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Publisher: Elsevier   (Total: 3049 journals)

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Showing 1 - 200 of 3089 Journals sorted alphabetically
A Practical Logic of Cognitive Systems     Full-text available via subscription   (Followers: 7)
AASRI Procedia     Open Access   (Followers: 15)
Academic Pediatrics     Hybrid Journal   (Followers: 25, SJR: 1.402, h-index: 51)
Academic Radiology     Hybrid Journal   (Followers: 22, SJR: 1.008, h-index: 75)
Accident Analysis & Prevention     Partially Free   (Followers: 86, SJR: 1.109, h-index: 94)
Accounting Forum     Hybrid Journal   (Followers: 25, SJR: 0.612, h-index: 27)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 30, 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: 363, 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   (Followers: 1)
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: 229, 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: 10, 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: 1)
Acta Poética     Open Access   (Followers: 4)
Acta Psychologica     Hybrid Journal   (Followers: 24, SJR: 1.365, h-index: 73)
Acta Sociológica     Open Access  
Acta Tropica     Hybrid Journal   (Followers: 6, 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: 4, 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)
Acute Pain     Full-text available via subscription   (Followers: 13)
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: 6)
Additive Manufacturing     Hybrid Journal   (Followers: 7, SJR: 1.039, h-index: 5)
Additives for Polymers     Full-text available via subscription   (Followers: 21)
Advanced Cement Based Materials     Full-text available via subscription   (Followers: 3)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 132, 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: 17, SJR: 0.739, h-index: 33)
Advances in Accounting     Hybrid Journal   (Followers: 9, 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: 26, 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: 11, SJR: 0.801, h-index: 26)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 22, 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: 25, 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 Cell Aging and Gerontology     Full-text available via subscription   (Followers: 4)
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: 27, 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: 9, SJR: 1.268, h-index: 45)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 29, 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 Dermatology     Full-text available via subscription   (Followers: 12)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 11)
Advances in Digestive Medicine     Open Access   (Followers: 7)
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: 45, SJR: 3.25, h-index: 43)
Advances in Engineering Software     Hybrid Journal   (Followers: 26, 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: 43, 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: 51, SJR: 0.674, h-index: 38)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
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: 22, SJR: 0.906, h-index: 24)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 9, SJR: 0.497, h-index: 31)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
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: 36, 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: 6)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 4)
Advances in Life Course Research     Hybrid Journal   (Followers: 8, SJR: 0.764, h-index: 15)
Advances in Lipobiology     Full-text available via subscription   (Followers: 2)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 9)
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: 6, 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: 22)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 10)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 8, SJR: 0.324, h-index: 8)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 4)
Advances in Oncobiology     Full-text available via subscription   (Followers: 3)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
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: 24, SJR: 0.4, h-index: 28)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 13)
Advances in Pharmacology     Full-text available via subscription   (Followers: 15, SJR: 1.718, h-index: 58)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 8, 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: 17)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 1.5, h-index: 62)
Advances in Psychology     Full-text available via subscription   (Followers: 62)
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: 2, SJR: 0.1, h-index: 2)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 5)
Advances in Space Research     Full-text available via subscription   (Followers: 360, SJR: 0.606, h-index: 65)
Advances in Structural Biology     Full-text available via subscription   (Followers: 8)
Advances in Surgery     Full-text available via subscription   (Followers: 7, SJR: 0.823, h-index: 27)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 30, SJR: 1.321, h-index: 56)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 16)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 13)
Advances in Virus Research     Full-text available via subscription   (Followers: 5, SJR: 1.878, h-index: 68)
Advances in Water Resources     Hybrid Journal   (Followers: 44, 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: 331, 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: 5, SJR: 0.344, h-index: 6)
Ageing Research Reviews     Hybrid Journal   (Followers: 8, SJR: 3.289, h-index: 78)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 417, SJR: 1.385, h-index: 72)
Agri Gene     Hybrid Journal  
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 16, SJR: 2.18, h-index: 116)
Agricultural Systems     Hybrid Journal   (Followers: 30, SJR: 1.275, h-index: 74)
Agricultural Water Management     Hybrid Journal   (Followers: 40, SJR: 1.546, h-index: 79)
Agriculture and Agricultural Science Procedia     Open Access  
Agriculture and Natural Resources     Open Access   (Followers: 2)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 55, 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: 5, 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: 11, SJR: 0.922, h-index: 66)
Alcoholism and Drug Addiction     Open Access   (Followers: 8)
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   (Followers: 1)
Algal Research     Partially Free   (Followers: 8, 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: 4, SJR: 0.776, h-index: 35)
Alpha Omegan     Full-text available via subscription   (SJR: 0.121, h-index: 9)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 9, SJR: 0.158, h-index: 9)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 46, SJR: 4.289, h-index: 64)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 4)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 49, SJR: 3.157, h-index: 153)
American J. of Cardiology     Hybrid Journal   (Followers: 48, SJR: 2.063, h-index: 186)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 40, SJR: 0.574, h-index: 65)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 9, 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: 26, SJR: 1.259, h-index: 81)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 32, SJR: 2.313, h-index: 172)
American J. of Medicine     Hybrid Journal   (Followers: 46, 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: 199, SJR: 2.255, h-index: 171)
American J. of Ophthalmology     Hybrid Journal   (Followers: 59, SJR: 2.803, h-index: 148)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 6)
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: 25, SJR: 0.59, h-index: 45)
American J. of Pathology     Hybrid Journal   (Followers: 27, SJR: 2.653, h-index: 228)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 25, SJR: 2.764, h-index: 154)
American J. of Surgery     Hybrid Journal   (Followers: 35, SJR: 1.286, h-index: 125)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.653, h-index: 70)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 6)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.066, h-index: 51)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 58, SJR: 0.124, h-index: 9)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 12)
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: 4, SJR: 2.577, h-index: 7)
Analytica Chimica Acta     Hybrid Journal   (Followers: 37, SJR: 1.548, h-index: 152)
Analytical Biochemistry     Hybrid Journal   (Followers: 167, SJR: 0.725, h-index: 154)
Analytical Chemistry Research     Open Access   (Followers: 8, SJR: 0.18, h-index: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 12)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 1)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 22, SJR: 0.421, h-index: 40)
Angiología     Full-text available via subscription   (SJR: 0.124, h-index: 9)
Angiologia e Cirurgia Vascular     Open Access  

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Journal Cover Algal Research
  [SJR: 2.05]   [H-I: 20]   [8 followers]  Follow
    
   Partially Free Journal Partially Free Journal
   ISSN (Online) 2211-9264
   Published by Elsevier Homepage  [3049 journals]
  • Draft genomes and phenotypic characterization of Tisochrysis lutea
           strains. Toward the production of domesticated strains with high added
           value
    • Authors: Gregory Carrier; Caroline Baroukh; Catherine Rouxel; Laëtitia Duboscq-Bidot; Nathalie Schreiber; Gaël Bougaran
      Pages: 1 - 11
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Gregory Carrier, Caroline Baroukh, Catherine Rouxel, Laëtitia Duboscq-Bidot, Nathalie Schreiber, Gaël Bougaran
      Tisochrysis lutea is a microalga species currently used in aquaculture as a feed for shellfish, oysters and shrimps. It also has many other potential industrial applications, such as the production of neutral lipids for biofuels or the production of ω-3 fatty acids for nutraceuticals (human food complements). To efficiently exploit the potential of this microalga, however, higher lipid productivities are needed. To this end, improvement programs need to be developed and optimized. The diversity of strains available in microalgae has not yet been exploited in such improvement programs. In this study, the intra-strain diversity was observed and exploited to increase neutral lipid productivity. New clonal strains with higher neutral lipid productivity were successfully selected. The best clonal strain selected accumulated 520% more triacylglycerols, with a similar growth rate to the wild-type strain in continuous light and nitrogen starvation conditions. In a photoperiod culture condition, this clonal stain also accumulated 84% more storage lipids and 30% less carbohydrates, compared to the wild-type strain. This clonal strain thus had a higher productivity which is of great interest for feed or biofuel applications. This study also focused on identifying the genomic mechanisms responsible for the improvements in these clonal strains. With this objective, the genome of Tisochrysis lutea was sequenced for the first time. It is the third genome of a Haptophyte microalga sequenced so far. Different genetic polymorphisms were identified between the sequenced genomes of the wild-type strain and clonal strains. Activity of transposable elements seems to have been involved in the genome reshuffling obtained through the improvement program. The contribution of transposable elements to the adaptive capacity of microalgae remains to be demonstrated.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.10.017
      Issue No: Vol. 29 (2017)
       
  • The effect of different light regimes on diatom frustule silicon
           concentration
    • Authors: Yanyan Su; Nina Lundholm; Marianne Ellegaard
      Pages: 36 - 40
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Yanyan Su, Nina Lundholm, Marianne Ellegaard
      Significant changes in frustule morphology of Coscinodiscus granii induced by different light regimes have previously been observed, but whether these changes are companied by similar changes in cellular silicon concentration or are solely due to reorganization is unknown. The influence of six different light regimes, blue (B), green (G), yellow (Y), red-orange (RO), red (R) and white (W), at two intensities (100 and 300μmolphotonsm−2 s−1) on cellular silicon content was therefore assessed for C. granii. Both the cellular Si content and the Si concentration per surface area were higher at 300 than at 100μmolphotonsm−2 s−1 for all tested wavelengths, except Y light. At the same light intensity, cells grown at B light had the highest cellular Si content (except W at 300μmolphotonsm−2 s−1) and Si concentration per surface area. At R, OR, G, B and W light, high intensity led to higher cellular Si content although the mean frustule size was smaller (opposite for Y light). As the higher Si content was not due to a larger cell size, we hypothesize that the effect is due to changes in valve thickness. The underlying adaptive significance of this phenomenon might be that at low irradiance (100μmolphotonsm−2 s−1), diatom buoyancy is modulated by accumulating less silicon in the cells, as the less silicified cells may have lower sinking rate and thus remain longer at the higher light in the upper part of the water column, which could partly contribute to the ecological success of the diatom.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.014
      Issue No: Vol. 29 (2017)
       
  • Economical DHA (Docosahexaenoic acid) production from Aurantiochytrium sp.
           KRS101 using orange peel extract and low cost nitrogen sources
    • Authors: Won-Kun Park; Myounghoon Moon; Sung-Eun Shin; Jun Muk Cho; William I. Suh; Yong Keun Chang; Bongsoo Lee
      Pages: 71 - 79
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Won-Kun Park, Myounghoon Moon, Sung-Eun Shin, Jun Muk Cho, William I. Suh, Yong Keun Chang, Bongsoo Lee
      The commercial production of microalgae-derived docosahexaenoic acid (DHA) has been expanding due to several advantages of algal over fish oil produced DHA. While the DHA production technology from microalgae is already economically competitive, alternatives to pure glucose and yeast extract still need to be explored to reduce the costs and increase the profits further. In the present study, orange peel waste (OPW) and various nitrogen sources were investigated as alternative nutrient sources for the economic cultivation of Aurantiochytrium sp. KRS101. The utilization of orange peel extract (OPE) supplemented with NaNO3 showed a higher DHA yield than that supplemented with NH4Cl or urea, and pH5.5 was found to be the optimum initial condition for Aurantiochytrium sp. KRS101. OPE optimized with supplemental NaNO3 (1.2g/L) resulted in a DHA yield of 0.63g/L, which was 2.5 fold greater than the yield obtained using a conventional basal medium containing a similar amount of total nitrogen and 67% greater total carbon sources. This result implied not only that the conventional use of glucose and yeast extract have lower efficiency levels during nutrient metabolism but also that the types of carbon and nutrient sources have a significant effect on the DHA yield. The addition of supplemental glucose further enhanced the biomass, fatty acid methyl esters (FAME), and DHA yields, which unveiled the high C:N ratio requirement of Aurantiochytrium sp. KRS101. These results suggest that the development and optimization of microalgae fermentation using OPE and NaNO3 is a possible route for the economical production of DHA and for the additional utilization of food waste.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.017
      Issue No: Vol. 29 (2017)
       
  • Process and economic feasibility for the production of functional food
           from the brown alga Ecklonia radiata
    • Authors: Suvimol Charoensiddhi; Andrew J. Lorbeer; Christopher M.M. Franco; Peng Su; Michael A. Conlon; Wei Zhang
      Pages: 80 - 91
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Suvimol Charoensiddhi, Andrew J. Lorbeer, Christopher M.M. Franco, Peng Su, Michael A. Conlon, Wei Zhang
      This article provides a case-study for the simulated industrial-scale production of high-value functional food products from the brown seaweed Ecklonia radiata. Three process scenarios at a batch processing scale of 2000kg seaweed were assessed for their economic feasibility: Scenario 1: Enzyme-assisted production of a crude seaweed extract; Scenario 2: Scenario 1, followed by fractionation based on different molecular weights (MW); Scenario 3: Ethanolic extraction, followed by enzyme-assisted extraction and separation into high and low MW fractions. Scenario 2 demonstrated greater profitability, with a payback time of 1.6years and a net present value (NPV) twice that of Scenario 1 (2.1years and US$ 45.03M). Scenario 3 was not economically feasible, with a negative NPV and payback time that was three times longer than Scenario 1. To improve profitability, Scenario 4 was assessed, which integrated Scenario 1 (at the batch processing scale of 500kg seaweed) with formulation of the extract as a functional ingredient into a juice-based beverage. This process was more profitable than Scenario 1, with a payback time and NPV of 1.1years and US$ 89.43M, respectively.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.022
      Issue No: Vol. 29 (2017)
       
  • Polysaccharide associated protein (PSAP) from the green microalga
           Botryococcus braunii is a unique extracellular matrix hydroxyproline-rich
           glycoprotein
    • Authors: Mehmet Tatli; Mayumi Ishihara; Christian Heiss; Daniel R. Browne; Lawrence J. Dangott; Stanislav Vitha; Parastoo Azadi; Timothy P. Devarenne
      Pages: 92 - 103
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Mehmet Tatli, Mayumi Ishihara, Christian Heiss, Daniel R. Browne, Lawrence J. Dangott, Stanislav Vitha, Parastoo Azadi, Timothy P. Devarenne
      The green colonial microalga Botryococcus braunii produces large amounts of liquid hydrocarbons that can be converted into transportation fuels. Colony cells are held together by a complex extracellular matrix (ECM) made up of a cross-linked long-chain hydrocarbon network around which liquid hydrocarbons are stored, a retaining wall for holding hydrocarbons within the cross-linked hydrocarbon network, and a polysaccharide fibrillar sheath radiating from the retaining wall and surrounding the entire colony. Analysis of “shells” shed from cell apical regions during cell division and containing the retaining wall and polysaccharide fibers shows association of a single protein where the fibers meet the retaining wall, suggesting involvement of this protein in polysaccharide fiber formation. Here we use peptide mass fingerprinting and bioinformatics to identify this protein called polysaccharide associated protein (PSAP). PSAP does not show similarity to any protein in databases, but contains several Proline-rich domains. Staining studies confirm PSAP as a glycoprotein, and mass spectrometry analysis identified ten N-linked glycosylation sites comprising seven different glycans containing mainly mannose and N-acetylglucosamine. Three of these glycans also contain fucose, with one of these glycans being unusual since it also contains arabinose. Additionally, four hydroxyproline residues have short O-linked glycans of mainly arabinose and galactose, with one also containing a 6-deoxyhexose. PSAP secretion and localization to shell material is confirmed using western blot analysis and microscopy. These studies indicate PSAP contains unique glycans and suggest its involvement in ECM polysaccharide fiber biosynthesis.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.018
      Issue No: Vol. 29 (2017)
       
  • Comparative transcriptome analysis between heat-tolerant and sensitive
           Pyropia haitanensis strains in response to high temperature stress
    • Authors: Wenlei Wang; Yinghui Lin; Fei Teng; Dehua Ji; Yan Xu; Changsheng Chen; Chaotian Xie
      Pages: 104 - 112
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Wenlei Wang, Yinghui Lin, Fei Teng, Dehua Ji, Yan Xu, Changsheng Chen, Chaotian Xie
      Pyropia haitanensis farms in South China often suffer from sustained high temperatures in autumn, which is the early seeding period, resulting in disease, premature senility, and eventual decay, ultimately leading to a substantial reduction in yield. However, the molecular mechanisms underlying the response to high temperature stress in P. haitanensis remain unknown. In the present study, we used the Illumina sequencing platform to examine the transcriptional profiles of heat-tolerant (THT) and heat-sensitive (WHT) P. haitanensis strains exposed to different durations of high temperature stress. THT exhibited more differentially expressed genes and greater fold-changes in transcripts under sustained temperature stress, suggesting that this strain is better able to increase transcriptional regulation in response to high temperature stress than WHT. Furthermore, heat stress induced different expression patterns in the thalli of the two strains. THT was able to maintain or increase the activities of energy metabolism, antioxidant systems, and phosphatidylinositol signal transduction to resist heat stress, while these processes were dramatically reduced in WHT, resulting in the thalli being unable to survive under sustained high temperatures. The present data provide a better understanding of the mechanisms underlying the response of P. haitanensis to high temperature stress, which may facilitate the development of technologies and breeding strategies for improving thermotolerance in Pyropia.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.026
      Issue No: Vol. 29 (2017)
       
  • Profiling phlorotannins from Fucus spp. of the Northern Portuguese
           coastline: Chemical approach by HPLC-DAD-ESI/MSn and UPLC-ESI-QTOF/MS
    • Authors: Graciliana Lopes; Mariana Barbosa; Fernando Vallejo; Ángel Gil-Izquierdo; Paula B. Andrade; Patrícia Valentão; David M. Pereira; Federico Ferreres
      Pages: 113 - 120
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Graciliana Lopes, Mariana Barbosa, Fernando Vallejo, Ángel Gil-Izquierdo, Paula B. Andrade, Patrícia Valentão, David M. Pereira, Federico Ferreres
      Several attempts have been made in recent years to fully characterize phlorotannin-rich extracts. Nevertheless, this remains a challenging quest, not only because of seaweed complex chemical composition, but also due to the diverse structural assemblage within phlorotannin molecules (i.e., type of linkage, modification site, and number of additional hydroxyl groups). In this work, 22 phlorotannins were tentatively identified and their presence confirmed, in purified extracts obtained from four Fucus species, by HPLC-DAD-ESI/MS n and UPLC-ESI-QTOF/MS analyses. The characterized phlorotannins exhibited molecular weights ranging from 370 to 746Da and relatively low degree of polymerization (3–6 phloroglucinol units). Isomers of fucophlorethol, dioxinodehydroeckol, difucophlorethol, fucodiphlorethol, bisfucophlorethol, fucofuroeckol, trifucophlorethol, fucotriphlorethol, tetrafucophlorethol, and of fucotetraphlorethol were identified. Among the analysed phlorotannin purified extracts, only the ones wild-sourced and from aquaculture-grown Fucus vesiculosus exhibited five and six-ringed phloroglucinol oligomers in their composition. The remaining extracts from Fucus guiryi, Fucus serratus and Fucus spiralis were richer in both trimers and tetramers. The variability observed for the overall phlorotannin composition points to the influence of species-specific and/or external factors. As far as we know, mass spectra confirming the presence and degree of polymerization of phlorotannins in Portuguese-sourced brown macroalgae, specifically F. guiryi and F. serratus, as well as of aquaculture-grown F. vesiculosus, are not found in literature. The information gained in this work ascertains the role of advanced analytical tools in facilitating the use of this valuable natural resource for the development of macroalgal-based products, opening doors for future application of phlorotannin-rich extracts in the commercial areas related to nutraceuticals, pharmaceuticals, and cosmetics.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.025
      Issue No: Vol. 29 (2017)
       
  • A comparative assessment of the activity and structure of phlorotannins
           from the brown seaweed Carpophyllum flexuosum
    • Authors: Rui Zhang; Alexander K.L. Yuen; Marie Magnusson; Jeffrey T. Wright; Rocky de Nys; Anthony F. Masters; Thomas Maschmeyer
      Pages: 130 - 141
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Rui Zhang, Alexander K.L. Yuen, Marie Magnusson, Jeffrey T. Wright, Rocky de Nys, Anthony F. Masters, Thomas Maschmeyer
      The extraction and antioxidant activity of phlorotannins from the brown seaweeds Carpophyllum flexuosum, Carpophyllum plumosum and Ecklonia radiata was investigated to identify an optimised extraction process for novel anti-oxidant extracts. Subsequently, the composition of the most active phlorotannin extracts was determined. Microwave assisted extraction (MAE) using water was the most efficient extraction process with shorter processing times and a higher purity product than obtained with any of the other methods tested. MAE resulted in the fast, effective decomposition of the cellular structure, as identified through scanning electron microscopy (SEM), and this related directly to the efficiency of extraction. Phlorotannins extracted from C. flexuosum by MAE had the strongest antioxidant activity (62.1mggallicacidequivalents(GAE)/g dw of seaweed) and more than 5.5-fold greater 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability than ascorbic acid after 7-day incubation periods at 30°C and at 60°C. Six major chemical species of phlorotannin, belonging to the fuhalol group, were identified within the MAE extract using NMR and HPLC-MS. The results confirm phlorotannins from C. flexuosum to be promising natural, bio-derived and bio-compatible antioxidants, while identifying the most effective method to extract the constituents and retain antioxidant activity.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.027
      Issue No: Vol. 29 (2017)
       
  • Identification and feeding characteristics of the mixotrophic flagellate
           Poterioochromonas malhamensis, a microalgal predator isolated from outdoor
           massive Chlorella culture
    • Authors: Mingyang Ma; Yingchun Gong; Qiang Hu
      Pages: 142 - 153
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Mingyang Ma, Yingchun Gong, Qiang Hu
      Chlorella is a strong candidate as a potential production organism for future biofuels and other algal-derived products, but contamination by grazing protozoa is a major constraint to its commercial production on a large scale. In this study, a mixotrophic flagellate chrysophyte that targeted Chlorella in mass culture was observed in samples from outdoor massive photobioreactor systems. Data from field studies demonstrated that once the predatory flagellate was observed in the algal culture, there was a dramatic reduction in Chlorella cell concentration. The grazer was identified as Poterioochromonas malhamensis, based on both morphology and molecular barcoding employing 18S rDNA gene sequences. Transmission electron microscopy revealed that P. malhamensis digested the ingested Chlorella sorokiniana cells within a food vacuole, with residual cell wall from the prey being observed in the final phase. It was noted that during the process of ingesting and digesting the C. sorokiniana cells, the chloroplast of P. malhamensis reduced in size, whereas the number and volume of mitochondria increased. After the prey had been completely digested, the chloroplast and mitochondria of P. malhamensis returned to their pre-feeding status. Feeding experiments in the laboratory demonstrated that cell concentrations of C. sorokiniana and P. malhamensis were negatively correlated. Furthermore, once P. malhamensis reached 5×105 cellsmL−1 and the ratio of C. sorokiniana to P. malhamensis was in the range 15:1 to 30:1, the cell concentration of the C. sorokiniana culture decreased dramatically. The optimal temperature for P. malhamensis grazing on C. sorokiniana was 25°C; the grazing ability of P. malhamensis in light conditions was higher than that in dark conditions; and P. malhamensis preferred weakly acidic conditions. In addition, it was demonstrated that this flagellate could graze on other common microalgae of commercial value. On the basis of its capacity to ingest a wide spectrum of phytoplankton, and its wide environmental range and global distribution, this contaminant has the potential to be a common problem in microalgal mass cultures and warrants further study.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.024
      Issue No: Vol. 29 (2017)
       
  • Effect of light spectrum on isolation of microalgae from urban wastewater
           and growth characteristics of subsequent cultivation of the isolated
           species
    • Authors: Mahsa Izadpanah; Reza Gheshlaghi; Mahmood Akhavan Mahdavi; Ali Elkamel
      Pages: 154 - 158
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Mahsa Izadpanah, Reza Gheshlaghi, Mahmood Akhavan Mahdavi, Ali Elkamel
      Light quality plays an important role in regulation of microalgae growth. The aim of this work was to investigate the role of light spectrum in isolation of different strains of microalgae from urban wastewater. Screening and isolation under three light spectrums of white, red, and blue resulted in three different strains of Chlorella sorokiniana IG-W-96, Chlorella vulgaris IG-R-96, and Chlorella sp. IG-B-96, respectively. The strains were identified and named based on morphological characterization under light and confocal microscopy followed by molecular characterization. It was revealed that the light spectrum had significant influence on microalgae cell size. The largest and smallest cells were observed under blue and red light, respectively. The isolated strain under blue light when subsequently cultured under blue light in suspension mode showed the highest biomass density of 1.21±0.00gl−1, as well as lipid density and productivity of 0.29±0.02gl−1 and 40.24±4.02mglipid l−1 day−1, respectively. Due to its shorter growth time, however, maximum biomass productivity was obtained for the isolated and cultured strain under red lights. The proposed illumination methodology in isolation and cultivation improved growth characteristics, in such a way that similar light spectra in both steps led to the highest amounts of biomass, lipid, and productivities for each strain.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.029
      Issue No: Vol. 29 (2017)
       
  • Enhanced hydrocarbon production and improved biodiesel qualities of
           Botryococcus braunii KMITL 5 by vitamins thiamine, biotin and cobalamin
           supplementation
    • Authors: Suneerat Ruangsomboon; Piyanuch Sornchai; Noratat Prachom
      Pages: 159 - 169
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Suneerat Ruangsomboon, Piyanuch Sornchai, Noratat Prachom
      Botryococcus braunii, a green microalga which is a potentially good biodiesel feedstock, was isolated from a freshwater fish pond in Bangkok, and the effects of B-vitamins—thiamine, biotin and cobalamin as well as their mixes—on its biomass, hydrocarbon production, carbohydrate content and biodiesel properties were investigated, using a control group that was not supplemented with any vitamins. The addition of thiamine increased the alga's biomass and hydrocarbon content, whereas addition of biotin, cobalamin and mixes of all three vitamins did not increase its hydrocarbon content. Among the vitamins tested, thiamine 150μgL−1 was the best for producing high biomass (2.08±0.07gL−1), hydrocarbon content (37.29±0.41%), hydrocarbon yield (0.77±0.03gL−1) and hydrocarbon productivity (90.32±3.05mgL−1 d−1). Maximum carbohydrate content (386±39mgg−1) was achieved by addition of 1μgL−1 cobalamin. Compared to the control group, the alga cultured in media supplemented with 100μgL−1 thiamine showed better biodiesel properties with lower iodine value (76.42g I2 100g−1), cold filter plugging point (9.90°C) and higher cetane number (54.30). Therefore, thiamine was shown to be a promising culture medium supplement for this strain for using it as a feedstock for biodiesel production. An investigation of vitamin B-related gene in B. braunii KMITL 5 found related genes for thiamine (thi), biotin (bioB and bioF) and cobalamin (metE and metH) vitamins, which are marks of vitamin autotrophy in algae.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.028
      Issue No: Vol. 29 (2017)
       
  • Assessing textile wastewater treatment in an anoxic-aerobic
           photobioreactor and the potential of the treated water for irrigation
    • Authors: Zaineb Dhaouefi; Alma Toledo-Cervantes; Dimas García; Ahmed Bedoui; Kamel Ghedira; Leila Chekir-Ghedira; Raúl Muñoz
      Pages: 170 - 178
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Zaineb Dhaouefi, Alma Toledo-Cervantes, Dimas García, Ahmed Bedoui, Kamel Ghedira, Leila Chekir-Ghedira, Raúl Muñoz
      The potential of an anoxic-aerobic photobioreactor for the treatment of synthetic textile wastewater (STWW) was evaluated in terms of carbon and nutrient removal, water and toxicity reduction. The potential of the treated water for irrigation of Raphanus sativus was also assessed. Despite the low C/N ratio of the STWW, microalgae-bacteria symbiosis supported steady-state removal efficiencies of total organic carbon, total nitrogen and total phosphorus of 48±3%, 87±11% and 57±5%, respectively, at a hydraulic retention time of 10days. In addition, a consistent decolorization of the STWW was observed, with disperse orange-3 and blue-1 removals of ~80% and ~75%, respectively. This effective STWW treatment was confirmed by the reduction in genotoxicity potential and enhanced growth of R. sativus during irrigation with treated water. Finally, the heavy metal content of the soils irrigated with treated water was lower than that of STWW irrigated soils, which highlights the potential of this anoxic-aerobic photobioreactor for the treatment of textile wastewater and water reuse. However, more studies are still needed to elucidate the long-term effects of the treated water over the final consumer health.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.032
      Issue No: Vol. 29 (2017)
       
  • Cyanobacterial community structure in hot water springs of Indian
           North-Western Himalayas: A morphological, molecular and ecological
           approach
    • Authors: Yadvinder Singh; Arvind Gulati; D.P. Singh; J.I.S. Khattar
      Pages: 179 - 192
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Yadvinder Singh, Arvind Gulati, D.P. Singh, J.I.S. Khattar
      Cyanobacterial diversity from nine hot water springs of North-Western Himalayas scattered over an area of approximately 20,000km2 has been studied using polyphasic approach in relation to important ecological factors. These hot springs have hard water, with variation of temperature from 40 to 90°C and pH from 6.8–8.0. A total of 625 cyanobacterial isolates were cultured from 150 samples. On the basis of morphology, these isolates were represented by 22 species of 11 genera. A total of 220 cyanobacterial isolates representing morpho-species from each sampling site were subjected to molecular characterization by amplified ribosomal DNA restriction analysis (ARDRA), 16S rRNA gene, rbcL gene and cpcB-IGS-cpcA phycocyanin locus region sequencing for elucidating their identity, diversity and phylogenetic relationships. ARDRA analysis revealed 22 groups of cyanobacterial isolates from selected hot water springs. Sequence analysis of 16S rRNA gene, rbcL gene and cpcB-IGS-cpcA phycocyanin locus region revealed that the identity of the majority of the cyanobacterial species was congruent with the identity based on morphological features. The identity of 3 taxa; Leptolyngbya sp. PUPCCC 112.22, Phormidium sp. PUPCCC 118.2 and Phormidium sp. PUPCCC 118.3, based on both morphological features and molecular markers, did not match with known cyanobacterial species, indicating these as new genera/species. Phylogenetic analyses revealed that taxa from selected hot springs belonging to Stigonematales are monophyletic, whereas Chroococcales and Oscillatoriales are polyphyletic. Canonical correspondence analysis of physico-chemical parameters and cyanobacterial community of each hot water spring revealed that temperature, pH, conductivity, nitrogen, sulphate and phosphate influenced cyanobacterial community structure. Further, our study has revealed that the cyanobacterial community of hot water springs is comprised of endemic as well as globally distributed representatives and is influenced by ecological parameters. The nature of the cyanobacterial community structure depended on the water chemistry rather than geographical location of the spring.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.023
      Issue No: Vol. 29 (2017)
       
  • Exploring the function of acyltransferase and domain replacement in order
           to change the polyunsaturated fatty acid profile of Schizochytrium sp.
    • Authors: Lu-jing Ren; Sheng-lan Chen; Ling-jun Geng; Xiao-jun Ji; Xian Xu; Ping Song; Song Gao; He Huang
      Pages: 193 - 201
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Lu-jing Ren, Sheng-lan Chen, Ling-jun Geng, Xiao-jun Ji, Xian Xu, Ping Song, Song Gao, He Huang
      Omega-3 fatty acids have received considerable attention due to their substantial health benefits. The aim of this study was to investigate the roles of acyltransferase (AT) domain and replace it for regulating fatty acid profile in Schizochytrium sp.. Herein, Schizochytrium sp. was engineered via gene deletion of AT and replacement of the native AT with its homologue, Shew-AT domain from Shewanella sp.. The docosahexaenoic acid (DHA) content in total fatty acids of the AT deficient strain observably decreased from 49.52% to 35.2% and the strain exhibited a low growth rate. Replacement with the Shew-AT gene recovered the cell growth and led to a high DHA content, with 3.7 times more eicosapentaenoic acid (EPA). This study will expand knowledge for synthesis of polyunsaturated fatty acid and facilitate the design of microbes with high yields of omega-3 fatty acids as a source of these valuable compounds for nutritional improvement.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.021
      Issue No: Vol. 29 (2017)
       
  • Hydroxyapatite and dittmarite precipitation from algae hydrolysate
    • Authors: Ali Teymouri; Ben J. Stuart; Sandeep Kumar
      Pages: 202 - 211
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): Ali Teymouri, Ben J. Stuart, Sandeep Kumar
      Several research efforts across the globe have been concerned with addressing the technical barriers in the commercialization of algae-based sustainable biorefineries. Nutrients cost and management and in particular, phosphorus, have been highlighted as one of the most significant challenges in algae cultivation and downstream processing. In this study, 83wt% of phosphorus present in Scenedesmus sp. microalgae was extracted as water-soluble phosphate in aqueous phase via flash hydrolysis process while preserving the algae lipids. Subsequently, the phosphate containing aqueous phase (algae hydrolysate) was used for producing dittmarite and hydroxyapatite by two different mineralization processes. In the first pathway, more than 97wt% of the phosphate in the hydrolysate was recovered in the form of carbonate-hydroxyapatite, a valuable biomaterial, at 280°C within one hour of residence time via hydrothermal mineralization process. Whitlockite as the secondary phase was also observed along with the hydroxyapatite. In the second pathway, 67wt% of the phosphate and 6wt% of nitrogen were recovered as dittmarite (magnesium ammonium phosphate), an effective slow-release fertilizer, at 20°C via an atmospheric precipitation process. The effects of seeding, temperature, reaction time, and mineralizers to PO4 molar ratio on phosphate removal as well as product yield were studied. This is the first kind of study in which flash hydrolysis and mineralization processes were integrated to provide an energy efficient platform for phosphorus recovery from microalgae in forms of value added compounds that could be suitable for long-term storage and handling. Through this experimental study, we report the shortest residence time for hydroxyapatite precipitation from an algal hydrolysate. The short residence could substantially save in reactor size and processing time as well as provide an option for high throughput which could result in a significant cost reduction in algae to bioproducts and biofuels.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.030
      Issue No: Vol. 29 (2017)
       
  • Extraction of lipids from wet microalga Auxenochlorella protothecoides
           using pulsed electric field treatment and ethanol-hexane blends
    • Authors: A. Silve; I. Papachristou; R. Wüstner; R. Sträßner; M. Schirmer; K. Leber; B. Guo; L. Interrante; C. Posten; W. Frey
      Pages: 212 - 222
      Abstract: Publication date: January 2018
      Source:Algal Research, Volume 29
      Author(s): A. Silve, I. Papachristou, R. Wüstner, R. Sträßner, M. Schirmer, K. Leber, B. Guo, L. Interrante, C. Posten, W. Frey
      Pulsed Electric Field (PEF) treatment was used as pre-treatment on the microalgae strain Auxenochlorella protothecoides (A.p.) prior to organic solvent extraction of lipids. Experiments were performed on fresh biomass from mixotrophic or autotrophic culture which both had an evaluated lipid content of 30–35% of cell dry weight. Lipid yield was determined gravimetrically and compared to the reference lipid content assessed by bead-milling and subsequent Soxhlet extraction. The biomass was concentrated at 10% w/w solids prior to PEF-treatment and further dewatered afterwards to approximately 25% w/w before extraction. PEF-treatment with an energy input of 1.5MJ per kilogram of dry matter induced electropermeabilisation of the microalgae cells detected by the increase of the conductivity of the microalgae supernatant. This greatly increased the lipid yield upon subsequent monophasic solvent extraction. A mixture of Water/Ethanol/Hexane 1:18:7.3 vol/vol/vol enabled to recover 92%, and 72%, of the evaluated lipid content of mixotrophically, and autotrophically respectively, grown A.p., after 2h of extraction. Recovery increased to 97%, and 90% respectively, after 20h of extraction. The same extraction system on untreated biomass yielded maximum 10% of lipid content. The highest yields were obtained with 80mL of solvent for 1g dry biomass but solvent volume could be reduced by a factor two in case of mixotrophically grown microalgae. However, the solvent:biomass ratio still remains high, and includes a water-miscible solvent, ethanol. Total lipid extraction was confirmed by nile red staining of residual biomass combined with fluorescence microscopy imaging and flow cytometry. Gas chromatography analyses of extracted lipids after transesterification revealed that PEF- treatment did not alter their fatty acid composition. Overall PEF-treatment shows promising features for upscaling especially in a biorefinery concept since it avoids potentially harmful temperature increase and small debris problematic for further processing.
      Graphical abstract image

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.11.016
      Issue No: Vol. 29 (2017)
       
  • Phlorotannin extracts from Fucales: Marine polyphenols as bioregulators
           engaged in inflammation-related mediators and enzymes
    • Authors: Mariana Barbosa; Graciliana Lopes; Federico Ferreres; Paula B. Andrade; David M. Pereira; Ángel Gil-Izquierdo; Patrícia Valentão
      Pages: 1 - 8
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Mariana Barbosa, Graciliana Lopes, Federico Ferreres, Paula B. Andrade, David M. Pereira, Ángel Gil-Izquierdo, Patrícia Valentão
      Phlorotannins are widely recognized as an inexhaustible family of naturally occurring molecules, with great potential in food and pharmaceutical industries. The present work explores the anti-inflammatory activity of phlorotannins from different Fucus species native from the Northern Atlantic coast, and from Fucus vesiculosus Linnaeus grown in an integrated multi-trophic aquaculture (IMTA) system, all scarcely studied regarding these compounds. Purified phlorotannin extracts were evaluated for their toxicity and anti-inflammatory potential in both cell (RAW 264.7 macrophages) and cell-free systems [lipoxygenase (LOX) inhibition and nitric oxide radical (NO) scavenging activity]. Phlorotannin content ranged between 110.28 and 288.36μgofphloroglucinol equivalents(PGE)/100mg dry purified extract (DE), wild species presenting higher content than those from IMTA. Regarding LOX, a strong correlation (r =−0.9118; p <0.0001) between the IC50 values and total phlorotannin content was found, Fucus guiryi G.I. Zardi, K.R. Nicastro, E.S. Serrão & G.A. Pearson exhibiting the best inhibitory capacity (IC50 =82.10μg/mL), while F. vesiculosus from IMTA was the less effective (IC50 >500μg/mL). Correlation was also observed for NO scavenging (r =−0.6363; p =0.0108). The anti-inflammatory capacity of phlorotannin extracts was further evaluated using RAW 264.7 macrophages stimulated with bacterial lipopolysaccharide, as model of inflammation. The extracts studied were not toxic at the tested concentrations (31.25–500μg/mL). F. vesiculosus from wild origin was the most effective in reducing NO in cell culture medium (IC25 =56.52μg/mL), closely followed by other seaweed species under study. The IMTA species was the less effective one (IC25 =317.41μg/mL). According to the results obtained, phlorotannin extracts from Fucales arise as potentially beneficial in inflammation-related conditions, effectively acting upon enzymatic and non-enzymatic inflammatory targets.
      Graphical abstract image

      PubDate: 2017-10-12T17:18:50Z
      DOI: 10.1016/j.algal.2017.09.009
      Issue No: Vol. 28 (2017)
       
  • Biological synthesis of gold nanoparticles by the diatom Stephanopyxis
           turris and in vivo SERS analyses
    • Authors: Nathalie Pytlik; Janine Kaden; Matthias Finger; Julia Naumann; Stefan Wanke; Susanne Machill; Eike Brunner
      Pages: 9 - 15
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Nathalie Pytlik, Janine Kaden, Matthias Finger, Julia Naumann, Stefan Wanke, Susanne Machill, Eike Brunner
      Cultivation of the sea water diatom Stephanopyxis turris (S. turris) in a gold salt containing medium leads to the formation of gold nanoparticles. These biosynthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). According to their diameter, they are classified into two groups with average diameters of around 30 and 10nm. It is demonstrated that both types of nanoparticles consist exclusively of gold. The location of the gold nanoparticles with respect to the diatom cell was revealed using surface enhanced Raman scattering (SERS). To ensure a reliable observation of SERS spectra in each measured cell, the concentration of the gold solution as well as the incubation time of S. turris in this solution were optimized. 3D Raman imaging of entire S. turris cells was performed to localize SERS spectra of compounds resulting from closely neighbored nanoparticles. Interestingly, intracellular SERS spectra were observed indicating the presence of gold nanoparticles inside S. turris cells. Further investigation shows that the SERS spectra generated by biosynthesized nanoparticles differ significantly from the conventional Raman spectrum of diatoms. While pigments are dominating the resonance enhanced Raman spectrum, SERS spectra exhibit a completely different appearance. Their bands coincide with bands in SERS spectra of various biologically relevant compounds, e.g., hydroxyurea and retinol. The biosynthesized gold nanoparticles therefore have a high potential for prospective in vivo research of algal metabolism and its regulation.
      Graphical abstract image

      PubDate: 2017-10-13T17:22:04Z
      DOI: 10.1016/j.algal.2017.10.004
      Issue No: Vol. 28 (2017)
       
  • Conversion of Chlamydomonas sp. JSC4 lipids to biodiesel using Fusarium
           heterosporum lipase-expressing Aspergillus oryzae whole-cell as
           biocatalyst
    • Authors: Jerome Amoah; Shih-Hsin Ho; Shinji Hama; Ayumi Yoshida; Akihito Nakanishi; Tomohisa Hasunuma; Chiaki Ogino; Akihiko Kondo
      Pages: 16 - 23
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Jerome Amoah, Shih-Hsin Ho, Shinji Hama, Ayumi Yoshida, Akihito Nakanishi, Tomohisa Hasunuma, Chiaki Ogino, Akihiko Kondo
      Lipid from Chlamydomonas sp. JSC4 was used as a feedstock for biodiesel production. The lipid was found to contain high amounts of phospholipids and free fatty acid in addition to the triglycerides. Two enzymatic methods for the efficient conversion of the heterogenous lipid to fatty acid methyl esters (FAME) were carried out. The method using either a lipase cocktail containing Candida cylindracea lipase and Thermomyces lanuginosus lipase combination (m I) or immobilized Fusarium heterosporum lipase-expressing Aspergillus oryzae whole-cells (m II) were both successful. However, the method using lipase cocktail showed 30.8% relative stability after the fourth batch, whereas the whole-cell biocatalyst showed 98.1%. Although the whole-cell biocatalyst tolerated a wide range of water content, an exploration of the effect of water-methanol interaction on the biocatalytic process showed that 24% water and 7:1 methanol to oil ratio is more favorable for FAME production. A higher initial methanol consumption rate facilitated a more stable system with the whole-cell biocatalyst, producing over 97% FAME in 32h. The efficient conversion of a highly heterogenous substrate in the presence of high amounts of water could be an effective technique for the enzymatic conversion of microalgal lipids.
      Graphical abstract image

      PubDate: 2017-11-02T14:21:19Z
      DOI: 10.1016/j.algal.2017.10.003
      Issue No: Vol. 28 (2017)
       
  • Selective removal of rotifers in microalgae cultivation using hydrodynamic
           cavitation
    • Authors: Donghyun Kim; Eun Kyung Kim; Hyun Gi Koh; Kyochan Kim; Jong-In Han; Yong Keun Chang
      Pages: 24 - 29
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Donghyun Kim, Eun Kyung Kim, Hyun Gi Koh, Kyochan Kim, Jong-In Han, Yong Keun Chang
      Rotifers in algal open ponds consume microalgae rapidly, eventually causing the pond to crash. Hydrodynamic cavitation (HC) has been suggested as a means of controlling rotifers, and its effect on Nannochlropsis salina was examined here. Rotifers were removed at a rate of 87% after a single pass of HC when the initial concentration was 1000 individuals/mL, and up to 99% after four passes, regardless of the initial concentration. The removal rate is expected to be higher than 96% with a single pass in an actual pond, as the rotifer concentration does not typically exceed 500individuals/mL, even under favorable environmental conditions. At the same intensity of HC, the reproductive capability of N. salina dropped by 12–15% however, the growth exhibited a constantly increasing overall tendency. In addition, the applied HC process was found to be the most energy efficient approach among the existing physical methods for controlling zooplanktons, requiring 6MJ of energy for treating 1m3 of algal suspension. Rotifers were sufficiently vulnerable and algae were relatively tolerant to the HC, and therefore HC can be adopted as a selective crop-protection method in microalgae cultivation.
      Graphical abstract image

      PubDate: 2017-11-02T14:21:19Z
      DOI: 10.1016/j.algal.2017.09.026
      Issue No: Vol. 28 (2017)
       
  • Direct transesterification of microalgae biomass and biodiesel refining
           with vacuum distillation
    • Authors: Simonet Torres; Gabriel Acien; Francisco García-Cuadra; Rodrigo Navia
      Pages: 30 - 38
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Simonet Torres, Gabriel Acien, Francisco García-Cuadra, Rodrigo Navia
      The objective of this study was the use of vacuum distillation to increase fatty acid methyl ester (FAME) content and quality of microalgae biodiesel produced through direct transesterification. Microalgae biodiesel obtained from direct transesterification of microalgae (crude biodiesel) has a FAME content of 64.98±2.88%, viscosity of 17.7±0.17 (mm2/s), and a humidity level of 3.72%. As biodiesel's properties are related to FAME content, to increase FAME content and produce higher quality biodiesel two vacuum distillation experiments were conducted using different vacuum conditions. The best results were obtained in experiment 2 with two consecutive distillations, where FAME content increased from 64.98±2.88% in crude biodiesel to 85.50±2.60% in the D2.2 fraction, while viscosity decreased from 17.70±0.17 (mm2/s) in crude biodiesel to 3.76±0.01 (mm2/s) in the D2.2 fraction. Vacuum distillation, therefore, may represent an excellent alternative for the purification of microalgae-based biodiesel.
      Graphical abstract image

      PubDate: 2017-11-02T14:21:19Z
      DOI: 10.1016/j.algal.2017.10.001
      Issue No: Vol. 28 (2017)
       
  • Ulvan from Ulva armoricana (Chlorophyta) activates the PI3K/Akt signalling
           pathway via TLR4 to induce intestinal cytokine production
    • Authors: Mustapha Berri; Michel Olivier; Sébastien Holbert; Joëlle Dupont; Hervé Demais; Matthieu Le Goff; Pi Nyvall Collen
      Pages: 39 - 47
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Mustapha Berri, Michel Olivier, Sébastien Holbert, Joëlle Dupont, Hervé Demais, Matthieu Le Goff, Pi Nyvall Collen
      The biological activities of water-soluble sulfated polysaccharides of green algae (ulvans) have been explored for use as bioactive molecules for the benefit of human and animal health. A purified ulvan fraction was prepared from the green algae Ulva armoricana harvested in the Brittany (France) and tested for its capacity to stimulate the immune response of the gut using an in vitro system of porcine intestinal epithelial (IPEC-1) cells. RT-qPCR and ELISA analyses showed a significant increase in the mRNA and protein expression of cytokines such as CCL20, IL8, and TNFα. Using human embryonic kidney (HEK) 293 reporter cell lines for pattern recognition receptors, ulvan was found to primarily stimulate TLR4. We also examined the effect of the ulvan fraction on different signalling pathways involved in the activation of cytokine gene expression. Western blot analyses of ulvan-treated HEK293-TLR4 cells showed an increase in the phosphorylation of Akt and the p65 subunit of nuclear factor-κB. Inhibition of Akt phosphorylation with the specific inhibitor abrogated the ulvan-mediated enhancement of IL-8 secretion. The overall results showed that ulvan is an immunostimulatory compound by itself, and furthermore, it could be used to effectively complex and deliver TLR ligands to relevant immune cells in vaccination strategies.

      PubDate: 2017-11-02T14:21:19Z
      DOI: 10.1016/j.algal.2017.10.008
      Issue No: Vol. 28 (2017)
       
  • Diurnal changes of photosynthesis and growth of Arthrospira platensis
           cultured in a thin-layer cascade and an open pond
    • Authors: Ana M. Silva Benavides; Karolína Ranglová; Jose Romel Malapascua; Jiří Masojídek; Giuseppe Torzillo
      Pages: 48 - 56
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Ana M. Silva Benavides, Karolína Ranglová, Jose Romel Malapascua, Jiří Masojídek, Giuseppe Torzillo
      Diel changes in photosynthetic performance and biomass productivity were thoroughly examined in Arthrospira platensis cultures grown outdoors in an open circular pond (OCP) and a thin-layer cascade (TLC). The two cultures were grown at the same areal biomass density, but temperature maxima were adjusted to optimal (33°C) and suboptimal (25°C). At the optimal temperature, the cultures grown in TLC showed about 20% higher photosynthetic activity than those in OCP, while at the suboptimal one photosynthetic activity dropped by 20% and 35% in the TLC and OCP, respectively. Accordingly, the highest biomass productivity over 20gm−2 d−1 was attained in the TLC at the optimal temperature, while at the suboptimal temperature the productivity decreased by 20%. In the OCP, the biomass productivity at both temperatures was about one third lower compared to those in the TLC. The better culture performance in the TLC was mainly ascribed to the shorter light path that promoted much faster light/dark cycles favourable for photosynthesis, as well as the faster warming of the cultures in the morning as compared to the OCP cultures. Monitoring photosynthesis performance of a culture can indicate design improvements, which may capitalize this photochemical advantage, increasing biomass productivity further.
      Graphical abstract image

      PubDate: 2017-11-02T14:21:19Z
      DOI: 10.1016/j.algal.2017.10.007
      Issue No: Vol. 28 (2017)
       
  • Hydrodynamic design of an enclosed Horizontal BioReactor (HBR) for algae
           cultivation
    • Authors: Tolga Pirasaci; Ahmet Y. Manisali; Ioannis Dogaris; George Philippidis; Aydin K. Sunol
      Pages: 57 - 65
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Tolga Pirasaci, Ahmet Y. Manisali, Ioannis Dogaris, George Philippidis, Aydin K. Sunol
      Modeling and optimization of key design parameters of bioreactors are critical for development of economically and technically viable algae technologies. The objective of this study is to use computational fluid dynamics (CFD) modeling to design a novel enclosed Horizontal BioReactor (HBR) equipped with a paddle wheel that incurs low capital and operating costs like raceway ponds, but achieves high productivities like enclosed photobioreactors. For the HBR the aspect ratio (length-to-width), paddle wheel diameter and positioning, culture depth, and baffle spacing can be manipulated to achieve adequate flow of the culture that minimizes the formation of low-velocity areas, below 20cm/s, termed “dead zones”. The CFD procedure focused on minimizing dead volume and power consumption. A small-scale HBR (3m2 of surface area) was used for development and validation of the hydrodynamic model, whose parameters were calculated using experimental data. The model was then applied to a pilot-scale HBR (40m2) that is operated outdoors. Placing the paddle wheel at either end of the reactor or incorporating baffles minimized the dead volume. The same effect was also achieved by increasing the size of the paddle wheel or the number of paddle wheels or the depth of the culture. On the other hand, increasing the reactor's aspect ratio resulted in more dead volume, although it decreased power consumption. These findings will be incorporated into the design of large-scale HBRs (200m2) for commercial deployment.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.009
      Issue No: Vol. 28 (2017)
       
  • Halo-adapted microalgae for fucoxanthin production: Effect of incremental
           increase in salinity
    • Authors: Tasneema Ishika; Navid R. Moheimani; Parisa A. Bahri; Damian W. Laird; Sandra Blair; David Parlevliet
      Pages: 66 - 73
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Tasneema Ishika, Navid R. Moheimani, Parisa A. Bahri, Damian W. Laird, Sandra Blair, David Parlevliet
      In order to commercially exploit microalgae for the production of fucoxanthin, species must remain productive in the increasingly saline environment typical in outdoor cultivation ponds. To this end, this study investigated the salinity range, growth, fucoxanthin content and productivity of two halotolerant and four marine microalgae under salinity increase condition. The semi-continuous cultivation followed by gradual salinity increase and slow adaptation helped saline microalgae to extend the salinity range up to 55%. Tested species showed about 12% to 90% more fucoxanthin content at their optimal salinity compared to when grown at non-optimal salinities. Fucoxanthin productivity was found directly linked to biomass productivity. Marine microalgae performed best at salinities <55‰ (ppt, parts per thousand) and halotolerant microalgae was best at salinities >55‰. Among marine species, the highest fucoxanthin content and productivity was observed in Chaetoceros muelleri which was 2.92mgg−1 and 0.072mgL−1 d−1 of ash free dry weight (AFDW), respectively, at 45‰ and fucoxanthin content was relatively consistent over the range of salinity between 35 and 55‰. Between two halotolerants, Amphora sp. showed the highest content and productivity of fucoxanthin which was 1.2mgg−1 and 0.053mgL−1 d−1 of AFDW, respectively at 85‰ salinity. The results indicate that it is most likely possible to achieve continuous production of fucoxanthin by cultivating marine and halotolerant species one after another when salinity rises due to evaporation. Details of fucoxanthin content and productivity for Chrysotila carterae, Chaetoceros muelleri, Amphora sp. and Navicula sp. are reported for the first time.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.002
      Issue No: Vol. 28 (2017)
       
  • Estimating fractal dimension of microalgal flocs through confocal laser
           scanning microscopy and computer modelling
    • Authors: Patricio Lopez Exposito; Angeles Blanco; Carlos Negro
      Pages: 74 - 79
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Patricio Lopez Exposito, Angeles Blanco, Carlos Negro
      Flocculation followed by settling is gaining momentum as a means to concentrate microalgal biomass due to the low investment and operation costs of the process. Microalgal flocculation can be further optimized by knowing the relationship between the hydrodynamic conditions applied in the process and the geometric properties of the flocs, namely characteristic size and fractal dimension, Df, given that settling rate is highly dependent on these two parameters. Current methods to characterize the geometry of flocs rely on estimating the 2D fractal dimension from microscopic images, which may result in inaccuracies caused by the overlapping or superimposition of aggregate structures prompted when the image of a 3D object is projected a on the plane, and due to the fact that the estimation performed is dependent on the orientation of the particle during image acquisition. The present paper describes a new procedure to estimate Df of Chlorella sorokiniana aggregates by correlating the 2D fractal dimension of the real aggregates microscopic images with the 2D fractal dimensions of computer generated flocs of prescribed 3D geometry. This procedure avoids the inaccuracies entailed with floc imaging and those due to the random orientation of the floc during image acquisition.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.011
      Issue No: Vol. 28 (2017)
       
  • Development and characterization of hybrid corn starch-microalgae films:
           Effect of ultrasound pre-treatment on structural, barrier and mechanical
           performance
    • Authors: María José Fabra; Marta Martínez-Sanz; Laura G. Gómez-Mascaraque; José M. Coll-Marqués; Juan Carlos Martínez; Amparo López-Rubio
      Pages: 80 - 87
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): María José Fabra, Marta Martínez-Sanz, Laura G. Gómez-Mascaraque, José M. Coll-Marqués, Juan Carlos Martínez, Amparo López-Rubio
      This work is aimed at evaluating the ability of the microalgae to partially substitute biodegradable materials with improved physicochemical properties. To this end, starch films containing the microalga Nannochloropsis gaditana sp. (N. gaditana) have been developed and characterized. Initially, different ultrasound treatments were evaluated for microalgae cell wall disruption. Although surfactant-aided sonication was the most efficient disruption method, the presence of the surfactant hampered continuous film formation. Subsequently, the ability of intact and ultrasound-treated N. gaditana cells to improve barrier properties of starch films was evaluated. Combined small and wide angle X-ray scattering experiments (SAXS/WAXS, respectively) evidenced slight nanostructural and crystallinity changes induced by the presence of N. gaditana cells. Incorporation of intact or ultrasound-treated microalgae into starch led to more hydrophobic films, with enhanced barrier properties for most of the formulations. However, the films containing the microalgae treated with the greatest ultrasound intensity, did not show any barrier improvement due to the plasticization promoted by the cell components (probably lipids) released during the ultrasound treatment, as suggested by SAXS/WAXS and the mechanical properties.
      Graphical abstract image

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.010
      Issue No: Vol. 28 (2017)
       
  • Cultivation in industrially relevant conditions has a strong influence on
           biological properties and performances of Nannochloropsis gaditana
           genetically modified strains
    • Authors: Giorgio Perin; Diana Simionato; Alessandra Bellan; Michele Carone; Andrea Occhipinti; Massimo E. Maffei; Tomas Morosinotto
      Pages: 88 - 99
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Giorgio Perin, Diana Simionato, Alessandra Bellan, Michele Carone, Andrea Occhipinti, Massimo E. Maffei, Tomas Morosinotto
      Microalgae are promising feedstocks for the production of biofuels thanks to their high biomass yield and the lack of competition with food crops for arable land. Algal industrial exploitation, however, still needs to address several technological challenges to reach energetic and economic sustainability. Genetic improvement of microalgae strains is seminal to fully exploit the potential of these organisms. In this work, we investigated how key environmental parameters affected productivity of a promising genetically modified algal strain cultivated in industrially relevant conditions. We observed that intensive growth conditions strongly influenced algae biology as evidenced by molecular and functional analyses. We also showed that specific operational conditions significantly affected performances, enhancing or reducing the advantages of the strains genetic modification, such as the chlorophyll content per cell and the abundance of photosynthetic apparatus components. This work demonstrates the presence of a strong influence of cultivation environment on the phenotype of improved strains, suggesting that operational parameters have a seminal influence on algae performances and must be taken into full account during strains development efforts.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.013
      Issue No: Vol. 28 (2017)
       
  • Optimization of seawater-based triacylglycerol accumulation in a
           freshwater green alga, Chlorella kessleri, through simultaneous imposition
           of lowered-temperature and enhanced-light intensity
    • Authors: Taihei Hayashi; Rie Otaki; Kazuho Hirai; Mikio Tsuzuki; Norihiro Sato
      Pages: 100 - 107
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Taihei Hayashi, Rie Otaki, Kazuho Hirai, Mikio Tsuzuki, Norihiro Sato
      Triacylglycerols (TG), the major components of crop oils used for the production of food oils and biodiesel fuel, accumulate in algal species under single environmental stress conditions including nitrogen-starvation. In a freshwater green alga, Chlorella kessleri, its TG content reached 24.7% in dry cell weight in 72h, on cultivation in 3-fold diluted seawater (1/3 SW), through the synergetic stimulating effects of hyperosmosis and nutrient-limitation. These observations would indicate the importance of combinatory stresses for strong induction of TG accumulation [Hirai et al. 2016]. We here searched for novel stresses in C. kessleri to elevate the seawater-based TG accumulation level through their additional actions. A higher light intensity (moderate light, ML) caused a small, but definite increase of TG, whereas a lowered growth temperature (LT) led to a large, but temporal increase of it until 48h, followed by severe degradation. The decrease of TG in LT cells was abolished on simultaneous imposition of ML. C. kessleri cells were then cultured in 1/3 SW under combinatory conditions of ML/LT, the TG content consequently increasing to as high as 48.5% in dry cells. These results indicated the validity of combinatory stresses for strong induction of algal TG accumulation. As to the fatty acid composition of TG, C. kessleri was intermediate between palm and the other three major oil crops including rapeseed. The rapid and abundant accumulation of TG with fatty acid composition suitable for industrial use demonstrated the great potential of development of the industrial algal TG production system with the use of the combinatory stresses in C. kessleri. TG of C. kessleri was also characteristic to contain C18 acids as representing 81mol% of its constituent fatty acids or 90% of fatty acids at its sn-2 position, which suggested a peculiar TG synthetic pathway in this oleaginous alga.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.016
      Issue No: Vol. 28 (2017)
       
  • Evaluation of waste activated sludge as a potential nutrient source for
           cultivation of Chlorella sorokiniana
    • Authors: Prathana Ramsundar; Abhishek Guldhe; Poonam Singh; Kriveshin Pillay; Faizal Bux
      Pages: 108 - 117
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Prathana Ramsundar, Abhishek Guldhe, Poonam Singh, Kriveshin Pillay, Faizal Bux
      Economical and sustainable microalgal biomass production is crucial for its commercial scale application for energy and other commodities. This work elucidates a novel cultivation strategy where nutrient-rich waste activated sludge (WAS) and final effluent (FE) from a municipal wastewater treatment process is used for microalgal biomass generation. This strategy reduces the use of synthetic nutrients, fertilizers and fresh water. Strategy development included investigation of pre-treatment/extraction methods for effective nutrient release and bacterial load reduction. Evaluation of growth kinetics, photosynthetic performance, nutrient removal efficiencies and biochemical composition of microalgae under mixotrophic (Mixo) and heterotrophic (Hetero) modes of cultivation was performed. Urea supplementation is studied to enhance the biomass productivity. Microalgae cultivation in acid pre-treated WAS+FE with urea supplementation of 1500mgL−1 showed biomass productivity of 298.75mgL−1 d−1. Microalgal biomass grown with WAS+FE using developed strategy showed higher lipid and protein productivities and comparable carbohydrate yields to the synthetic media.
      Graphical abstract image

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.006
      Issue No: Vol. 28 (2017)
       
  • Diversity of monosaccharides in marine macroalgae from the Eastern
           Mediterranean Sea
    • Authors: Arthur Robin; Patrick Chavel; Alexander Chemodanov; Alvaro Israel; Alexander Golberg
      Pages: 118 - 127
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Arthur Robin, Patrick Chavel, Alexander Chemodanov, Alvaro Israel, Alexander Golberg
      Macroalgae are primary producers bearing key roles in the normal functioning of marine environments. The critical energy carriers that macroalgae produce are carbohydrates, which support marine ecosystems and are used in biorefineries. In this work, we quantified the monosaccharide content and diversity of macroalgal species common to the Eastern Mediterranean shores representing the three major seaweed divisions, namely, Chlorophyta (Ulva sp. and Cladophora pellucida), Rhodophyta (Nemalion helminthoides, Galaxaura rugosa and Gracilaria sp.) and Ochrophyta (Padina pavonica and Sargassum vulgare). We found that the most abundant monosaccharide was different in 5 out of the 7 investigated species. The monosaccharide diversity profile was specific to each taxonomic group, especially in the first two orders of diversity, which correspond to Shannon entropy and Simpson concentration. The content of monosaccharides released by acid hydrolysis varied by 153% between Ulva sp., C. pellucida, G. rugosa, N. helminthoides, Gracilaria sp., P. pavonica, and S. vulgare collected from the same site. Ulva sp. collected at different sites at different months showed up to 79% variance in the total released monosaccharides, with up to 270% variance in the content of individual monosaccharides. The cultivation of Ulva sp. in a photobioreactor under more stable conditions reduced the diversity and the variability of the total carbohydrates to only 2%. By comparing amounts and types of monosaccharides derived from macroalgae, microalgae and terrestrial plants, it appears that Ulva sp. has the highest economic potential of all photosynthetic organisms, between $1733kg−1 and $3140kg−1 of Ulva biomass.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.005
      Issue No: Vol. 28 (2017)
       
  • Effect of enhanced biomass retention by sequencing batch operation on
           biomethanation of sulfur-rich macroalgal biomass: Process performance and
           microbial ecology
    • Authors: Heejung Jung; Jaai Kim; Changsoo Lee
      Pages: 128 - 138
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Heejung Jung, Jaai Kim, Changsoo Lee
      This study investigated the anaerobic digestion of Ulva biomass as an approach to diversifying energy sources and managing seaweed waste in a cost-effective manner. Ulva species are often identified as the main culprit of serious macroalgal blooms around the world, and their sulfur-rich nature causes difficulties in handling the biomass. Two reactors in continuous (Rc) and sequencing batch (Rs) modes were operated with decreasing hydraulic retention time in a stepwise manner from 20 to 6days. Rs allowed significantly higher methane productivity (0.19–0.22L/g chemical oxygen demand [COD] fed) and biomass retention capacity than Rc (0–0.16L/g COD fed) throughout the experiment. Interestingly, sulfide production was also higher in Rs than in Rc. These findings, together with microbial quantification results, suggested that Rs operation enhanced biomass retention and the activity of both methanogens and sulfate-reducing bacteria. The Rc microbial community was less diverse and more variable than the Rs community. Accordingly, the performance of Rc was more significantly affected by changes in hydraulic and thus organic loads. Aceticlastic Methanosaetaceae dominated the methanogen community in both reactors, with the abundance of methanogens being significantly higher in Rs than in Rc. This may explain the more efficient and stable methane production despite the greater sulfidogenic activity in Rs, particularly at high hydraulic loads. Together, the results suggest that sequencing batch operation is advantageous over conventional continuous flow operation for the biomethanation of Ulva biomass and potentially other sulfur-rich feedstocks.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.018
      Issue No: Vol. 28 (2017)
       
  • Exploring the metabolic and physiological diversity of native microalgal
           strains (Chlorophyta) isolated from tropical freshwater reservoirs
    • Authors: Renan Paulo Rocha; Mariana Machado; Marcelo Gomes Marçal Vieira Vaz; Christina C. Vinson; Maurício Leite; Rafael Richard; Leonardo Brantes Bacellar Mendes; Wagner L. Araujo; Camila Caldana; Marcio Arêdes Martins; Thomas C.R. Williams; Adriano Nunes-Nesi
      Pages: 139 - 150
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Renan Paulo Rocha, Mariana Machado, Marcelo Gomes Marçal Vieira Vaz, Christina C. Vinson, Maurício Leite, Rafael Richard, Leonardo Brantes Bacellar Mendes, Wagner L. Araujo, Camila Caldana, Marcio Arêdes Martins, Thomas C.R. Williams, Adriano Nunes-Nesi
      Microalgae have attracted interest as a potential feedstock for biodiesel and valuable co-products such as bioethanol and protein. However, production at a commercial scale is still costly in part due to a lack of knowledge of their biology which in turn limits our ability to increase their overall growth rate or alter their metabolism and composition through changes in culture conditions or genetic engineering. We therefore isolated ten strains of freshwater microalgae (Chlorophyta) and characterized them at the morphological, molecular and biochemical level under autotrophic conditions. Two Scenedesmus strains (BR003 and BR024) differed from others strains in respect to their fatty acid profile, with high levels of C16 and C18:1 and low levels of polyunsaturated fatty acids. Interestingly, Chlamydomonas sp. BR020 and Chlorella vulgaris BR017 showed high levels of α-linolenic acid (C18:3), while BR017 also exhibited higher protein levels (14% of total dry weight), suggesting that these may be interesting strains to be used within the biorefinery concept. Furthermore, Monoraphidium sp. BR023 showed higher lipid content (29% of total dry weight), and transesterifiable fatty acid production (43.2μgmg−1 dry weight) and lower starch levels (164μmolmg−1 dry weight) while Chlamydomonas sp. BR020 exhibited the opposite trend. The results suggest that Scenedesmus bajacalifornicus BR024, Selenastrum capricornutum BR009 and Scenedesmus obliquus BR003 represent potential strains for biomass and biodiesel production, presenting 1.81, 1.73 and 2.14mgmL−1 dry weight of biomass, respectively, and 21.6, 16.4 and 17% of total dry weight of lipid, respectively. Additionally, the two Scenedesmus species showed the highest lipid productivity (23mgL−1 d−1 and 24mgL−1d−1). Overall we were able to access a new source of microalgal biodiversity and perform a robust characterization of native tropical microalgae strains leading to the identification of strains with high potential for biotechnological applications.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.021
      Issue No: Vol. 28 (2017)
       
  • MALDI-TOF MS based discrimination of coccoid green microalgae
           (Selenastraceae, Chlorophyta)
    • Authors: Rodrigo V. Mello; Fabrício S. Meccheri; Inessa L. Bagatini; Edson Rodrigues-Filho; Armando A.H. Vieira
      Pages: 151 - 160
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Rodrigo V. Mello, Fabrício S. Meccheri, Inessa L. Bagatini, Edson Rodrigues-Filho, Armando A.H. Vieira
      The morphological simplicity of the cells in the family Selenastraceae has been a barrier to a good establishment of well-defined taxonomic groups, and consequently impairing the application of these organisms in the biotechnological field. Biomolecules are phenotypic expressions that can be useful in the taxonomy of microorganisms. In this scenario, the present study used the spectra of organic compounds (mainly proteins) of whole cells obtained by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique as a tool to differentiate freshwater coccoid green microalgae of the family Selenastraceae at the species and strains levels. Firstly, a test to choose the matrix and sample preparation method that could result in higher signal-to-noise ratio was performed with the species Ankistrodesmus fusiformis and Coelastrum sphaericum. The best spectra were obtained using α-cyano-4-hydroxycinnamic acid (HCCA) and matrix suspension method, which were used for chemotaxonomic analysis of 18 microalgal strains belonging to 12 different species. Spectra of microalgae cells were collected in two different mass ranges, from 0.4 to 2.0kDa and from 2.0 to 20.0kDa. Each strain yielded unique spectra with a good resolution of peaks and reproducibility, which was used for the cluster analyses. The dissimilarity analysis showed that it was possible to distinguish microalgal strains and species based on the obtained spectra. Geographic differences for the genus Selenastrum were evidenced in both mass ranges analyzed. Furthermore, our data corroborated some previous studies with Selenastraceae, using molecular markers, regarding to the polyphyly of the genus Monoraphidium. The spectra collected at higher masses contained more significant information for the taxonomy of green coccoid microalgae, allowing a better distinction between the genus Ankistrodesmus and Monoraphidium. The good classification results allied with practicability and quickness for data acquisition using MALDI-TOF MS favors its application in taxonomic studies.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.015
      Issue No: Vol. 28 (2017)
       
  • Factors influencing algal photobiohydrogen production in algal-bacterial
           co-cultures
    • Authors: Gergely Lakatos; Daniella Balogh; Attila Farkas; Vince Ördög; Péter Tamás Nagy; Tibor Bíró; Gergely Maróti
      Pages: 161 - 171
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Gergely Lakatos, Daniella Balogh, Attila Farkas, Vince Ördög, Péter Tamás Nagy, Tibor Bíró, Gergely Maróti
      Algal-bacterial co-cultures represent an alternative way for algal biohydrogen generation. Efficient algal hydrogen production requires anaerobiosis and electrons accessible for the algal FeFe‑hydrogenases. A number of factors strongly influence the development of this optimal environment. Various algal strains were tested for hydrogen evolution with a selected bacterial partner, a fully hydrogenase deficient Escherichia coli. During the hunt for the most efficient algae strains, gas-to-liquid phase ratio, algal optical density and algal cell size were identified as crucial factors influencing algal hydrogen evolution rate, accumulated algal hydrogen yield, carbon dioxide and oxygen levels as well as acetic acid consumption in illuminated algal-bacterial cultures. The highest accumulated hydrogen yields were observed for the different algal partners under similar experimental setup. The combination of a gas-to-liquid phase ratio of 1/1 with an algae cell density of 3.96∗108 algae cellml−1 (OD750: 1) resulted in the highest accumulated algal hydrogen yields under continuous illumination of ~50μmolm−2 s−1 light at 25°C irrespective of the applied algae strain. Accumulated hydrogen yield was also strongly influenced by the algal cell size, smaller cell size correlated with higher hydrogen evolution rate. The highest accumulated algal hydrogen yield (88.98±2.19mlH2 l−1 d−1) was obtained with Chlorella sp. MACC 360 -E. coli ΔhypF co-culture.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.024
      Issue No: Vol. 28 (2017)
       
  • Antenna size reduction and altered division cycles in self-cloned,
           marker-free genetically modified strains of Haematococcus pluvialis
    • Authors: Revital Sharon-Gojman; Stefan Leu; Aliza Zarka
      Pages: 172 - 183
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Revital Sharon-Gojman, Stefan Leu, Aliza Zarka
      The microalga Haematococcus pluvialis (H. pluvialis) is widely used for the commercial production of the red high value pigment astaxanthin. The major limitations of this species for supplying cheap natural astaxanthin in large scale cultivation are its slow growth rate and sensitivity to contaminants. We have applied recently developed advanced tools to genetically engineer H. pluvialis, by inserting two genes, the low CO2 inducible gene lciA (predicted to be a bicarbonate transporter) and mutated nucleic acid binding protein I, nabI* (a constitutively active translational repressor of the LHCII proteins), which were previously reported to enhance biomass productivity when overexpressed in various microalgae. Both genes were successfully integrated into the H. pluvialis genome, either separately or together, using the endogenous norflurazon resistant mutated gene of phytoene desaturase as a selection marker. Successful incorporation and expression of both genes using a linear purified DNA fragment, containing exclusively rearranged lciA, mutated pds and nabI* genes of H. pluvialis, represents to our knowledge the first functional self-cloning approach in microalgae, a breakthrough that can facilitate the widespread use of genetically altered microalgae. Initial detailed characterization of the growth physiology of two transformed strains revealed important information as to the impact of those two genes. Overexpression of the lciA gene alone resulted in alterations in growth physiology and division cycle, but with little impact on biomass productivity. A transformed strain expressing both lciA and mutated nabI* displayed a significant reduction in chlorophyll content, an altered division cycle and possibly enhanced biomass and carotenoid productivity under certain conditions. However, further work and additional progress exploring an array of optimizing options will be required towards creation of modified strains of truly advanced biotechnological potential for commercial applications.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.09.015
      Issue No: Vol. 28 (2017)
       
  • Enhanced extracellular polysaccharide production and growth by microalga
           Netrium digitus in a porous substrate bioreactor
    • Authors: Alice Ekelhof; Michael Melkonian
      Pages: 184 - 191
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Alice Ekelhof, Michael Melkonian
      Desmids (Zygnematophyceae) often secrete enormous amounts of extracellular polysaccharides with potential biotechnological applications. By using a porous substrate bioreactor (PSBR), the effects of light, pH and nitrogen availability on extracellular polysaccharide (EP) production of Netrium digitus, a desmid with excessive EP secretion, were investigated in immobilized cultures. The cultivation of a microalga in a PSBR, in contrast to conventional suspension culture, separates growth medium from biomass and therefore allows exchange and manipulation of the growth medium without physical disturbance of the biofilm. Over a cultivation period of at least 12days, cellular biomass growth and EP concentration per growth area were monitored under various abiotic conditions. Growth and EP production were positively influenced by light intensity as an increased growth rate of 3.2g∙m−2 of growtharea∙d−1 compared to 1.8g∙m−2 ∙d−1 and an EP concentration of 32.4g∙m−2 versus 21.4g∙m−2 were observed after 18days at 330 and 70μmolphotons∙m−2 ∙s−1, respectively. Further, a correlation between the pH of the culture medium and the ratio of EP to cell dry weight was observed. The lower the pH, the higher this ratio was with a maximum of 0.61 at a pH of 4.5. Omitting the nitrogen source after 6days of growth did not affect the growth rate of cell dry weight compared to a medium with nitrogen, but EP production ceased completely. In contrast, increasing the nitrate concentration to 3.85mM, increased the EP concentration by 18% and resulted in an EP concentration of 25.0g∙m−2 at 330μmolphotonsm−2 ∙s−1 after 6days with increased nitrogen supply. The results provide a roadmap to improve the yield of EP in immobilized cultivation of desmids and thus make them amenable for future biotechnological applications.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.11.003
      Issue No: Vol. 28 (2017)
       
  • Effects of pH on cell growth, lipid production and CO2 addition of
           microalgae Chlorella sorokiniana
    • Authors: Renhe Qiu; Song Gao; Paola A. Lopez; Kimberly L. Ogden
      Pages: 192 - 199
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Renhe Qiu, Song Gao, Paola A. Lopez, Kimberly L. Ogden
      Microalgae have emerged as one of the most promising alternative energy feedstocks. Some advantages include the simple cellular structure, short production cycle, high lipid content, and fast growth. However, high production costs due to high CO2 usage and low lipid productivity have been some of the major challenges impeding the commercial production of algal biodiesel. Here, cell growth and lipid content of Chlorella sorokiniana DOE1412 were first evaluated at different pH in flask cultivation. Culture pH was manipulated by CO2 addition. The optimal pH for DOE1412 is approximately 6.0 when only accounting for cell growth and lipid production and not considering the CO2 efficiency. A flat panel airlift photobioreactor (PBR) was used for scale-up cultivation at five different pH levels (6.5, 7, 7.5, 8 and 8.5). Data of pH values and CO2 addition was collected by a data logger. Biomass productivity increased with decreasing pH. By taking into account not only the cell growth and lipid production but also CO2 addition, the lowest value of CO2 addition was achieved at pH8 (2.01g CO2/g biomass). The fatty acid profiles and biodiesel properties, such as iodine value (IV), saponification value (SV), cetane number (CN), degree of unsaturation (DU), long-chain saturated factor (LCSF), and cold filter plugging point (CFPP), were determined as a function of pH. CN of biodiesel produced at pH6.5, 7 and 7.5 satisfied the US standard ASTM D6751; among them, the pH6.5 products met the European standard EN 14214. Finally, protein content in microalgal biomass increased with increasing pH, while C/N ratio in cells decreased.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.11.004
      Issue No: Vol. 28 (2017)
       
  • Responses of photosynthesis and CO2 concentrating mechanisms of marine
           crop Pyropia haitanensis thalli to large pH variations at different time
           scales
    • Authors: Kai Xu; Hongzhao Chen; Wenlei Wang; Yan Xu; Dehua Ji; Changsheng Chen; Chaotian Xie
      Pages: 200 - 210
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Kai Xu, Hongzhao Chen, Wenlei Wang, Yan Xu, Dehua Ji, Changsheng Chen, Chaotian Xie
      Wild and cultivated populations of Pyropia haitanensis have frequently experienced extremely low pH conditions in the last few decades. This could potentially threaten the development of the aquaculture of this economically important marine crop. To gain a broader perspective, we investigated the short- (4h) and long- (7days) term responses of CO2 concentrating mechanisms (CCMs) of P. haitanensis thalli to large variations in pH. Our study found that a pH of 4 and 5, which mimicked the decreased pH caused by acid rain, resulted in decreased photosynthesis and respiration while leading to the death of P. haitanensis thalli. Thus, acid rain would result in a decline in P. haitanensis production and threaten wild seaweed sources. However, a pH of 6 and 7 enhanced the growth of P. haitanensis thalli by >30%, mainly because increased CO2 levels favored photosynthesis, while the algae need to effectively maintain intracellular pH homeostasis to support rapid growth rates. The contributions of extracellular carbonic anhydrases (eCAs) to photosynthetic rates remained at >77% when pH≥7, regardless of the treatment time. However, at pH6, the contribution of eCAs to photosynthesis increased from 25% for a short-term treatment to 66% for a long-term treatment. Thus, except for work on carbon assimilation, this study proposes that the CCMs component involved in the movement and metabolism of inorganic carbon may play an important role in pH homeostasis. In addition, pH9 also led to the death of P. haitanensis thalli, which is consistent with observations of the natural distribution of this algae and hints that P. haitanensis thalli prefer to use inorganic carbon via eCAs when pH≥7. The present study suggested that the actual variation in pH experienced by marine organisms needs to be considered in the experimental design of related studies.

      PubDate: 2017-11-09T14:55:06Z
      DOI: 10.1016/j.algal.2017.10.023
      Issue No: Vol. 28 (2017)
       
  • Development of a bio-refinery process for the production of speciality
           chemical, biofuel and bioactive compounds from Laminaria digitata
    • Authors: Emily T. Kostas; Daniel A. White; David J. Cook
      Pages: 211 - 219
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Emily T. Kostas, Daniel A. White, David J. Cook
      The development of cascading bio-refinery processes that are capable of producing a range of valuable products is of increasing significance and will help to ensure that mankind makes efficient usage of bioresources. Seaweed feedstocks have the potential to be refined into fractions used for biofuel production, as renewable sources of platform chemicals or for a range of potentially interesting bioactive compounds. This study describes the development of a putative bio-refinery approach using Laminaria digitata as feedstock. Firstly, the commercially valuable polysaccharides fucoidan and alginate were extracted. Analysis of the monosaccharide and sulphate contents of the fucoidan extract confirmed its isolation with a purity of ca. 65%. Analysis of the composite residue remaining after extraction of alginate and fucoidan from L. digitata showed an increase in crude fibre content, of which the predominant monosaccharide was glucose (161.9mg glucose per g residue), making this residue a potential feedstock for bioethanol production. After dilute acid hydrothermal pre-treatment (1.5N H2SO4, 24min, 121°C, 25% [biomass/reactant] solids loading) and enzymatic saccharification of this residue, a 93.8% of theoretical glucose yield was achieved. This hydrolysate was fermented using Saccharomyces cerevisiae NCYC2592 and a yield of ca. 94.4% of the theoretical ethanol yield was achieved. To add value to the biorefining process, waste streams from the production of alginate, fucoidan and bioethanol were collected and screened for a range of bioactivities. Subsequently, a methanol extract prepared from the liquor waste stream which remained after polysaccharide extraction was shown to exhibit both anti-oxidant (EC50 15.3mg/mL) and anti-microbial activity against the human bacterial pathogen Burkholderia cenocepacia. The identification of extracts with bioactive attributes which have been recovered from a seaweed-based bio-refinery process is novel, and offers a potential route through which added value can be derived from natural resources such as L. digitata.

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.10.022
      Issue No: Vol. 28 (2017)
       
  • Identification and expression profile of an alpha-COPI homologous gene
           (COPA1) involved in high irradiance and salinity stress in Haematococcus
           pluvialis
    • Authors: Qiulan Luo; Jingjing Ning; Zhangli Hu; Chaogang Wang
      Pages: 220 - 228
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Qiulan Luo, Jingjing Ning, Zhangli Hu, Chaogang Wang
      In response to stresses, Haematococcus pluvialis accumulates triacylglycerols (TAGs) and astaxanthin, which are highly positively correlated in cells. Coatomer protein I (COPI) complexes play important roles in protein and lipid transportation between endoplasmic reticulum (ER) and Golgi apparatus. The proposed functions of COPI alpha-subunit (COPA1) were to maintain the integrity of endomembrane system and to regulate cellular physiological activities (such as autophagy, protein sorting, secretory trafficking and lipid metabolism). However, only scarce information has been reported on this subunit. In this study, the full-length cDNA encoding H. pluvialis COPA1 (HpCOPA1) and its promoter were cloned and further analyzed by bioinformatics tools. The predicted length of HpCOPA1 was 1234 amino acids (AAs), including WDR, Coatomer-WDAD and COPI-C motifs. The AA sequence of HpCOPA1 was highly identical (78%–99%) to other algal COPA1 and had a highly conserved WDR domain at the N terminus. The promoter of HpCOPA1 contained cis-elements in relation to light and salt stresses, such as AE-box, MNF1, CCAAT-box and TCA-element. Moreover, real-time qPCR analyses showed that the mRNA level of HpCOPA1 was strongly induced by treatments with either high irradiance, or high salinity (45mM sodium acetate) or in combination. HpCOPA1 revealed a delayed but higher peak expression level in treatments with high salinity (12.5-fold at 4h) compared with high irradiance (4.7-fold at 2h). To investigate its subcellular localization, HpCOPA1 was expressed in tobacco lower epidermal leaf cells in fusion with GFP. The results showed that HpCOPA1 was localized to plasma membrane and endomembrane system, partly similar to the localization of COPA1 in higher plants and animals. Taken together, the present results would contribute to the further elucidation of the regulatory mechanisms underlying the biosynthesis and transportation of lipids and astaxanthin in H. pluvialis.

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.10.012
      Issue No: Vol. 28 (2017)
       
  • Contaminations in mass cultivation of cyanobacteria: Highly resilient
           Colpoda steinii leads to rapid crash of Synechocystis sp. cultures and is
           inhibited by partially anoxic conditions
    • Authors: Clemens Troschl; Ines Fritz; Katharina Sodnikar; Bernhard Drosg
      Pages: 229 - 234
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Clemens Troschl, Ines Fritz, Katharina Sodnikar, Bernhard Drosg
      Contaminations in microalgae cultures are one of the major drawbacks when cultivating in an industrial scale. What is often experienced as culture crash has been rarely investigated in detail. Here, we show that the ciliated protozoa Colpoda steinii is capable to clear a dense culture of the cyanobacterium Synechocystis sp. within 2–3days. In a 200L tubular photobioreactor, this ciliate frequently appeared and led to great losses. The ciliate was isolated and characterized in the laboratory. Its grazing rate exceeded the growth rate of three tested Synechocystis strains (Synechocystis PCC6803, Synechocystis CCALA192 and Synechocystis minuscula SAG 258.80) by far. Due to its devastating effect on Synechocystis sp., its ability to form cysts and its resilience, Colpoda steinii was experienced as serious threat for large scale cultures of Synechocystis sp. The most common means against contaminations are high salinities and high pH values. Though, cultivating with salinities up to 20‰ and pH values up to 10 did not inhibit Colpoda steinii. Other strategies like high ammonia concentration, carbon dioxide (CO2) asphyxiation and anoxic conditions during the dark period were tested against the ciliate as well. While high ammonia concentration and CO2 asphyxiation did no inhibit Colpoda steinii, partially anoxic conditions inhibited this ciliate effectively and appears to be a promising cultivation method for Synechocystis sp. under non-sterile conditions.

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.11.002
      Issue No: Vol. 28 (2017)
       
  • Towards energy neutral microalgae-based wastewater treatment plants
    • Authors: Fabiana Passos; Raquel Gutiérrez; Enrica Uggetti; Marianna Garfí; Joan García; Ivet Ferrer
      Pages: 235 - 243
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Fabiana Passos, Raquel Gutiérrez, Enrica Uggetti, Marianna Garfí, Joan García, Ivet Ferrer
      The aim of this study was to assess the energy balance of a hypothetical microalgae-based wastewater treatment plant (10,000 PE) located in the Mediterranean Region, where harvested microalgal biomass and primary sludge would be co-digested to produce biogas and bioenergy. The assessment was based on experimental results obtained over one year in pilot high rate algal ponds followed by anaerobic digesters for biogas production from harvested microalgal biomass and primary sludge. The energy balance compared four scenarios: 1) anaerobic co-digestion of microalgal biomass and primary sludge, and cogeneration from biogas in a combined with heat and power (CHP) unit; 2) co-digestion with thermal pretreatment of microalgal biomass, and cogeneration from biogas in a CHP unit; 3) co-digestion and heat generation from biogas in a boiler; and 4) co-digestion with thermal pretreatment of microalgal biomass, and heat generation from biogas in a boiler. According to the results, when biogas was used to cogenerate electricity and heat (scenarios 1 and 2), the electricity balance was always positive, and the best results were obtained with pretreated microalgal biomass (scenario 2). Similarly, the heat balance was always positive when biomass was thermally pretreated (scenario 2). On the other hand, when biogas was only used to produce heat (scenarios 3 and 4), heat requirements were covered during the whole year. The sensibility analysis of the scenarios with pretreatment (2 and 4) confirmed that the microalgae-based WWTP would be energy neutral or even net energy producer.
      Graphical abstract image

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.11.006
      Issue No: Vol. 28 (2017)
       
  • Understanding lipid metabolism in high-lipid-producing Chlorella vulgaris
           mutants at the genome-wide level
    • Authors: Ehsan Sarayloo; Mehmet Tardu; Yigit Sabri Unlu; Salim Simsek; Gul Cevahir; Can Erkey; Ibrahim Halil Kavakli
      Pages: 244 - 252
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Ehsan Sarayloo, Mehmet Tardu, Yigit Sabri Unlu, Salim Simsek, Gul Cevahir, Can Erkey, Ibrahim Halil Kavakli
      In this study, physical and chemical mutagenesis methods were applied to enhance lipid productivity in Chlorella vulgaris. Then, de novo RNA-seq was performed to observe lipid metabolism changes at the genome-wide level. Characterization of two mutants, UV-715 and EMS-25, showed marked increases in lipid contents, i.e., 42% and 45%, respectively. In addition, the biomass productivity of the UV-715 cells was 9% higher than that of wild-type cells. Furthermore, gas chromatography-mass spectrophotometry analysis showed that both mutants have higher fatty acid methyl ester (FAME) contents than wild-type cells. To understand the effect of mutations that caused yield changes in UV-715 and EMS-25 cells at a genome-wide level, we carried out de novo RNA-seq. As expected, the transcriptional levels of the lipid biosynthesis genes were up-regulated, while the transcriptional levels of genes involved in lipid catabolism were down-regulated. Surprisingly, the transcriptional levels of the genes involved in nitrate assimilation and detoxification of reactive oxygen species (ROS) were significantly increased in the mutants. The genome-wide analysis results highlight the importance of nitrate metabolism and detoxification of ROS for high biomass and lipid productivity.

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.11.009
      Issue No: Vol. 28 (2017)
       
  • Evaluation of light energy to H2 energy conversion efficiency in thin
           films of cyanobacteria and green alga under photoautotrophic conditions
    • Authors: Sergey Kosourov; Gayathri Murukesan; Michael Seibert; Yagut Allahverdiyeva
      Pages: 253 - 263
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Sergey Kosourov, Gayathri Murukesan, Michael Seibert, Yagut Allahverdiyeva
      Cyanobacteria and green algae harness solar energy to split water and to fix CO2. Under specific conditions, they are capable of photoproduction of molecular hydrogen (H2). This study compares the light-energy-to-hydrogen-energy conversion efficiency (LHCE) in two heterocystous, N2-fixing cyanobacteria (wild-type Calothrix sp. strain 336/3 and the ΔhupL mutant of Anabaena sp. strain PCC 7120) and in the sulfur-deprived green alga, Chlamydomonas reinhardtii strain CC-124, after entrapment of the cells in thin Ca2+-alginate films. The experiments, performed under photoautotrophic conditions, showed higher LHCEs in the cyanobacteria as compared to the green alga. The highest efficiency of ca. 2.5% was obtained in films of the entrapped ΔhupL strain under low light condition (2.9Wm−2). Calothrix sp. 336/3 films produced H2 with a maximum efficiency of 0.6% under 2.9Wm−2, while C. reinhardtii films produced H2 most efficiently under moderate light (0.14% at 12.1Wm−2). Exposure of the films to light above 16Wm−2 led to noticeable oxidative stress in all three strains, which increased with light intensity. The presence of oxidative stress was confirmed by increased (i) degradation of chlorophylls and some structural carotenoids (such as β-carotene), (ii) production of hydroxylated carotenoids (such as zeaxanthin), and (iii) carbonylation of proteins. We conclude that the H2 photoproduction efficiency in immobilized algae and cyanobacteria can be further improved by entrapping cultures in immobilization matrices with increased permeability for gases, especially oxygen, while matrices with low porosity produced increased amounts of xanthophylls and other antioxidant compounds.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.09.027
      Issue No: Vol. 28 (2017)
       
  • A new endoparasite Olpidiopsis heterosiphoniae sp. nov. that infects red
           algae in Korea
    • Authors: Tatyana A. Klochkova; Min Seok Kwak; Gwang Hoon Kim
      Pages: 264 - 269
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Tatyana A. Klochkova, Min Seok Kwak, Gwang Hoon Kim
      A new species of Olpidiopsis, which infects dasyaceaen algae in Korea, is established. This endoparasite was first collected from Heterosiphonia pulchra, thus we named it O. heterosiphoniae. The infection process and asexual life history of O. heterosiphoniae were similar to previously reported Olpidiopsis species except for the cell type-specific infection in its host. The infection occurred mainly at the distal cells of determinate branches and was rarely observed in the other parts of the filament. The pathogen was transferred to another host, Heterosiphonia japonica, and the host-parasite dual culture has been kept in the laboratory for more than ten years since it was collected in May 2006. Up to 15 sporangia of 20–100μm in size developed in a single infected host cell. One sporangium contained between 8 and 128 zoospores at maturity. Zoospores were kidney-shaped, 3–4μm in size, with two laterally inserted flagella. Multigene analyses combining 18S rRNA, cox1 and cox2 genes showed that O. heterosiphoniae belonged to the lineage infecting filamentous red algae from the orders Ceramiales and Bonnemaisoniales. Epidemiological studies in Pyropia farms in Korea showed that O. heterosiphoniae may not be a main causative agent of Olpidiopsis blight in sea farms, although it is able to occasionally infect gametophyte blades of Pyropia tenera.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.09.019
      Issue No: Vol. 28 (2017)
       
  • Determination of the life cycle climate change impacts of land use and
           albedo change in algal biofuel production
    • Authors: Marie-Odile P. Fortier; Griffin W. Roberts; Susan M. Stagg-Williams; Belinda S.M. Sturm
      Pages: 270 - 281
      Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28
      Author(s): Marie-Odile P. Fortier, Griffin W. Roberts, Susan M. Stagg-Williams, Belinda S.M. Sturm
      Life cycle assessments (LCAs) of algal biofuels have typically ignore direct land use change impacts (DLUC), although a few papers have recently shown that the carbon lost from removing the original biomass and disrupting soil organic carbon (SOC) during pond construction can significantly contribute to the climate change impacts. In this study, LCA methods were developed to integrate climate change impacts of DLUC associated with cultivation of microalgae in open ponds and the effects of temporal and geographic variables on algal growth. In addition to direct land use change impacts due to loss of original biomass and the disruption of SOC, this study presents DLUC impacts caused by changing the surface albedo of an area and changing the carbon flux on the land. The methodology is presented with two LCA cases for the production of renewable gasoline from microalgae in climatically similar regions: the Everglades ecoregion and the Tamaulipas-Texas Semi-Arid Plain ecoregion. These were chosen to isolate the differences in DLUC impacts that are created by different land cover types, equalizing the life cycle impacts caused by temperature and solar radiation on algal growth. The DLUC impacts arising from albedo change and carbon flux change contributed significantly to the life cycle climate change impacts and differed between the two climatically similar regions. The baseline life cycle climate change impacts with DLUC impacts in the Everglades are 46.7% higher than those of conventional gasoline, while production in the Tamaulipas-Texas Semi-Arid Plain leads to a 3.0% reduction. The inclusion of albedo change impacts into the DLUC impacts contributed 10.2% of the life cycle climate change impacts in the Everglades and 36.4% in the Tamaulipas. This methodology can help assess the geographically specific sustainability of algal biofuels on a life cycle basis and can guide siting decisions for algal biofuel feedstock production.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.06.009
      Issue No: Vol. 28 (2017)
       
  • Inside Front Cover - Editorial Board Page/Cover image legend if applicable
    • Abstract: Publication date: December 2017
      Source:Algal Research, Volume 28


      PubDate: 2017-12-09T03:51:12Z
       
  • Empirical operating strategy to reduce the light-specific energy
           consumption of a flat-panel airlift photobioreactor with intrinsic static
           mixers cultivating Thermosynechococcus elongatus BP-1
    • Authors: Peter Bergmann; Walter Trösch
      Abstract: Publication date: Available online 22 November 2017
      Source:Algal Research
      Author(s): Peter Bergmann, Walter Trösch
      During photoautotrophic cultivations using optimized synthetic media, light is the limiting “substrate” of high-density cultures, especially throughout outdoor cultivations prohibiting adjustment of photon-flux density (PFD). Convective mass transfer (turbulence) is the method of choice to cope with that limiting effect. Then again, turbulence comes at costs through the energy required for its generation. In this context and based on laboratory data generated with Thermosynechococcus elongatus BP-1, an empiric operating strategy for flat-panel airlift photobioreactors with intrinsic static mixers is suggested. Repeated cultivations were performed from sub- to supra-saturating PFD (180 to 780μmolm−2 s−1) at aeration rates ranging from 0.11 to 0.83vvm assessing the cultures' productivities along the courses of biomass concentrations. The results indicate that, owing to the culture-flow directing mixers, there is a strong interrelation between the effects of PFD, biomass concentration and aeration rate (thus energy input) applied. Hereby, the positive impact of directed turbulence on the cultures' performance with respect to productivity and yield was greatest at high biomass concentration (>5gDW L−1) and PFDs with effects becoming less dominant while the latter two were reduced. Based on the quantitative findings and utilizing the easily monitored parameters PFD and biomass concentration, a computational model may be defined automatically controlling the easily adjustable parameter aeration rate. Without a negative influence on cultures' performance, this will allow for both, increase of culture performance at times of intense light and high biomass concentration as well as reduction of operational expenditures (OPEX) at times of dim light or low biomass concentration. Compared to the standard, continuous aeration regime, this may lead to a reduction of energy required for the generation of turbulence of 37%, especially when considering outdoor cultivations in temperate climate zones.

      PubDate: 2017-12-09T03:51:12Z
      DOI: 10.1016/j.algal.2017.10.014
       
  • Starch-based flocculant outperformed aluminium sulfate hydrate and
           polyaluminium chloride through effective bridging for harvesting acicular
           microalga Ankistrodesmus
    • Authors: Sook Yan Choy; Krishna Murthy Nagendra Prasad; Ta Yeong Wu; Mavinakere Eshwaraiah Raghunandan; Siew-Moi Phang; Joon Ching Juan; Ramakrishnan Nagasundara Ramanan
      Abstract: Publication date: Available online 15 November 2017
      Source:Algal Research
      Author(s): Sook Yan Choy, Krishna Murthy Nagendra Prasad, Ta Yeong Wu, Mavinakere Eshwaraiah Raghunandan, Siew-Moi Phang, Joon Ching Juan, Ramakrishnan Nagasundara Ramanan
      Microalgae represent a diversified pool of resources famed for valuable raw materials which are favoured over terrestrial crops in certain applications. Even so, limited green microalgae strains have been explored and studied till date. Thus, the highlight of this study is to comparatively evaluate the performance of pH-induced settling, use of chemical coagulants and starches as natural coagulants for efficient harvesting of acicular-shaped Ankistrodesmus. Biomass recoveries were determined through conventional jar tests and small scale coagulation-flocculation studies. Increased acidity at pH3 and enhanced basicity above pH11.5 have facilitated self-flocculation of cells leading to rapid settling. Despite that, potential reduction in chlorophyll contents and contamination from resulting precipitation of hydroxides evident from field-emission scanning electron microscopy micrographs may limit further applications of harvested biomass. By adding 12mg/L of alum or 4.8mg/L of polyaluminium chloride, up to 36.6% and 40% of the initial biomass was harvested respectively at pH6. Their poor performances were deduced to be the effect of buoyancy due to the long, curved needle-like structure with tapered ends of Ankistrodesmus. Remarkably, the use of 120mg/L of autoclaved rice starch has enhanced the biomass recovery to at least 80%; improvement of 2 fold from those achieved using chemical coagulants. The bridging mechanism induced by the use of starches coupled with the effect of slow mixing has been found to be paramount for enhancing the floc formation process through effective linking of neighbouring cells. Subsequently, an extended blanket of Ankistrodesmus cells was formed which facilitated its heightened settling upon treatment with starches.

      PubDate: 2017-11-17T02:10:52Z
      DOI: 10.1016/j.algal.2017.11.001
       
 
 
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