11  
  Partially Free Journal Partially Free Journal
ISSN (Online) 2211-9264
Published by Elsevier Homepage  [3183 journals]
  • Photoautotrophic production of succinate via the oxidative branch of the
           tricarboxylic acid cycle influences glycogen accumulation in Synechocystis
           sp. PCC 6803
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Magdalena Mock, Andreas Schmid, Katja Bühler Cyanobacteria are interesting biocatalysts for the sustainable production of value-added compounds, but a functional link of biocatalytic efficiency and cell physiology is missing. Especially the role and structure of the tricarboxylic acid (TCA) cycle in cyanobacteria is not fully understood. Succinate dehydrogenase (SDH) is an essential enzyme linking the TCA cycle to the quinone pool and its substrate succinate is an important platform chemical. We utilized Synechocystis sp. PCC 6803 as a host organism for the photoautotrophic production of succinate via the oxidative branch of the TCA cycle. In Synechocystis sp. PCC 6803 SDH is described to be encoded by three open reading frames (ORF). Four SDH deletion mutants were created and characterized regarding the formation of succinate. Synechocystis_∆sll1625 was the best performing strain accumulating 420 mg L−1 succinate during cultivation in a 1.8 L-photobioreactor under constant illumination. Furthermore, deletion of the SDH resulted in a non-bleaching phenotype and concomitant accumulation of glycogen and succinate during growth at 5% CO2. This substantially influenced cell physiology of the mutant, reflected in decreased cell numbers and higher cell volumes. Thus, the TCA cycle seems to have a key role in controlling carbon fluxes from CO2 into biomass, storage compounds like glycogen, and other carbon sinks.
  • Bioremoval of heavy metals from metal mine tailings water using microalgae
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Cynthia Urrutia, Erwin Yañez-Mansilla, David Jeison The copper industry generates large quantities of mine tailings water. Thus, this study aims to select a microalgae species that is both tolerant and capable of the bioremoval of heavy metals from metal mine tailings water as well as the potential biorefinery of this microalgae biomass. Chlorella vulgaris and Scenedesmus spinosus were tested for tolerance to metal mine tailings water (MTW) in northern Chile and synthetic treatments of Cu and Mo (0.1 and 0.5 mg/L). Additionally, the biomass generated was characterized to evaluate its potential applications. The main results showed greater tolerance of C. vulgaris cultured in MTW treatment. In fact, high removal efficiency of Cu and Mo was detected for this microalgae in MTW: 64.7% and 99.9%, respectively. Similarly, Cu (55%) and Mo (80.3%) removal was observed at 0.5 mg/L synthetic concentration treatments after 72 h. However, cell wall fluorescence and chlorophyll parameters were mainly affected by 0.5 mg/L Cu synthetic concentration, where the mean fluorescence intensity (MFI) was 878, compared with the other treatments (≥1800). Morphological cell changes in the MTW treatment were observed using SEM images. The presence of Mo on the microalgae surface was detected by 0.47% and 0.82% in both Mo synthetic treatments exposed. Additionally, the characterization of microalgae biomass exposed to MTW showed a higher protein content and a minor difference of lipid content compared with the control treatment, which could be used in biorefinery processes. This study reveals the capability of C. vulgaris to remove heavy metals from this mine tailings water and the effect that occurs in microalgae cells.
  • Effect of pulsed electric field treatment on enzymatic hydrolysis of
           proteins of Scenedesmus almeriensis
    • Abstract: Publication date: Available online 14 September 2019Source: Algal ResearchAuthor(s): Sahar Akaberi, Christian Gusbeth, Aude Silve, Divya Senthil Senthilnathan, Elvira Navarro-López, Emilio Molina-Grima, Georg Müller, Wolfgang Frey Amino acids concentrates derived from microalgae biomass through enzymatic protein hydrolysis can improve plant growth by saving the energy that is required for amino acid synthesis from conventional mineral fertilizer resources. To obtain high enzymatic hydrolysis yields, pre-treatment of microalgae biomass prior to enzymatic hydrolysis is suggested for facilitating enzyme access to proteins.Pulsed electric field (PEF) treatment was introduced as a pre-treatment to fresh and concentrated (50 g·kgsus−1 to 80 g·kgsus−1) Scenedesmus almeriensis biomass prior to enzymatic hydrolysis. The concentrated microalgae suspension was treated at an initial conductivity of σ = 1 mS·cm−1 with 1 μs long pulses at an electric field strength of 40 kV·cm−1 and a treatment energy of 75 kJ·kgsus−1 and 150 kJ·kgsus−1. For benchmarking, additional biomass samples were processed by high pressure homogenization (HPH) at 2 kbar and up to 5 passes. Enzymatic hydrolysis was performed by applying the commercial enzymes Alcalase 2.5 L and Flavourzyme 1000 L for 180 min. The amino acids content in supernatant was determined by using the orto-phthaldialdehyde (OPA) assay.PEF treatment at both energy inputs and HPH treatment at 2 kbar, 5 passes, revealed the same hydrolysis kinetics and the same final value of the degree of hydrolysis (DH) of 50% ± 2%. The energy demand for PEF pre-treatment amounts to 0.75 MJ·kgdw−1 when processing biomass at 100 gdw·l−1. After both pretreatments, incomplete protein hydrolysis could be detected by SDS-PAGE analysis of residual biomass. Most feasible, hydrophobic protein fractions and protein aggregation impede complete protein hydrolysis by the applied enzyme cocktail.Since PEF treatment preserves cell shape and biomass separability and thus enables cascade processing, it is suggested as alternative downstream processing method for the production of amino acids concentrates from microalgae biomass.Graphical abstractUnlabelled Image
  • Corrigendum to “Application of aqueous alkaline extraction to remove ash
           from algae harvested from an algal turf scrubber” [Algal Res. 35 (2018)
    • Abstract: Publication date: Available online 13 September 2019Source: Algal ResearchAuthor(s): John E. Aston, Bradley D. Wahlen, Ryan W. Davis, Anthony J. Siccardi, Lynn M. Wendt
  • Combination of Light Emitting Diodes (LEDs) for photostimulation of
           carotenoids and chlorophylls synthesis in Tetradesmus sp.
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Vanessa Daneluz Gonçalves, Márcia Regina Fagundes-Klen, Daniela Estelita Goes Trigueros, Adilson Ricken Schuelter, Alexander Dimitrov Kroumov, Aparecido Nivaldo Módenes In this work, Tetradesmus sp. was investigated regarding biomass and pigment production. The cultivation of Tetradesmus sp. was carried out in a BG-11 medium in addition to a vertical tubular photobioreactor (PBR) irradiated with different spectral combinations and intensities, within a 24:00 h photoperiod. The LEDs emitting light with white; red; yellow; green and blue spectrum were used alone and/or combined, with intensities varying from 13 to 190 μmol m−2 s−1. ANOVA suggested significant effects of the light combination, intensity and interaction between the factors on biomass, carotenoid and chlorophyll responses. The blue light accelerated the growth of Tetradesmus sp. in all three experiments. The combinations white:green (95 μmol m−2 s−1), red:blue (50 μmol m−2 s−1) and blue (25 μmol m−2 s−1) favored biomass growth; while white:green (190 μmol m−2 s−1), red:green (50 μmol m−2 s−1) and red (25 μmol m−2 s−1) favored the synthesis of carotenoids and chlorophylls. Culture reproduction under the spectral regions favoring pigment synthesis indicated that Tetradesmus sp. was photostimulated to synthesize both pigments, especially with red:green (50,50%) at 50 μmol m−2 s−1, where the highest production of carotenoids (6.09 ± 0.29 mg (g biomass)−1) and chlorophyll a (10.08 ± 0.75 mg (g biomass)−1) was obtained.Graphical abstractUnlabelled Image
  • Productivity of Nannochloropsis oceanica in an industrial closely spaced
           flat panel photobioreactor
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): N.H. Norsker, M. Michiels, P.M. Slegers, G.L.A.M. Swinkels, M.J. Barbosa, R.H. Wijffels
  • Demonstration of the potential of Picochlorum soloecismus as a microalgal
           platform for the production of renewable fuels
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): C. Raul Gonzalez-Esquer, Kimberly T. Wright, Nilusha Sudasinghe, Carol K. Carr, Claire K. Sanders, Aiko Turmo, Cheryl A. Kerfeld, Scott Twary, Taraka Dale Photosynthetic microbes are considered promising biofactories for transforming inorganic carbon from the atmosphere into a renewable source of chemicals and precursors of industrial interest; however, there continues to be a need for strains that demonstrate high productivity, environmental robustness, and the potential to be genetically manipulated. Genome sequencing and biochemical characterization of promising culture collection microalgae strains, as well as the isolation of previously unidentified strains from the environment or mixed cultures, bring us closer to the goal of decreasing the cost-per-gallon of algal biofuels by identifying new and promising potential production strains. The halotolerant alga Picochlorum soloecismus was isolated from the culture collection strain, Nannochloropsis salina CCMP 1776. Here, we show that P. soloecismus accumulates moderate levels of fatty acids and high levels of total carbohydrates and that it can effectively grow in a range of salinities. In addition, we make use of its sequenced genome to compare it to other biofuel production platforms and to validate the capacity for engineering this strain's genome. Our work shows that Picochlorum soloecismus is a candidate production strain for the generation of renewable bioproducts.
  • Prospects of using biomass of N2-fixing cyanobacteria as an organic
           fertilizer and soil conditioner
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Mauro Do Nascimento, Marina E. Battaglia, Lara Sanchez Rizza, Rafael Ambrosio, Andres Arruebarrena Di Palma, Leonardo Curatti Increasing production of N-fertilizers is mandatory to support the expected demand of food over the next decades. While reduced access to N-fertilizers compromises food security in some regions of the world, incorrect management in other regions causes detrimental effects on the environment. Biological N2-fixation is a natural process for N-fertilization of plants in natural environments which could only be partially exploited in intensive agriculture. This is mainly because the current technology of crop inoculation with live microorganisms is often constrained by the inoculant's survival and propagation in the agricultural environment.In this study, we pursued a controlled eutrophication approach to recycling nutrients from agro-industrial runoffs for the production of an organic fertilizer and soil conditioner. Biomass of a N2-fixing cyanobacterium was obtained using a P-enriched fermentation vinasse as a sole source of macronutrients. The cyanobacterial biomass substituted for urea in wheat growth in artificial semi-arid soil, especially when sporadic watered simulating a semi-arid rainfall regime. Comparative analyses suggested a higher persistence of the organic fertilizer in the soil than an equivalent amount of urea.This study advocates the convenience of concentrating nutrients from industrial wastewater into biomass of N2-fixing cyanobacteria for their re-use in crop fertilization. It discusses the advantages of separating biological fertilizer production from crop cultivation in order to circumvent the odds of the microorganisms' acclimation to the agronomic conditions, and the techno-economic challenges towards maturation of the proposed technology.Graphical abstractUnlabelled Image
  • Phosphorus starvation and luxury uptake in green microalgae revisited
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Alexei Solovchenko, Inna Khozin-Goldberg, Irina Selyakh, Larisa Semenova, Tatiana Ismagulova, Alexandr Lukyanov, Ilgar Mamedov, Elizaveta Vinogradova, Olga Karpova, Ivan Konyukhov, Svetlana Vasilieva, Peter Mojzes, Cor Dijkema, Margarita Vecherskaya, Ivan Zvyagin, Ladislav Nedbal, Olga Gorelova Phosphorus (P) is central to storing and transferring energy and information in living cells, including those of microalgae. Many microalgal species dwelling in low P environments are naturally equipped to take up and store P whenever it becomes available through a complex phenomenon known as “luxury P uptake.” Its research is required for better understanding of the nutrient geochemical cycles in aquatic environments but also for biotechnological applications such as sequestration of nutrients from wastewater and production of algal fertilizers. Here, we report on our recent insights into luxury P uptake and polyphosphate formation originating from physiological, ultrastructural, and transcriptomic evidence. The cultures pre-starved of P and re-fed with inorganic phosphate (Pi) exhibited a bi-phasic kinetics of Pi uptake comprising fast (1–2 h after re-feeding) and slow (1–3 d after re-feeding) phases. The rate of Pi uptake in the fast phase was ca. 10 times higher than in the slow phase with an opposite trend shown for the cell division rate. The transient peak of polyphosphate accumulation was determined 2–4 h after re-feeding and coincided with the period of slow cell division and fast Pi uptake. In this phase, the microalgal cells reached the highest P content (up to 5% of dry cell weight). The P re-feeding also reversed the characteristic changes in cell lipids induced by P starvation, namely increase in the major membrane glycolipid (DGDG/MGDG) ratio and betaine lipids. These changes were reversed upon Pi re-feeding of the starved culture. Electron microscopy revealed the ordered organization of vacuolar polyphosphate indicative of the possible involvement of an enzyme (complex) in their synthesis. A candidate gene encoding a protein similar to the vacuolar transport chaperone (VTC) protein, featuring an expression pattern corresponding to polyphosphate accumulation, was revealed. Implications of the findings for efficient biocapture of phosphorus are discussed.
  • Hydrothermal liquefaction of residual microalgae biomass after pulsed
           electric field-assisted valuables extraction
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Bingfeng Guo, Boda Yang, Aude Silve, Sahar Akaberi, Daniel Scherer, Ioannis Papachristou, Wolfgang Frey, Ursel Hornung, Nicolaus Dahmen Efficient extraction of valuable products from microalgae and utilization of the residual biomass for biofuel production appear to bring economic benefits for the microalgae biorefineries. The pulsed electric field (PEF) method has been proposed as a promising pre-treatment for microalgae wet extraction. For conversion of microalgae biomass and residues, hydrothermal liquefaction (HTL) is considered a suitable method. Here, a combination of PEF-assisted valuables extraction of microalgae and HTL of the residual biomass is studied for the first time. The microalgae Auxenochlorella protothecoides, Chlorella vulgaris, and Scenedesmus almeriensis were cultivated, harvested, treated by PEF, and then subjected to lipid extraction, protein extraction, or extraction of amino acids after enzymatic protein hydrolysis. The residual biomass obtained from PEF-assisted valuables extraction was subjected to HTL in micro autoclaves at a temperature of 350 °C and pressure of 25 MPa for 15 min holding time. Product yields and analytical results obtained by elemental content measurement, 1H-nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and gel permeation chromatography show that PEF alone has no significant direct influence on microalgae HTL. The harsh HTL conditions decisively determine the product yields and biocrude quality. However, PEF enhances the lipid extraction yield from 4 wt% to 33 wt%. Consequently, the biocrude yield decreases from 58 wt% to 43.2 wt%. Moreover, PEF boosts the protein extraction yield from almost zero to 41.6 wt% of the total protein, resulting in an increased biocrude yield by about 2 wt%. Finally, PEF accelerates the formation of amino acids by enzymatic hydrolysis, improving the extraction efficiency up to 150% in the first 60 min of the extraction. The extracted residue promises to produce a biocrude yield higher by 6 wt% and a better biocrude quality with lower nitrogen content. An overall mass balance of PEF-assisted valuables extraction and HTL is presented.Graphical abstractUnlabelled Image
  • The genus Prototheca (Trebouxiophyceae, Chlorophyta) revisited:
           Implications from molecular taxonomic studies
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Tomasz Jagielski, Zofia Bakuła, Jan Gawor, Kacper Maciszewski, Wolf-Henning Kusber, Mariusz Dyląg, Julita Nowakowska, Robert Gromadka, Anna Karnkowska The only algae which are able to inflict disease on humans and other mammals through active invasion and spread within the host tissues belong to either of two genera: Chlorella and Prototheca. Whereas Chlorella infections are extremely rare, with only two human cases reported in the literature, protothecosis is an emerging disease of humans and domestic animals, especially dairy cows. The genus Prototheca, erected by Krüger in 1894, has undergone several significant revisions, as more phenotypic, chemotaxonomic, and molecular data have become available. Due to this, a large number of Prototheca strains have been accumulated in public culture collections, over the years, where they still exist under outdated or invalid infraspecific or species names. In this study, the partial cytb gene was used as a marker to revise the taxonomy and nomenclature of a set of Prototheca strains, preserved in major algae culture repositories worldwide.Within the genus, two main lineages were observed, with a dominance of typically dairy cattle-associated (i.e. P. ciferrii, formerly P. zopfii gen. 1, the here validated P. blaschkeae, and one newly erected species, namely P. bovis, formerly P. zopfii gen. 2) and human-associated (i.e. P. wickerhamii, P. cutis, P. miyajii) species, respectively. In the former lineage, three newly described species were allocated, namely P. cookei sp. nov., P. cerasi sp. nov., and P. pringsheimii sp. nov., and the lecto- and epitypified P. zopfii species. The second, or so-called P. wickerhamii lineage, incorporated a newly proposed species of P. xanthoriae sp. nov. These protothecans were shown as the closest relatives of the photosynthetic genera, Chlorella and Auxenochlorella. The environmental species P. ulmea was synonymized with the lecto- and epitypified P. moriformis species.For circumscription and differentiation of Prototheca spp., the use of phenotypic characters, and morphology in particular, is of limited value and should rather be auxiliary to molecular marker-based approaches. As demonstrated in our previous study and corroborated in the present one, the cytb gene provides higher resolution than the conventional rDNA markers, and currently represents the most efficient barcode for the Prototheca algae.Graphical abstractUnlabelled Image
  • Functional and phenotypic flow cytometry characterization of
           Picochlorum soloecismus
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Christina R. Steadman Tyler, Claire K. Sanders, Reece S. Erickson, Taraka Dale, Scott N. Twary, Babetta L. Marrone Multiple physiological traits essential for efficient cellular function are important when considering the selection and engineering of algal species for biofuel and bioproduct generation. Bioengineering methods have become more ubiquitous producing several novel algal lines with potentially enhanced traits. Complex metabolic interactions, however, require greater depth in characterizing cellular responses to delineate mechanistic understanding. We have developed fluorescence-based high-throughput flow cytometry protocols to facilitate characterization of cell morphology, membrane permeability, metabolic activity, cell viability, intracellular pH, and reactive oxygen species in isolates derived from the species Picochlorum soloecismus. Flow cytometry parameters were optimized for each assay. This suite of molecular flow cytometry probes and procedures can be utilized for rapid screening of optimal phenotypes in microalgae under various environmental conditions as new technical strategies for improving algae strain productivity are established.Graphical abstractUnlabelled Image
  • Simultaneous dissolution and uptake of nutrients in microalgal treatment
           of the secondarily treated digestate
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Nilüfer Ülgüdür, Tuba H. Ergüder, Göksel N. Demirer Anaerobic digestion processes result in large volumes of digestates which still require the development of elaborate and viable management options to improve the sustainability of these processes. Coupling of secondary anaerobic treatment with a microalgal nutrient removal process may serve benefits such as residual biogas and associated greenhouse gas capture from the digestate content, microalgal biomass build-up and its further valorization. This study investigated the applicability a microalgal nutrient removal process in a secondarily treated digestate (the digestate of a digestate) as a complementary unit. The results indicated that up to 100% dissolved reactive phosphorus (DRP), 97.8% total dissolved phosphorus (TDP) and 93.7% ammonium nitrogen (NH4+-N) removal could be attained in the treatment of the digestate of a digestate using microalgal cultures. Folding phosphorus concentrations via dissolution was found to compensate for dilution related phosphorus deficiency for microalgal growth. Microalgal biomass obtained by the end of operation could be concentrated from 6.4‐15.5 mg/L to 164.2–502.6 mg/L (2100–7900%) by simple gravity settling which was correlated with the prevalence of agglomerated particles in the size range of 10–100 μm. The results demonstrated not only the applicability of the microalgal process after secondary anaerobic treatment of the digestate, but also brought about the dissolution concept for nutrients during microalgal growth.Graphical abstractUnlabelled Image
  • Effects of gluconate on biomass improvement and light stress tolerance of
           Haematococcus pluvialis in mixotrophic culture
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Na Pang, Xiangyu Gu, Xiao Fu, Shulin Chen Mixotrophic culture shows great potential for improving microalgal growth. Currently, the complex roles of organic carbon for biomass enhancement in mixotrophic culture remain a topic of investigation. In this study, the green microalgae Haematococcus pluvialis was cultured for biomass production under mixotrophic conditions using a new organic carbon source, sodium gluconate. Experiments feeding H. pluvialis with sodium gluconate, sodium acetate, and ribose were conducted. The best growth performance was achieved with sodium gluconate exposed to high light intensity. With the addition of 2 g/L gluconate, the maximum cell number achieved 2.43 × 106/mL at 105 ± 3 μmol m−2 s−1 light intensity, a five-fold increase over that of heterotrophic culture and 89.8% increase over ribose-fed mixotrophic culture. The maximum dry cell weight was 2.09 g/L with a specific growth rate of 0.48 d−1, an increase of 77.1% over that with optimal ribose conditions. The cellular motility of microalgae was affected by the culture age and light intensity. At lower light intensity (45 ± 3 μmol m−2 s−1), the highest motile cell number was 7.33 × 105/mL with gluconate. Under mixotrophic conditions, the culture with gluconate kept high numbers of motile cells with the increase of light intensity, 3.17 × 105/mL at 105 ± 3 μmol m−2 s−1. Even high light intensity caused decrease in cellular motility, gluconate-fed microalgae still had active cell activity with more motile cells compared with that fed with ribose. Microalgae with gluconate triggered resistant response against high light intensity under mixotrophic conditions. Moreover, H. pluvialis showed great potential in effective photosynthesis with higher chlorophyll content under high light condition. These results indicate that gluconate is an effective organic carbon source for improving biomass productivity, cell activity, and photosynthesis efficiency for H. pluvialis in mixotrophic culture.
  • Investigating the modulation of metabolites under high light in
           mixotrophic alga Asteracys sp. using a metabolomic approach
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Akanksha Agarwal, Kashif M. Shaikh, Krushna Gharat, Pannaga P. Jutur, Reena A. Pandit, Arvind M. Lali Metabolomic fluctuations in microalgal cells under mixotrophic growth regimes are scarcely understood. Our study explores these changes in an oleaginous microalga, Asteracys sp. when grown mixotrophically under high irradiances. Biomass production under autotrophic and mixotrophic regimes were studied at two light intensities (LL; 100 μmol photons m−2 s−1 and HL; 900 μmol photons m−2 s−1) for Asteracys sp. Studies on supplementation of external carbon such as glucose (mixotrophic mode) under different light intensities has not been demonstrated in context with enhanced biomass production. In the present study, we have provided external source of carbon as glucose in LL and HL regimes and observed a marked influence of glucose assimilation on the overall machinery of the cell. Our qualitative metabolomics reveals a stress-like phenomenon in Asteracys sp. under HL with enhanced biomass. In overview, our data analysis highlights few metabolites such as trehalose, proline and α-tocopherol that showed significant changes in response to light as well as in growth regime. Our analysis predicts an interrelation cross talk between maltose and sucrose pathways within cells owing to possible alteration in starch degradation under the influence of light. However, mixotrophy with additional carbon supplementation in presence of light did not alter or enhance lipid biosynthesis. In conclusion, our hypothesis indicates modulation of metabolites in presence of glucose under high light would rather facilitate rearrangement in metabolic pathways for enhanced biomass production.
  • Chlorella vulgaris bioaccumulates excess manganese up to 55× under
           photomixotrophic conditions
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Amanda L. Smythers, Nicole L. Perry, Derrick R.J. Kolling Manganese is a transition metal that can accumulate in waterways in concentrations above natural abundance due to the mining, metallurgy, and agricultural industries. While chemical technologies for manganese removal are abundantly available, the high solubility of manganese in aqueous solutions causes steep decreases in removal efficiency and generates hazard waste that can be problematic to store. Chlorella vulgaris, a robust, unicellular green alga, offers an environmentally friendly alternative to chemical methods with the added economic potential of generating value-added products. In this study, C. vulgaris was exposed to increasing concentrations of manganese and monitored for bioaccumulation and adsorption. Additionally, cells were monitored for biochemical changes by assaying for terminal biochemical composition and determining photosynthetic activity throughout the life cycle of the culture. Evidence suggests that C. vulgaris can bioaccumulate manganese to an intracellular concentration of 733.3 mM and remove up to 56.74% of the manganese from highly concentrated media through both intracellular bioaccumulation and membrane-bound adsorption. Interestingly, the cultures exposed to high concentrations were able to accumulate manganese up to 55× the external concentration without experiencing inhibitory effects resulting from metal toxicity. Furthermore, cultures exposed to increased manganese displayed higher amounts of protein biosynthesis and an increase in photosynthetic capacities, potentially related to structural changes in the light harvesting antenna complexes of photosystem II.
  • Predicting removal kinetics of biochemical oxygen demand (BOD) and
           nutrients in a pilot scale fed-batch algal wastewater treatment system
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Isuru S.A. Abeysiriwardana-Arachchige, Nagamany Nirmalakhandan Our previous reports have presented single-step treatment of primary-settled urban wastewater by a mixotrophic alga, Galdieria sulphuraria. Here, we present an approach to predict the operational cycle time, t*, required to meet the discharge standards for ammoniacal-nitrogen (NH3-N), phosphate (PO4) and biochemical oxygen demand (BOD) in fed-batch mode, under varying influent concentrations. First order removal rates of NH3-N, PO4 and BOD, determined using data from 10 fed-batch cycles in a pilot scale system (700 L), were used to predict their temporal fate and t* in 30 other cycles. Predicted concentrations of NH3-N, PO4, and BOD and t* over a wide range of influent concentrations agreed well with the measured ones, with root mean square errors, respectively, of 2.06 mg/L, 0.23 mg/L, 2.88 mg/L and 0.30 days. The coefficient of determination between the measured and the predicted values were as follows: for NH3-N: r2 = 0.82, n = 90; for PO4: r2 = 0.87, n = 90; for BOD: r2 = 0.70, n = 30; and for t*: r2 = 0.61, n = 30. The validity of the model in predicting temporal concentration profiles of NH3-N, PO4 and BOD reflected by Janus quotient (respectively of 0.85, 0.87 and 0.61) is comparable to or better than those reported in the literature. Sensitivity analysis procedures identified the influent concentration of PO4 as the most sensitive parameter in predicting t*.Graphical abstractUnlabelled Image
  • Mono- and poly-unsaturated triacylglycerol fractionation from Chlorella
           sp. using supercritical carbon dioxide
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Thomas Alan Kwan, Julie Beth Zimmerman Extraction of unsaturated triacylglycerols from microalgae is important towards the viability of a sustainable biorefinery. Supercritical carbon dioxide was used to extract and enrich the mono- and poly-unsaturated triacylglycerols using a step-wise extraction scheme where the supercritical carbon dioxide density was increased from 450 to 550 to 750 mg/ml over a total of 170 min. At the lowest density of 450 mg/ml, saturated fatty acid triacylglycerols comprised 88% (mol) of the extract while mono- and poly-unsaturated triacylglycerols were over 60% and 80% (mol) at 550 and 750 mg/ml supercritical carbon dioxide respectively. This extraction scheme was informed by solubility and intermolecular interactions of mixed triacylglycerols. Chrastil's solubility parameters suggested that saturated fatty acid triacylglycerols were susceptible to intermolecular interactions while mono- and poly-unsaturated triacylglycerols are less susceptible to these interactions. Combined with the low solubility of mono- and poly-unsaturated triacylglycerols and high solubility of saturated fatty acid triacylglycerols at low densities, these phenomena were combined to demonstrate how supercritical carbon dioxide can be tuned to fractionate mono- and poly-unsaturated triacylglycerols from saturated fatty acids from microalgae. This is significant as supercritical carbon dioxide extraction technology is scalable and suitable as a first unit process for separations in a biorefinery setting.Graphical abstractUnlabelled Image
  • Homogenization significantly enhances growth of macroalga Saccharina
           japonica female gametophytes
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Yun Zhang, Yingdi Zhang, Mengying Li, Li Li, Xianming Tang, Jiangtao Gao In this work, a novel photobioreactor with blade impellers was designed and developed to enhance filamentous cell cultures derived from gametophytes of the brown macroalga Saccharina japonica. Such design efficiently homogenized and dispersed the culture filaments in the photobioreactor, which favored the vegetable growth by providing even exposure of almost all of female gametophytes to sufficient light and nutrients in the culture. As compared to conventional photobioreactors, the biomass productivity and specific growth rate increased by 141% and 51%, respectively, which resulted from the enhanced photosynthetic efficiency.The photobioreactor developed in this work enables an efficient light-to-biomass conversion, demonstrates a hitherto undescribed significant enhancement in photosynthesis activity and algal biomass and provides a viable and promising window for large-scale indoor applications.
  • Benchtop flow NMR spectroscopy as an online device for the in vivo
           monitoring of lipid accumulation in microalgae
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Dylan Bouillaud, Vladimir Heredia, Thomas Castaing-Cordier, Delphine Drouin, Benoît Charrier, Olivier Gonçalves, Jonathan Farjon, Patrick Giraudeau The sustainable production of lipids by microalgae is widely developed among the bioprocess community targeting various applications such as feed, food, health or bioenergy. The cultivation of microalgae needs dedicated systems with the optimal illumination geometry. Performing non-invasive online analyses on these bioprocesses is limited to few analytical techniques, often based on optical properties and can however rarely be related to intracellular products. The real-time knowledge of the lipids accumulation in microalgae is –in this case– not possible. In this article, the proof-of-concept that the recent benchtop NMR spectroscopy device can be used for the non-invasive and selective detection of lipids inside microalgae cells is carried out. Three cultures of Nannochloropsis gaditana were analyzed in flow conditions. The relative quantitative feature is confirmed by the correlation with a reference technique classically used for lipid analysis, i.e. the FAME (Fatty Acid Methyl Ester) profiling by gas chromatography.Graphical abstractUnlabelled Image
  • Identification and theoretical explanation of chemical composition against
           α-amylase in the n-hexane extract from Sargassum fusiforme
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Jiao Yang, Chang Liu, Hengjiang Cai, Dongyu Gu, Zhenni Ji, Xinfeng Guo, Jing Tian, Jing Meng, Yi Yang Sargassum fusiforme is an edible alga that possesses a number of bioactivities, such as antidiabetic effects. In the present study, the n-hexane extract of S. fusiforme showed inhibitory activity against α-amylase. To interpret the α-amylase inhibitory activity of this extract, a method based on GC–MS and molecular docking was established. A total of 25 compounds were identified using GC–MS and then individually docked with α-amylase to simulate interactions between the latter and the ligands. Among the compounds determined, phenol, 2,2′-methylenebis[6-(1,1-dimethylethyl)-4-methyl- (PMDM) was completely enfolded in the active site of α-amylase via hydrophilic and electrostatic interactions, van der Waals forces, hydrogen bonds and π-π stacking interactions and showed the lowest binding energy (−6.25 kcal/mol). The activity of PMDM against α-amylase was further tested and verified in vitro, and its IC50 was found to be 79.96 ± 0.34 μM. Thus, this compound is responsible for the α-amylase inhibitory activity of the n-hexane extract of S. fusiforme.Graphical abstractUnlabelled Image
  • An effective approach of bacterial siderophore as nitrogen source
           triggering the desired biochemical changes in microalgae Chlorella
           variabilis ATCC 12198
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Soundarya Rajapitamahuni, Khushbu Bhayani, Pooja Bachani, Vamsi Bharadwaj S.V, Sandhya Mishra The present study was aimed to check whether catecholate siderophore can serve as a nitrogen source besides iron for microalgae. Catecholate siderophore from Idiomarina loihiensis RS 14 contains 13% nitrogen which can be a potential nitrogen source. Bacterial supernatant containing siderophores with different inoculum ratio was used to check the growth of Chlorella variabilis ATCC 12198. Nitrogen starvation with two stage cultivation was employed here to trigger the accumulation of lipid and carbohydrate. In continuous cultivation, the highest productivity of DCW was observed in 1%, 760 mg/L compared to culture grown at 0.5%, with an increase of 42.2% higher biomass productivity (21.66 mg/L/day). Similarly, in 1%, C. variabilis produced total 30% of lipid content which contains 75% of neutral lipid. Highest carbohydrate was (49.29%) found in cells grown under 9 days of stress in 1% followed by cells grown under 3 days of stress in 5% (46.52%) in stage II cultivation.Graphical abstractUnlabelled Image
  • Compatible solutes profiling and carbohydrate feedstock from diversified
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Nitin Keshari, Muriel Gugger, Tao Zhu, Xuefeng Lu Cyanobacteria are promising cell factories for producing high-value bioproducts. They accumulate low molecular mass organic molecules under salinity stress conditions, which are known as compatible solutes, e.g. sucrose, trehalose, and glucosylglycerol (GG). The physiological properties of compatible solutes sort them as the potential bioproducts for applications in the field of health, pharmacy, and cosmetic sectors. During last few decades, mostly model cyanobacterial strains (unicellular from freshwater and marine habitats) have been targeted for the biochemical and molecular characterization of compatible solutes accumulation, while, the study on other cyanobacteria from extreme/stressful habitats are scanty. The advantage for selecting multicellular cyanobacteria in the present study is their easier harvesting mode over unicellular strains which are one of the primary concerns for the cost-effective production of desired products at pilot scale. Therefore, five cyanobacterial strains with diverse morphotypes belonging to subsection I (Unicellular), II (Baeocytous), III (Filamentous), and V (Ramified) isolated from extreme/stressful habitats (sewage pond and hot spring including freshwater strain as a reference) were screened for salt tolerance, compatible solutes profiling, and sugar feedstock production. High GG, sucrose, and glycogen production were found in Leptolyngbya sp. PCC 8913, Chroogloeocystis siderophila NIES-1031 and Fischerella major NIES-592, respectively. Under salt stress, Leptolyngbya sp. PCC 8913 showed a GG production of 101 ± 12 mg/L/OD730, which is significantly higher than that of the model strain Synechocystis sp. PCC 6803. Fischerella major NIES-592 and Oscillatoria laetevirens NIES-31 were identified as novel trehalose-producing cyanobacteria. The key genes involved in production of compatible solutes among these cyanobacteria were also studied. Thus, the results not only displayed the potential cyanobacteria for production of GG, sucrose, trehalose and glycogen but also address the metabolic pathways for the compatible solutes biosynthesis in diversified cyanobacteria, which can be further targeted for the in-depth study to enhance the production using molecular approaches.
  • Towards phosphorus recycling for agriculture by algae: Soil incubation and
           rhizotron studies using 33P-labeled microalgal biomass
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Nina Siebers, Diana Hofmann, Henning Schiedung, Alexander Landsrath, Bärbel Ackermann, Lu Gao, Peter Mojzeš, Nicolai D. Jablonowski, Ladislav Nedbal, Wulf Amelung Algae effectively accumulate phosphorus (P) from the environment, qualifying them as a promising novel P fertilizer. We hypothesized that P in algae can be rapidly transformed in soil and mobilized for plant growth. To determine the fate of algal fertilizer in soil and to trace its efficiency for plant uptake, we labeled the algae Chlorella vulgaris with the radioisotope 33P. To optimize the labeling we studied P-uptake dynamics in detail using a pre-starved culture and additionally monitored polyphosphate (Poly-P) and organic carbon (C) reserve pools by Raman microscopy. Using an optimized labeling procedure, the concentrations and distribution of both algae-derived 33P and mineral fertilizer 33P (control) were characterized in incubation and rhizotron experiments. Soil incubation was performed with four major reference groups (Andosol, Alisol, Cambisol, and Vertisol). To assess 33P plant uptake we grew wheat in rhizotrons on Cambisol. Soil analyses at different incubation times demonstrated sequential 33P fractionation, while plant uptake of algae-derived 33P was followed using sequential autoradiographic imaging. We found that the algae increased labile P pools comprising Resin- and NaHCO3-extractable P in soils during the first 2 weeks of incubation, similar to the effects of NPK fertilizer. The soils with elevated concentrations of Fe- and Al-oxides (Andosol and Alisol) immediately bound 55 to 80% of the applied fertilizer 33P into the moderately available NaOH-P fraction, whereas the soils with lower concentrations of Fe/Al-oxides (Cambisol, Vertisol) stored 35–71% of the algal-P in the labile fraction. The rhizotron experiments visually supported the release and plant-uptake of algal 33P, thus verifying the suitability of algal-fertilizer for plant growth.
  • Comparative proteomics investigation of central carbon metabolism in
           Euglena gracilis grown under predominantly phototrophic, mixotrophic and
           heterotrophic cultivations
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Mafruha T. Hasan, Angela Sun, Bishal Khatiwada, Leon McQuade, Mehdi Mirzaei, Junior Te'o, Graham Hobba, Anwar Sunna, Helena Nevalainen Euglena gracilis can use a wide range of organic carbon sources, as well as CO2 from the atmosphere. This metabolic versatility is owed to the genome of E. gracilis that can encode a wide range of enzymes. Many of these enzymes are regulated post-transcriptionally, allowing the cells to adapt quickly to changes in their surroundings. Here we investigated the effect of predominantly phototrophic (PT), mixotrophic (MT) and heterotrophic (HT) cultivation on central carbon metabolism in E. gracilis Z using label-free shotgun proteomics. Differential expression between isozymes was observed based on the cultivation condition. A hexokinase enzyme identified in the published transcriptome was not detected in the proteome. Instead, a high-specificity glucokinase appeared to conduct the first step of glycolysis. Two candidates for paramylon synthase were identified (EgGSL1 and EgGSL2), of which the predominant EgGSL2 protein was detected across all growth conditions, while EgGSL1 was only detected in the presence of light (PT and MT cultivations). Proteomic analysis revealed that the oxidative pentose phosphate pathway also plays a key role in glucose metabolism under MT and HT cultivation. Some chloroplast-encoded proteins and enzymes of the Calvin pathway were detected under HT cultivation indicating regulation at the post-translational level. The carbon metabolic pathways investigated here in terms of proteomic changes provide new information, as well as validate data presented elsewhere with quantitative proteomics, adding to the existing knowledge of metabolism in E. gracilis. Putative functional annotations of several proteins that were previously unidentified are also provided.
  • Determination of individual chain length and chain-length distribution of
           polyphosphates in microalgae by 31P-DOSY-NMR
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Liming Wang, Christina Kuchendorf, Sabine Willbold Due to its ecological and biotechnological relevance, polyphosphate in microalgae is currently the focus of intense research. Numerous biological functions are performed by or dependent on polyphosphate, and they depend, among other factors, on its chain length. Chain length determination is important for understanding polyphosphate metabolism and for maximizing intracellular polyphosphate abundance per unit weight of biomass. 31P-DOSY NMR virtually separates various polyphosphate polymers in a mixture based on different translational diffusion coefficients. The diffusion coefficient of a polyphosphate molecule correlates with its molecular weight, enabling determination of individual chain lengths. Moreover, the polydispersity index can also be uniquely determined by DOSY as a measure of the overall chain-length distribution of polyphosphates. By contrast, conventional 31P NMR is only able to estimate the average chain length of the entire polyphosphate pool. Therefore, DOSY provides the opportunity to deepen our insight into polyphosphate metabolism and dynamics in algal biomass.
  • The past, present and future of algal continuous cultures in basic
           research and commercial applications
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): William J. Henley Photoautotrophic continuous cultures (chemostat, turbidostat or exponential fed-batch operation) of algae began seventy-five years ago in the laboratory and nearly sixty years ago in large-scale outdoor wastewater treatment. Despite this deep and rich history, continuous culture approaches have been used in a small fraction of publications involving algal culturing over the last fifty-five years. Algae grown in continuous cultures are indefinitely in exponential balanced growth, poised at a particular physiological steady state, or a cyclical steady state under a light-dark cycle (cyclostat). This enables mechanistic linking of culture conditions to physiology much more precisely than in batch cultures, where conditions (light, nutrient and possibly CO2 availability), physiological state and specific growth rate change progressively. Continuous cultures also yield consistent biomass composition over time and have the potential to exhibit higher time-averaged biomass production than batch cultures, because growth rate does not decelerate. Commercial algal culture for various products has been studied almost exclusively in batch culture at all scales. The prevailing dogma is that elevated TAG content (the most extensively studied product) occurs only when cell division ceases due to nutrient depletion. Limited recent experimental evidence from continuous cultures suggests that this is not necessarily the case, thus warranting further investigation. Continuous cultures may be particularly useful for customizing biomass composition in favor of desirable high value bioproducts. Innovative continuous culture approaches, including hybrid designs and manipulated steady state, therefore promise to advance basic algal research and, pending scaled-up experimentation, may be useful for commercial biomass production in some contexts. There is insufficient information to date to conclude whether continuous culture (or hybrid) approaches can be commercially successful for any application, thus it is premature to dismiss commercial continuous cultures as impracticable or to assert them as suitable or superior.
  • Expression and characterization of human lactoferrin with tandem zinc
           finger protein in Chlamydomonas reinhardtii
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Xiaonan Pang, Yuxi Tong, Fang Li, Xuan Wei, Xiwen Chen, Jia Liu, Defu Chen Lactoferrin (LF) is a naturally occurring iron-binding glycoprotein with a number of biological functions. However, its bioavailability remains a major limitation for clinical applications. In this study, we explored the expression of functional human lactoferrin (hLF) containing tandem zinc finger protein (ZFP) repeats in Chlamydomonas reinhardtii. Codon-optimized ZFPn-hLF fusion genes, where n donates 0, 1, 2, or 3 repeats of ZFP, were transformed into C. reinhardtii CW-15 strain. A total of 23 ZFPn-hLF-expressing clones were obtained. The expression levels of the ZFPn-hLF proteins ranged from 1.97% to 2.32% of the total soluble protein. The expression of ZFPn-hLF proteins did not compromise the proliferation of C. reinhardtii. The recombinant ZFPn-hLFs retained the antibacterial activities toward Escherichia coli and Klebsiella variicola IV-3, and also the antioxidant activities toward DPPH and hydroxyl free radicals. ZFP fusion did not compromise the stability of hLF and enabled efficient internalization of hLF into normal human small intestine cells. Efficiency of the internalization was found to be dependent on the number of tandem ZFPs, incubation time and incubation temperature. Our results indicate that recombinant ZFPn-hLFs expressed in C. reinhardtii promotes the absorption of lactoferrin in human intestinal epithelial cells, and thus provide an effective strategy to enhance the bioavailability of lactoferrin for its utilization in clinical applications.Graphical abstractUnlabelled Image
  • Efficient hydrolysis of glycogen from engineered Synechocystis sp. PCC
           6803 catalyzed by recyclable surface functionalized nanoparticles for
           ethanol production
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Rajendran Velmurugan, Aran Incharoensakdi The availability of sugars is a key factor for industrial ethanol production. In this study, recyclable surface functionalized metal oxides were prepared and used as catalysts to obtain sugars directly from engineered Synechocystis sp. PCC 6803 (hereafter Synechocystis) biomass. The individual, sulphonated and tungstenated forms of Al2O3, CaO, Fe3O4, TiO2 and ZrO2 were screened for the hydrolysis of Synechocystis glycogen under ultrasound irradiation. Among them, the sulphonated ZrO2 produced a maximum fermentable sugar yield of 40.2 g/L, whereas the tungstenated ZrO2 produced 37.8 g/L. This improvement was due to the combined action of ultrasound irradiation and acidic groups conferred by sulphur or tungsten on metal oxides. In recycling, tungstenated metal oxides were superior to sulphonated metal oxides in terms of recovery and hydrolysis efficiency. The compatibility of the tungstenated metal oxides mediated hydrolysis with fermentation using Saccharomyces cerevisiae MTCC-170 produced the highest ethanol concentration (16.5 g/L), which favors the overall process.Graphical abstractSchematic representation of surface functionalized metal oxide mediated hydrolysis for ethanol production.Unlabelled Image
  • Long-term treatment with 9-cis-β-carotene rich alga Dunaliella bardawil
           ameliorates photoreceptor degeneration in a mouse model of retinoid cycle
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Victoria Edelshtain, Alon Peled, Adi Tzameret, Sarah Pri Chen, Hana Ziv, Estela Derazne, Dror Harats, Rachel Greenberg, Ayelet Harari, Aviv Shaish, Ifat Sher, Ygal Rotenstreich The retinoid cycle is the enzymatic pathway that regenerates the vision chromophore, 11-cis retinal, after it is bleached during light absorption. Genetic insults to this cycle result in incurable blinding retinal dystrophies such as retinitis pigmentosa and Leber congenital amaurosis. Previous studies demonstrated that oral treatment with 9-cis-β-carotene rich Dunaliella bardawil powder significantly improved visual and retinal function in patients with fundus albipunctatus night blindness and retinitis pigmentosa. Here we examined the effect of oral treatment with the Dunaliella powder on retinal function and structure in RPE65rd12 mice, a model of a genetic defect in the retinoid cycle. Mice were fed with a control diet, vitamin A deficient diet (VAD) or VAD diet supplemented with Dunaliella powder for 13 months. Mice fed with Dunaliella presented significantly higher dark-adapted (35.7 μV ± 3.1 vs. 6.9 μV ± 2.5, p 
  • Harmless disposal and resource utilization of wastes from the lake in
           China: Dewatering, composting and safety evaluation of fertilizer
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Shiqun Han, Jinlian Li, Qing Zhou, Guofeng Liu, Tao Wang Removal of waste (cyanobacteria, macrophytes and sediment) from Chaohu Lake, a large freshwater lake in China, might cause secondary environmental pollution due to improper disposal. Bioleaching dewatering and composting were performed in this study to dispose these wastes. The results showed that bioleaching could effectively decrease the water content in the cyanobacteria-macrophytes-sediment mixture. The reduced nitrogen-loss rate and increased humus content were observed in the compost after inoculating with microbial agent. High-throughput DNA sequencing showed that the microbial inoculants influenced microbial community composition. The degradation rates of microcystin variant with leucine (MC-LR) and microcystin variant with arginine (MC-RR) in the treatment of composting plus microbial inoculation were significantly higher than those in the natural placement. Seeds of Chinese cabbage were grown in the soil supplemented with mature compost for 67 days. The content of heavy metals in the organic fertilizer, soil and cabbage were much lower than the corresponding limited values of the national standard in China. In conclusion, the cyanobacteria, macrophytes and sediment in China Chaohu Lake could be used safely as raw materials for composting.Graphical abstractUnlabelled Image
  • Extraction and purification of eicosapentaenoic acid and docosahexaenoic
           acid from microalgae: A critical review
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Xiangping Li, Juping Liu, Guanyi Chen, Jianguang Zhang, Chuanbin Wang, Bin Liu EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) products have been widely applied due to their medical and healthcare value. In this paper, the methods for extracting DHA and EPA from microalgae and related purification methods were summarized and analyzed. The yields of DHA and EPA from different species of microalgae were investigated. The optimal extraction and purification methods and microalgae species that are suitable for the extraction of EPA and DHA products were determined. Currently, organic solvents are extensively used to extract oil from microalgal biomasses. The supercritical fluid extraction technique is an ideal method for lipid extraction. Based on the findings presented in this paper, a combination of multiple methods is a better choice to extract and purify EPA and DHA from microalgae.
  • Enhancing Scenedesmus obliquus biofilm growth and CO2 fixation in a
           gas-permeable membrane photobioreactor integrated with additional rough
    • Abstract: Publication date: November 2019Source: Algal Research, Volume 43Author(s): Chenglong Guo, Danru Duan, Yahui Sun, Yuying Han, Sha Zhao Microalgae biofilm photobioreactors (PBRs) have been gaining more and more attention worldwide attributed to their advantages of lower water requirement and simpler harvesting process. In this work, aiming at enhancing microalgae biofilm growth and gas-liquid mass transfer based on previous biofilm PBRs, a gas-permeable membrane PBR integrated with additional rough surface (GMPBR-RS) was designed. By attaching an additional piece of stainless steel mesh onto the upper surface of the newly prepared gas-permeable membrane, the roughness of the substratum surface for Scenedesmus obliquus biofilm adhesion was enhanced and therefore resulted in a 28.27% improvement in areal biomass density of S. obliquus relative to the control PBR. Moreover, responses of S. obliquus biofilm adsorption growth and CO2 fixation in the GMPBR-RS to various liquid flow rates and gas flow rates were investigated. Notably, the maximum areal biomass density of S. obliquus biofilm and CO2 removal efficiency of the GMPBR-RS reached 31.44 g m−2 and 65.05%, respectively.
  • Metabolic plasticity of the starchless mutant of Chlorella sorokiniana and
           mechanisms underlying its enhanced lipid production revealed by
           comparative metabolomics analysis
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Mingcan Wu, Hu Zhang, Wenchao Sun, Yanhua Li, Qiang Hu, Hantao Zhou, Danxiang Han The unicellular green alga Chlorella sorokiniana is of great industrial interest for biofuels production due to its rapid growth, high lipid content, and capabilities in tolerating broad environment and cultivation conditions. C. sorokiniana can grow under both heterotrophic and photoautotrophic conditions, which offers opportunities to produce lipids from this species/strain by employing coupled heterotrophic and phototrophic cultivation mode. In this study, a starchless mutant SLM2 was successfully obtained by high-throughput screening of the chemical mutagenesis pool of a C. sorokiniana strain that has the potential to achieve high cell density under heterotrophic conditions, aiming to enhance its lipid content and productivity. Unexpectedly, enhanced lipid production was only observed in photoautrophically-grown SLM2 cells subjected to stress conditions (i.e. high-light and nutrient limitation). When the heterotrophically-grown cells were subjected to the same stress conditions that can trigger lipid accumulation, less differences in lipid productivities were observed between wild type (WT) and SLM2. To understand metabolic basis underlying such a discrepancy, comparative time-course metabolomics analysis was performed for SLM2 and WT from different cultivation conditions. The results highlighted up-regulated metabolic flux related to the increased lipid biosynthesis in the phototrophically-grown starchless mutant cells, which included enhanced oxidative pentose phosphate pathway in a mode favoring NADPH production, and the augmented glycolysis pathway providing precursors for both fatty acids and glycerol backbone synthesis. In SLM2, the classical TCA cycle is down-regulated, while its bypass the gamma-aminobutyric acid (GABA) shunt is triggered, which is speculated to contribute to enhanced lipid accumulation in the starchless mutant as well. In addition to revealing the metabolic plasticity possessed by starchless mutant, it is suggested that photoautotrophic cultivation mode is more suitable than coupled heterotrophic and photoautotrophic cultivation mode for production of lipids by using the starchless mutant SLM2 obtained in this study.
  • Fatty acids and proteins from marine cold adapted microalgae for
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Peter S.C. Schulze, Christopher J. Hulatt, Daniela Morales-Sánchez, René H. Wijffels, Viswanath Kiron Cold-adapted microalgae display unexpectedly high biomass production, pointing to their potential to produce high-value bioproducts under cold and light-limited conditions. From culture collections, we screened eight cold-adapted strains of different genera (Chlamydomonas, Chlorella, Tetraselmis, Pseudopleurochloris, Nannochloropsis and Phaeodactylum) for the production of fatty acids and proteins under low temperature and light regimes (T = 8, 15 °C; I = 50, 100 μmol s−1 m−2). Among the strains, the Arctic isolate Chlamydomonas sp. (RCC 2488) had better growth at 8 °C compared to 15 °C (up to 0.5 gDW L−1 d−1) and highest productivities of protein and polyunsaturated fatty acids (PUFA) (70 and 65 mg L−1 d−1, respectively). Two tested Tetraselmis strains (SAG 1.96, RCC 2604) achieved highest biomass productivities (0.7–1 gDW L−1 d−1), containing up to 50 mg PUFA gDW−1 and 15% proteins. Pseudopleurochloris antarctica (SAG 39.98) grew well at 15 °C (0.4 g L−1 d−1), with 23% proteins in biomass and the highest eicosapentaenoic acid (EPA) productivity (7.6 mg L−1 d−1). Chlorella stigmatophora (RCC 661) achieved productivities of 0.4 gDW L−1 d−1 at 15 °C and produced extracellular polymeric substances (EPS). The major cause for the observed shifts in biochemical profiles was biomass concentration, which is an indicator for the prevailing growth stage. Based on the current experimental design, Chlamydomonas sp. (RCC 2488), T. chuii and P. antarctica can be suggested as the most promising strains for the production of protein and (polyunsaturated-) fatty acids at low temperatures. However, additional strain-specific studies are necessary to statistically validate these findings.Graphical abstractUnlabelled Image
  • The inhibition effect of recycled Scenedesmus acuminatus culture media:
           Influence of growth phase, inhibitor identification and removal
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Jun Sha, Zhiying Lu, Jing Ye, Gaohong Wang, Qiang Hu, Yongsheng Chen, Xuezhi Zhang Existing research shows that the presence of algogenic organic matter (AOM) in recycled media can inhibit the growth of algae. However, the characteristics and occurrence of the inhibitors are not well understood. In this study, changes in the algogenic organic matter present in culture media and the influence of these changes on the recultivation of Scenedesmus acuminatus were investigated. A hydrophobic humic substance was then extracted from the recycled medium, and its inhibitory effects on the growth of Scenedesmus acuminatus were assessed. The efficiency of the removal of the humic substance from the recycled media using granular activated carbon (GAC) treatment was evaluated. The results showed that the later the growth phase at which the recycled media was harvested, the stronger the growth inhibition was. In addition, it was found that the percentage of total carbohydrates, fatty acids, and proteins in the algogenic organic matter decreased with the prolongation of growth phase, while the percentage of the hydrophobic humic substance in algogenic organic matter increased as the algae gradually went into the declining phase. Furthermore, an inhibitory effect of the hydrophobic humic substances on the growth of Scenedesmus acuminatus was identified. The effectiveness of inhibitor removal using granular activated carbon column adsorption was confirmed. The results of this study can be applied to the sustainable utilization of water and nutrients in the mass production of microalgal biomass.Graphical abstractUnlabelled Image
  • Microalgae of interest as food source: Biochemical composition and
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Alberto Niccolai, Graziella Chini Zittelli, Liliana Rodolfi, Natascia Biondi, Mario R. Tredici Microalgae are considered a very interesting source for the development of new food products and can be used to enhance the nutritional value of conventional foods, due to their valuable biochemical composition.The aim of this study was to investigate the biochemical composition, the fatty acid profile and the in vitro digestibility of twelve microalgal biomasses (Arthrospira platensis F&M-C256; a bloom mainly composed of Aphanizomenon flos-aquae from Klamath Lake; Nostoc sphaeroides F&M-C117; Chlorella sorokiniana F&M-M49; Chlorella sorokiniana IAM C-212; Chlorella vulgaris Allma; Tetraselmis suecica F&M-M33, in nutrient replete medium and starved; Porphyridium purpureum F&M-M46; Phaeodactylum tricornutum F&M-M40; Tisochrysis lutea F&M-M36; Nannochloropsis oceanica F&M-M24) of interest as food source.The three cyanobacteria and the Chlorella species presented high protein (50–65%) and low lipid (5–20%) content. A high fiber content (14–17%) was found in T. suecica grown in nutrient replete medium, P. purpureum and P. tricornutum.Biomasses of marine species contained high concentrations of polyunsaturated fatty acids, mainly C20:5ω3 and C22:6ω3, along with substantial amounts of C16:1ω7, C18:1ω9 and C16:0. The freshwater algae contained high amounts of C18:3ω3 and an even higher amount of C16:0.A. platensis, C. sorokiniana IAM-C212 and C. vulgaris showed the highest digestibility, while T. suecica, P. tricornutum, and P. purpureum were the least digestible, likely because of the presence of robust cell walls or of exopolysaccharides that might have limited the action of digestive enzymes.Graphical abstractUnlabelled Image
  • Enhanced lipid productivity of an oleaginous microalgal mutant strain
           Scenedesmus sp. Z-4 and the underlying differences responsible for its
           superior lipid accumulation over wild strain Scenedesmus sp. MC-1
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Chao Ma, Hongyu Ren, Defeng Xing, Guojun Xie, Nanqi Ren, Bingfeng Liu In this work, the lipid productivity of an oleaginous microalgal mutant strain Scenedesmus sp. Z-4 was improved to a maximum of 204.2 mg L−1 d−1 by single factor optimization, when 10 g L−1 glucose, 0.8 g L−1 NaNO3, 0.04 g L−1 K2HPO4 and initial pH of 7.0 were used in batch culture. Furthermore, multi-scale comparisons between mutant strain Z-4 and wild strain MC-1 were made, including cell surface elements and functional groups, biomass production, lipid accumulation and intracellular component percentages. The total EPS (extracellular polymeric substances) content of mutant strain Z-4 was 42.1% higher than that of wild strain MC-1, mainly due to the increase of extracellular protein and polysaccharide. Remarkable decrease of intracellular polysaccharide was found in the cells of mutant strain Z-4, implying the reallocation of carbon fluxes. These findings may be beneficial to understand the superior lipid production of mutant strain Scenedesmus sp. Z-4.
  • Cost minimization of deoxygenation for control of Vampirovibrio
           chlorellavorus in Chlorella sorokiniana cultures
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): S. Attalah, P. Waller, S. Steichen, C.C. Brown, Y. Mehdipour, K. Ogden, J.K. Brown Deoxygenation is a strategy for preventing Vampirovibrio chlorellavorus infection of Chlorella sorokiniana cultures. Deoxygenation cost was minimized by sparging with nitrogen gas for only 1 h at the onset of night and relying on naturally-occurring dark-respiration to maintain low oxygen concentrations throughout the night. This technique substantially reduced V. chlorellavorus infection in laboratory co-cultures. The cost of the approach was evaluated in outdoor experiments with one pure water and one pathogen-free C. sorokiniana culture, grown in a 150-L sealed, vented, translucent-polyethylene reactor. Unlike the small laboratory reactors, which were also sealed and vented, the much larger outdoor reactor maintained the dissolved oxygen concentration in the C. sorokiniana culture at near zero concentration throughout the night cycle. This demonstrates that large covered tanks in commercial applications would keep oxygen concentration near zero for the entire night. The total nitrogen sparged, per night, per liter of algal culture, was determined for the 150-L reactor, and used to estimate the cost per m2 for large scale raceways. Onsite nitrogen generators are the most cost-effective method to supply a high flow of nitrogen gas to commercial scale raceways. The cost of deoxygenation treatment ranged from $16/ton AFDW algae for a shallow (2 cm) gravity flow system with 75% harvest prior to deoxygenation to over $1300/ton for a 20 cm depth raceway with plastic tanks.
  • Evaluation of Ulva ohnoi as functional dietary ingredient in juvenile
           Senegalese sole (Solea senegalensis): Effects on the structure and
           functionality of the intestinal mucosa
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): A.J. Vizcaíno, M. Fumanal, M.I. Sáez, T.F. Martínez, M.A. Moriñigo, C. Fernández-Díaz, V. Anguis, M.C. Balebona, F.J. Alarcón This study evaluates the effects of the macroalgae Ulva ohnoi on growth and intestinal functionality and integrity of Solea senegalensis juveniles in a 90-day feeding trial. Ulva diet (U-5) included 5% dry U. ohnoi biomass, whereas an algae-free diet was used as control. After being fed for 45 and 90 days, fish body weight was recorded for growth evaluation, and biological samples were taken. The inclusion of U. ohnoi (5%) significantly affected growth performance of sole juveniles, given that after being fed for 45 and 90 days fish showed lower body weight, specific growth and weight gain rates than fish fed with the control diet. Compared to fish fed with control diet, protease activities measured in the pancreatic secretion was also reduced when Ulva was included in the diet, but these fish also showed increased alkaline phosphatase activity in their intestinal mucosa. Quantitative PCR revealed changes in the relative expression of a set of genes coding for enzymes involved in lipid absorption and metabolism, several digestive enzymes, as well as for some stress response indicators. Electron microscopy revealed a lack of damage in the intestinal mucosa, as well as significantly increased mucosal absorptive surface in those fish fed with Ulva-supplemented diet for 45 days, compared to control fish. The results suggest that U. ohnoi at low inclusion level could protect the intestinal epithelium of fish, but a relatively short administration period is recommended with the aim of avoiding negative effects on Senegalese sole growth and proteolytic digestive enzyme activities.Graphical abstractUnlabelled Image
  • Evaluating microalgal cell disruption upon ultra high pressure
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Tom M.M. Bernaerts, Lore Gheysen, Imogen Foubert, Marc E. Hendrickx, Ann M. Van Loey The impact of (ultra) high pressure homogenization on the degree of cell disruption was investigated for Nannochloropsis sp. suspensions. The degree of cell disruption was studied by combining four evaluation methods: turbidity measurement, scanning electron microscopy, hexane:isopropanol extraction efficiency, and fluorescence microscopy using the viability stain SYTOX green. Applying an ultra high pressure of 250 MPa obviously reduced the number of homogenization passes required to obtain a specific degree of cell disruption compared to 100 MPa. However, heating of the sample occurred at 250 MPa, resulting in extensive aggregate formation of the released intracellular material after multiple homogenization passes. Furthermore, cell wall integrity was not necessarily linked to membrane integrity, implying that moderate (U)HPH conditions are possibly sufficient for certain applications by damaging the cell membrane, without achieving full rupture of the cell wall. Once again it was proven that different methods for evaluation of cell disruption should be combined to get comprehensive insight into the disruption of microalgae.
  • Validation of a spectrophotometric methodology for a rapid iodine analysis
           in algae and seaweed casts
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): N. Nunes, S. Valente, S. Ferraz, Maria Carmo Barreto, M.A.A. Pinheiro de Carvalho Iodine plays an important role in human metabolism and its deficiency is particularly harmful in pregnancy and childhood. It remains a major public health concern in many countries, especially in Portugal. The main purpose of this work was to develop a validated spectrophotometric analysis for a fast and reliable iodine quantification in algal samples. Absorbance was determined at 410 nm demonstrating a good linearity (R2 ≈ 1.0) in the range of 0–0.06 mg I/100 g. LOD and LOQ were 1.7 × 10−3 and 5.0 × 10−3 mg I/100 g, respectively. Accuracy was determined using recovery and varied between 101 and 118%. For precision analysis, an intra-day test performance (RSD = 8.7%) and a repeatability assay (RSD = 3.8%) were performed. Matrix effect assessment demonstrated that this had a negligible effect (3.2%) in the iodine quantification. The spectrophotometric method was externally validated, for iodine quantification in algal samples, by INSA certified laboratory. The correlation coefficient between external iodine quantification and our work was R2 ≈ 0.9, showing a good correlation. Applicability was assessed in 25 macroalgae species (5 green, 9 red and 11 brown), 12 seaweed casts, collected in Canary Islands and 1 microalga (Isochrysis galbana) provided by ITC (Instituto Tecnologico de Canarias).
  • Timing is everything: Diel metabolic and physiological changes in the
           diatom Cyclotella cryptica grown in simulated outdoor conditions
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Olga Gaidarenko, Corinne Sathoff, Kenneth Staub, Michael H. Huesemann, Maria Vernet, Mark Hildebrand Microalgal cultures grown on a light-dark cycle experience diel patterns in metabolic and physiological processes, including cell cycle synchronization, but the implications for productivity in terms of biomass and commercially-appealing molecules are not commonly appreciated. Despite a long history of diel response studies, only recently have photobioreactor technology advances enabled the use of sinusoidal light and temperature to more accurately mimic outdoor conditions. The present study investigates cell cycle progression and dynamic changes on a 24-hour scale in triacylglycerol (TAG), photosynthetic pigments, and optical density at 750 nm (OD750) as a proxy for biomass in the production candidate diatom Cyclotella cryptica grown using a sinusoidal light and temperature regime. Cell division synchronized to occur predominantly in the middle of the light period while OD750 started to increase several hours earlier, as the cells prepared to divide. TAG levels increased during the day and decreased at night, with a mid-day dip corresponding to the time when lipid needs for cell division-associated membrane biosynthesis would be high. Photosynthetic pigment dynamics data was overlaid with cell cycle progression, indicating that while some photosynthetic pigments respond primarily to light, others are influenced by the cell cycle. Additionally, the results indicate that in a synchronized culture, potential product yields change substantially throughout the day. This may inform harvest timing to significantly increase yield.
  • Resource partitioning strategies during toxin production in Microcystis
           aeruginosa revealed by integrative omics analysis
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Di Pan, Shruti Pavagadhi, Shivshankar Umashankar, Amit Rai, Peter I. Benke, Megha Rai, Gourvendu Saxena, Vamshidhar Gangu, Sanjay Swarup Escalating rates of urbanization and climate change have led to increased occurrence of harmful algal blooms (HABs) in natural waters. HABs caused by Microcystis aeruginosa produce toxic secondary metabolites, such as microcystins (MCs). To understand resource partitioning strategies between cell growth and MC production in response to environmental triggers, we tested the effect of interactions between light and nitrogen on Microcystis aeruginosa PCC 7806. Statistical models revealed that both light and nitrogen affected the transcriptome and metabolome, however, light was the most important of these two factors driving changes at the transcriptome level. On the contrary, effects at metabolome level were less pronounced and were restricted to a few inter-related networks that share rate-limiting substrates and pathway intermediates. Through the integrative systems level approach, we found certain networks belonging to cellular growth, cellular scavenging and secondary metabolites that drive the overall resource partitioning strategy in Microcystis. Additionally, rate limiting metabolites (malonyl-CoA and metabolite couplet SAM; S-adenosyl methionine–SAH; S-S-Adenosyl-L-homocysteine) that occur at the crossroads of the light and nitrogen dependent pathways were identified, thus controlling the metabolic flux and resource allocation in Microcystis cultures. Through these observations, we provide a conceptual model for environmental responses of Microcystis. This model could be validated through controlled feeding experiments and specific genetic mutants to obtain further insights.
  • Stoichiometric and sterol responses of dinoflagellates to changes in
           temperature, nutrient supply and growth phase
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Mengna Chen, Rong Bi, Xi Chen, Yang Ding, Hailong Zhang, Li Li, Meixun Zhao Climate changes as well as the inherent properties of phytoplankton have important and complex effects on the ecology and biogeochemical cycles of the oceans. Dinoflagellates are often dominant groups in harmful algae blooms (HABs) and red tides, while the impact of environmental changes on chemical composition in typical dinoflagellates is currently unclear, which limits our understanding of the role of dinoflagellates in planktonic trophodynamics in the changing ocean. Here, we investigated the responses of elemental stoichiometry and sterol contents in three dinoflagellate species (Prorocentrum donghaiense, Prorocentrum minimum and Karenia mikimotoi) to changes in temperatures (15, 20 and 25 °C), N:P supply ratios (molar ratios 10:1, 24:1 and 63:1) and growth phases (exponential and stationary growth phases) in batch culture experiments. Both dinosterol and brassicasterol were produced by all the three species, but the cellular contents of dinosterol were up to 10 times higher than brassicasterol. Overall, growth phase changes showed the most pronounced effects, while warming and nutrient deficiency had moderate effects on the ratios of particulate organic nitrogen and carbon (PON:POC) and sterol contents. Our observations imply that under future ocean scenarios (warming and imbalanced N:P supply ratios), PON:POC may decrease but carbon-normalized sterol contents may increase in the three species. Such parallel changes in PON:POC and sterol contents may influence the dinoflagellate-grazer relationship and have significant consequences for ecological functions of the future ocean.
  • Evaluation of disruption/permeabilization methodologies for Microcystis
           aeruginosa as alternatives to obtain high yields of microcystin release
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Pedro Geada, Luís Loureiro, José A. Teixeira, Vítor Vasconcelos, António A. Vicente, Bruno D. Fernandes The extraction of the wide range of useful bioactive compounds produced by cyanobacteria is still a major bottleneck at industrial scale. In addition to the high costs, extraction efficiencies are also commonly low, with low cell disruption efficiencies playing a particularly significant role in intracellular compounds' release. To increase the chances of an extended use of the cyanobacteria toxin microcystin in several biotechnological fields, we aimed to optimize five different disruption techniques: bead milling, microwave, freeze-thaw cycles, high-speed homogenization, and sonication. For each of the methods tested, the conditions that maximized the intracellular organic matter release were: i) 20% of beads and treatment time of 7 min (bead milling); ii) 800 W for 1.5 min (microwave); iii) three 12-h freeze-thaw cycles at −20 °C; iv) 15,000 rpm for 7 min (high-speed homogenization); and v) 40 kHz for 10 min (sonication).Sonication and freeze-thaw cycles followed by sonication revealed to be the most effective methodologies to ensure a maximum intracellular organic matter release and, consequently, microcystin availability for being extracted. The decrease of cells' viability was however more evident in freeze-thaw cycles, freeze-thaw cycles followed by sonication, and microwave where only 0.3, 0.05 and 0.9% of the initial cells, respectively, maintained their viability after being treated. On the other hand, sonication and bead milling reduced the viability of the original culture to 5 and 15.5%, respectively, while high-speed homogenization did not show any significant differences compared to control.According to the results obtained in this study, the most suitable methodology to maximize the release of microcystin was therefore the use of sonication (40 kHz) during 10 min.
  • A critical review on production of bioethanol from macroalgal biomass
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Niyam Dave, Raja Selvaraj, Thivaharan Varadavenkatesan, Ramesh Vinayagam In order to combat emerging concerns due to global climate change and increasing conventional fuel prices, bioethanol appears to be a sustainable green resource as co-fuel to meet the future energy demand for transportation. As per the present scenario, bioenergy research emphasizes on bioethanol production from alternate non-terrestrial substrates, like microalgae and macroalgae. Among them, macroalgae represent a rich source of carbohydrates for bioethanol production. The production of bioethanol from macroalgal biomass mainly involves three steps namely mechanical pre-processing, pretreatment and microbial fermentation. Of these, the pretreatment step is the most crucial that tends to improve the saccharification efficiency for efficient bioethanol production. Currently, there are three main types of pretreatment methods used for macroalgae viz., physical/physicochemical, chemical and biological. In addition, the two-step saccharification or combinational pretreatment approach is also utilized to enhance the yield of reducing sugars, which can be fermented to bioethanol using suitable microbial strain(s) under restrained conditions. The current review provides a critical assessment and detailed overview about the sequential process for bioethanol production from macroalgal biomass. Additionally, this paper gives an insight on various statistical optimization approaches using response surface methodology for the biomass pretreatment step and provides a viewpoint about the technical advances in third-generation bioethanol production.Graphical abstractUnlabelled Image
  • Acetic acid uptake rate controls H2 production in
           Chlamydomonas-bacteria co-cultures
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Neda Fakhimi, Omid Tavakoli, Sayed-Amir Marashi, Hamid Moghimi, Mohammad Reza Mehrnia, Alexandra Dubini, David González-Ballester Photobiological hydrogen production by green microalgae is considered as a promising alternative for renewable biofuel production. We have evaluated hydrogen production in the model microalga Chlamydomonas reinhardtii in co-cultures with different bacteria, including Pseudomonas spp., Escherichia coli and Rhizobium etli cultured in acetate-containing nutrient-replete media at three different light intensities (12, 50 and 100 PPFD). Co-culturing Pseudomonas spp. with Chlamydomonas can significantly improve algal hydrogen production, especially at moderate to high light intensities (50–100 PPFD). Enhancement of hydrogen production in co-cultures was clearly related to the lower capacity of these co-cultures to consume the acetic acid from the media. The longer the acetic acid remained in the media, the longer the cultures were able to sustain hypoxia and support hydrogen production.
  • An integrated approach towards agricultural wastewater remediation with
           fatty acid production by two cyanobacteria in bubble column
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Prakash Chandra Gorain, Ishita Paul, Pratapbhanu Singh Bhadoria, Ruma Pal Cyanobacteria are capable of rapidly sequestering CO2 into lipid-enriched biomass while utilizing dissolved inorganic nutrients in wastewater. Semi-batch 30-d cultures of Anabaena sphaerica and A. variabilis were simultaneously monitored for biomass and lipid productivities, CO2 sequestration rates and dissolved macronutrient (N, P) utilization rates under varying photoperiods (8, 10, 12, 14, 16 and 18 h) and CO2 concentrations (control (air), 2% and 5%) in media supplemented with 15% (v/v) agricultural run-off water in bubble column photobioreactors. Effect of enhanced CO2 supply was significantly beneficial for all parameters. Longer or shorter photoperiods from the originally acclimated 14 h led to diminished and enhanced parameters respectively, but these changes were staggered due to inherent adaptibilities. The long-chain fatty acid (LCFA) profiles of A. sphaerica and A. variabilis were respectively dominated by saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA). Eight LCFAs were common between the two species while the SFA myristic acid was found in A. sphaerica and the ω-6 PUFA cis-8,11,14-eicosatrienoic acid was found in A. variabilis. It was concluded that A. sphaerica and A. variabilis showed potential in biodiesel and nutraceutical production, respectively. However, culture conditions including photoperiod and CO2 supply were found to affect the LCFA profiles slightly.
  • Utilization of phenolic compounds by microalgae
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Astrid Victoria Lindner, Daniel Pleissner Wastewater streams from fruit processing (e.g., olives) are usually rich in phenolic compounds, such as tyrosol, hydroxytyrosol and oleuropein. Even though phenolic compounds are considered as pollutants due to their toxicity to many organisms, they possess a potential to serve as carbon and energy sources for microorganisms, and as substrates for biochemical conversion into high-value products. The present review had the aim to collect information available on the utilization of phenolic compounds and to identify underlying mechanisms to develop processes for an efficient valorization of wastewater streams, such as olive mill wastewater, using microalgae. Microalgae are of particular of interest, as they have been used in various waste utilization approaches to form multiple high-value products. Although research has already been done in the field of biodegradation of phenolic compounds using microalgae, a satisfying utilization approach has not been presented yet, as the mechanism of degradation of phenolic compounds remains unclear. In this review, reported degradation of phenolic compounds is presented and classified into: Mineralization, biotransformation and removal under dark or light condition. Details of single experiments are presented and relevant conclusions from outcomes have been made in order to develop future utilization approaches.
  • Mitigation of variable seasonal productivity in algae biomass through
           blending and ensiling: An assessment of compositional changes in storage
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Bradley D. Wahlen, Lynn M. Wendt, J. Austin Murphy, Fábio Seibel Microalgae biomass has gained considerable attention in recent years as an attractive feedstock for biofuel production. However, seasonal variability in algae growth presents a challenge to delivering a consistent feedstock supply to a conversion facility. Drying is one approach to preserving algae produced in productive summer months for conversion in winter, but is energy intensive and costly. Ensiling is an alternative to drying that preserves algae in wet anaerobic conditions in the presence of organic acids. We have previously demonstrated that dry matter loss of algae:corn stover blends can be limited to 8% over 35 days using this approach. However, longer storage durations will be required to maintain a consistent feedstock supply to a biorefinery. Furthermore, the impacts to biomass quality that occur during storage are unknown. A Box-Behnken design of experiment was conducted to determine the influence of moisture, soluble sugar, and algae content on dry matter loss of algae:corn stover blends in wet anaerobic storage over a 30-day period. Using one-way analysis of variance (ANOVA) moisture and soluble sugar content were found to significantly affect dry matter loss in storage. The results of experimental design were then used to inform the initiation of a 180 day storage study that evaluated the storage performance and biomass composition of algae:corn stover blends containing 5, 20 or 40% algae. After 180 days of storage dry matter loss ranged from 6 to 17%. A relative increase in nitrogen content of stored blends indicates that protein content was unaffected by storage, while the carbohydrate fraction was most impacted, decreasing by 5–15%. For each stored blend the oxygen content decreased in storage resulting increased higher heating values (HHV). The impact that changes to biochemical and elemental composition of algae:corn stover blends has on biomass conversion to fuels and chemicals is discussed.
  • Gasification of lipid-extracted microalgae biomass promoted by waste
           eggshell as CaO catalyst
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Abdul Raheem, Hao Liu, Guozhao Ji, Ming Zhao Significant amounts of lipid-extracted microalgae biomass (LMB) could be generated as a by-product from biodiesel production, therefore its ability to be processed into and converted into a more valuable product needs to be explored to determine its true potential market value. In this study, the catalytic gasification of two LMB's, Spirulina platensis and Chlorella vulgaris, were performed in a thermogravimetric analyzer with mass spectrometry. The CaO based catalyst, naturally derived from waste eggshell, was varied to determine influence of catalyst loading (10, 30 and 50 wt%). The reactions were conducted over a 30–800 °C temperature range, in 5% O2/Ar at a 500 mL min−1 flow rate. Scanning electron microscopy and X-ray diffraction methods were utilized to characterize and observe physicochemical changes among the standard, fresh and calcined catalysts. For Spirulina platensis, H2 yield was improved with an increased catalyst loading from 53.6 to 110.0%, whereas CO and CO2 yields decreased by 58 and 52%, respectively, compared with the absence of the catalyst. For Chlorella vulgaris, H2 yields were increased as a result of increasing catalyst loading from 21.2 to 114.4%, whereas CO and CO2 decreased by 50.0 and 55.0%, respectively, compared with the absence of the catalyst. The CaO catalyst promoted the catalytic activity and captured CO2 via CaO absorption property which encouraged the water gas shift reaction to occur to a greater extent, which in turn increased the H2 production.
  • Enhancing the colouration of the marine ornamental fish Pseudochromis
           fridmani using natural and synthetic sources of astaxanthin
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Jufeng Jiang, Waldo Nuez-Ortin, Alex Angell, Chaoshu Zeng, Rocky de Nys, Matthew J. Vucko This study quantifies the effects of astaxanthin concentration as a dietary supplement (25, 50, 75, and 100 ppm) and supplementation time (0, 14, 28, 42, 56, and 70 days) on the colouration of the marine ornamental fish Pseudochromis fridmani (Orchid dottyback), using natural (as vegetative Haematococcus pluvialis) and synthetic (as Carophyll Pink®) sources. The colouration of experimental fish was quantified every two weeks and compared to a commercial standard, which had the desired colouration of an intense magenta/raspberry. A model was subsequently developed to quantify the predicted minimum colour distance to the commercial standard for each dietary source and concentration of astaxanthin, where shorter distances are desired. Although colour improved with increasing concentration and supplementation time for either astaxanthin source, natural astaxanthin improved colour more effectively and at the end of the feeding trial, the colour distances between the two sources at each concentration, ranged between 3.87 ± 0.60 and 4.90 ± 0.56, where a colour distance above 3.5 is noticeable to a standard observer. The most effective treatment was natural astaxanthin at a concentration of 100 ppm for 70 days (colour distance from the commercial standard of 4.91 ± 0.69). Importantly, the predicted minimum colour distances for each source could be quantified for all treatments except for concentrations of 100 ppm of both sources, where the distances were outside the concentrations tested. Therefore, increasing the concentration of astaxanthin beyond the highest level tested in this study is predicted to further improve the colour of the fish. Demonstrating the combined, interactive relationship between the dietary concentration and time of supplementation on the colour of P. fridmani, provides a fundamental understanding of how astaxanthin affects colour in marine ornamental species, and encourages a shift away from synthetic ingredients.
  • The bio-methane potential of whole plant and solid residues of two species
           of red seaweeds: Gracilaria manilaensis and Gracilariopsis persica
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Mohammad Javad Hessami, Siew Moi Phang, Jelveh Sohrabipoor, Fatemeh Fazeli Zafar, Solmaz Aslanzadeh Macroalgae, known commonly as seaweed, is extensively used in industry for extraction of its valuable products such as agar and carrageenan. This extraction process generates a large amount of waste in the form of biomass residues. In this study, bio-methane potential of two red seaweeds, Gracilaria manilaensis and Gracilariopsis persica, both as whole plant and their industrial residues, were compared after a mild acid pre-treatment at pH 2, 100 °C and 1 h in batch assays. The results showed that the pre-treated residual biomass of both G. manilaensis and G. persica had higher bio-methane potentials at 70% and 62% of the theoretical yield, respectively, compared to the whole plant biomass which achieved only 48% and 46% of the theoretical yield, respectively. The pre-treatment step increased the initial reaction rate of the residues by 47% and 77% compared to the untreated samples. On the other hand, the pre-treatment step only enhanced the initial reaction rates by 25% and 39%, respectively, with the whole plant sample. The results confirm that the seaweed residues are more suitable as a feedstock for anaerobic digestion compared to whole plant biomass.Graphical abstractUnlabelled Image
  • Comparative assessment of salinity tolerance based on physiological and
           biochemical performances in Ulva australis and Pyropia yezoensis
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Palas Samanta, Sookkyung Shin, Sojin Jang, Jang Kyun Kim Physiological and biochemical responses of Ulva australis and Pyropia yezoensis were studied under short-term (1-day) and long-term (7-, 14- and 28-day) salinity stresses (5, 30 and 55 practical salinity unit, psu) to explore the salinity tolerance on comparative basis. Reduced growth rate was recorded in both species under the hyposaline (5 psu) condition compared with control (30 psu), and significant (p 
  • Influence of the algal microbiome on biofouling during industrial
           cultivation of Nannochloropsis sp. in closed photobioreactors
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Javier B. Giraldo, Willem Stock, Lachlan Dow, Luc Roef, Anne Willems, Sven Mangelinckx, Peter G. Kroth, Wim Vyverman, Mark Michiels Industrial cultivation of microalgae is becoming increasingly important, yet the process is still hampered by many factors, including contamination and biofouling of the algal reactors. We characterized a subset of microorganisms occurring in the broth and different biofilm stages of industrial scale photobioreactors applied for the cultivation of Nannochloropsis sp. A total of 69 bacterial strains were isolated, belonging to at least 24 different species. In addition, a green microalga was isolated and identified as Chlamydomonas hedleyi. The effect of C. hedleyi and 24 of the bacterial isolates on the productivity of Nannochloropsis was evaluated through growth and biofilm assays. C. hedleyi was shown to reduce growth and induce biofilm formation in Nannochloropsis. These effects were however indirect as they could be attributed to the bacteria associated to C. hedleyi and not C. hedleyi itself. Although most bacterial strains reported no effect, several were able to induce biofilm formation.
  • The individual and synergistic impacts of feedstock characteristics and
           reaction conditions on the aqueous co-product from hydrothermal
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): David C. Hietala, Casey M. Godwin, Bradley J. Cardinale, Phillip E. Savage We examined the individual and synergistic impacts of reaction conditions and microalgal feedstock characteristics, including previously unreported combinations of variables, on the yield and properties of aqueous co-product (ACP) from hydrothermal liquefaction. Explicitly, we measured the effects of temperature (150 to 350∘C), reaction time (1 to 100min), slurry concentration (30 and 120 g Lrxn−1), biochemical composition (5.2 to 28.5 wt.% lipid, 14.7 to 50.9 wt.% protein), and species identity (Nannochloropsis, Chlorella, and Spirulina) on ACP characteristics. Measured properties included gravimetric yield, elemental (CHNSOP) recoveries, NH4+-N and PO43−-P recoveries, and pH. The impacts of slurry concentration and species identity on the properties of ACP produced from microalgae are examined in-depth for novel combinations of reaction variables, with all probed variables affecting ACP yield and composition. Temperature exhibited the most influence, followed by time (at 200∘C) and biochemical composition (at 300∘C). Lower slurry concentration led to increased ACP yields and recovery of NH4+-N, total nitrogen, PO43−-P, total phosphorus, and sulfur; in fact, the data suggested that increased slurry concentration promotes Maillard reactions that inhibit NH4+-N recovery in the ACP and promote N recovery in the biocrude. High-lipid, 30 g Lrxn−1 slurries reacted at 200∘C for 31.6 min are a potential “win-win” set of conditions for both maximizing key ACP-recyclability metrics while limiting N and S recovery in the biocrude to
  • A systematic study on the effects of dynamic environments on microalgae
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Ergys Pahija, Chi-Wai Hui The usage of calibration curves for the determination of microalgae concentration is common, and it consists of a correlation between the optical density and the number of cells. Although this tool is very useful for determining the concentration of microalgae, it requires the generation of a new calibration curve when the environmental conditions (e.g., temperature, light, etc.) change, since the size of microalgae may vary from one condition to another. We propose a novel methodology to determine the number of microalgae in a solution, emphasizing a correlation with optical density and the size distribution of cells. Considering that microalgal physiology is affected by environmental conditions, the proposed procedure allows for the calculation of the concentration of microalgae in changing ambient conditions without requiring the preparation of additional calibration curves.
  • Annual outdoor cultivation of the diatom Thalassiosira weissflogii:
           productivity, limits and perspectives
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Filomena Monica Vella, Angela Sardo, Carmela Gallo, Simone Landi, Angelo Fontana, Giuliana d'Ippolito Diatoms are a promising source of renewable biomass for production of energy and functional ingredients and food products. The eurythermal diatom Thalassiosira weissflogii shows great resistance and robustness, and can be considered a suitable candidate for outdoor cultivation. In this study we investigated the resilience of one strain of this species during one-year outdoor experimentation in inclined tubular photobioreator with a working volume of 40 L. Cells of T. weissflogii overcome temperature and irradiance fluctuations by adapting their growth rate at the different environmental conditions. Calculation of areal biomass productivity based on 30 cultures along the year showed a median value of 3.83 g m−2 day−1 with maximal values of biomass (6.8 g m−2 day−1) and lipids (1.2 g m−2 day−1) reached in February and July, respectively. We observed a decline in biomass productivity with temperature increase, whereas lipid content (10–20% of dry biomass) was not significantly affected by the environmental conditions as far as a high concentration of nutrients was maintained. The outdoor experimentation successfully proved one year-round production of biomass from a single diatom species in closed photobioreactor, making T. weissflogii a suitable candidate for guaranteeing stable annual productive cycles in outdoor plant.
  • Metabolic effects of vitamin B12 on physiology, stress resistance, growth
           rate and biomass productivity of Cyanobacterium stanieri planktonic and
           biofilm cultures
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Pavlo Bohutskyi, Ryan S. McClure, Eric A. Hill, William C. Nelson, William B. Chrisler, Jamie R. Nuñez, Ryan S. Renslow, Moiz A. Charania, Stephen R. Lindemann, Alexander S. Beliaev Although synthesized only by bacteria and archaea, cobalamin (vitamin B12) is essential for virtually all living cells. One major function is its role in methionine synthesis, as a co-factor for the B12-dependent methionine synthase MetH. However, a large number of microbes avoid requirements for B12 by encoding cobalamin-independent enzymes, such as the B12-independent methionine synthase MetE. Interestingly, many such microbes retain transporters for exogenous B12, produced by neighboring microbes. We hypothesize that selection for retention of B12 transport suggests preservation of unrevealed but critical roles for cobalamin in photoautotroph fitness. To identify the impacts of B12 on photoautotrophic metabolism, we studied the physiological and transcriptional adaptation of Cyanobacterium stanieri HL-69 to varying irradiance and oxidative stress in the presence and absence of B12. The metabolic flexibility of C. stanieri, which possesses both MetH and MetE, allows comparative analysis of cobalamin impacts on its global metabolism. As anticipated, B12 availability governed transcription of cobalamin transporter btuB, metH and a number of genes involved in the methionine-folate cycle. Surprisingly, however, B12 impacted the cell integrity, growth rate and biomass productivity of C. stanieri under conditions of likely oxidative stress due to biofilm growth or under high partial pressures of O2. Furthermore, C. stanieri response to B12 globally rewired cellular metabolic networks, including nitrogen metabolism, energy metabolism, redox homeostasis and oxidative stress response. These findings demonstrate previously-unappreciated roles for B12 metabolism beyond methionine synthesis and reveal how interactions with cobalamin-producing heterotrophs may affect phytoplankton function and dynamics in natural microbial communities. Further comprehension and mastering of the natural oxidative stress resistance mechanisms modulated by cobalamin could be used for the design and implementation of more robust algal bioprocesses retaining high biomass productivities especially under stress conditions.
  • Phycocyanin and phycoerythrin: Strategies to improve production yield and
           chemical stability
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Ming Hsieh-Lo, Gustavo Castillo, Mario Alberto Ochoa-Becerra, Luis Mojica Phycocyanin and phycoerythrin are photosynthetic pigments extracted from microalgae with great biotechnological potential due to their intense colors, fluorescent properties and potential health benefits. Their principal applications are as nutritional supplements, natural colorants in foods and cosmetics, and as a reagent for immunological assays. However, the main challenges for their commercialization and implementation in food and cosmetic applications are their low yield during production and limited chemical instability. This review compares the use of different methods to increase biomass and pigment production yield, including the mechanisms associated with the microorganisms adaptative response to different light wavelengths. It also explores different methods reported to improve phycocyanin and phycoerythrin chemical stability and commercially available products.
  • Phytoremediation of bark-hydrolysate fermentation effluents and
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Jean-Baptiste Beigbeder, Iulian Zoltan Boboescu, Jérémie Damay, Xavier Duret, Shabana Bhatti, Jean-Michel Lavoie Recent years marked an increased focus towards the valorization of biorefinery side-streams for the production of various high added-value molecules and platform chemicals. The present study tackles the opportunity of using liquid ethanol fermentation effluents of bark hydrolysates for microalgal conversion to various marketable molecules. Initially, 12 green microalgae strains were screened for their ability to thrive on these substrates and uptake some of the available organic compounds. Once the most suitable strains were identified, three mixed microalgal consortia were formulated and investigated in order to maximize, either individually or both simultaneously, their biomass production and phytoremediation performances. For instance, the consortium α containing Scenedesmus obliquus, Acutodesmus obliquus, Chlorella sorokiniana and Chlorella vulgaris strains was able to consume up to 70% of C5 sugars (xylose and arabinose) and 60% of C6 sugars (fucose and hexose). The uptake of these organic compounds initially present in the fermentation effluent accounted for the removal of 27% of the total organic carbon. In addition, the microalgal community produced 55 mg/L/d, 41 mg/L/d and 26 mg/L/d of carbohydrates, lipids and proteins respectively. The photosynthetic pigments accumulated in the harvested biomass comprised of 25.8 mg/L of total chlorophyll and 5.9 mg/L of carotenoids. Finally, the pyrolysis characteristics of the algal biomass were evaluated trough thermogravimetric analysis and the elemental composition was compared with conventional lignocellulosic feedstocks. Thus, this work proves the dual opportunity of both reducing the toxicity of lignocellulosic ethanol fermentation effluents as well as generating high-value biomass by employing specifically-designed microalgal populations.Graphical abstractUnlabelled Image
  • Evaluation of fucoxanthin contents in seaweed biomass by vortex-assisted
           solid-liquid microextraction using high-performance liquid chromatography
           with photodiode array detection
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): N. Nunes, João M. Leça, Ana C. Pereira, Vanda Pereira, S. Ferraz, Maria Carmo Barreto, José C. Marques, M.A.A. Pinheiro de Carvalho Fucoxanthin is considered an important marine bioactive compound with biological properties with promising effects, namely on health. A simple and efficient analytical methodology is proposed for its quantification in seaweed biomass by using vortex-assisted solid-liquid microextraction (VASLME) followed by reversed phase high-performance liquid chromatography (RP-HPLC) photodiode array detection (PDA) analysis. This microextraction uses reduced quantities of sample (25 mg) and solvent (300 μL of ethanol) to efficiently extract this high-valued xanthophyll, in a vortex time of 15 min. These extraction parameters were optimized performing a Central Composite Design (CCD) analysis, running 32 individual experiments. In turn, the method validation was assessed. The linearity of the method was confirmed (R2 = 0.99998) in a concentration range from 12 to 3600 μg·g−1 dw. Also, good sensitivity and accuracy results were observed through the LOD (3.33 μg·g−1), LOQ (10.09 μg·g−1) and recovery (varied from 95 to 97%) assessments. Good precision was also verified, with intra-day variation within 2.0–3.3%, and inter-day within 1.0–3.8%. Matrix effect was also evaluated and an acceptable variation of 3.4% was found. The method applicability was confirmed by the analysis of 22 seaweed biomass samples and fucoxanthin content was found to vary from about 10 to 853 μg·g−1 dw. This method demonstrated a good performance and can be successfully implemented for a rapid, reliable and accurate screening of fucoxanthin in seaweed biomass.
  • Elicitation of pharmaceutical alkaloids biosynthesis by salicylic acid in
           marine microalgae Arthrospira platensis
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Mahnaz Hadizadeh, Hamideh Ofoghi, Mehran Kianirad, Zohreh Amidi Background and objectiveArthrospira platensis, an edible microalga approved by the World Health Organization, is known to be a rich natural source of valuable secondary metabolites with medicinal properties. The aim of this research was to determine the effect of salicylic acid (an abiotic elicitor) on biomass production, as well as the amount of alkaloids accumulated in Arthrospira platensis.Materials and methodsSalicylic acid was added to the medium culture at different concentrations on the third, seventh, tenth, fourteenth, and seventeenth days and its effects were determined after 24 h. The presence of alkaloid in the methanol extracts was confirmed by thin layer chromatography and quantified by bromocresol green.ResultsThe biomass and alkaloid production was increased with 5 and 20 μM salicylic acid treatment, whereas salicylic acid at 100 μM had a negative effect on the growth and biomass accumulation. The concentrations of alkaloids in control cultures ranged from 31.0 ± 1.0 to 44.1 ± 0.7 μg Atropine/mg extract. The highest value of total alkaloids was obtained in cells treated with salicylic acid at a concentration of 5 μM, followed by 20 μM by the 15th day of culture; the levels were 1.7 and 1.4 times of the control, respectively.ConclusionFrom the study, it is clear that the positive effect of salicylic acid on the growth and alkaloid production would make this elicitor an interesting candidate for increasing productivity in large scale process enterprises.
  • An integrated microfluidic chip for treatment and detection of microalgae
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Junsheng Wang, Ge Wang, Mengmeng Chen, Yanjuan Wang, Gege Ding, Yichi Zhang, Yuejun Kang, Xinxiang Pan As the most economic means of international transportation for massive cargo, marine transportation contributes significantly to the world trading and economics. However, there are large number of microalgae cells and other exotic organisms carried in the ballast water, which may seriously damage the marine ecological environment along the transportation routes of the ships. Microalgae cells and online treatment of the microalgae-rich ballast water have become a pressing demand for ballast water management. Herein, we developed an automatic microfluidic system based on laser-induced chlorophyll fluorescence for real-time detection of microalgae in ballast water samples. This system is highly advantageous compared to the conventional method that requires tedious operation procedures, prolonged detection time, and complex analytical process. Moreover, we introduced chemical methods for fast and effective treatment of the microalgae cells in ballast water. For this purpose, a microfluidic concentration gradient generator was used for fast screening the optimal concentration of chemicals to rapidly reduce the microalgae population in the corresponding ballast water. To the best of our knowledge, this is the first time to combine an automatic high-throughput detection system and a gradient concentration chip for in situ analysis and treatment of ballast water.
  • Arsenic-contaminated sediment from mining areas as source of morphological
           and phylogenetic distinct cyanobacterial lineages
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Ifeyinwa S. Obuekwe, Marcelo G.M.V. Vaz, Diego B. Genuário, Naira Valle Castro, Allan V.M. Almeida, Renato W. Veloso, Gillian Nunes Pinto, Luna V. Alvarenga, Jaime V. Mello, Adriano Nunes-Nesi, Wagner L. Araújo The prospection of cyanobacteria from tropical/subtropical ecosystems and from man-made environments has attracted attention as source of novel strains favoring studies on systematics, molecular/chemical prospection, physiology and biotechnology. Here, a deep characterization of abiotic variables of surface water and sediment samples collected from an Arsenic (As) contaminated region in a gold mining area was provided coupled with a complete morphological and phylogenetic evaluation of isolated cyanobacterial strains. Sediment samples presented higher As content than water samples, indicating As contamination as a result of mining activities. From the sediment samples, eight filamentous strains were isolated. These novel strains were placed into six distinct phylogenetic lineages, considering 16S rRNA sequences, from which two may correspond to novel genera. This is the first report of an Anagnostidinema strain from a brazilian environment as well as Desmonostoc and Kamptonema strains from As-impacted environment. In addition, Pseudanabaena strain displaying microcystin biosynthetic genes was also documented. The isolation and culturing of these novel cyanobacterial strains are not solely relevant for systematics, but it also represent a step further to better understand the role of cyanobacteria in the circulation of As in aquatic environments as well as for their application in As bioremediation.Graphical abstractUnlabelled Image
  • Fast non-invasive monitoring of microalgal physiological stage in
           photobioreactors through Raman spectroscopy
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Christopher Lieutaud, Ali Assaf, Olivier Gonçalves, Gaëtane Wielgosz-Collin, Gérald Thouand Microalgal bioprocesses are increasing in multiple industrial sectors for production at large scales. Nevertheless, classical sensors are still used but are not adapted for production monitoring, leading to monoparametric, invasive and time-consuming solutions. Future approaches should eliminate those weaknesses and take advantage of optical methods to optimize the monitoring. This work is focussed on the concrete application of Raman spectroscopy to characterize the physiological kinetics of a microalgal process. The monitoring of Chlamydomonas reinhardtii growth in photobioreactors led us to build its specific Raman spectral database. The complex Raman signatures acquired showed 35 reproducible bands for each day of growth, corresponding to the spectral fingerprints of the cell metabolites, such as chlorophyll a, beta-carotene, nucleic acids and lipids. In total, 2688 spectra were compiled in a database representing the cellular chemical fingerprints in three physiological stages and showed progressive variations between the days of acquisition. New data acquisitions allowed us to build a trial for blind validation and to characterize the bioprocesses with 89.2% accuracy. To complete the study, transcriptomic experiments following the transcript expression of two different metabolic pathways of the microalgae confirmed the cell physiology attributions made by the Raman spectroscopy. This work enables us to query the bioprocess status directly from the cells by attributing a spectrum to the current cell physiology.
  • Apparent nutrient and fatty acid digestibilities of microbial raw
           materials for rainbow trout (Oncorhynchus mykiss) with comparison to
           conventional ingredients
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Hüseyin Sevgili, Soner Sezen, Adil Yılayaz, Özgür Aktaş, Faruk Pak, Inga M. Aasen, Kjell Inge Reitan, Michael Sandmann, Sascha Rohn, Gamze Turan, Mahir Kanyılmaz Determination of apparent digestibility coefficients (ADC) of ingredients has a central importance in formulation of aquaculture diets. Heterotrophic and phototrophic grown microalgae are considered as one of the best eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) as well as protein alternatives for fish oil and fish meal (FM) to sustain further growth in aquaculture production. This study aimed to determine nutrient and fatty acid ADCs of microbial materials including Nannochloropsis oceanica, Phaeodactylum tricornutum and two thraustochytrid strains (T29 and T66) with comparison to commonly used ingredients such as two batches of FMs, poultry-by product meal (PBM), soybean meal (SBM), corn gluten meal (CGM), wheat gluten meal (WGM) and whole wheat flour (WF) in rainbow trout, Oncorhynchus mykiss. Each ingredient was tested using Cr2O3 as an indigestible marker in triplicated cylindro-conical tanks for 2 weeks. Protein ADCs of microbial ingredients ranged between 77.6% in T66 and 84.4% in P. tricornutum and were close to those of FMs and PBM. N. oceanica had generally significantly lower lipid and fatty acid ADCs than those of P. tricornutum, thraustochytrids and the conventional feed ingredients probably due to their thick cell walls. Between the thraustochytrids strains, the T66 appeared to have slightly lower lipid, energy, organic matter, saturated, monounsaturated, long chain n-6 and long chain n-3 fatty acid ADCs than T29. P. tricornutum showed comparable nutrient ADC values to the two FMs used in the study. The results suggest that even if the microbial ingredients were used at 30% in reference diet without exposition to a pretreatment process, they can be utilized at acceptable rates by rainbow trout.
  • Cyanophycin and arginine metabolism in cyanobacteria
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Enrique Flores, Sergio Arévalo, Mireia Burnat Cyanobacteria are oxygenic phoautotrophs that can utilize inorganic nitrogen salts, atmospheric nitrogen and some amino acids such as arginine as nitrogen source. Under unbalanced growth in the presence of sufficient nitrogen, many cyanobacteria accumulate cyanophycin, a co-polymer of aspartate and arginine that serves as a nitrogen reservoir. Cyanophycin metabolism enzymes include cyanophycin synthetases, cyanophycinase and isoaspartyl dipeptidase. The latter splits β‑aspartyl arginine released from cyanophycin by cyanophycinase into aspartate and arginine. The arginine catabolic pathway of cyanobacteria has been recently elucidated and consists of two bifunctional enzymes, arginine-guanidine removing enzyme (AgrE) and proline oxidase (PutA). This pathway makes available to metabolism the four nitrogen atoms of arginine, three as ammonia and one as glutamate. A variant of the pathway cycles ornithine (an intermediate in the AgrE-catalyzed reactions) back to arginine incorporating aspartate and, hence, recovering its nitrogen atom for metabolism. Many cyanobacteria also make use of this pathway to utilize arginine taken up from the outer medium through a high-affinity ABC transporter. An analysis of co-occurrence in cyanobacteria of genes encoding cyanophycin metabolism and arginine catabolism enzymes and arginine and aspartate transporters indicates a strong correlation between the presence of cyanophycin and the AgrE/PutA pathway.
  • Intronserter, an advanced online tool for design of intron containing
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Daniel Jaeger, Thomas Baier, Kyle J. Lauersen Regulatory intron insertion into cDNA can greatly enhance nuclear transgene expression in many eukaryotic hosts, especially in the green microalga Chlamydomonas reinhardtii where intron spreading is required to enable reliable and robust expression. We determined here that the first intron of C. reinhardtii rbcS2 (rbcS2i1) improves nuclear transgene expression 5.5-fold over eight other endogenous introns. For the convenient, reliable and standardized design of intron-containing transgenes, we developed the web tool “Intronserter”: Intronserter implements back translation/codon optimization of input amino acid sequence(s) with user-defined codon usage tables, removes undesired sequence elements, performs systematic intron insertion to minimize exon lengths, and generates ready-to-synthesize DNA sequences for expression of any target. Although by default Intronserter will optimize transgenes for algal nuclear expression, all parameters are fully customizable. This flexibility enables its application to any other target organism and will encourage the broader implementation of advanced transgene design strategies in other eukaryotic hosts.
  • Osteogenic activity of non-genotoxic sulfated polysaccharides from the
           green seaweed Caulerpa sertularioides
    • Abstract: Publication date: Available online 27 June 2019Source: Algal ResearchAuthor(s): G.P. Chaves Filho, A.F.G. de Sousa, R.L.S. Viana, H.A.O. Rocha, S.R. Batistuzzo de Medeiros, S.M.G. Moreira Biocompatibility is a requirement for new molecules with potential applications in bone regeneration. Molecules with such potential applications in regenerative medicine include sulfated polysaccharides (SPs) isolated from seaweed. In this study, we evaluated the cytotoxicity and genotoxicity of SPs extracted from the green seaweed, Caulerpa sertularioides, and demonstrated its osteogenic activity in human mesenchymal stem cells (hMSCs). Seaweed samples were collected along the coast of Rio Grande do Norte, Brazil, and the results of chemical composition analyses of the samples revealed a high sugar and sulfate content. hMSCs treated with seaweed SPs (1–10 μg/mL) did not alter 3-(4,5-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction activity, and alkaline phosphatase activity was increased by approximately 30–40% when cells were treated with 5–10 μg/mL SPs. In addition, 21 days of continuous treatment resulted in increased calcium deposition in the extracellular matrix. Comet assay and the cytokinesis-block micronucleus cytome assay did not reveal significant changes in the frequency of nuclear alterations after 24 h of treatment. Together, our results show, for the first time, the osteogenic activity and non-genotoxicity of SPs from C. sertularioides, suggesting their potential in therapeutic applications in bone regeneration.
  • Production of quality seaweed biomass through nutrient optimization for
           the sustainable land-based cultivation
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Poornima Suthar, Tejal K. Gajaria, C.R.K. Reddy The Ulva fasciata Delile is a rapidly growing intertidal green marine macroalga and is a potential source of numerous value-added products such as mineral salts, ulvan, cellulose, and proteins. It is among the edible seaweeds that can bring down the pressure on to the terrestrial crop farming. The cultivation of such economically valuable species presents two major advantages: their higher photosynthetic efficiency that leads to the higher level of atmospheric CO2 sequestration and the biomass produced can effectively be employed in food formulations to combat the food security issues. In this study, the optimum concentration of nutrients namely, nitrate and phosphate were estimated to maximize the biomass production to achieve higher growth rates with the best biochemical contents. The optimization of nutrient regimes resulted in the modulation of algal cell-cycle as evidenced by the highly varying growth rates (ranging from 6% to 56%) as well as dynamic nutrient uptake kinetics. The biochemical analysis of biomass grown in optimized nutrient combination (N2: 60 μM nitrate; 6 μM phosphate) contained proteins 9.3 ± 0.32%, carbohydrates 20.2 ± 2.51% and lipids 6.28 ± 0.84% on dry weight basis. Further, the cultures with the optimized nutrient combination were found to have healthy green leaf-like thallus with reduced or no incidence of deterioration of biomass. The findings reported in this study would be useful for the sustainable production of Ulva in land-based systems.Graphical abstractUnlabelled Image
  • Single-step treatment of primary effluent by Galdieria sulphuraria:
           Removal of biochemical oxygen demand, nutrients, and pathogens
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): D. Tchinda, S.M. Henkanatte-Gedera, I.S.A. Abeysiriwardana-Arachchige, H.M.K. Delanka-Pedige, S.P. Munasinghe-Arachchige, Y. Zhang, N. Nirmalakhandan Our previous reports have documented a single-step algal process for removing biochemical oxygen demand (BOD5) and nutrients from primary effluent in batch mode. In the current study, we report results from continuous fed-batch operation of this algal system demonstrating consistent removal of BOD5 and nutrients as well as significant reduction of pathogenic bacteria from primary effluent. The active volume of the algal bioreactor under fed-batch operation was 700 L, of which, 400 L was discharged at the end of every cycle and replenished with fresh primary effluent to start a new cycle. Results from thirty such cycles run over 120 days, under varying influent loadings and ambient conditions, confirmed that the discharge standards for BOD5 and nutrients could be attained in a fed-batch cycle time of
  • An integrated Ulva-periphyton biofilter for mariculture effluents:
           Multiple nitrogen removal kinetics
    • Abstract: Publication date: September 2019Source: Algal Research, Volume 42Author(s): Lior Guttman, Amir Neori, Suzanne E. Boxman, Roy Barkan, Ben Shahar, Andrea M. Tarnecki, Nathan P. Brennan, Kevan L. Main, Muki Shpigel Biofilters made of Ulva and periphyton differ in their effectiveness in removing ammonia and nitrate from mariculture effluents. Our research evaluated the practicality of a combination of these two biofilters in improving the overall removal of dissolved N, where efficient removal of ammonia by the seaweed is followed by efficient removal of nitrate by periphyton. A paired Ulva-periphyton biofilter was exposed to various areal loads of ammonia and nitrate, the primary nitrogen forms in fishpond effluents.A first upstream macroalgae biofilter stocked with Ulva was fed with fishpond effluents at different areal loads of ammonia and nitrate, while a second downstream periphyton biofilter was paired for further nitrogen removal from the effluent. Ulva removed ammonia at a rate of 0.7–5.4 g TAN m−2 d−1, in correlation with the TAN areal load, with Vmax of 5.1 and Km of 4.4 g TAN m−2 d−1. Downstream periphyton was exposed to a lower TAN, but nitrate-rich effluent, and revealed similar capacities for the removal of both N forms, at removal rates of up to 1.7 and 1.8 g N m−2 d−1, respectively. Compared to nitrate, areal load of TAN had a greater impact on the removal dynamics of both N forms by periphyton. Overall, the paired biofilter resulted in a nearly total depletion of ammonia (97%) and efficient nitrate removal (67%), when areal loads in fishpond effluents were below 2 and 4 g N m−2 d−1 of TAN and NO3-N, respectively.
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