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Showing 1 - 200 of 3031 Journals sorted alphabetically
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 20, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 16, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 79, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 22, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 27, SJR: 2.515, h-index: 90)
Achievements in the Life Sciences     Open Access   (Followers: 4)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 5, SJR: 0.338, h-index: 19)
Acta Astronautica     Hybrid Journal   (Followers: 302, SJR: 0.726, h-index: 43)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Biomaterialia     Hybrid Journal   (Followers: 25, SJR: 2.02, h-index: 104)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription  
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 8, SJR: 0.172, h-index: 29)
Acta Haematologica Polonica     Free   (SJR: 0.123, h-index: 8)
Acta Histochemica     Hybrid Journal   (Followers: 3, SJR: 0.604, h-index: 38)
Acta Materialia     Hybrid Journal   (Followers: 195, SJR: 3.683, h-index: 202)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.615, h-index: 21)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.442, h-index: 21)
Acta Oecologica     Hybrid Journal   (Followers: 9, SJR: 0.915, h-index: 53)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription   (Followers: 1)
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 3, SJR: 0.311, h-index: 16)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 21, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 5, SJR: 1.059, h-index: 77)
Acta Urológica Portuguesa     Open Access  
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 4)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 3)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.383, h-index: 19)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 2)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 5, SJR: 0.141, h-index: 3)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 4, SJR: 0.112, h-index: 2)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 4)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.967, h-index: 57)
Addictive Behaviors     Hybrid Journal   (Followers: 15, SJR: 1.514, h-index: 92)
Addictive Behaviors Reports     Open Access   (Followers: 5)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 119, SJR: 5.2, h-index: 222)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 11, SJR: 1.265, h-index: 53)
Advanced Powder Technology     Hybrid Journal   (Followers: 16, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 8, SJR: 0.299, h-index: 15)
Advances in Agronomy     Full-text available via subscription   (Followers: 15, SJR: 2.071, h-index: 82)
Advances in Anesthesia     Full-text available via subscription   (Followers: 24, SJR: 0.169, h-index: 4)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 3)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 6, SJR: 1.054, h-index: 35)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 10, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 21, SJR: 1.286, h-index: 49)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 16, SJR: 3.31, h-index: 42)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.277, h-index: 43)
Advances in Botanical Research     Full-text available via subscription   (Followers: 3, SJR: 0.619, h-index: 48)
Advances in Cancer Research     Full-text available via subscription   (Followers: 26, SJR: 2.215, h-index: 78)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 0.9, h-index: 30)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 2.139, h-index: 42)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 12)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 24, SJR: 0.183, h-index: 23)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 10, SJR: 0.665, h-index: 29)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 8, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 28, SJR: 0.938, h-index: 33)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 18, SJR: 2.314, h-index: 130)
Advances in Computers     Full-text available via subscription   (Followers: 16, SJR: 0.223, h-index: 22)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 4)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 5)
Advances in Drug Research     Full-text available via subscription   (Followers: 22)
Advances in Ecological Research     Full-text available via subscription   (Followers: 39, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 25, SJR: 0.486, h-index: 10)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 7)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 38, SJR: 5.465, h-index: 64)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 3)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 8)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 41, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 14)
Advances in Genetics     Full-text available via subscription   (Followers: 15, SJR: 2.558, h-index: 54)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11)
Advances in Geophysics     Full-text available via subscription   (Followers: 6, SJR: 2.325, h-index: 20)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 18, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 8, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 22)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 2, SJR: 0.396, h-index: 27)
Advances in Immunology     Full-text available via subscription   (Followers: 33, SJR: 4.152, h-index: 85)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 1.132, h-index: 42)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 3, SJR: 1.274, h-index: 27)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 4)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 7, SJR: 0.764, h-index: 15)
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: 16, SJR: 1.645, h-index: 45)
Advances in Mathematics     Full-text available via subscription   (Followers: 10, SJR: 3.261, h-index: 65)
Advances in Medical Sciences     Hybrid Journal   (Followers: 5, SJR: 0.489, h-index: 25)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 5)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 4, SJR: 1.44, h-index: 51)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 21)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 6, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 3)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 15, SJR: 2.885, h-index: 45)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.148, h-index: 11)
Advances in Parasitology     Full-text available via subscription   (Followers: 7, SJR: 2.37, h-index: 73)
Advances in Pediatrics     Full-text available via subscription   (Followers: 20, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 14)
Advances in Pharmacology     Full-text available via subscription   (Followers: 13, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.384, h-index: 26)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.248, h-index: 11)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 8)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 5)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 18)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 17, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 56)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 5, SJR: 0.478, h-index: 32)
Advances in Radiation Oncology     Open Access  
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 1, SJR: 0.1, h-index: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 332, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 7)
Advances in Surgery     Full-text available via subscription   (Followers: 6, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 28, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 14)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 12)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 42, SJR: 2.408, h-index: 94)
Aeolian Research     Hybrid Journal   (Followers: 5, SJR: 0.973, h-index: 22)
Aerospace Science and Technology     Hybrid Journal   (Followers: 303, SJR: 0.816, h-index: 49)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.318, h-index: 36)
African J. of Emergency Medicine     Open Access   (Followers: 4, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 7, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 389, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 15, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 29, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 36, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 1)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 48, SJR: 1.879, h-index: 120)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.434, h-index: 14)
Air Medical J.     Hybrid Journal   (Followers: 3, SJR: 0.234, h-index: 18)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.285, h-index: 3)
Alcohol     Hybrid Journal   (Followers: 9, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 5)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 1, SJR: 0.436, h-index: 12)
Alexandria J. of Medicine     Open Access  
Algal Research     Partially Free   (Followers: 7, SJR: 2.05, h-index: 20)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 3)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.46, h-index: 29)
Allergology Intl.     Open Access   (Followers: 5, SJR: 0.776, h-index: 35)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 6, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 45, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 5)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 3)
American Heart J.     Hybrid Journal   (Followers: 45, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 47, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 34, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 6, SJR: 1.091, h-index: 45)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.653, h-index: 93)
American J. of Human Genetics     Hybrid Journal   (Followers: 32, SJR: 8.769, h-index: 256)
American J. of Infection Control     Hybrid Journal   (Followers: 25, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 31, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 48, SJR: 2.023, h-index: 189)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 173, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 51, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 2)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.249, h-index: 88)
American J. of Otolaryngology     Hybrid Journal   (Followers: 22, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 23, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 21, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 32, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 13, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 5)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 52, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 3)
Anales de Cirugia Vascular     Full-text available via subscription  
Anales de Pediatría     Full-text available via subscription   (Followers: 2, SJR: 0.209, h-index: 27)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription   (SJR: 0.104, h-index: 3)
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 2, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 38, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 152, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 7, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 10)
Anesthésie & Réanimation     Full-text available via subscription  
Anesthesiology Clinics     Full-text available via subscription   (Followers: 21, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  
Animal Behaviour     Hybrid Journal   (Followers: 141, SJR: 1.907, h-index: 126)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 5, SJR: 1.151, h-index: 83)
Animal Reproduction Science     Hybrid Journal   (Followers: 5, SJR: 0.711, h-index: 78)
Annales d'Endocrinologie     Full-text available via subscription   (SJR: 0.394, h-index: 30)
Annales d'Urologie     Full-text available via subscription  
Annales de Cardiologie et d'Angéiologie     Full-text available via subscription   (SJR: 0.177, h-index: 13)
Annales de Chirurgie de la Main et du Membre Supérieur     Full-text available via subscription  
Annales de Chirurgie Plastique Esthétique     Full-text available via subscription   (Followers: 2, SJR: 0.354, h-index: 22)
Annales de Chirurgie Vasculaire     Full-text available via subscription   (Followers: 1)

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Journal Cover Algal Research
  [SJR: 2.05]   [H-I: 20]   [7 followers]  Follow
   Partially Free Journal Partially Free Journal
   ISSN (Online) 2211-9264
   Published by Elsevier Homepage  [3031 journals]
  • Harvesting of microalgae Chlorella vulgaris using
           electro-coagulation-flocculation in the batch mode
    • Authors: Nidal Fayad; Tania Yehya; Fabrice Audonnet; Christophe Vial
      Pages: 1 - 11
      Abstract: Publication date: July 2017
      Source:Algal Research, Volume 25
      Author(s): Nidal Fayad, Tania Yehya, Fabrice Audonnet, Christophe Vial
      The aim of this study was to evaluate the harvesting of microalgae Chlorella vulgaris by electro-coagulation-flocculation (ECF) using aluminum and iron electrodes, assess the mechanisms responsible for microalgae recovery, quantify the metal contamination in the effluent and biomass, analyze power requirements, and investigate the effect of ECF on lipid and pigment content in the biomass. The influence of six operating parameters (electrode material, sedimentation time, current density, stirring speed, initial pH (pHi) and inter-electrode distance) on the harvesting efficiency was tested. A specific strategy involving flotation and pH-controlled ECF experiments was developed to identify the prevailing mechanism of harvesting: adhesion on flocs was shown to be negligible; flotation contributed to a maximum of 36.6% of microalgae recovery; zeta potential highlighted that the main mechanism responsible for microalgae recovery was charge neutralization at pHi 4 and 6, and sweep flocculation at pHi 8. The most energy saving conditions for the harvesting of Chlorella vulgaris involved aluminum electrodes, and 60min electrolysis with a current density of 2.9mA/cm2, pHi 4, stirring speed 250rpm and an inter-electrode distance of 1cm. Economic and competitive energy input (1kWh/kg microalgae) could be achieved by adding 1.5g/L NaCl. In addition, ECF did not affect significantly the amount of microalgal lipids and pigments.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.015
      Issue No: Vol. 25 (2017)
  • Evaluating Marinichlorella kaistiae KAS603 cell size variation, growth and
           TAG accumulation resulting from rapid adaptation to highly diverse trophic
           and salinity cultivation regimes
    • Authors: Eva L. Sánchez-Alvarez; Grisele González-Ledezma; José A. Bolaños Prats; José L. Stephano-Hornedo; Mark Hildebrand
      Pages: 12 - 24
      Abstract: Publication date: July 2017
      Source:Algal Research, Volume 25
      Author(s): Eva L. Sánchez-Alvarez, Grisele González-Ledezma, José A. Bolaños Prats, José L. Stephano-Hornedo, Mark Hildebrand
      The ability of a microalgal species to adapt to changes in cultivation environment is likely to be beneficial for a successful biofuel/bioproduct production system, because the species could maintain high yields under diverse seasonal or cultivation conditions. Examining factors that enable culturing flexibility in a single species could provide clearer insights than when comparing different species because it will reduce interspecies variability. Marinichlorella kaistiae KAS603 is an excellent model to evaluate mechanisms involved in adaptation to different cultivation regimes. We have studied cell growth, size, triacylglycerol (TAG) accumulation and life cycle stages in this multiple fission dividing strain under a wide variety of conditions, ranging from autotrophic growth in freshwater to mixotrophic growth in fresh and seawater, and to autotrophic growth under saline and hypersaline conditions. Such conditions influence the division mode of the strain, which is linked to biomass and TAG yield. Based on lab and pilot plant experiments, we have discovered that the fastest TAG accumulation takes place under mixotrophy in freshwater, highest yield (culture density plus TAG) condition occurs under mixotrophy in sea water, and the best outdoor culture condition to achieve growth with fewer invasive species is hypersaline natural seawater. In addition to characterizing growth and TAG accumulation characteristics under a wide variety of cultivation conditions, this work sets the stage for investigation into the mechanisms that enable diverse cultivation adaptations, and contribute to the development of this environmentally flexible microalga as a production feedstock.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.027
      Issue No: Vol. 25 (2017)
  • Managing variability in algal biomass production through drying and
           stabilization of feedstock blends
    • Authors: Bradley D. Wahlen; Mohammad S. Roni; Kara G. Cafferty; Lynn M. Wendt; Tyler L. Westover; Dan M. Stevens; Deborah T. Newby
      Pages: 9 - 18
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Bradley D. Wahlen, Mohammad S. Roni, Kara G. Cafferty, Lynn M. Wendt, Tyler L. Westover, Dan M. Stevens, Deborah T. Newby
      The uncertainty and variability of algal biomass production presents several challenges to the nascent algal biofuel industry, including equipment scaling and feedstock supply. Ideally, on-site processing equipment will be scaled to minimize overall biofuel production costs, which means at times biomass production could exceed down-stream processing capacity due to seasonal variation. Biomass produced in excess of conversion capacity during summer months must be stabilized by some method, such as drying, until needed later in the year. Because of algae's high moisture content and its cohesive nature, drying is challenging. Blending algae with terrestrial biomass may provide a cost-effective method to enable drying and stabilization of algae by reducing moisture content and improving rheological (i.e. flowability) properties. To test the technical feasibility of this approach, bench-scale rotary drum dyers were constructed and tested with blends of algae (Scenedesmus sp.), ground pine (2mm grind), sorghum, corn stover (6mm), sieved sand, and dried algae. In these studies, blends up to 40% algae exhibited drying behavior similar to that of pine alone, and reached dryness (2% moisture) in half of the time it took to dry algae alone. Thermogravimetric analyses performed on blends and neat blend materials provided drying curves consistent with the bench-scale dryers. Preliminary logistics analysis for production-scale operations were performed to determine cost and availability of feedstock materials for blending as compared to drying algae directly. This analysis indicates that revenue lost due to idle processing capacity had a significant impact on the per gallon gasoline equivalent feedstock cost. The blending approach, described herein, reduced feedstock-related costs, including procurement, drying, and storage by 35% relative to drying algae directly. Our results indicate that blending algae with terrestrial biomass enables the use of rotary dryers and has the potential to improve overall algal biofuel economics.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.005
      Issue No: Vol. 24 (2017)
  • A novel option for reducing the optical density of liquid digestate to
           achieve a more productive microalgal culturing
    • Authors: F. Marazzi; C. Sambusiti; F. Monlau; S.E. Cecere; D. Scaglione; A. Barakat; V. Mezzanotte; E. Ficara
      Pages: 19 - 28
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): F. Marazzi, C. Sambusiti, F. Monlau, S.E. Cecere, D. Scaglione, A. Barakat, V. Mezzanotte, E. Ficara
      The liquid fraction of digestate produced by agricultural biogas plants is rich in macro and micronutrients that are valuable for the culturing of microalgae. Nonetheless, the high ammonium concentration may cause toxicity and the high optical density may reduce light penetration, negatively affecting the biomass production rate. Dilution with fresh water has been frequently suggested as a mean for improving the digestate characteristics in view of microalgal culturing. In this paper, the feasibility of culturing microalgae on undiluted raw digestate or on digestate after pretreatment by stripping and adsorption was investigated. First, adsorption tests were performed using commercial activated carbon from wood in order to identify appropriate conditions for optical density (OD) reduction. Up to 88% reduction was obtained by dosing 40gL−1 after 24h of contact time. Then, culturing tests were performed on a microalgal inoculum including mainly Chlorella spp. and Scenedesmus spp. under controlled temperature and light conditions during 6–14weeks. Raw, stripped, and stripped and adsorbed digestate samples were tested. The biomass production rate increased from 27±13mgTSSL−1 d−1 on raw digestate, to 82±18mgTSSL−1 d−1 by using stripped digestate, and to 220±78mgTSSL−1 d−1 by using the stripped and adsorbed digestate. Moreover, nitrification was constantly suppressed when using the stripped and adsorbed digestate, while relevant nitrite built-up was observed when using raw and stripped digestate. These results suggest that microalgae are able to grow on the raw digestate, provided that long hydraulic retention times are applied. A much faster growth (up to 10 times) can be obtained by pretreating the liquid fraction of digestate by stripping and adsorption, which may be an effective means of improving the areal productivity of microalgal culturing on digestates.
      Graphical abstract image

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.014
      Issue No: Vol. 24 (2017)
  • A hybrid approach integrating arsenic detoxification with biodiesel
           production using oleaginous microalgae
    • Authors: Neha Arora; Khushboo Gulati; Alok Patel; Parul A. Pruthi; Krishna Mohan Poluri; Vikas Pruthi
      Pages: 29 - 39
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Neha Arora, Khushboo Gulati, Alok Patel, Parul A. Pruthi, Krishna Mohan Poluri, Vikas Pruthi
      A novel combinatorial approach integrating toxic and carcinogenic heavy metal arsenic (III, V) mitigation coupled to biodiesel production using oleaginous microalgae grown in synthetic soft water (SSW) was undertaken in this investigation. Among the four prospective microalgal species tested, Chorella minutissima and Scenedesmus sp. IITRIND2 were able to tolerate 500mgL−1 of both the forms of As (III) and As (V) with a high metal bioconcentration factor (BCF) indicating that these strains can be categorized as hyper bioaccumulators of arsenic. These arsenic spiked microalgae showed a significant enhancement in the lipid production by accumulating large lipid droplets with minimal morphological changes. The biochemical composition analysis of these microalgal cells showed apparent decline in the protein, carbohydrate and photosynthetic pigments suggesting that the arsenic intake by the cells has remodeled its cellular composition in order to cope up with the heavy metal induced stress. The biodiesel derived from the microalgae was amenable and comparable to plant oil methyl esters with a high cetane number, oxidative stability and low cold flow plugging properties. This salient approach exhibits two fold advantages, which include safe removal of carcinogenic metal arsenic from potable water sources as well as high yield of lipid production. This novel integrative innovative technology has a strong prospective path for verdurous environment and renewable fuels resulting in socioeconomic welfare.
      Graphical abstract image

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.012
      Issue No: Vol. 24 (2017)
  • Assessment of potential zooplankton control treatments for wastewater
           treatment High Rate Algal Ponds
    • Authors: Valerio Montemezzani; Ian C. Duggan; Ian D. Hogg; Rupert J. Craggs
      Pages: 40 - 63
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Valerio Montemezzani, Ian C. Duggan, Ian D. Hogg, Rupert J. Craggs
      Cladocerans and rotifers rapidly consume beneficial microalgae and reduce the performance of High Rate Algal Ponds (HRAPs) for wastewater treatment and algal production. Potential zooplankton control treatments for HRAPs have been proposed and tested at a laboratory scale including CO2 asphyxiation, biological control using competitor species, filtration, and mechanical disruption using hydrodynamic shear stress. This paper aims to validate these treatments using outdoor mesocosms with physicochemical and operational conditions similar to those of full scale HRAPs. A continuous CO2 concentration of ~100mg/L maintained low pond water zooplankton densities, while a continuous concentration of ~180mg/L killed all microcrustaceans and rotifers present. As biocontrol agents, the cladoceran Moina tenuicornis at ~2000 individuals/L reduced average rotifer densities by 90% while the ostracod Heterocypris incongruens at ~1000 individuals/L removed all rotifers. Mechanical filtration using 300μm and 500μm filters eradicated M. tenuicornis after one and four filtration periods, respectively. Mechanical hydrodynamic stress killed up to 100% of microcrustaceans, and ~50% of larger rotifers. Furthermore, phototaxis-induced migration promoted higher densities of M. tenuicornis in the upper layer of the water column in an 8m3 HRAP during periods of low solar radiation, suggesting that mechanical treatments should be performed at night and to the upper layer of the pond water. Overall, CO2 asphyxiation appeared to be the most reliable, versatile, and effective zooplankton control treatment.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.013
      Issue No: Vol. 24 (2017)
  • Reproductive sterility increases the capacity to exploit the green seaweed
           Ulva rigida for commercial applications
    • Authors: Guang Gao; Anthony S. Clare; Craig Rose; Gary S. Caldwell
      Pages: 64 - 71
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Guang Gao, Anthony S. Clare, Craig Rose, Gary S. Caldwell
      Periodic biomass losses caused by reproduction have greatly limited the expansion of the land-based cultivation of the seaweed Ulva. In an attempt to resolve this, we obtained a sterile mutant (SM) of U. rigida by mutating a wild type (WT) strain using ultraviolet radiation (UVC). The SM grew five times faster than the WT with 40.0% and 30.9% higher nitrate and phosphate uptake rates. Crucially, the SM remained in the vegetative state throughout the 27-day trial, unlike the WT. The lipid content was more than double that of the WT with more monounsaturated, polyunsaturated, omega-3 and omega-6 fatty acids but with a 26.3% lower protein content. The swelling, water holding, and oil holding capacities were all lower than the WT. The rapidly growing SM showed distinct promise for application to carbon capture and wastewater bioremediation and for more conventional aquaculture practices. Despite some modified nutritional and functional properties, the SM still retained a desirable nutritional profile.
      Graphical abstract image

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.008
      Issue No: Vol. 24 (2017)
  • Polyphasic toxicological screening of Cylindrospermopsis raciborskii and
           Aphanizomenon gracile isolated in Poland
    • Authors: Piotr Rzymski; Barbara Poniedziałek; Joanna Mankiewicz-Boczek; Elisabeth J. Faassen; Tomasz Jurczak; Ilona Gągała-Borowska; Andreas Ballot; Miquel Lürling; Mikołaj Kokociński
      Pages: 72 - 80
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Piotr Rzymski, Barbara Poniedziałek, Joanna Mankiewicz-Boczek, Elisabeth J. Faassen, Tomasz Jurczak, Ilona Gągała-Borowska, Andreas Ballot, Miquel Lürling, Mikołaj Kokociński
      Aphanizomenon gracile and Cylindrospermopsis raciborskii are extensively studied Nostocales of wide geographical distribution and have potential to produce toxins. However, a number of knowledge gaps regarding their toxicity and related health risks in certain locations, including Europe, exists. The present study applied a polyphasic approach to screen the toxicity of different strains of C. raciborskii (LBY-Cr, LBO-Cr and LKM-Cr) and A. gracile (LBY-Ag, LBN-Ag and LWI-Ag) isolated from five freshwater lakes of Western Poland. The following investigations were carried out: (i) in vitro toxicological studies employing human cells isolated from healthy donors; (ii) analytical screening for the presence of cylindrospermopsin (CYN), guanidinoacetate (GAA; initial CYN precursor and postulated general cyanobacterial metabolite), three microcystin (MC) analogues, β-N-methylamino-l-alanine (BMAA) and its isomer α-γ,-diaminobutyric acid (DAB), anatoxin-a (ATX) and ten saxitoxin (STX) analogues; and (iii) molecular studies of genes involved in CYN, GAA, MCs and ATX biosynthesis. Extracts of C. raciborskii LBY-Cr and A. gracile LBN-Ag caused a significant increase in the intracellular reactive oxygen content in human neutrophils during short-term (1h) exposure and also led to lipid peroxidation and cell death. No cytotoxic effects were noted for the other tested strains. None of the toxin genes (cyrA, cyrJ, anaF and mcyE) and toxins (CYN, GAA, MCs, BMAA, ATX and STX) were detected. The only exception was DAB found at a concentration below 1.0μgg−1 dw in A. gracile LWI-Ag. It is the first time that cyanobacterial DAB producer has been identified in the Central European region. The study points to the production of as yet unknown metabolite(s) that may pose a relevant threat to human health through strains of C. raciborskii and A. gracile isolated from two Polish lakes, and adds to the general understanding of the toxicity of European strains of both species.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.02.011
      Issue No: Vol. 24 (2017)
  • Seeding filamentous Ulva tepida on free-floating surfaces: A novel
           cultivation method
    • Authors: Christina Praeger; Rocky de Nys
      Pages: 81 - 88
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Christina Praeger, Rocky de Nys
      The selection of seaweed species for the integrated cultivation in land-based aquaculture systems is primarily based on the ability to grow in free-floating cultures thereby increasing stocking densities and areal biomass productivity. We assessed a novel approach to enable the free-floating cultivation of seaweed species that are dependent on the attachment to surface structures by seeding zoids of Ulva tepida onto small surfaces which float in the water column. In this study we firstly assessed how the density of settlement surfaces (hereafter referred to as ‘bioballs’) and density of zoids influenced the settlement onto bioballs, and secondly how the stocking density of these seeded bioballs affected the biomass yield in outdoor cultivation over a 35day period. Settlement was not affected by the density of bioballs with zoids settling evenly across bioball treatments. The number of zoids that settled successfully increased with increasing density. However, both seeding factors (density of bioballs and zoids) had a minimal effect on growth rates, yield of biomass per bioball and total biomass harvested, which were primarily affected by stocking density. Low stocking density generally resulted in higher growth rates and yield of biomass per bioball, although the total yield was lower compared to higher stocking densities. Overall, growth rates decreased over time for all stocking densities with a sharp decrease from 27days of outdoor cultivation and onwards due to reproductive events. Our study demonstrates that the rate of biomass production of U. tepida is primarily driven by the stocking density of seeded bioballs, and underlines the importance of short cultivation cycles with harvest prior to reproduction. This novel cultivation method enables the free-floating cultivation of species that normally depend on attachment to fixed surfaces and thereby expands the range of seaweed species for land-based cultivation.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.003
      Issue No: Vol. 24 (2017)
  • Metal bioremediation by CrMTP4 over-expressing Chlamydomonas reinhardtii
           in comparison to natural wastewater-tolerant microalgae strains
    • Authors: Aniefon Ibuot; Andrew P. Dean; Owen A. McIntosh; Jon K. Pittman
      Pages: 89 - 96
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Aniefon Ibuot, Andrew P. Dean, Owen A. McIntosh, Jon K. Pittman
      Metal pollution in freshwater bodies is a long-standing challenge with large expense required to clean-up pollutants such as Cd. There is widespread interest in the potentially low-cost and sustainable use of biological material to perform bioremediation, such as the use of microalgae. Efficient metal bioremediation capacity requires both the ability to tolerate metal stress and metal accumulation. Here, the role of a Chlamydomonas reinhardtii metal tolerance protein (MTP) was examined for enhanced Cd tolerance and uptake. The CrMTP4 gene is a member of the Mn-CDF clade of the cation diffusion facilitator family of metal transporters but is able to provide tolerance and sequestration for Mn and Cd, but not other metals, when expressed in yeast. Over-expression of CrMTP4 in C. reinhardtii yielded a significant increase in tolerance to Cd toxicity and increased Cd accumulation although tolerance to Mn was not increased. In comparison, the metal tolerance of three chlorophyte microalgae strains (Chlorella luteoviridis, Parachlorella hussii, and Parachlorella kessleri) that had previously been adapted to wastewater growth was examined. In comparison to wild type C. reinhardtii, all three natural strains showed significantly increased tolerance to Cd, Cu, Al and Zn, and furthermore their Cd tolerance and uptake was greater than that of the CrMTP4 over-expression strains. Despite CrMTP4 gene over-expression being a successful strategy to enhance the Cd bioremediation potential of a metal-sensitive microalga, a single gene manipulation cannot compete with naturally adapted strain mechanisms that are likely to be multigenic and due in part to oxidative stress tolerance.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.algal.2017.03.002
      Issue No: Vol. 24 (2017)
  • Domoic acid: Attributes, exposure risks, innovative detection techniques
           and therapeutics
    • Authors: Abdullah F. Saeed; Saima Ashraf Awan; Sumei Ling; Rongzhi Wang; Shihua Wang
      Pages: 97 - 110
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Abdullah F. Saeed, Saima Ashraf Awan, Sumei Ling, Rongzhi Wang, Shihua Wang
      Domoic acid is a potent neurotoxin, glutamate agonist and natural marine biotoxin. It is produced by several diatom algal species of genetically diverse genus Pseudo-nitzschia, red alga Chondria armata and other related species. Historically, widespread domoic acid intoxication incidents have occurred globally. Particularly, in 1987, domoic acid caused an outbreak of human poisoning in Canada by the consumption of contaminated blue mussels (Mytilus edulis) that gave rise to countless clinical illnesses and human deaths. The toxin targets glutamate receptors present in various vital organs and a cascade of ailments characterized the poisoning. The specifically listed neural disorders include memory impairment, coma, recurrent seizures, and epilepsy that led to the name amnesic shellfish poisoning. The occurrence of domoic acid in test samples has been determined by various novel techniques such as liquid chromatography-mass spectrometry, biosensors, enzyme-linked immunosorbent assay and other related hi-tech detection methods. Since the Canada incident, the toxin has intoxicated several marine mammals, sea birds, and contaminated colonized coastal waters around the globe. Subsequently, domoic acid producing algal blooms are accelerating frequently worldwide. Therefore, it poses a global health, safety threat and exposure risks to a significant number of marine and human lives. Genetics of domoic acid producing algal species, molecular markers and therapeutics are currently least known. Therefore, the present review addresses intriguing attributes of domoic acid, such as physicochemical, pharmacological and biological features, sources, and genetic diversity of the producers. In addition, exposure risks including toxicologic pathology of domoic acid poisoning, neurotoxic pathways, detection methods and therapeutics have been inclusively discussed.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.02.007
      Issue No: Vol. 24 (2017)
  • Green compressed fluid technologies for downstream processing of
           Scenedesmus obliquus in a biorefinery approach
    • Authors: Bienvenida Gilbert-López; José A. Mendiola; Lambertus A.M. van den Broek; Bwee Houweling-Tan; Lolke Sijtsma; Alejandro Cifuentes; Miguel Herrero; Elena Ibáñez
      Pages: 111 - 121
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Bienvenida Gilbert-López, José A. Mendiola, Lambertus A.M. van den Broek, Bwee Houweling-Tan, Lolke Sijtsma, Alejandro Cifuentes, Miguel Herrero, Elena Ibáñez
      The fractionation of algae biomass in several high-value compounds that can be used as ingredients in other applications sets the basis of the algae biorefinery approach. The present study aimed at the extraction and fractionation of bioactive compounds from the microalga Scenedesmus obliquus, by means of applying a sequential process without the manipulation of the biomass in the extraction cell. This integrated platform of compressed fluid extraction technologies of low-environmental impact was designed in order to produce increases of solvent polarity using non-toxic solvents. The process involved the following steps:(1) supercritical fluid extraction (SFE) using supercritical carbon dioxide (ScCO2); (2) gas expanded liquids (GXL) using 75% ethanol and 25% ScCO2 (v/v) and; (3) pressurized liquid extraction (PLE) using water. Extraction conditions were optimized using response surface methodology (RSM) and kinetic studies. Extraction yield, antioxidant activity as well as contents of total phenols, carotenoids, proteins and sugars were the studied response variables. High performance liquid chromatography coupled to evaporative light-scattering detector (HPLC-ELSD) analyses of the fractions revealed that triacylglycerols were mainly extracted by SFE. Lutein and β-carotene were the main pigments identified in the extracts by HPLC coupled to diode array and mass spectrometry detectors (HPLC-DAD-MS/MS), which were preferentially extracted in the GXL step. Polar compounds such as proteins and sugars remained predominantly in the residue. Therefore, the green downstream platform developed in this study for valorization of the microalgae biomass, is able to produce different fractions with potential application in the food, pharmaceutical and cosmetic industries.
      Graphical abstract image

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.011
      Issue No: Vol. 24 (2017)
  • Identification of the role of polar glycerolipids in lipid metabolism and
           their acyl attribution for TAG accumulation in Nannochloropsis oceanica
    • Authors: Yingying Meng; Xupeng Cao; Changhong Yao; Song Xue; Qing Yang
      Pages: 122 - 129
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Yingying Meng, Xupeng Cao, Changhong Yao, Song Xue, Qing Yang
      Nannochloropsis, an ocean microalgal genus, is a promising resource of biodiesel feedstock because of its capacity for triacylglycerol (TAG) accumulation. Polar glycerolipids have big contribution for TAG accumulation by providing acyl group or diacylglycerol (DAG). Due to the diversities and amount of polar glycerolipids in species, a suitable approach has not been developed well to quantify and qualify, which veils the clarification of how important roles the polar glycerolipids play in microalgal lipid metabolism and TAG accumulation. In this study, a total of 112 polar glycerolipid species, covering eight classes, were identified using UPLC/Q-TRAP plus Orbitrap coupled with quantified using UPLC/Q-TOF. A comprehensive profiling of polar glycerolipid was established to study the polar glycerolipids variations in response to nitrogen deprivation in Nannochloropsis oceanica. Through targeted lipidomics analysis it was proposed that in N. oceanica, phosphatidylcholine (PC) serve as linoleic and γ-linolenic acyl donors via oleic acyl desaturation, and under nitrogen stress condition PC transfers acyl 16:0 and 18:1 to TAG. The result disclosed PC played import roles for TAG accumulation not only in high plants but also in PC-containing microalgae even PC is not the most extraplastidial lipid. In addition, it was showed that phosphatidylethanolamine (PE) and diacylglyceryl-N-trimethylhomoserine (DGTS) are suppliers of eicosapentaenoic acid (EPA) to other lipids. These new discoveries reveal the diversity of microalgae in acyl metabolism and shed light on the understanding of lipid biosynthesis by stoichiometry.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.004
      Issue No: Vol. 24 (2017)
  • Neutral sugars determination in Chlorella: Use of a one-step dilute
           sulfuric acid hydrolysis with reduced sample size followed by HPAEC
    • Authors: Marcella Fernandes de Souza; Daniel Santos Pereira; Suely Pereira Freitas; Elba Pinto da Silva Bon; Marcoaurélio Almenara Rodrigues
      Pages: 130 - 137
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Marcella Fernandes de Souza, Daniel Santos Pereira, Suely Pereira Freitas, Elba Pinto da Silva Bon, Marcoaurélio Almenara Rodrigues
      The accurate determination of the chemical composition of microalgae is essential when evaluating their potential as feedstock for the production of biofuels and biochemicals. The usual methodology for the determination of total microalgal carbohydrate content combines a two-step acid hydrolysis of the microalgal biomass with an analysis of the released monosaccharides using phenol-sulfuric acid, but the latter is a hazardous procedure. Alternatively, the sugar monomers that are present in the acid hydrolysate can be identified using high performance liquid chromatography (HPLC), whose accuracy may be compromised by compounds derived from the complex cell composition of the microalgae. Aiming to further the extant analytical procedures for determination of the neutral sugar content in microalgae of the Chlorella genus, the present study evaluated a one-step dilute sulfuric acid hydrolysis followed by the analysis of the released monosaccharides using high performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). The proposed HPAEC-PAD method proved to be specific, sensitive, accurate, precise and robust. The one-step dilute sulfuric acid hydrolysis process showed an acceptable correlation with the widely used two-step technique for the determination of total neutral sugars in Chlorella, despite the use of a sixfold smaller sample size. The method was also successfully applied to Mychonastes homosphaera, another green microalga of the phylum Chlorophyta, indicating its applicability for broader use beyond the Chlorella genus. Furthermore, the combination of both methods is proposed as a useful tool to evaluate recalcitrant glucose moieties in microalgal biomass.
      Graphical abstract image

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.019
      Issue No: Vol. 24 (2017)
  • Potential prebiotic oligosaccharides from aqueous thermopressurized
           phosphoric acid hydrolysates of microalgae used in treatment of gaseous
           steakhouse waste
    • Authors: Bruna Elise Sauer Leal; Marcelo Real Prado; Adelia Grzybowski; Marcela Tiboni; Heidegrid Siebert Koop; Lucas Blitzkow Scremin; Anderson Cardoso Sakuma; Alexandre Akira Takamatsu; Augusto Farfus dos Santos; Valeria Ferreira Cavalcanti; José Domingos Fontana
      Pages: 138 - 147
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Bruna Elise Sauer Leal, Marcelo Real Prado, Adelia Grzybowski, Marcela Tiboni, Heidegrid Siebert Koop, Lucas Blitzkow Scremin, Anderson Cardoso Sakuma, Alexandre Akira Takamatsu, Augusto Farfus dos Santos, Valeria Ferreira Cavalcanti, José Domingos Fontana
      Microalgae have been utilized in CO2 biomitigation processes for the production of cellular biomass, which can be utilized for nutritional and commercial purposes. In this study, potential prebiotic oligosaccharides were obtained from microalgal biomass via phosphoric acid hydrolysis under moderate pH and thermopressurization conditions. The biomass extracted from a gaseous effluent treatment system at a local steakhouse was compared with the commercial microalga Chlorella vulgaris and cyanobacterium Arthrospira platensis. These biomasses were microscopically and physico-chemically analyzed, subjected to a 32 factorial design, and partially hydrolyzed by thermopressurization. The resulting oligosaccharide samples were used as carbon sources for culturing the probiotic microorganisms Bifidobacterium animalis and Lactobacillus casei. These oligosaccharides allowed for beneficial bacterial growth and the production of short-chain fatty acids, such as lactic and acetic acids. This research indicates the feasibility of potential prebiotic oligosaccharide production from microalgal biomass and simultaneously adds value to this by-product of gaseous waste treatment.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.020
      Issue No: Vol. 24 (2017)
  • Modification of hydrothermal liquefaction products from Arthrospira
           platensis by using carbon dioxide
    • Authors: Dongho Choi; Jechan Lee; Yiu Fai Tsang; Ki-Hyun Kim; Jörg Rinklebe; Eilhann E. Kwon
      Pages: 148 - 153
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Dongho Choi, Jechan Lee, Yiu Fai Tsang, Ki-Hyun Kim, Jörg Rinklebe, Eilhann E. Kwon
      This study mainly reports that utilizing CO2 as a reaction medium in hydrothermal liquefaction of Arthrospira platensis, as a model feedstock of microalgal biomass, provides a means for modifying the chemical constituents in microalgal bio-oil produced via hydrothermal liquefaction. Prior to hydrothermal liquefaction, the total lipid content of A. platensis was measured as ~3.5wt% (dry basis). Thermal degradation of A. platensis and the major pyrolytic gases from the thermal degradation of A. platensis were characterized to gain an insight into the physico-chemical influences of CO2 in hydrothermal liquefaction. Based on the experiment's findings, hydrothermal liquefaction of A. platensis was conducted to evaluate the influence of CO2. Hydrothermal liquefaction of A. platensis in CO2 decreased the composition of N-containing species from 63 to 59% and that of O-containing species from 31 to 27% in the bio-oil, significantly suggesting that using CO2 improves the quality of bio-oil as a transportation fuel.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.017
      Issue No: Vol. 24 (2017)
  • Cross-study analysis of factors affecting algae cultivation in recycled
           medium for biofuel production
    • Authors: Sarah E. Loftus; Zackary I. Johnson
      Pages: 154 - 166
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Sarah E. Loftus, Zackary I. Johnson
      Current high costs of commercial-scale algal biofuel production prevent the widespread use of this renewable fuel source. One cost-saving approach is the reuse of algae cultivation water after biomass harvesting, which reduces water pumping and treatment costs. However, dissolved compounds, cell debris, and microorganisms remaining in the water could affect subsequent algae generations. Previous studies demonstrate a variety of effects of recycled medium on algae growth, yet their results have not been collectively analyzed. Here we integrate data across 86 studies to determine the relative importance of different factors influencing algae growth in recycled medium. We found that algae taxa can have the greatest influence, while the harvesting method is less influential on growth outcomes. This meta-analysis identifies favorable taxa and thus provides a tool for algae cultivation decision-making when medium reuse is an important driver. Results can also aid in estimating relative algae yield and growth rates for technoeconomic assessments that incorporate water recycling.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.007
      Issue No: Vol. 24 (2017)
  • Polyelectrolyte flocculants in harvesting microalgal biomass for food and
           feed applications
    • Authors: Lucie Van Haver; Sasi Nayar
      Pages: 167 - 180
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Lucie Van Haver, Sasi Nayar
      Harvesting microalgal biomass at industrial scale is a techno-economic bottleneck for the algal biomass industry, compounded by the small cell size of microalgae and dilute biomass concentrations in culture. As a result, large volumes of water need to be removed during harvesting, making the process energy and cost intensive, accounting for up to 30% of the total cost of biomass production. Among the various harvesting techniques adopted commercially, flocculation is convenient and cost effective. The choice of a flocculant depends on its effectiveness on multiple microalgal strains, efficiencies at low biomass concentrations, its environmental footprint, being inexpensive and non-toxic for end application of the recovered biomass. Of the various flocculants, polyelectrolyte flocculants are widely utilised for various industrial applications such as wastewater treatment and mining, but also for effective harvesting of mass cultures of microalgae. Polyelectrolyte flocculants are polymers that are either branched or linear, but carrying ionic charge along their chain. They are accordingly classified as cationic, anionic or non-ionic polymers. These flocculants neutralise surface charges on cells and bind particles together by physical or chemical forces. The efficiency of polyelectrolyte flocculants depend on the type of polymer used, its molecular weight and charge density, dosage concentrations, cell concentration in the medium, type of strain, ionic strength and pH of the medium, and other parameters. Bulk harvesting of toxicant free microalgal biomass by polyelectrolyte flocculants is regarded to be one of the most economically viable techniques, with the cost of flocculants ranging between US$1.50 and 7.50kg−1, and requiring very low dosage for effective harvesting. This review focusses on polyelectrolyte flocculants to harvest cultivated microalgae for non-toxic residue free applications of the harvested biomass in the food and the feed industry and evaluates various commercial polyelectrolyte flocculants, their properties and application in harvesting microalgal biomass from high density cultures.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.022
      Issue No: Vol. 24 (2017)
  • Pulsed Electric Field for protein release of the microalgae Chlorella
           vulgaris and Neochloris oleoabundans
    • Authors: G.P. 't Lam; P.R. Postma; D.A. Fernandes; R.A.H. Timmermans; M.H. Vermuë; M.J. Barbosa; M.H.M. Eppink; R.H. Wijffels; G. Olivieri
      Pages: 181 - 187
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): G.P. 't Lam, P.R. Postma, D.A. Fernandes, R.A.H. Timmermans, M.H. Vermuë, M.J. Barbosa, M.H.M. Eppink, R.H. Wijffels, G. Olivieri
      Pulsed Electric Field (PEF) is currently discussed as promising technology for mild and scalable cell disintegration of microalgae. In this study Chlorella vulgaris and Neochloris oleoabundans have been subjected to batch and continuous PEF treatments under a wide range of operating conditions (1–40 pulses, 0.05–5ms pulses, 7.5–30kV cm−1, 0.05–150 kWhkgDW −1). In many cases after treatment, both algal species show release of ions, which indicates that PEF treatment resulted in permeabilization of the algal cell. However, the electroporation effect was not sufficient to substantially release intracellular proteins. Even at severe energy input (10 to 100 times higher than bead milling) only up to 13% of proteins released from the cells in comparison to 45–50% after bead milling.

      PubDate: 2017-04-02T13:07:37Z
      DOI: 10.1016/j.algal.2017.03.024
      Issue No: Vol. 24 (2017)
  • Catalytic upgrading of fractionated microalgae bio-oil (Nannochloropsis
           oculata) using a noble metal (Pd/C) catalyst
    • Authors: Hyungseok Nam; Changkyu Kim; Sergio C. Capareda; Sushil Adhikari
      Pages: 188 - 198
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Hyungseok Nam, Changkyu Kim, Sergio C. Capareda, Sushil Adhikari
      Pyrolytic bio-oil was chemically upgraded after physically distilled upgrades to meet the petroleum transportation fuel substitute. A Pd/C catalyst was used to upgrade the microalgae pyrolytic bio-oil to determine the effect of different distillation fractions and catalytic upgrading conditions on the yields and properties. The middle distillation fraction (F2) was upgraded under various temperature (130 to 250°C) and pressure (4.1 to 8.3MPa) conditions based on response surface methodology (RSM). The light distillation fraction (F1) and raw bio-oil were also catalytically upgraded for the comparison. The distillation step prior to catalytic upgrading led to a better quality of upgraded bio-oil compared to the direct bio-oil upgrades. Both the oxygen and hydrogen contents of light and middle fraction upgrades were improved, while the upgraded raw bio-oil showed limited improvement. The other properties of HHV and TAN with the middle fraction upgrades were improved to 42.9MJ/kg and 1.09mgKOH/g, respectively, at the severe condition as most of the ketones in upgrades were removed. Also, paraffin and aromatic chemical groups were significantly produced at the expense of the olefin groups through hydrogenation and hydrodeoxygenation. Thus, the catalytic upgrading after a distillation stage enhanced the quality of biofuel that can be a petroleum fuels substitute or additives.
      Graphical abstract image

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.021
      Issue No: Vol. 24 (2017)
  • Enhancement of microalgae anaerobic digestion by thermo-alkaline
           pretreatment with lime (CaO)
    • Authors: Maria Solé-Bundó; Hélène Carrère; Marianna Garfí; Ivet Ferrer
      Pages: 199 - 206
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Maria Solé-Bundó, Hélène Carrère, Marianna Garfí, Ivet Ferrer
      The aim of this study was to evaluate for the first time the effect of a thermo-alkaline pretreatment with lime (CaO) on microalgae anaerobic digestion. The pretreatment was carried out by adding different CaO doses (4 and 10%) at different temperatures (room temperature (25°C), 55 and 72°C). The exposure time was 4days for pretreatments at 25°C, and 24h for pretreatments at 55 and 72°C. Following, a biochemical methane potential test was conducted with pretreated and untreated microalgae. According to the results, the pretreatment enhanced proteins solubilisation by 32.4% and carbohydrates solubilisation by 31.4% with the highest lime dose and temperature (10% CaO and 72°C). Furthermore, anaerobic digestion kinetics were improved in all cases (from 0.08 to 0.14day−1 for untreated and pretreated microalgae, respectively). The maximum biochemical methane potential increase (25%) was achieved with 10% CaO at 72°C, in accordance with the highest biomass solubilisation. Thus, lime pretreatment appears as a potential strategy to improve microalgae anaerobic digestion.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.025
      Issue No: Vol. 24 (2017)
  • A novel activation domain is essential for CIA5-mediated gene regulation
           in response to CO2 changes in Chlamydomonas reinhardtii
    • Authors: Bo Chen; Kwanghong Lee; Tom Plucinak; Deqiang Duanmu; Yingjun Wang; Kempton M. Horken; Donald P. Weeks; Martin H. Spalding
      Pages: 207 - 217
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Bo Chen, Kwanghong Lee, Tom Plucinak, Deqiang Duanmu, Yingjun Wang, Kempton M. Horken, Donald P. Weeks, Martin H. Spalding
      The inducible CO2 concentrating mechanism (CCM) of microalgae is essential for their acclimation to highly variable aquatic inorganic carbon levels. The key transcriptional regulator, CIA5, affects expression of thousands of genes in Chlamydomonas reinhardtii, but the molecular characteristics of this important protein are poorly understood. This study identifies a functional activation domain in CIA5 and demonstrates the functionality of a mini-CIA5 including only the zinc-binding domain and the identified activation domain. A highly conserved 130aa region from CIA5 exhibits auto-activation in yeast and appears responsible for the markedly slow migration of CIA5 when analyzed by SDS-PAGE. This 130aa region or either half of this region also effectively replaced the activation domain of a modified designer Transcription Activator-like Element (dTALE) in targeted activation of an endogenous Chlamydomonas gene. Additionally, a mini-CIA5 combining the conserved zinc-binding domain with the 130aa putative activation domain complemented the growth phenotype of the cia5 mutant and triggered CO2-regulated gene expression patterns similar to wild-type cells or cia5 complemented with the full-length CIA5. Although the mini-CIA5 complementation did not fully restore wild-type growth rates or full gene induction/repression amplitudes, especially in very low CO2, this newly identified activation domain combined with the previously described zinc-binding domain are demonstrated to be the key essential components of CIA5 that permit rapid CIA5-mediated responses to changes in CO2 concentrations.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.006
      Issue No: Vol. 24 (2017)
  • Growth of microalgae on undiluted anaerobic digestate of piggery effluent
           with high ammonium concentrations
    • Authors: Jeremy Miles Ayre; Navid Reza Moheimani; Michael Armin Borowitzka
      Pages: 218 - 226
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Jeremy Miles Ayre, Navid Reza Moheimani, Michael Armin Borowitzka
      Anaerobic digestate of piggery effluent (ADPE) is extremely high in ammonia toxic to many microorganisms. Bioprospecting and nutrient enrichment of several freshwater and wastewater samples combined and further acclimation resulted in a mixed culture containing at least three microalgae species capable of growing on undiluted ADPE. Outdoor growth of the mixed culture using raceway ponds showed potential for up to 63.7±12.1mg N-NH 4 + L −1 d −1 ammonium removal from the ADPE. The microalgal consortium was dominated by Chlorella sp. and was stable at between 800 and 1600mg N-NH 4 + L −1. Regulation of CO2 addition to the ponds to maintain a pH of 8 increased chlorophyll content of the microalgal consortium. Average microalgal biomass productivity of 800mg N-NH 4 + L −1 culture conditions during five weeks semicontinuous growth was 18.5mgash-freedryweightL −1 d −1. Doubling the ammonium concentration from 800 to 1600mg N-NH 4 + L −1 resulted in a 21% reduction of productivity, however the culture grown at 1600mg N-NH 4 + L −1 with the addition of CO2 by keeping pH at pH=8 led to a 17% increase in biomass productivity.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.023
      Issue No: Vol. 24 (2017)
  • A comparative study of photosynthetic unit models for algal growth rate
           and fluorescence prediction under light/dark cycles
    • Authors: Paul Rudnicki; Xi Gao; Bo Kong; R. Dennis Vigil
      Pages: 227 - 236
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Paul Rudnicki, Xi Gao, Bo Kong, R. Dennis Vigil
      Accurate description of light-limited algal growth, especially under short light/dark (L/D) cycles, is crucial for prediction of photobioreactor performance and for optimization of operating conditions. Here, a variety of widely used photosynthetic unit (PSU)-based models are evaluated to determine their ability to predict algal specific growth rate and photochemical efficiency under a range of light/dark cycle conditions. Six models were fit to previously published experimental data for algal specific growth rate and photochemical efficiency. Subsequently the weighted sum of squared error (SSE) values, normalized sensitivities to parameter change, and corrected Akaike Information Criterion (AICc) scores were compared. The quality of the fits and the model sensitivities were used to evaluate the assumptions and relative merits of the models considered. For the available data under light/dark cycling conditions, the Bernardi Model scored significantly better on the AICc measure and shows good potential for future use in predicting algal behavior under L/D cycles.

      PubDate: 2017-04-09T10:44:46Z
      DOI: 10.1016/j.algal.2017.03.028
      Issue No: Vol. 24 (2017)
  • The glutathione transferase family of Chlamydomonas reinhardtii:
           Identification and characterization of novel sigma class-like enzymes
    • Authors: Marianna Chatzikonstantinou; Dimitrios Vlachakis; Evangelia Chronopoulou; Louis Papageorgiou; Anastassios C. Papageorgiou; Nikolaos E. Labrou
      Pages: 237 - 250
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Marianna Chatzikonstantinou, Dimitrios Vlachakis, Evangelia Chronopoulou, Louis Papageorgiou, Anastassios C. Papageorgiou, Nikolaos E. Labrou
      Understanding the genetic and molecular basis of the detoxifying mechanism in Chlamydomonas reinhardtii is an important goal towards the development of bioremediation tools for contaminated environments. Glutathione transferases (GSTs, EC are phase II metabolic enzymes that play important role in the detoxification of xenobiotic compounds. GSTs have been characterized extensively in land plants and animals but no evidence has yet been reported for their presence in C. reinhardtii. A genome survey of C. reinhardtii revealed the presence of fifteen GST-like isoenzymes (CrGSTs). Comparison by multiple sequence alignment generated a dendrogram, revealing the phylogenetic relationships of CrGSTs with other well-characterized GST classes. Notably, we identified sequences that are most closely related to the sigma class enzymes which so far have only been found in animals. Two sigma class related isoenzymes (CrGST10 and CrGST7) were cloned, expressed in E. coli and their substrate specificity and kinetic properties were determined towards a range of different xenobiotic substrates. The structural and kinetic features of the enzymes were studied by molecular modelling and site-directed mutagenesis. The catalytic role of active-site residue Tyr7 and the roles of Trp99 in determining substrate specificity and thermostability were investigated. Analysis of GSTome in green algae provides an opportunity to shine light on the roles of GSTs in cellular detoxification mechanism as well as to develop new biotechnological and environmental applications.

      PubDate: 2017-04-16T11:25:30Z
      DOI: 10.1016/j.algal.2017.03.010
      Issue No: Vol. 24 (2017)
  • Simulation of energy balance and carbon dioxide emission for microalgae
           introduction in wastewater treatment plants
    • Authors: Eva Nordlander; Jesper Olsson; Eva Thorin; Emma Nehrenheim
      Pages: 251 - 260
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Eva Nordlander, Jesper Olsson, Eva Thorin, Emma Nehrenheim
      A case study is described in which the activated sludge process is replaced with a microalgae-activated sludge process. The effects on the heat and electricity consumption and carbon dioxide emissions were evaluated in a system model, based on mass and energy balances of biological treatment and sludge handling process steps. Data for use in the model was gathered from three wastewater treatment plants in Sweden. The evaluation showed that the introduction of microalgae could reduce electricity and heat consumption as well as CO2 emissions but would require large land areas. The study concludes that a 12-fold increase in the basin surface area would result in reductions of 26–35% in electricity consumption, 7–32% in heat consumption and 22–54% in carbon dioxide emissions. This process may be suitable for wastewater treatment plants in Nordic countries, where there is a higher organic load in summer than at other times of the year. During the summer period (May to August) electricity consumption was reduced by 50–68%, heat consumption was reduced by 13–63% and carbon dioxide emissions were reduced by 43–103%.

      PubDate: 2017-04-16T11:25:30Z
      DOI: 10.1016/j.algal.2017.03.026
      Issue No: Vol. 24 (2017)
  • A perspective on renewable bioenergy from photosynthetic algae as
           feedstock for biofuels and bioproducts
    • Authors: Lieve M.L. Laurens; Melodie Chen-Glasser; James D. McMillan
      Pages: 261 - 264
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Lieve M.L. Laurens, Melodie Chen-Glasser, James D. McMillan
      There has been substantial technical progress in developing algae-based bioenergy in recent years and a large part of industry and academic research and deployment projects have pivoted away from a pure biofuels strategy. This letter summarizes the findings of a recently completed, comprehensive report, that represents a collaborative effort of at least 20 co-authors, where we analyzed the prospects for using microalgae and macroalgae as feedstocks for biofuels and bioenergy production. The scope of this report includes a discussion of international activities advancing bioenergy and non-energy bioproducts from algae, progress on the use of macroalgae (both cast and cultivated seaweeds) for biogas applications, distinct biochemical and thermochemical conversion pathways, multi-product biorefining opportunities, as well as a thorough review of process economics and sustainability considerations. It is envisioned that a higher value algal biomass-based bioproducts industry will provide the additional revenue needed to reduce the net cost of producing algae-based biofuels. As such, a biorefinery approach that generates multiple high-value products from algae will be essential to fully valorize algal biomass and enable economically viable coproduction of bioenergy. To accelerate the implementation of algae-based production, minimizing energy, water, nutrients and land use footprints of integrated algae-based operations needs to be a primary objective of larger scale demonstrations and future research and development.

      PubDate: 2017-04-16T11:25:30Z
      DOI: 10.1016/j.algal.2017.04.002
      Issue No: Vol. 24 (2017)
  • Microalgal biomass dewatering using forward osmosis membrane: Influence of
           microalgae species and carbohydrates composition
    • Authors: Mathieu Larronde-Larretche; Xue Jin
      Pages: 12 - 19
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Mathieu Larronde-Larretche, Xue Jin
      The potential application of forward osmosis (FO) in microalgae dewatering requires an improved understanding of the factors that control membrane fouling which can reduce dewatering performance in terms of water flux through membrane and algae recovery. The aim of this study was to elucidate the influence of algae cell wall carbohydrate composition on the FO dewatering performance using three types of draw solutions (sea salts, MgCl2 and CaCl2). Experimental results suggest that the interaction between microalgae and back diffused draw solutes plays a key role. Scenedesmus obliquus with fructose and abundant glucose and mannose in its cell wall showed strong response to the back diffusion of calcium ions which encouraged S. obliquus to produce more extracellular carbohydrates and formed a stable gel network between algal biomass and extracellular carbohydrates, leading to algae aggregation and severe loss in both water flux and algae biomass during FO dewatering with Ca2+-containing draw solution. Chlamydomonas reinhardtii without fructose but great galactose showed a similar response to the calcium back diffusion but to a lower extent. Both S. obliquus and C. reinhardtii did not cause obvious membrane fouling but dramatic algae biomass loss at the end of FO filtration with MgCl2 draw solution due to their interaction with back diffused Mg2+ ions which led to the deposition of algae flocs onto membrane surface and/or feed spacer. Chlorella vulgaris without fructose was the most suitable microalgae species to be dewatered by FO with algae recovery over 81% and negligible flux decline regardless of which draw solution was applied. The findings improve mechanical understanding of FO membrane fouling by microalgae; have significant implications for the algae species selection; and are critical for the development and optimization of FO dewatering processes.

      PubDate: 2017-01-14T18:45:03Z
      DOI: 10.1016/j.algal.2016.12.020
      Issue No: Vol. 23 (2017)
  • Parameterization of a light distribution model for green cell growth of
           microalgae: Haematococcus pluvialis cultured under red LED lights
    • Authors: Xin Gao; Xinyu Wang; Haijun Li; Sanja Roje; Shyam S. Sablani; Shulin Chen
      Pages: 20 - 27
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Xin Gao, Xinyu Wang, Haijun Li, Sanja Roje, Shyam S. Sablani, Shulin Chen
      A light distribution model is a prerequisite for establishing an algal growth model. Based on approaches to account for light intensity, algal productivity models can be divided into three types, Type I models predict the rate of photosynthesis, Type II models computes productivity and Type III models considers the impacts of both light gradients and short light cycles. Among these, Type II models may offer the best compromise between accuracy and practicability for full-scale engineering applications. Addressing the need for examining indoor seed preparation of Haematococcus pluvialis under red LED irradiation, this study advanced a Type II model based on light distribution. The model was parameterized for green cell growth of Haematococcus pluvialis using the Gauss-Newton and bootstrap methods. The parameters k1 and k2 from the hyperbolic Beer-Lambert law of the two-flux model were 118.8±5.2m−1 and 0.25±0.04gL−1, with 95% confidence intervals of (111.6, 129.8) and (0.20, 0.33), respectively. The parameterized model was validated against experimental results, with the largest error and relative error of 0.08μmol/m2/s and 10.5%, respectively. Validation results demonstrate that the established model was reliable and could accurately predict the light intensity for indoor cultivation of Haematococcus pluvialis in the green stage. This study demonstrated that the effectiveness of using the bootstrap method to accurately estimate the parameters in these types of models. It provided information on model parameters, including standard deviation and 95% confidence intervals. This model also applied many more data points (89 in this study) to estimate parameters to reduce error. The results filled a technological gap for modeling the light distribution of indoor seed preparation of Haematococcus pluvialis under red LED lights. The approach can be used to estimate the values of parameters from parametric models for other similar applications using the bootstrap method.

      PubDate: 2017-01-14T18:45:03Z
      DOI: 10.1016/j.algal.2016.12.018
      Issue No: Vol. 23 (2017)
  • A comparative assessment of microwave assisted (MAE) and conventional
           solid-liquid (SLE) techniques for the extraction of phloroglucinol from
           brown seaweed
    • Authors: Marie Magnusson; Alexander K.L. Yuen; Rui Zhang; Jeffrey T. Wright; Richard B. Taylor; Thomas Maschmeyer; Rocky de Nys
      Pages: 28 - 36
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Marie Magnusson, Alexander K.L. Yuen, Rui Zhang, Jeffrey T. Wright, Richard B. Taylor, Thomas Maschmeyer, Rocky de Nys
      Brown seaweeds are rich in polyphenols with a basic building block of 1,3,5-trihydroxybenzene (phloroglucinol) and were investigated as a bioresource for the extraction of polyphenols for biopolymers and bioproducts. Species of seaweed with high contents of polyphenols were identified through meta-analysis and selected for the comparative assessment of the extraction efficiency of polyphenols using microwave assisted (MAE) vs. conventional solid-liquid (SLE) extraction. Out of ten species from Australia and New Zealand screened by SLE, Carpophyllum flexuosum (8.6%) and C. plumosum (7.5%) had the highest contents of polyphenols and were selected for MAE along with commercially available Ecklonia radiata. C. flexuosum was identified as the key species for extraction of polyphenols, with a 70% increase in yield using optimized MAE (aqueous, biomass:solvent ratio 1:30, 160°C, 3min) compared to SLE. The cell-wall bound fraction of polyphenols in brown seaweed may be larger than previously thought and is accessible through MAE.

      PubDate: 2017-01-14T18:45:03Z
      DOI: 10.1016/j.algal.2017.01.002
      Issue No: Vol. 23 (2017)
  • Microalgae for oil. Assessment of fatty acid productivity in continuous
           culture by two high-yield strains, Chlorococcum oleofaciens and
           Pseudokirchneriella subcapitata
    • Authors: Esperanza Del Río; Elena García-Gómez; José Moreno; Miguel G. Guerrero; Mercedes García-González
      Pages: 37 - 42
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Esperanza Del Río, Elena García-Gómez, José Moreno, Miguel G. Guerrero, Mercedes García-González
      The influence of nitrate supply on the performance of Chlorococcum oleofaciens and Pseudokirchneriella subcapitata has been assessed in bubble-column photochemostats operating in continuous regime. Limitation in nitrate availability resulted in both increased fatty acid levels and diminished biomass productivity, although a disparity in the specific response of the strains was apparent. Evaluation of fatty acid productivity under different levels of nitrate supply revealed the superiority of P. subcapitata, with maximal values of 160mg fatty acids L−1 d−1, in comparison to 110 for C. oleofaciens. Under conditions of maximal oil yield, entailing moderate nitrate limitation, the biomass of both microalgae was enriched in saturated and monounsaturated fatty acids, thus displaying a more suitable profile as raw material for biodiesel. An analysis of the relationship between nitrogen content of the biomass and fatty acid levels reaffirmed the differential response of the strains to the restriction in nitrate availability. Differently from C. oleofaciens, accumulation of fatty acids in P. subcapitata was triggered with moderate nitrogen limitation, which had a mild effect on biomass production. The results support the adequacy of Pseudokirchneriella subcapitata as a high-yield source of fatty acids for biodiesel production.

      PubDate: 2017-01-21T09:00:44Z
      DOI: 10.1016/j.algal.2017.01.003
      Issue No: Vol. 23 (2017)
  • Establishment of axenic cultures from cyanobacterium Aphanizomenon
           flos-aquae akinetes by micromanipulation and chemical treatment
    • Authors: Sigitas Šulčius; Kristina Slavuckytė; Milda Januškaitė; Ričardas Paškauskas
      Pages: 43 - 50
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Sigitas Šulčius, Kristina Slavuckytė, Milda Januškaitė, Ričardas Paškauskas
      Filamentous cyanobacteria are an environmentally and biotechnologically important species. However, the isolation and purification techniques for these organisms remain poorly developed and rarely used in studies of their biology, ecology and growth requirements, mainly due to the need of species- or strain-specific approaches and labour-intensive work. Here we propose a simple protocol for the establishment of an axenic (pure) culture of filamentous cyanobacterium Aphanizomenon flos-aquae from its akinetes. We tested the effect of different physical and chemical treatments on akinetes viability and germination time, removal of epiphytic and contaminating bacteria and growth of the recovered cultures. The protocol consists of three steps: 1) capturing the A. flos-aquae akinetes using a micromanipulator, 2) akinete treatment with a TESC buffer, containing 1% of CTAB and 3) transferring the akinetes to the growth medium. We further demonstrate the increased growth of axenic A. flos-aquae compared to their bactericized counterparts, which provides insights into cyanobacteria-bacteria interactions.

      PubDate: 2017-01-28T17:00:58Z
      DOI: 10.1016/j.algal.2017.01.006
      Issue No: Vol. 23 (2017)
  • Alkaline phosphatase promoter as an efficient driving element for exogenic
           recombinant in the marine diatom Phaeodactylum tricornutum
    • Authors: Hung-Yun Lin; Shao-Chieh Yen; Po-Chih Kuo; Chih-Yu Chung; Kuan-Lin Yeh; Ching-Huei Huang; Jeng Chang; Han-Jia Lin
      Pages: 58 - 65
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Hung-Yun Lin, Shao-Chieh Yen, Po-Chih Kuo, Chih-Yu Chung, Kuan-Lin Yeh, Ching-Huei Huang, Jeng Chang, Han-Jia Lin
      A highly inducible promoter capable of actively expressing exogenous genes in diatoms is critical to further improving the utility of this organism as a low-cost platform for industrial applications. In this study, the functional promoter of alkaline phosphatase gene in Phaeodactylum tricornutum (PtAPase) was used to develop a novel vector. The pPhAP1-EGFP vector containing the putative promoter region of PtAPase (pPhAP1) with EGFP (enhanced green fluorescent protein) open reading frame attached to downstream side. Transgenic diatom clones containing the introduced pPhAP1-EGFP vector did not express EGFP fluorescent at high phosphate concentration, and exhibit growth curves similar to that of wild type strain. EGFP fluorescent was induced and actively expressed when ambient phosphate concentration was decreased to 3.6μM or lower. The endogenous alkaline phosphatase activity had the same expression pattern, indicating that the pPhAP1 possessed uncompromised regulatory capability. In terms of the quantity of EGFP generated by expression vectors, the yield of pPhAP1-EGFP was 9.3 to 10.5 times greater than those of other diatom vectors. These results suggested that pPhAP1 is an outstanding expression vector for diatoms with desirable characteristics of no interference with algal growth, easily tunable conditions for gene induction, and high yield of recombinant proteins.

      PubDate: 2017-01-28T17:00:58Z
      DOI: 10.1016/j.algal.2017.01.007
      Issue No: Vol. 23 (2017)
  • Effects of chrysolaminarin synthase knockdown in the diatom Thalassiosira
           pseudonana: Implications of reduced carbohydrate storage relative to green
    • Authors: Mark Hildebrand; Kalpana Manandhar-Shrestha; Raffaela Abbriano
      Pages: 66 - 77
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Mark Hildebrand, Kalpana Manandhar-Shrestha, Raffaela Abbriano
      In all organisms, the flux of carbon through the fundamental pathways of glycolysis, gluconeogenesis and the pyruvate hub is a core process related to growth and productivity. In unicellular microalgae, the complexity and intracellular location of specific steps of these pathways can vary substantially. In addition, the location and chemical nature of storage carbohydrate can be substantially different. The role of starch storage in green algae has been investigated, but thus far, only a minimal understanding of the role of carbohydrate storage in diatoms as the β-1,3-glucan chrysolaminarin has been achieved. In this report, we aimed to determine the effect of specifically reducing the ability of Thalassiosira pseudonana cells to accumulate chrysolaminarin by knocking down transcript levels of the chrysolaminarin synthase gene. We monitored changes in chrysolaminarin and triacylglycerol (TAG) levels during growth and silicon starvation. Transcript-level changes in genes encoding steps in chrysolaminarin metabolism, and cytoplasmic and chloroplast glycolysis/gluconeogenesis, were monitored during silicon limitation, highlighting the carbon flux processes involved. We demonstrate that knockdown lines accumulate less chrysolaminarin and have a transiently increased TAG level, with minimal detriment to growth. The results provide insight into the role of chrysolaminarin storage in diatoms, and further discussion highlights differences between diatoms and green algae in carbohydrate storage processes and the effect of reducing carbohydrate stores on growth and productivity.

      PubDate: 2017-02-04T08:30:50Z
      DOI: 10.1016/j.algal.2017.01.010
      Issue No: Vol. 23 (2017)
  • Production of lipid-based fuels and chemicals from microalgae: An
           integrated experimental and model-based optimization study
    • Authors: M. Bekirogullari; I.S. Fragkopoulos; J.K. Pittman; C. Theodoropoulos
      Pages: 78 - 87
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): M. Bekirogullari, I.S. Fragkopoulos, J.K. Pittman, C. Theodoropoulos
      Cultivation of microalgae is a promising long-term, sustainable candidate for biomass and oil for the production of fuel, food, nutraceuticals and other added-value products. Attention has been drawn to the use of computational and experimental validation studies aiming at the optimisation and the control of microalgal oil productivity either through the improvement of the growth mechanism or through the application of metabolic engineering methods to microalgae. Optimisation of such a system can be achieved through the evaluation of organic carbon sources, nutrients and water supply, leading to high oil yield. The main objective of this work is to develop a novel integrated experimental and computational approach, utilising a microalgal strain grown at bench-scale, with the aim to systematically identify the conditions that optimise growth and lipid production, in order to ultimately develop a cost-effective process to improve the system economic viability and overall sustainability. To achieve this, a detailed model has been constructed through a multi-parameter quantification methodology taking into account photo-heterotrophic biomass growth. The corresponding growth rate is based on carbon substrate concentration, nitrogen and light availability. The developed model also considers the pH of the medium. Parameter estimation was undertaken using the proposed model in conjunction with an extensive number of experimental data taken at a range of operating conditions. The model was validated and utilised to determine the optimal operating conditions for bench-scale batch lipid oil production.

      PubDate: 2017-02-04T08:30:50Z
      DOI: 10.1016/j.algal.2016.12.015
      Issue No: Vol. 23 (2017)
  • Biphasic ROS accumulation and programmed cell death in a cyanobacterium
           exposed to salinity (NaCl and Na2SO4)
    • Authors: Prashant Swapnil; Amarish Kumar Yadav; Saurabh Srivastav; Naveen K Sharma; Saripella Srikrishna; Ashwani K Rai
      Pages: 88 - 95
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Prashant Swapnil, Amarish Kumar Yadav, Saurabh Srivastav, Naveen K Sharma, Saripella Srikrishna, Ashwani K Rai
      High salinity increases antioxidative activities in plants; however, their significance for overall plant salt tolerance remains to be established. This work provided in vivo evidence of salinity induced biphasic reactive oxygen species (ROS) accumulation evoking oxidative stress in the cyanobacterium Anabaena fertilissima. First, a transient increase in ROS (intense and short-lived) was observed within 5min of salt exposure, which peaked within 15min and reached basal level by 2h. This was followed by a second relatively long-lived and low magnitude ROS accumulation that started at 4h of salt stress, attained its maximal at 6h, followed by a gradual decline but did not attain the basal level by the end of experimentation (12h). Phase I ROS accumulation timing corresponded to the reaction of cyanobacterial cells to the salt stress, while altered photosynthetic and respiratory parameters corresponded with the phase II ROS generation. Relatively lower magnitude of ROS generation during phase II may be attributed to the rapid activation of robust antioxidative systems in cyanobacteria. Consequently, ROS generation lead to the activation of programmed cell death (PCD) undergoing various apoptotic stages such as externalization of phosphatidylserine, DNA laddering and loss of plasma membrane integrity. A. fertilissima exposed to salt in the presence of SO4¯ was relatively better equipped to deal with salt stress.

      PubDate: 2017-02-09T12:00:16Z
      DOI: 10.1016/j.algal.2017.01.014
      Issue No: Vol. 23 (2017)
  • Transcriptome changes of blue-green algae, Arthrospira sp. in response to
           sulfate stress
    • Authors: Venkatesh Kumaresan; Faizal Nizam; Gayathri Ravichandran; Kasi Viswanathan; Rajesh Palanisamy; Prasanth Bhatt; Mariadhas Valan Arasu; Naif Abdullah Al-Dhabi; Kanchana Mala; Jesu Arockiaraj
      Pages: 96 - 103
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Venkatesh Kumaresan, Faizal Nizam, Gayathri Ravichandran, Kasi Viswanathan, Rajesh Palanisamy, Prasanth Bhatt, Mariadhas Valan Arasu, Naif Abdullah Al-Dhabi, Kanchana Mala, Jesu Arockiaraj
      Arthrospira platensis, a protein-rich blue-green alga is utilized as feed supplements for human and animals, which primarily depend upon nutrients such as carbon, nitrogen, phosphorus and sulfur in the presence of sunlight for their growth and survival. Cyanobacteria depend on sulfur for the synthesis and modification of a variety of biomolecules but, the exact mechanism of sulfur metabolism and impact of sulfate deprivation on A. platensis remain unclear. In this study, we analysed the change in growth and difference in the expression of key molecules of A. platensis during sulfate deprivation by comparing the transcriptome profiles of A. platensis grown at normal and sulfur deprived culture conditions. Observations showed that sulfate stress affected the levels of pigments in spirulina with slightly reduced growth. Transcriptome profile showed that expression profiles of different genes involved in various sulfur-dependent pathways were altered due to sulfur depletion. Major genes that were down-regulated include iron-sulfur clusters biosynthesis due to the absence of sulfur. Expression of genes involved in pathways such as translation, amino acid biosynthesis, protein folding, rRNA binding, were down-regulated, whereas genes involved in carbohydrate metabolism, phosphor relay sensor kinase activity, integral components of membrane, plasma membrane, thylakoid membrane, metal ion binding and DNA repair, were up-regulated during sulfur stress. Genes involved in transcription were up-regulated and hence there is a higher number of transcripts in A. platensis grown in sulfur depleted state. However, genes involved in translation were down-regulated; thus, there was a reduction in total protein content. Based on this analysis, it could be concluded that A. platensis was able to sustain sulfate stress, by its ability to alter the expression of genes that are specifically involved in sulfur metabolism and various other sulfur-dependent pathways.
      Graphical abstract image

      PubDate: 2017-02-09T12:00:16Z
      DOI: 10.1016/j.algal.2017.01.012
      Issue No: Vol. 23 (2017)
  • Microfiltration of algae: Impact of algal species, backwashing mode and
           duration of filtration cycle
    • Authors: Mayank Shekhar; Amritanshu Shriwastav; Purnendu Bose; Shemeera Hameed
      Pages: 104 - 112
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Mayank Shekhar, Amritanshu Shriwastav, Purnendu Bose, Shemeera Hameed
      The objective of this study was to investigate and compare the microfiltration characteristics of mixed algal cultures containing two species of green microalgae: Chlorella vulgaris and Chlamydomonas reinhardtii. Submerged membrane filtration experiments with 300mgL−1 suspensions of pure algal cultures indicated that while membrane fouling potential was comparable in both cases, Chlorella vulgaris had a lower cake formation potential. Filtration experiments were carried out with 1000mgL−1 suspensions of mixed algal culture over several 12-h cycles with backwashing, either in the on-line or off-line mode. While on-line backwashing caused more fouling, this did not significantly affect the flux through the membrane, which was controlled by the cake formation on the membrane. The algal mixed culture was also filtered over many 3-h cycles with on-line backwashing. Lower cycle duration resulted in lower average cake resistance and hence allowed more membrane throughput, but at the cost of more frequent backwashing. Chemical washing of the membrane could remove the fouling resistance only partially. Thus, despite periodic chemical washing, the intrinsic membrane resistance increased consistently with cumulative throughput through the membrane.

      PubDate: 2017-02-09T12:00:16Z
      DOI: 10.1016/j.algal.2017.01.013
      Issue No: Vol. 23 (2017)
  • Interactive effects of light and temperature on pigments and n-3
           LC-PUFA-enriched oil accumulation in batch-cultivated Pavlova lutheri
           using high-bicarbonate supply
    • Authors: Freddy Guihéneuf; Dagmar B. Stengel
      Pages: 113 - 125
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Freddy Guihéneuf, Dagmar B. Stengel
      We investigated the simultaneous effects of light and temperature on pigments, lipid remodeling, and omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) partitioning into lipid classes of P. lutheri. Biomass was produced in batch cultivation using high bicarbonate supply, and hence, any potential accumulation of lipid and triacylglycerols (TAG) containing n-3 LC-PUFA was triggered by nitrogen (N) limitation. The maximum productivities of both eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were obtained after nitrate-depletion when P. lutheri was cultivated at optimal growth conditions; these occurred at an intermediate temperature of 18°C and low light intensity (40μmolphotons·m−2·s−1) for EPA, but there was no impact of light (40 or 200μmolphotons·m−2·s−1) for DHA production. Under these respective optimum conditions, TAG accounted for 82–84% of TFA on day 15 of cultivation, which contained up to 76–84% of the total cellular EPA and 67–81% of total cellular DHA. Our results clearly demonstrate the process of lipid remodeling in P. lutheri and, for the first time, a potential membrane lipid turnover with transfer of n-3 LC-PUFA (EPA and DHA) from membranes (polar lipids, PL) to storage lipids (TAG), highlighting the accumulation of n-3 LC-PUFA-rich oil during N-starvation (i.e., TAG containing: EPA ~12–13% and DHA ~5–6% of TFA). When cultivated under low light conditions, P. lutheri additionally accumulated substantial quantities of antioxidant pigments (i.e., fucoxanthin, diadinoxanthin and β-carotene), which add value to extracted bioactive oil for functional food applications. Omega-3 rich oil accumulation and pigment levels in P. lutheri appear to be simultaneously regulated by both light and temperature, in addition to N-limitation during batch-cultivation.

      PubDate: 2017-02-15T12:04:47Z
      DOI: 10.1016/j.algal.2017.02.002
      Issue No: Vol. 23 (2017)
  • Enhanced NADPH production in the pentose phosphate pathway accelerates
           lipid accumulation in the oleaginous diatom Fistulifera solaris
    • Authors: Kyoko Osada; Yoshiaki Maeda; Tomoko Yoshino; Daisuke Nojima; Chris Bowler; Tsuyoshi Tanaka
      Pages: 126 - 134
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Kyoko Osada, Yoshiaki Maeda, Tomoko Yoshino, Daisuke Nojima, Chris Bowler, Tsuyoshi Tanaka
      As a consequence of the environmental concerns linked with the exploitation of fossil fuel reserves, biofuel production using microalgae has been widely considered because of their higher productive capacity compared with land plants. However, genetic modifications will likely be required to further improve the lipid productivity of native microalgae and to tailor it to the compositions required for different fuel types. In this study, genes encoding two NADPH-producing enzymes in the pentose phosphate pathway (PPP), glucose-6-phosphate dehydrogenase (G6PD) and phosphogluconate dehydrogenase (PGD), were overexpressed in the oleaginous diatom Fistulifera solaris. The native expression levels of the PGD and G6PD selected in this study were not up-regulated but constant and down-regulated, respectively. By overexpression of the genes encoding these enzymes, NADPH enhancement was confirmed in the transformant cells as compared to wild type cells, as was the acceleration of lipid accumulation. The promotion effect of G6PD (oil content: 37.2±5.6%) on neutral lipid accumulation was higher than that of PGD (26.1±3.32%) at early stages (24h after nutrient depletion, 20.5±4.3% for wild type), although the final lipid content at 60h was not significantly different between wild type and transformant cells (47.5±2.9%, 48.6±3.8%, 52.2±2.9% for wild type, PGD, and G6PD, respectively). Overexpression of G6PD elevated lipid productivity by 1.5-fold. We therefore propose that NADPH-producing enzymes in PPP can contribute to lipid synthesis in F. solaris, indicating that their further manipulation may provide breakthroughs for an even more effective biodiesel fuel production with this diatom.

      PubDate: 2017-02-15T12:04:47Z
      DOI: 10.1016/j.algal.2017.01.015
      Issue No: Vol. 23 (2017)
  • De novo transcriptomic profiling of Dunaliella salina reveals concordant
           flows of glycerol metabolic pathways upon reciprocal salinity changes
    • Authors: Lei Fang; Shuyuan Qi; Zhenyu Xu; Wei Wang; Jing He; Xin Chen; Jianhua Liu
      Pages: 135 - 149
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Lei Fang, Shuyuan Qi, Zhenyu Xu, Wei Wang, Jing He, Xin Chen, Jianhua Liu
      Regulation of glycerol contents is vital for adaptation to salinity changes in Dunaliella salina. However, transcriptional regulation of genes encoding enzymes involved in glycerol metabolisms upon salinity changes remains controversial. To address this issue, we de novo assembled D. salina transcriptome by using Illumina PE90 strategy with an average 700-fold coverage. Transcriptomic profiling analysis of D. salina cells in response to reciprocal salinity changes within the range of optimal growth conditions reveals 330 and 553 differentially transcribed ESTs out of a total of 6700 annotated ones upon salinity increase and decrease, respectively. We found 130 common differentially-transcribed ESTs under both conditions, nearly all of which display salinity-correlated transcriptional response. Based on 33 enzymes involved in metabolisms of glycerol and its potential carbon sources, 8 out of 10 common differentially-transcribed ESTs appear to encode enzymes at key sites. Cluster analysis indicated that 28 out of 33 enzymes exhibit salinity-correlated transcriptional profiles in response to reciprocal salinity changes. Transcriptional profiles of the enzymes are in full agreement with the flow of glycerol metabolisms upon salinity changes. This result is consistent with the observation that glycerol and starch contents are positively and negatively correlated with salinity. Furthermore, it indicates that photosynthetic sugar preferentially avails upon salinity decrease, suggesting that photosynthetic sugar is a preferential carbon source for starch accumulation but not glycerol synthesis. Taken together, our analyses demonstrate that transcriptional profiling in response to reciprocal salinity alterations within the range of optimal growth conditions greatly enriches for salinity-specific responsive ESTs in D. salina. Under these conditions, we are able to show that transcriptional regulation plays a clear role in controlling enzymatic activities involved in metabolisms of glycerol and its potential carbon sources in D. salina. We propose that transcriptional regulation of osmobalancing is likely to be evolutionarily conserved in other halotolerant unicellular organisms.

      PubDate: 2017-02-15T12:04:47Z
      DOI: 10.1016/j.algal.2017.01.017
      Issue No: Vol. 23 (2017)
  • Nitrogen-doped carbon dots prepared from bovine serum albumin to enhance
           algal astaxanthin production
    • Authors: Said Abu Ghosh; Vijay Bhooshan Kumar; Dror Fixler; Zvy Dubinsky; Aharon Gedanken; David Iluz
      Pages: 161 - 165
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Said Abu Ghosh, Vijay Bhooshan Kumar, Dror Fixler, Zvy Dubinsky, Aharon Gedanken, David Iluz
      The aim of this work was to use green and simply synthesized nitrogen-doped carbon dots (N@CDs) based on carbonized bovine serum albumin (BSA) to boost the accumulation of astaxanthin in microalgae. The BSA carbon dots revealed a high blue emission having a quantum yield of up to 44%, which is superior to all previously reported carbon dots. By directly adding the N@CDs at low concentrations (1mgL−1) to the algal culture of Haematococcus pluvialis, astaxanthin production increased more than two-fold (66mgL−1), compared to the control (29mgL−1), in a shorter time of 1week instead of 2weeks at the reddening stage. After 1month of continuous irradiation, the HRTEM images and fluorescence spectra of N@CDs looked similar to as-prepared N@CDs, suggesting their photostability and reusability. Our novel N@CDs could be a promising tool for the future industry of natural astaxanthin and other value-added products from microalgae.
      Graphical abstract image

      PubDate: 2017-02-22T12:11:24Z
      DOI: 10.1016/j.algal.2017.01.011
      Issue No: Vol. 23 (2017)
  • Light distribution and spectral composition within cultures of
           micro-algae: Quantitative modelling of the light field in photobioreactors
    • Authors: David Fuente; Joseph Keller; J. Alberto Conejero; Matthias Rögner; Sascha Rexroth; Javier F. Urchueguía
      Pages: 166 - 177
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): David Fuente, Joseph Keller, J. Alberto Conejero, Matthias Rögner, Sascha Rexroth, Javier F. Urchueguía
      Light, being the fundamental energy source to sustain life on Earth, is the external factor with the strongest impact on photosynthetic microorganisms. Moreover, when considering biotechnological applications such as the production of energy carriers and commodities in photobioreactors, light supply within the reactor volume is one of the main limiting factors for an efficient system. Thus, the prediction of light availability and its spectral distribution is of fundamental importance for the productivity of photo-biological processes. The light field model here presented is able to predict the intensity and spectral distribution of light throughout the reactor volume based on the incident light and the spectral characteristics of the photosynthetic microorganism. It takes into account the scattering and absorption behaviour of the micro-algae, as well the adaptation of the biological system to different light intensities. Although in the form exposed here the model is optimized for photosynthetic microorganism cultures inside flat- type photobioreactors, the theoretical framework is easily extensible to other geometries. Our calculation scheme has been applied to model the light field inside Synechocystis sp. PCC 6803 wild-type and Olive antenna mutant cultures at different cell-density concentrations exposed to white, blue, green and red LED lamps, delivering results with reasonable accuracy, despite the data uncertainties. To achieve this, Synechocystis experimental attenuation profiles for different light sources were estimated by means of the Beer-Lambert law, whereby the corresponding downward irradiance attenuation coefficients Kd (λ) were obtained through inherent optical properties of each organism at any wavelength within the photosynthetically active radiation band. The input data for the algorithm are chlorophyll-specific absorption and scattering spectra at different mean acclimatisation irradiance values for a given organism, the depth of the photobioreactor, the cell-density and also the intensity and emission spectrum of the light source. In summary, the model is a general tool to predict light availability inside photosynthetic microorganism cultures and to optimize light supply, in respect to both intensity and spectral distribution, in technological applications. This knowledge is crucial for industrial-scale optimisation of light distribution within photobioreactors and is also a fundamental parameter for unravelling the nature of many photosynthetic processes.

      PubDate: 2017-02-22T12:11:24Z
      DOI: 10.1016/j.algal.2017.01.004
      Issue No: Vol. 23 (2017)
  • Cultivation of an indigenous Chlorella sorokiniana with phytohormones for
           biomass and lipid production under N-limitation
    • Authors: A. Giridhar Babu; Xiaoge Wu; Akhil N. Kabra; Dong-Pyo Kim
      Pages: 178 - 185
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): A. Giridhar Babu, Xiaoge Wu, Akhil N. Kabra, Dong-Pyo Kim
      Nitrogen starvation promotes lipid accumulation in microalgal cells, but leads to low biomass production which directly influences the lipid yield. Growth stimulators may activate simultaneous increase in biomass and metabolite productivity under nutrition stress conditions. In this work, the dual effect of phytohormone (indole-3-acetic acid (IAA), diethyl aminoethyl hexonate (DA-6)) supplementation and nitrogen limitation conditions on the biomass and lipid production of an indigenous microalga Chlorella sorokiniana DPK-5 was thoroughly investigated by monitoring the fatty acid compositions, oxidative stress alleviation and anti-oxidative defense system, including gene expression level. The optimized concertation of IAA (10−5 M) or DA-6 (10−9 M) were applied under a series of N limitation in range 100% to 12.5% to promote the both biomass and lipid production of DPK-5. Interestingly, very minimal dose of IAA and DA-6 under 50% N concentration produced the highest biomass productivity of 201mg/L/d (22% increase) and 236mg/L/d (43% increase) from the control (166mg/L/d), leading to outstanding lipid productivity of 69mg/L/d (49% increase) and 86mg/L/d (84% increase) from the control (32mg/L/d). In addition, abundance of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) as a measurement of biodiesel quality were also enhanced. Furthermore, it was proven that treatment with IAA and DA-6 induced the activity of antioxidants enzymes, which protect cells from damages caused by abiotic stresses. In addition, the intracellular levels of RuBisCO and ACCase were considerably up-regulated by IAA and DA-6 under N limitation. These findings indicate that hormone addition-based autotrophic-N limitation is a promising cultivation strategy to improve the lipid production potential of microalgae without substantial loss in biomass for generation of high quality biodiesel.

      PubDate: 2017-02-22T12:11:24Z
      DOI: 10.1016/j.algal.2017.02.004
      Issue No: Vol. 23 (2017)
  • A fast and reliable strategy to generate TALEN-mediated gene knockouts in
           the diatom Phaeodactylum tricornutum
    • Authors: M. Serif; B. Lepetit; K. Weißert; P.G. Kroth; C. Rio Bartulos
      Pages: 186 - 195
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): M. Serif, B. Lepetit, K. Weißert, P.G. Kroth, C. Rio Bartulos
      Reverse genetics techniques are powerful tools for studying gene functions. In the model diatom Phaeodactylum tricornutum, RNAi-mediated knockdown of genes still is the most commonly used reverse genetics technique. Due to the diploidic life cycle missing reproduction in lab cultures, many commonly used techniques to create knockout instead of knockdown lines are not applicable in P. tricornutum. These limitations can be overcome by using genome editing approaches like TALEN (Transcription activator-like effector nucleases), and/or CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats), allowing the introduction of targeted mutagenesis events. Both techniques have recently been adapted exemplarily for diatoms, however, no concise guidelines exist yet for routine utilization of these tools and the subsequent characterization of the mutants. We therefore have adapted a cost-effective TALEN generation system previously established for mammalian cells for the use in P. tricornutum, allowing the assembly of TALENs in about two weeks. We further provide protocols for: a) choosing a TALEN target site in order to avoid potentially ineffective and/or off-target prone TALEN constructs, b) efficient transformation of P. tricornutum with both TALEN constructs, utilizing two antibiotics resistance markers, c) effective screening of the transformants. In order to test our system we chose the blue-light dependent transcription factor Aureochrome 1a (PtAureo1a) as a target gene due to the known phenotype of previously characterized P. tricornutum RNAi knockdown strains. Our TALEN approach appears to be highly efficient: targeted mutation events were detected in 50% of all transformants obtained, whereas 21% of the transformants were found to be bi-allelic knockout lines. Furthermore, most TALEN transformed cell lines were found to be genetically homogeneous without the need for re-plating, which greatly facilitates the screening process.

      PubDate: 2017-02-22T12:11:24Z
      DOI: 10.1016/j.algal.2017.02.005
      Issue No: Vol. 23 (2017)
  • Proteome response of Dunaliella parva induced by nitrogen limitation
    • Authors: Changhua Shang; Shunni Zhu; Zhongming Wang; Lei Qin; Mohammad Asraful Alam; Jun Xie; Zhenhong Yuan
      Pages: 196 - 202
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Changhua Shang, Shunni Zhu, Zhongming Wang, Lei Qin, Mohammad Asraful Alam, Jun Xie, Zhenhong Yuan
      Nitrogen limitation is the most widely used method for directing metabolic flux to lipid biosynthesis in microalgae. Protein level changes induced by environmental stress could be investigated by proteomics analysis, which was a favourable approach for understanding the induction mechanisms. Although, we previously provided the results of transcriptome sequencing of Dunaliella parva under nitrogen limitation stress, the effects of nitrogen limitation on the microalgal proteome were not reported. The impact of nitrogen limitation on the proteome of green alga D. parva was investigated using iTRAQ quantitative proteomics technique. A total of 227 proteins were up-regulated, and 159 proteins were down-regulated under the nitrogen limitation condition. Functional analyses of differentially expressed proteins revealed that nitrogen limitation could induce protein level changes related to photosynthesis, stress response, lipid metabolism, carbohydrate metabolism and nitrogen metabolism. This study, together with our previous transcriptome sequencing of D. parva, therefore provides a foundation for understanding the regulatory mechanism of lipid biosynthesis induced by nitrogen limitation, which could further guide the genetic modification of lipid accumulation in D. parva.

      PubDate: 2017-02-22T12:11:24Z
      DOI: 10.1016/j.algal.2017.01.016
      Issue No: Vol. 23 (2017)
  • Pyrene degradation by Chlorella sp. MM3 in liquid medium and soil slurry:
           Possible role of dihydrolipoamide acetyltransferase in pyrene
    • Authors: Suresh R. Subashchandrabose; Panneerselvan Logeshwaran; Kadiyala Venkateswarlu; Ravi Naidu; Mallavarapu Megharaj
      Pages: 223 - 232
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): Suresh R. Subashchandrabose, Panneerselvan Logeshwaran, Kadiyala Venkateswarlu, Ravi Naidu, Mallavarapu Megharaj
      Microalgae inhabiting the real contaminated sites are capable of degrading organic pollutants. In the present study, the potential of a microalga, Chlorella ssp. MM3, a soil isolate from a former cattle dip site, was assessed in degrading pyrene both in aqueous medium and soil slurry. Strain MM3 can grow on pyrene in culture medium at concentrations as high as 250μM. When grown in presence of 50μM pyrene, the cell density increased from 1.1×105 cellsmL−1 to 16.45×105 cellsmL−1 within 7days. With an initial cell density of 3×107 cellsmL−1, nearly 70% of 50μM pyrene was degraded after 7days of incubation. When compared with Triton X-100, Tween 80 was a better non-ionic surfactant for pyrene biodegradation. Nearly 20% increase in degradation of pyrene was observed with the use of 0.005% Tween 80. Differential protein expression in pyrene-grown cells of the microalga resulted in distinct accumulation of dihydrolipoamide acetyltransferase (or dihydrolipoyl transacetylase), one of the three components of pyruvate dehydrogenase complex, indicating a possible role of this enzyme in microalgal degradation of pyrene. The microalgal cells immobilized in calcium alginate completely degraded 50μM of pyrene within 10days in nonsterile soil slurry treated with 0.005% Tween 80. Our results clearly indicate that the strain MM3 has a great potential for its use in remediating soils contaminated with pyrene.

      PubDate: 2017-03-08T06:12:17Z
      DOI: 10.1016/j.algal.2017.02.010
      Issue No: Vol. 23 (2017)
  • A methodological study of adhesion dynamics in a batch culture of the
           marine microalga Nannochloropsis gaditana
    • Authors: O. Zeriouh; J.V. Reinoso-Moreno; L. López-Rosales; B. Sierra-Martín; M.C. Cerón-García; A. Sánchez-Mirón; A. Fernández-Barbero; F. García-Camacho; E. Molina-Grima
      Pages: 240 - 254
      Abstract: Publication date: April 2017
      Source:Algal Research, Volume 23
      Author(s): O. Zeriouh, J.V. Reinoso-Moreno, L. López-Rosales, B. Sierra-Martín, M.C. Cerón-García, A. Sánchez-Mirón, A. Fernández-Barbero, F. García-Camacho, E. Molina-Grima
      This paper addresses a complete set of procedures to study and to better understand the emerging problem of the biofouling formation in photobioreactors (PBRs). Methodologies are described in detail for: (i) PBR and microalgae mat surface preparation, (ii) contact angles (CA) and zeta potential (ZP) measurements for both microalgal cells and PBR surfaces, and (iii) microscopic methods for studying the evolution of adhesion intensity. The impact that these methodologies may have on the photosynthetic apparatus of the cells, the biomass concentration and cell viability are also quantified. A lab-scale flat-plate PBR was used to perform a long-term batch culture of the marine microalgae Nannochloropsis gaditana, in which a devised rack of 25 PBR glass surfaces were submerged. To study the cell-to-cell and cell-to-PBR surface interactions, the existing surface thermodynamics and colloidal theories (XDLVO) were used. The major outcomes were: (1) that N. gaditana has a exposure time threshold to the electric field produced by the ZP meter; (2) a linear equation is provided for predicting the PBR surface potential as a function of the culture medium's ionic strength; (3) the biofouling growth curve on the PBR surface varied in line with the growth kinetic followed by the freely suspended culture cells; (4) the devised PBR slide rack system offers a versatile experimental platform for generating biofouling results, making it suitable for the in situ efficiency evaluation of antibiofouling coatings; (5) there was a significant variation in the surface free energy of the PBR surfaces and algal mats with respect to that present at the beginning of the culture, and, consequently, the application of thermodynamic theories failed to predict cell adhesion over long-term cultivation. However, the XDLVO model satisfactorily explained the dynamics of the adhesion studied. The reported results might be useful for research in the microalgal production and PBR engineering area.

      PubDate: 2017-03-14T06:34:39Z
      DOI: 10.1016/j.algal.2017.02.008
      Issue No: Vol. 23 (2017)
  • Comprehensive computational model for combining fluid hydrodynamics, light
           transport and biomass growth in a Taylor vortex algal photobioreactor:
           Eulerian approach
    • Authors: Xi Gao; Bo Kong; R. Dennis Vigil
      Pages: 523 - 530
      Abstract: Publication date: June 2017
      Source:Algal Research, Volume 24, Part A
      Author(s): Xi Gao, Bo Kong, R. Dennis Vigil
      A comprehensive Eulerian approach for integrating a three-phase CFD model, a sophisticated detailed model for radiation transport, and a transport equation for algal growth kinetics is developed and utilized to predict the performance of a Taylor vortex algal photobioreactor. Simulation predictions are compared with corresponding experimental data and with simulation predictions obtained using the more commonly employed Lagrangian particle tracking method. The Eulerian simulations correctly predict the experimental trend that biomass productivity increases with increased rates of mixing, and they also suggest that there are limits to these productivity increases as the mixing rate becomes very large. Simulation over-prediction of biomass productivity at high azimuthal Reynolds numbers can be attributed to the fact that at high biomass loadings most radiation is absorbed near illuminated reactor surfaces, and it becomes increasingly important, but also more difficult, to properly resolve the thinning hydrodynamic and radiative boundary layers.

      PubDate: 2017-03-27T11:10:25Z
      DOI: 10.1016/j.biortech.2016.10.080
      Issue No: Vol. 224 (2017)
  • Fucoxanthin production by heterokont microalgae
    • Authors: Maria Petrushkina; Evgeniy Gusev; Boris Sorokin; Nikita Zotko; Anna Mamaeva; Alla Filimonova; Maxim Kulikovskiy; Yevhen Maltsev; Ilia Yampolsky; Elena Guglya; Vladimir Vinokurov; Zorigto Namsaraev; Denis Kuzmin
      Abstract: Publication date: Available online 20 April 2017
      Source:Algal Research
      Author(s): Maria Petrushkina, Evgeniy Gusev, Boris Sorokin, Nikita Zotko, Anna Mamaeva, Alla Filimonova, Maxim Kulikovskiy, Yevhen Maltsev, Ilia Yampolsky, Elena Guglya, Vladimir Vinokurov, Zorigto Namsaraev, Denis Kuzmin
      Fucoxanthin is one of the most abundant carotenoids in nature. It is a major carotenoid in heterokont and haptophyte groups of algae that includes >20 thousand species. Fucoxanthin also has many beneficial health effects including anticancer, antihypertensive, anti-inflammatory, and antiobesity effects. Microalgae are a promising source of fucoxanthin for commercial production. To find the most efficient fucoxanthin producing strains of microalgae, we isolated seven new strains of microalgae from multiple locations in Russia and Vietnam and studied their growth parameters and fucoxanthin content. Based on these results we isolated a novel strain of Mallomonas sp. (Synurophyceae) with the highest known content of fucoxanthin in biomass (26.6mgg−1 DW). The analysis of available data on heterokont and haptophyte algae shows that three groups of algae are the most promising for commercial production of fucoxanthin: diatoms (up to 21.67mgg−1 DW), Synurophyceae (up to 26.6mgg−1 DW) and Prymnesiophyceae (up to 18.23mgg−1 DW).

      PubDate: 2017-04-24T06:44:48Z
      DOI: 10.1016/j.algal.2017.03.016
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