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BIOTECHNOLOGY (227 journals)                  1 2 | Last

Showing 1 - 200 of 227 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 7)
Advances in Bioscience and Biotechnology     Open Access   (Followers: 15)
Advances in Genetic Engineering & Biotechnology     Hybrid Journal   (Followers: 8)
African Journal of Biotechnology     Open Access   (Followers: 6)
Algal Research     Partially Free   (Followers: 9)
American Journal of Biochemistry and Biotechnology     Open Access   (Followers: 69)
American Journal of Bioinformatics Research     Open Access   (Followers: 8)
American Journal of Polymer Science     Open Access   (Followers: 30)
Animal Biotechnology     Hybrid Journal   (Followers: 10)
Annales des Sciences Agronomiques     Full-text available via subscription  
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 42)
Applied Bioenergy     Open Access  
Applied Biosafety     Hybrid Journal  
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 62)
Applied Mycology and Biotechnology     Full-text available via subscription   (Followers: 5)
Arthroplasty Today     Open Access   (Followers: 1)
Artificial Cells, Nanomedicine and Biotechnology     Hybrid Journal   (Followers: 2)
Asia Pacific Biotech News     Hybrid Journal   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 9)
Asian Pacific Journal of Tropical Biomedicine     Open Access   (Followers: 2)
Australasian Biotechnology     Full-text available via subscription   (Followers: 1)
Banat's Journal of Biotechnology     Open Access  
BBR : Biochemistry and Biotechnology Reports     Open Access   (Followers: 4)
Bio-Algorithms and Med-Systems     Hybrid Journal   (Followers: 1)
Bio-Research     Full-text available via subscription   (Followers: 2)
Bioactive Materials     Open Access   (Followers: 1)
Biocatalysis and Agricultural Biotechnology     Hybrid Journal   (Followers: 4)
Biocybernetics and Biological Engineering     Full-text available via subscription   (Followers: 5)
Bioethics UPdate     Hybrid Journal  
Biofuels     Hybrid Journal   (Followers: 11)
Biofuels Engineering     Open Access   (Followers: 1)
Biological & Pharmaceutical Bulletin     Full-text available via subscription   (Followers: 5)
Biological Cybernetics     Hybrid Journal   (Followers: 10)
Biomarkers and Genomic Medicine     Open Access   (Followers: 5)
Biomarkers in Drug Development     Partially Free   (Followers: 1)
Biomaterials Research     Open Access   (Followers: 4)
BioMed Research International     Open Access   (Followers: 6)
Biomédica     Open Access  
Biomedical Engineering Research     Open Access   (Followers: 7)
Biomedical glasses     Open Access  
Biomedical Reports     Full-text available via subscription  
BioMedicine     Open Access  
Bioprinting     Hybrid Journal  
Bioresource Technology Reports     Hybrid Journal  
Bioscience, Biotechnology, and Biochemistry     Hybrid Journal   (Followers: 22)
Biosimilars     Open Access   (Followers: 1)
Biosurface and Biotribology     Open Access  
Biotechnic and Histochemistry     Hybrid Journal   (Followers: 2)
BioTechniques : The International Journal of Life Science Methods     Full-text available via subscription   (Followers: 28)
Biotechnologia Acta     Open Access   (Followers: 1)
Biotechnologie, Agronomie, Société et Environnement     Open Access   (Followers: 2)
Biotechnology     Open Access   (Followers: 7)
Biotechnology & Biotechnological Equipment     Open Access   (Followers: 5)
Biotechnology Advances     Hybrid Journal   (Followers: 33)
Biotechnology and Applied Biochemistry     Hybrid Journal   (Followers: 44)
Biotechnology and Bioengineering     Hybrid Journal   (Followers: 160)
Biotechnology and Bioprocess Engineering     Hybrid Journal   (Followers: 6)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 14)
Biotechnology and Health Sciences     Open Access   (Followers: 1)
Biotechnology and Molecular Biology Reviews     Open Access   (Followers: 1)
Biotechnology Annual Review     Full-text available via subscription   (Followers: 7)
Biotechnology for Biofuels     Open Access   (Followers: 11)
Biotechnology Frontier     Open Access   (Followers: 2)
Biotechnology Journal     Hybrid Journal   (Followers: 16)
Biotechnology Law Report     Hybrid Journal   (Followers: 4)
Biotechnology Letters     Hybrid Journal   (Followers: 34)
Biotechnology Progress     Hybrid Journal   (Followers: 39)
Biotechnology Reports     Open Access  
Biotechnology Research International     Open Access   (Followers: 2)
Biotechnology Techniques     Hybrid Journal   (Followers: 10)
Biotecnología Aplicada     Open Access  
Biotribology     Hybrid Journal  
BMC Biotechnology     Open Access   (Followers: 16)
Chinese Journal of Agricultural Biotechnology     Full-text available via subscription   (Followers: 4)
Communications in Mathematical Biology and Neuroscience     Open Access  
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computer Methods and Programs in Biomedicine     Hybrid Journal   (Followers: 8)
Contributions to Tobacco Research     Open Access   (Followers: 3)
Copernican Letters     Open Access   (Followers: 1)
Critical Reviews in Biotechnology     Hybrid Journal   (Followers: 20)
Crop Breeding and Applied Biotechnology     Open Access   (Followers: 4)
Current Bionanotechnology     Hybrid Journal  
Current Biotechnology     Hybrid Journal   (Followers: 4)
Current Opinion in Biomedical Engineering     Hybrid Journal   (Followers: 1)
Current Opinion in Biotechnology     Hybrid Journal   (Followers: 55)
Current Pharmaceutical Biotechnology     Hybrid Journal   (Followers: 9)
Current Research in Bioinformatics     Open Access   (Followers: 14)
Current trends in Biotechnology and Pharmacy     Open Access   (Followers: 9)
EBioMedicine     Open Access  
Electronic Journal of Biotechnology     Open Access   (Followers: 1)
Entomologia Generalis     Full-text available via subscription  
Environmental Science : Processes & Impacts     Full-text available via subscription   (Followers: 4)
Experimental Biology and Medicine     Hybrid Journal   (Followers: 3)
Folia Medica Indonesiana     Open Access  
Food Bioscience     Hybrid Journal  
Food Biotechnology     Hybrid Journal   (Followers: 13)
Food Science and Biotechnology     Hybrid Journal   (Followers: 9)
Frontiers in Bioengineering and Biotechnology     Open Access   (Followers: 6)
Frontiers in Systems Biology     Open Access   (Followers: 2)
Fungal Biology and Biotechnology     Open Access   (Followers: 1)
GM Crops and Food: Biotechnology in Agriculture and the Food Chain     Full-text available via subscription   (Followers: 1)
GSTF Journal of BioSciences     Open Access  
HAYATI Journal of Biosciences     Open Access  
Horticulture, Environment, and Biotechnology     Hybrid Journal   (Followers: 11)
IEEE Transactions on Molecular, Biological and Multi-Scale Communications     Hybrid Journal   (Followers: 1)
IET Nanobiotechnology     Hybrid Journal   (Followers: 2)
IIOAB Letters     Open Access  
IN VIVO     Full-text available via subscription   (Followers: 4)
Indian Journal of Biotechnology (IJBT)     Open Access   (Followers: 2)
Indonesia Journal of Biomedical Science     Open Access   (Followers: 1)
Indonesian Journal of Biotechnology     Open Access   (Followers: 1)
Industrial Biotechnology     Hybrid Journal   (Followers: 18)
International Biomechanics     Open Access  
International Journal of Bioinformatics Research and Applications     Hybrid Journal   (Followers: 15)
International Journal of Biomechatronics and Biomedical Robotics     Hybrid Journal   (Followers: 4)
International Journal of Biomedical Research     Open Access   (Followers: 2)
International Journal of Biotechnology     Hybrid Journal   (Followers: 5)
International Journal of Biotechnology and Molecular Biology Research     Open Access   (Followers: 2)
International Journal of Biotechnology for Wellness Industries     Partially Free   (Followers: 1)
International Journal of Environment, Agriculture and Biotechnology     Open Access   (Followers: 5)
International Journal of Functional Informatics and Personalised Medicine     Hybrid Journal   (Followers: 4)
International Journal of Medicine and Biomedical Research     Open Access   (Followers: 1)
International Journal of Nanotechnology and Molecular Computation     Full-text available via subscription   (Followers: 3)
International Journal of Radiation Biology     Hybrid Journal   (Followers: 4)
Iranian Journal of Biotechnology     Open Access  
ISABB Journal of Biotechnology and Bioinformatics     Open Access  
Italian Journal of Food Science     Open Access   (Followers: 1)
Journal of Biometrics & Biostatistics     Open Access   (Followers: 3)
Journal of Bioterrorism & Biodefense     Open Access   (Followers: 6)
Journal of Petroleum & Environmental Biotechnology     Open Access   (Followers: 2)
Journal of Advanced Therapies and Medical Innovation Sciences     Open Access  
Journal of Advances in Biotechnology     Open Access   (Followers: 5)
Journal Of Agrobiotechnology     Open Access  
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 7)
Journal of Animal Science and Biotechnology     Open Access   (Followers: 6)
Journal of Applied Biomedicine     Open Access   (Followers: 3)
Journal of Applied Biotechnology     Open Access   (Followers: 2)
Journal of Applied Biotechnology Reports     Open Access   (Followers: 2)
Journal of Applied Mathematics & Bioinformatics     Open Access   (Followers: 5)
Journal of Biologically Active Products from Nature     Hybrid Journal   (Followers: 1)
Journal of Biomaterials and Nanobiotechnology     Open Access   (Followers: 6)
Journal of Biomedical Photonics & Engineering     Open Access  
Journal of Biomedical Practitioners     Open Access  
Journal of Bioprocess Engineering and Biorefinery     Full-text available via subscription  
Journal of Bioprocessing & Biotechniques     Open Access  
Journal of Biosecurity, Biosafety and Biodefense Law     Hybrid Journal   (Followers: 3)
Journal of Biotechnology     Hybrid Journal   (Followers: 68)
Journal of Chemical and Biological Interfaces     Full-text available via subscription   (Followers: 1)
Journal of Chemical Technology & Biotechnology     Hybrid Journal   (Followers: 10)
Journal of Chitin and Chitosan Science     Full-text available via subscription  
Journal of Colloid Science and Biotechnology     Full-text available via subscription  
Journal of Commercial Biotechnology     Full-text available via subscription   (Followers: 6)
Journal of Crop Science and Biotechnology     Hybrid Journal   (Followers: 7)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 3)
Journal of Experimental Biology     Full-text available via subscription   (Followers: 25)
Journal of Genetic Engineering and Biotechnology     Open Access   (Followers: 5)
Journal of Ginseng Research     Open Access  
Journal of Industrial Microbiology and Biotechnology     Hybrid Journal   (Followers: 16)
Journal of Integrative Bioinformatics     Open Access  
Journal of International Biotechnology Law     Hybrid Journal   (Followers: 3)
Journal of Medical Imaging and Health Informatics     Full-text available via subscription  
Journal of Molecular Microbiology and Biotechnology     Full-text available via subscription   (Followers: 14)
Journal of Nano Education     Full-text available via subscription  
Journal of Nanobiotechnology     Open Access   (Followers: 4)
Journal of Nanofluids     Full-text available via subscription   (Followers: 2)
Journal of Organic and Biomolecular Simulations     Open Access  
Journal of Plant Biochemistry and Biotechnology     Hybrid Journal   (Followers: 6)
Journal of Science and Applications : Biomedicine     Open Access  
Journal of the Mechanical Behavior of Biomedical Materials     Hybrid Journal   (Followers: 11)
Journal of Trace Elements in Medicine and Biology     Hybrid Journal   (Followers: 1)
Journal of Tropical Microbiology and Biotechnology     Full-text available via subscription  
Journal of Yeast and Fungal Research     Open Access   (Followers: 1)
Marine Biotechnology     Hybrid Journal   (Followers: 5)
Messenger     Full-text available via subscription  
Metabolic Engineering Communications     Open Access   (Followers: 4)
Metalloproteinases In Medicine     Open Access  
Microalgae Biotechnology     Open Access   (Followers: 2)
Microbial Biotechnology     Open Access   (Followers: 9)
MicroMedicine     Open Access   (Followers: 3)
Molecular and Cellular Biomedical Sciences     Open Access  
Molecular Biotechnology     Hybrid Journal   (Followers: 16)
Molecular Genetics and Metabolism Reports     Open Access   (Followers: 3)
Nanobiomedicine     Open Access  
Nanobiotechnology     Hybrid Journal   (Followers: 3)
Nanomaterials and Nanotechnology     Open Access  
Nanomaterials and Tissue Regeneration     Open Access  
Nanomedicine and Nanobiology     Full-text available via subscription  
Nanomedicine Research Journal     Open Access  
Nanotechnology Reviews     Hybrid Journal   (Followers: 5)
Nature Biotechnology     Full-text available via subscription   (Followers: 521)
Network Modeling and Analysis in Health Informatics and Bioinformatics     Hybrid Journal   (Followers: 3)
New Biotechnology     Hybrid Journal   (Followers: 4)
Nigerian Journal of Biotechnology     Open Access  
Nova Biotechnologica et Chimica     Open Access  
NPG Asia Materials     Open Access  
npj Biofilms and Microbiomes     Open Access  
OA Biotechnology     Open Access  
Plant Biotechnology Journal     Open Access   (Followers: 10)
Plant Biotechnology Reports     Hybrid Journal   (Followers: 4)
Preparative Biochemistry and Biotechnology     Hybrid Journal   (Followers: 4)

        1 2 | Last

Journal Cover Algal Research
  [SJR: 2.05]   [H-I: 20]   [9 followers]  Follow
   Partially Free Journal Partially Free Journal
   ISSN (Online) 2211-9264
   Published by Elsevier Homepage  [3177 journals]
  • The responses of two genes encoding phytoene synthase (Psy) and phytoene
           desaturase (Pds) to nitrogen limitation and salinity up-shock with special
           emphasis on carotenogenesis in Dunaliella parva
    • Authors: Changhua Shang; Wen Wang; Shunni Zhu; Zhongming Wang; Lei Qin; Mohammad Asraful Alam; Jun Xie; Zhenhong Yuan
      Pages: 1 - 10
      Abstract: Publication date: June 2018
      Source:Algal Research, Volume 32
      Author(s): Changhua Shang, Wen Wang, Shunni Zhu, Zhongming Wang, Lei Qin, Mohammad Asraful Alam, Jun Xie, Zhenhong Yuan
      Green alga Dunaliella parva can adapt to environmental stresses such as salinity up-shock and nitrogen limitation which are associated with carotenoid accumulation. However, the underlying molecular basis related to the change of carotenoid content needs further study. In the present study, we cloned two carotenoid biosynthesis genes coding for phytoene synthase and phytoene desaturase. In addition, the effects of salinity up-shock and nitrogen limitation on carotenoid content and expression of these two genes were studied in D. parva FACHB-815. The results showed that both salinity up-shock and nitrogen limitation had important effect on carotenoid yield and expression of these two genes. Cloning and expression analysis of these two genes will contribute to the understanding of molecular basis in stress-induced carotenoid accumulation, which is favorable for performing metabolic and genetic engineering to improve traits of D. parva.

      PubDate: 2018-03-18T15:48:21Z
      DOI: 10.1016/j.algal.2018.03.002
      Issue No: Vol. 32 (2018)
  • Non-steroidal anti-inflammatory drugs initiate morphological changes but
           inhibit carotenoid accumulation in Haematococcus pluvialis
    • Authors: István Bácsi; József Deli; Sándor Gonda; Ilona Mészáros; Gréta Veréb; Dalma Dobronoki; Sándor Alex Nagy; Viktória B-Béres; Gábor Vasas
      Pages: 1 - 13
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): István Bácsi, József Deli, Sándor Gonda, Ilona Mészáros, Gréta Veréb, Dalma Dobronoki, Sándor Alex Nagy, Viktória B-Béres, Gábor Vasas
      The economic role of certain types of cysts is unquestionable, since the production of several valuable biomolecules is connected to the resting stages of algae, including the red ketocarotenoid astaxanthin. It is relatively well known, how adverse environmental conditions induce cyst formation and astaxanthin accumulation. In the contrary, there is very limited information about stressors inhibiting these processes. An undesirable consequence of increasing drug use of the human and veterinary medicine is the appearance of the drugs both in natural and in mains water. Therefore, to study the effects of micro-contaminants, e.g. pharmaceuticals to non-target aquatic organisms is a recent issue both from ecological and economical point of view. In this study, the effects of three non-steroidal anti-inflammatory drugs (NSAIDs: diclofenac, diflunisal and mefenamic acid) on growth, cyst formation and astaxanthin accumulation of the flagellated green alga Haematococcus pluvialis were investigated. All three drugs inhibited growth, inhibition ranged from 29 to 81% on the basis of vegetative cell numbers on the 14th day of the experiments. Higher concentrations of the drugs led to higher proportion of cysts, which exceeded 60% of total cell number to the 14th day in diclofenac and diflunisal treatments. On the contrary, astaxanthin contents of treated cultures were lower with the increasing drug concentration, the pigment was undetectable in the presence of 0.075 and 0.05 mg ml−1 diclofenac. Results of carotenoid and chlorophyll content analysis suggest more specific processes behind the observed phenomena than membrane damage. Furthermore, the different phenomena or different extents of the same phenomena suggest that NSAIDs with diverse chemical structures may have different target points in physiological processes. Our results clearly show that NSAIDs could have much wider effective spectra than expected, long-term effects on microalgae might have unexpected ecological or economical consequences due to continuous exposure to these chemicals.
      Graphical abstract image

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.007
      Issue No: Vol. 31 (2018)
  • Potential new genera of cyanobacterial strains isolated from thermal
           springs of western Sichuan, China
    • Authors: Jie Tang; Dong Jiang; Yifan Luo; Yuanmei Liang; Liheng Li; Md. Mahfuzur R. Shah; Maurycy Daroch
      Pages: 14 - 20
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Jie Tang, Dong Jiang, Yifan Luo, Yuanmei Liang, Liheng Li, Md. Mahfuzur R. Shah, Maurycy Daroch
      Cyanobacteria have shown great potential for energy and environmental applications. Cyanobacterial resources, however, are still largely unexplored. Here, forty-nine out of one hundred thirty-two cyanobacterial isolates recovered from thermal springs of western Sichuan, China, were characterized. The phylogenetic analysis of 16S rRNA gene sequences categorized the isolates into three genera, Thermosynechococcus (63.3%), Leptolyngbya (34.7%) and Stanieria (2.0%). Based on sequence similarity, five phylotypes were identified as either putative new species of genus Leptolyngbya or possibly completely new genera. Temperature test showed that all isolates were thermotolerant and twenty-five isolates were capable of growth at temperature of 60 °C, suggesting that these isolates may have strong biotechnological potential. Additionally, three isolates exhibited NaHCO3 tolerance as high as 1 M, indicating that the isolates are promising candidates for bicarbonate-based cyanobacteria production system. Overall, this research laid solid basis for taxonomy and future exploration of extremophilic cyanobacteria for biotechnological and environmental applications.

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2018.01.008
      Issue No: Vol. 31 (2018)
  • Multistage wet lipid extraction from fresh water stressed Neochloris
           oleoabundans slurry – Experiments and modelling
    • Authors: Ying Du; Boelo Schuur; Sascha R.A. Kersten; D.W.F. (Wim) Brilman
      Pages: 21 - 30
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Ying Du, Boelo Schuur, Sascha R.A. Kersten, D.W.F. (Wim) Brilman
      Algae are considered an important renewable feedstock for lipid extraction to produce biofuels. Algae strain Neochloris oleoabundans used in this research can yield a high lipid content under stressed conditions. N-ethyl butylamine (EBA) as a switchable solvent has previously shown outstanding performance on energy efficient lipid extraction from non-broken wet algae slurry. In this work, a model was developed that describes the equilibrium state of lipid extraction from fresh water (FW)-stressed Neochloris oleoabundans algae slurry using EBA as solvent. When assuming that the cell interior is almost completely filled with the solvent phase during extraction, the model estimated extraction yields showed good agreement with those obtained in experiments. The developed model can predict the amount of crude lipid being recovered from any stage of a multistage extraction process.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.001
      Issue No: Vol. 31 (2018)
  • Enhancing fermentation wastewater treatment by co-culture of microalgae
           with volatile fatty acid- and alcohol-degrading bacteria
    • Authors: Wenqiang Qi; Shouhua Mei; Yizhong Yuan; Xuyang Li; Tao Tang; Quanyu Zhao; Minghong Wu; Wei Wei; Yuhan Sun
      Pages: 31 - 39
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Wenqiang Qi, Shouhua Mei, Yizhong Yuan, Xuyang Li, Tao Tang, Quanyu Zhao, Minghong Wu, Wei Wei, Yuhan Sun
      Co-culture of microalgae and bacteria is a promising method for wastewater treatment. The suitable selection of the bacteria in co-cultures with microalgae is critical for wastewater treatment. Three bacteria, Exiguobacterium aurantiacum, Stenotrophomonas acidaminiphila, and Chryseobacterium scophthalmus, were the dominant bacterial species in fermentation wastewater treated by microalgae and activated sludge. Pure cultures and co-cultures of microalgae (Chlorella sorokiniana L3) and these bacteria were evaluated for the treatment of fermentation wastewater, which contains high concentrations of acetate acid, butyric acid, ethanol and butanol. The performance of the co-cultures was better than that of pure cultures of microalgae or bacteria for the removal of four organic compounds, and the removal efficiency of volatile fatty acids and alcohols in the best co-culture case was increased by 22.70% compared to that of pure cultures. Butanol and butyric acid were much more difficult for microalgae and bacteria to remove than were acetic acid and ethanol. The co-cultures of Chlorella sorokiniana L3 with Stenotrophomonas acidaminiphila or Chryseobacterium scophthalmus had the highest removal efficiencies for the four organic compounds in all treatments. The co-cultures of Chlorella sorokiniana L3 with Exiguobacterium aurantiacum, Stenotrophomonas acidaminiphila or Chryseobacterium scophthalmus promoted not only chlorophyll a + b production but also biomass accumulation of Chlorella sorokiniana L3 during the 3 days of cultivation compared with those in pure cultures. More than 77.8% of NH4 +-N, 45.6% of total PO4 3−-P and 63.7% of COD (chemical oxygen demand) were removed in all co-cultures. These three bacteria are potential candidates for wastewater treatment through co-culture with microalgae.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.012
      Issue No: Vol. 31 (2018)
  • Carbon use efficiency diagnostics in Nannochloropsis salina
    • Authors: Tawanda Zidenga; Munehiro Teshima; George Perkins; Thom Rahn; Scott Twary; Jeffrey M. Heikoop
      Pages: 40 - 46
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Tawanda Zidenga, Munehiro Teshima, George Perkins, Thom Rahn, Scott Twary, Jeffrey M. Heikoop
      Carbon dioxide (CO2) can be a significant resource input affecting the cost of algae biomass production on an industrial scale. Improvements in biofuel productivity therefore require characterization of CO2 use efficiency (CUE). RuBisCO saturation with CO2 is an important factor influencing biomass productivity. During CO2 fixation by RuBisCO, fractionation of carbon isotopes occurs, with preferential fixation of 12CO2, resulting in assimilation of the lighter isotope in algae. This photosynthetic discrimination (ΔDIC-algae), approximated by the difference between the δ13C of external medium and that of algae, is a function of the proportion of CO2 fixed relative to supply. ΔDIC-algae has been applied to the study of photosynthesis in algae over the past few decades and we have adopted the tool to characterize improvements in conditions optimized for biofuel productivity, such as controlled photobioreactors. We report the use of ΔDIC-algae as a tool for characterizing CO2 dynamics and RuBisCO saturation in Nannochloropsis salina CCMP 1776, a benchmark strain in algal biofuels research. We use ΔDIC-algae to describe the conditions under which RuBisCO saturation can be achieved to maximize biomass productivity. Our results suggest that determination of ΔDIC-algae can provide important feedback to support engineering and cultural improvements that can impact carbon use efficiency and biomass productivity.

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2018.01.011
      Issue No: Vol. 31 (2018)
  • Cultivation of Emiliania huxleyi for coccolith production
    • Authors: I. Jakob; F. Weggenmann; C. Posten
      Pages: 47 - 59
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): I. Jakob, F. Weggenmann, C. Posten
      Graphical abstract image

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2018.01.013
      Issue No: Vol. 31 (2018)
  • Effect of pulsed electric fields and high pressure homogenization on the
           aqueous extraction of intracellular compounds from the microalgae
           Chlorella vulgaris
    • Authors: Daniele Carullo; Biresaw Demelash Abera; Alessandro Alberto Casazza; Francesco Donsì; Patrizia Perego; Giovanna Ferrari; Gianpiero Pataro
      Pages: 60 - 69
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Daniele Carullo, Biresaw Demelash Abera, Alessandro Alberto Casazza, Francesco Donsì, Patrizia Perego, Giovanna Ferrari, Gianpiero Pataro
      Pulsed Electric Fields (PEF) and High Pressure Homogenization (HPH) are promising and scalable cell disruption technologies of microalgae cells. In this work, the permeabilization degree, morphological properties, and extractability of intracellular compounds from microalgae Chlorella vulgaris suspensions (1.2%, w/w) were investigated as a function of PEF treatment at different electric field strengths (10–30 kV/cm) and total specific energy input (20–100 kJ/kg), in comparison with the more disruptive HPH treatment (150 MPa) at different number of passes (nP = 1–10). The conductivity and the particle size analyses, as well as the SEM images, clearly showed that PEF induces the permeabilization of the cell membranes in an intensity-dependent manner, without producing any cell debris, whereas HPH treatment causes the total disruption of the algae cells into small fragments. Coherently with the lower permeabilization capability, PEF promoted the selective extraction of carbohydrates (36%, w/w, of total carbohydrates), and low molecular weight proteins (5.2%, w/w, of total proteins). On the other hand, HPH induced the undifferentiated release of all the intracellular content, resulting in a 1.1 and 10.3 fold higher yields than PEF, respectively of carbohydrates and protein. These results suggest that, in a multi-stage biorefinery, PEF could represent a suitable cell disruption method for the selective recovery of small-sized cytoplasmic compounds, while HPH should be placed at the end the cascade of operations allowing the recovery of high molecular weight intracellular components.
      Graphical abstract image

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2018.01.017
      Issue No: Vol. 31 (2018)
  • Effect of carbon dioxide on biomass and lipid production of Chlorella
           pyrenoidosa in a membrane bioreactor with gas-liquid separation
    • Authors: Lei Zhang; Yong-Zhong Wang; Shengwei Wang; Ke Ding
      Pages: 70 - 76
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Lei Zhang, Yong-Zhong Wang, Shengwei Wang, Ke Ding
      In this work, an immobilized-cell biofilm photo-bioreactor, in which the CO2-rich gaseous phase was separated from the nutrient-rich liquid phase by a polytetrafluoroethylene membrane, was proposed to enhance the adsorption of CO2 by algal cells and the formation of biofilm on the membrane surface by reducing the disturbance from bubbles. The biomass productivity and biochemical composition, CO2 removal efficiency, and fatty acid profile were measured to evaluate effect of CO2 concentration on biomass and lipid production for biotechnological applications of the photo-bioreactor. The maximal biomass productivity (4.06 g/m2/d), lipid productivity (0.64 g/m2/d), and CO2 removal efficiency (52.5%) were obtained at 3% CO2 concentration, and C16–C18 fatty acids in this cultivated biofilm accounted for 96.28% to 98.61% of the total fatty acids in all runs. The results indicate that the productivities of lipid and biomass were significantly improved using the immobilized-cell cultivation method.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.014
      Issue No: Vol. 31 (2018)
  • Measurement of acoustic properties of microalgae and implications for the
           performance of ultrasonic harvesting systems
    • Authors: Esteban Hincapié Gómez; Jessica Tryner; Alyssa J. Aligata; Jason C. Quinn; Anthony J. Marchese
      Pages: 77 - 86
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Esteban Hincapié Gómez, Jessica Tryner, Alyssa J. Aligata, Jason C. Quinn, Anthony J. Marchese
      Microalgae are a promising feedstock for biofuel production, but difficulties associated with harvesting suspended cultures contribute to the high costs of algal feedstock production. Ultrasonic harvesting has been identified as a potential low-cost technique, but limited data are available on the response of microalgae cells in the presence of an acoustic field. The acoustic radiation force acting on a cell depends upon cell size and the acoustic contrast factor (ACF) of the cell in the media. The ACF depends upon the density and compressibility of the cell and the media. Cell size and ACF were measured for Microchloropsis gaditana, Nannochloropsis oculata, Phaeodactylum tricornutum, and Chlamydomonas reinhardtii. The average ACFs, which were determined by measuring the densities and sound velocities of suspensions containing varying concentrations of cells in growth media, were 0.04 (range = 0.03–0.05) for M. gaditana, 0.02 (range = 0.01–0.04) for N. oculata, 0.05 (range = 0.04–0.07) for P. tricornutum, and 0.05 (range = 0.049–0.053) for C. reinhardtii. The ratio of the acoustic radiation force to the drag force would be highest for C. reinhardtii cells due to their larger effective radius (5.6 μm compared to 1.9–2.7 μm for the other species). The effective ACF of C. reinhardtii was also evaluated by recording the motion of cells in the presence of an acoustic field, using particle tracking velocimetry, and then modeling the recorded motion using COMSOL Multiphysics software. The result (ACF = 0.04) demonstrated agreement with the density/sound velocity meter method. Experiments with starch null sta6 mutant C. reinhardtii cells demonstrated that the effective ACF can transition from positive to zero and eventually become negative as microalgae cells accumulate lipids. The dynamic nature of the ACF represents an opportunity and a challenge for acoustic harvesting of algal cells.
      Graphical abstract image

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.015
      Issue No: Vol. 31 (2018)
  • A pilot-scale bioprocess to produce amphidinols from the marine microalga
           Amphidinium carterae: Isolation of a novel analogue
    • Authors: A. Molina-Miras; A. Morales-Amador; C.R. de Vera; L. López-Rosales; A. Sánchez-Mirón; M.L. Souto; J.J. Fernández; M. Norte; F. García-Camacho; E. Molina-Grima
      Pages: 87 - 98
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): A. Molina-Miras, A. Morales-Amador, C.R. de Vera, L. López-Rosales, A. Sánchez-Mirón, M.L. Souto, J.J. Fernández, M. Norte, F. García-Camacho, E. Molina-Grima
      Marine dinoflagellate microalgae belonging to the genus Amphidinium are a key source of an interesting group of polyketide metabolites with potent bioactivities, wide-ranging functional diversity and stereochemical complexity, but low natural availabilities. The feasibility of a microalgae dinoflagellate-based sustainable bioprocess for producing amphidinols (APDNs) by photoautotrophic culture of Amphidinium carterae in a pilot-scale LED-illuminated bubble column photobioreactor (PBR) was therefore investigated. A fed-batch culture mode with pulse feeding strategy provided a growth pattern strongly limited by the availability of phosphate content in the culture medium that stimulated the production of cellular APDNs. Since A. carterae was found to be much more shear-sensitive than other shear-tolerant non-dinoflagellate microalgae, the culture height and air flow rate were established to ensure the absence of damaging levels of hydrodynamic stress. The biomass capacity yielded by the PBR at the end of the culture (0.540 g d.w. L−1 equivalent to 1.70 × 106 cell mL−1) corresponded to that estimated stoichiometrically from the experimentally determined biomass P-molar formula (C329 O126 H732 N69 S3 P1) and the total phosphorus and nitrogen balances. The downstream processing section was initially conceived to recover APDNs excreted by cells into the supernatant. A dry APDN-enriched extract concentration of 49 mg per liter of supernatant was obtained. This purification process led to partitioning of the extract into several fractions and sub-fractions thereof. Only two sub-fractions were studied, yielding thereof highly pure (>95% pure) luteophanol D and lingshuiol A, and a new, roughly purified (>80% pure) APDN, namely amphidinol 20. The percentages of luteophanol D, lingshuiol A and amphidinol 20 by dry weight of the APDN-enriched extract obtained were 1%, 0.39% and 0.31%, respectively, thus representing a concentration in the culture supernatant of 490, 191 and 152 μg L−1, respectively.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.010
      Issue No: Vol. 31 (2018)
  • Comparative assessment of algal oil with other vegetable oils for deep
    • Authors: Ashish Waghmare; Sonal Patil; Jean Guy LeBlanc; Sachin Sonawane; Shalini S. Arya
      Pages: 99 - 106
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Ashish Waghmare, Sonal Patil, Jean Guy LeBlanc, Sachin Sonawane, Shalini S. Arya
      Algae is an emerging source of vegetable oil. In this study, a comparative assessment of algal oil for deep frying with sunflower and palm oil was performed. Potato sticks were fried for four consecutive days in each of the individual oils under study. These oils were analyzed for density, refractive index, viscosity, oil uptake, acid value, percentage free fatty acid, acidity, peroxide value, total polar compounds, color, radical scavenging activity and fatty acid profile. Fried potato sticks were evaluated for texture and sensorial properties, the latter was performed using a fuzzy logic method. Principle component analysis was done for a variety of physicochemical parameters. This study revealed that the algal oil had the highest physical and chemical stability during the frying process compared to sunflower and palm oils. Potato sticks fried in algal oil had a superior texture and improved sensorial properties. Based on these results it can be concluded that algal oil has a great potential to be used for deep frying foods.

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2018.01.019
      Issue No: Vol. 31 (2018)
  • Is exploitation of microalgae economically and energetically
    • Authors: Laura Barsanti; Paolo Gualtieri
      Pages: 107 - 115
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Laura Barsanti, Paolo Gualtieri
      Microalgae are a diverse group of single-cell photosynthetic organisms, both prokaryotes and eukaryotes, which can rapidly grow in a wide range of habitats under photoautotrophic conditions. Recently, microalgae have been the object of increasing interest due to the attractive potential they offer in the current scenario of dwindling energy and food resources. Microalgae are flexible systems with the potential for production of feedstock biomass and high valuable natural products. Their productivities may be further improved with strain selection, genetic amelioration, and process engineering. However, though microalgae are considered the best alternative feedstock for the production of 3rd generation biofuel, the high cost of biomass production and biorefinery currently makes them uncompetitive with the cost of fossil fuels and traditional renewable energy resources. The development of microalgae culture technologies at commercial scale is, therefore, limited to a few profitable facilities around the world, producing very high value products (e.g., carotenoids, poly unsaturated fatty acids, immune-stimulants polysaccharides, etc.), whose high selling price can guarantee the return on investment. Our review deals with currently known natural high value products from microalgae, divided according to their potential use (i.e., energy- and non-energy based), their target market, and their cost-benefit balance beyond the biomass production. We analyze the economics of algal feedstock production and biorefinery, together with an overall energetic effectiveness of the cultivation process.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.001
      Issue No: Vol. 31 (2018)
  • Optimization of the levulinic acid production from the red macroalga,
           Gracilaria verrucosa using methanesulfonic acid
    • Authors: Mi-Ra Park; Sung-Koo Kim; Gwi-Taek Jeong
      Pages: 116 - 121
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Mi-Ra Park, Sung-Koo Kim, Gwi-Taek Jeong
      In this study, Gracilaria verrucosa, which is a red marine macroalgae and potential renewable resource, and methanesulfonic acid (MSA), which is known to be a strong and biodegradable acid catalyst, are introduced to produce levulinic acid (LA), which is a platform chemical, under hydrothermal conversion. Under the optimized conditions of the MSA-catalyzed hydrothermal conversion of G. verrucosa, a 22.02% LA yield based on biomass weight (36.92% based on carbohydrate) was obtained under the conditions of 180 °C, 10% biomass, 0.5 M MSA, and 20 min. In the same conditions, only 0.27% 5-HMF, 1.23% glucose, and 0.47% galactose were obtained. In the relationship of LA yield and combined severity factor (CSF) value, the LA yield was sharply increased to CSF 3.5 and then slightly decreased. Additionally, it fits well with a quadratic polynomial regression model. From these results, the MSA-catalyzed hydrothermal conversion of red-macroalgae G. verrucosa as a potential resource was concluded to be a valuable method for platform chemical production.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.004
      Issue No: Vol. 31 (2018)
  • The influence of exogenous organic carbon assimilation and photoperiod on
           the carbon and lipid metabolism of Chlamydomonas reinhardtii
    • Authors: Richard T. Smith; D. James Gilmour
      Pages: 122 - 137
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Richard T. Smith, D. James Gilmour
      Microalgae are a promising platform for the production of renewable fuels and oleochemicals. Despite significant research efforts to understand the mechanisms of algal lipid accumulation, the influence of commercially relevant growth conditions on the lipid metabolism is poorly understood. To characterise the impact of differing organic carbon availabilities and photoperiod on the response of the model alga Chlamydomonas reinhardtii to nitrogen stress, the expression of key genes involved in the central carbon metabolism were monitored over a time-course of nitrogen deprivation. In addition, the growth, PSII integrity, chlorophyll content, triacylglycerol (TAG) content, starch content, and fatty acid composition were characterised. Results indicate that both organic carbon availability and photoperiod regulate the lipid accumulation response of C. reinhardtii. Under mixotrophic conditions, organic carbon uptake is favoured over photosynthesis, transcript abundance of lipid synthesis genes rapidly increase and acetate is funnelled to TAG synthesis. In contrast, autotrophic cultures lacking organic carbon experienced a slower rate of photosynthetic degradation and funnelled the majority of sequestered carbon to starch synthesis. Dark periods induced catabolism of both starch and TAG in autotrophic cultures but TAG alone in mixotrophic cultures. Furthermore, diurnal light enhanced starch synthesis under mixotrophic conditions. Finally, transcript analysis indicated that PGD1, important for the routing of oleic acid to TAG, was reliant on organic carbon availability, resulting in reduced C18:1 fatty acid accumulation in autotrophic cultures.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.01.020
      Issue No: Vol. 31 (2018)
  • Energy-efficient outdoor cultivation of oleaginous microalgae at northern
           latitudes using waste heat and flue gas from a pulp and paper mill
    • Authors: Susanne Ekendahl; Mathias Bark; Johan Engelbrektsson; Carl-Anton Karlsson; Domitille Niyitegeka; Niklas Strömberg
      Pages: 138 - 146
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Susanne Ekendahl, Mathias Bark, Johan Engelbrektsson, Carl-Anton Karlsson, Domitille Niyitegeka, Niklas Strömberg
      Energy efficient cultivation is the major bottleneck for microalgal biomass production on a large scale and considered very difficult to attain at northern latitudes. In this study an unconventional method for industrial microalgae cultivation for bio-oil production using pulp and paper mill waste resources while harvesting only once a year was performed, mainly in order to investigate the energy efficiency of the process. Algae were cultivated for three months in 2014 in covered pond systems with access to flue gas and waste heat from the industry, and the biomass was recovered as thick sediment sludge after dewatering. The cultivation systems, designed to manage the waste resources, reached a promising photosynthetic efficiency of at most 1.1%, a net energy ratio (NER) of 0.25, and a projected year-round energy biomass yield per area 5.2 times higher than corresponding rapeseed production at the location. Thus, microalgae cultivation was, for the first time, proven energy efficient in a cold continental climate. Energy-rich indigenous communities quickly out-competed the oleaginous monocultures used for inoculation. The recovered biomass had higher heating values of 20–23MJkg−1 and contained 14–19% oil dominated by C16 followed by C18 fatty acids. The cultivation season at 59°15′N, 14°18′E was projected to be efficient for 10months and waste heat drying of the biomass is suggested for two winter months. The technique is proposed for carbon sequestering and energy storage in the form of microalgal sludge or dry matter for later conversion into biochemicals.
      Graphical abstract image

      PubDate: 2018-02-14T00:20:43Z
      DOI: 10.1016/j.algal.2017.11.007
      Issue No: Vol. 31 (2018)
  • Bacterial community changes in an industrial algae production system
    • Authors: Scott P. Fulbright; Adam Robbins-Pianka; Donna Berg-Lyons; Rob Knight; Kenneth F. Reardon; Stephen T. Chisholm
      Pages: 147 - 156
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Scott P. Fulbright, Adam Robbins-Pianka, Donna Berg-Lyons, Rob Knight, Kenneth F. Reardon, Stephen T. Chisholm
      While microalgae are a promising feedstock for production of fuels and other chemicals, a challenge for the algal bioproducts industry is obtaining consistent, robust algae growth. Algal cultures include complex bacterial communities and can be difficult to manage because specific bacteria can promote or reduce algae growth. To overcome bacterial contamination, algae growers may use closed photobioreactors designed to reduce the number of contaminant organisms. Even with closed systems, bacteria are known to enter and cohabitate, but little is known about these communities. Therefore, the richness, structure, and composition of bacterial communities were characterized in closed photobioreactor cultivations of Nannochloropsis salina in F/2 medium at different scales, across nine months spanning late summer – early spring, and during a sequence of serially inoculated cultivations. Using 16S rRNA sequence data from 275 samples, bacterial communities in small, medium, and large cultures were shown to be significantly different. Larger systems contained richer bacterial communities compared to smaller systems. Relationships between bacterial communities and algae growth were complex. On one hand, blooms of a specific bacterial type were observed in three abnormal, poorly performing replicate cultivations, while on the other, notable changes in the bacterial community structures were observed in a series of serial large-scale batch cultivations that had similar growth rates. Bacteria common to the majority of samples were identified, including a single OTU within the class Saprospirae that was found in all samples. This study contributes important information for crop protection in algae systems, and demonstrates the complex ecosystems that need to be understood for consistent, successful industrial algae cultivation. This is the first study to profile bacterial communities during the scale-up process of industrial algae systems.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2017.09.010
      Issue No: Vol. 31 (2018)
  • Influence of spectral light quality on the pigment concentrations and
           biomass productivity of Arthrospira platensis
    • Authors: Gustavo M. Lima; Pedro C.N. Teixeira; Cláudia M.L.L. Teixeira; Diego Filócomo; Celso L.S. Lage
      Pages: 157 - 166
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Gustavo M. Lima, Pedro C.N. Teixeira, Cláudia M.L.L. Teixeira, Diego Filócomo, Celso L.S. Lage
      The species in the Arthrospira genus are cultured at a large scale throughout the world primarily for food supplements for human and animal diets. These species are valued for the rich composition of their biomass, which contains minerals, antioxidants, proteins and essential amino acids. This biomass can also be used for high-value product extraction, for example, the pigments chlorophyll a, β-carotene and phycocyanin as well as essential fatty acids. The use of LEDs is a solution for optimizing the productivity and biochemical composition of biomass produced by these microalgae. In this study, an innovative strategy for using LEDs was evaluated for Arthrospira platensis cultivation to increase its biomass productivity and high-value pigments (chlorophyll a, total carotenoids and phycocyanin). Microalgae suspensions were cultured in 250 mL Erlenmeyer flasks containing 120 mL of culture (George-modified Zarrouk's medium, pH 8.90) at 32 ± 1 °C with constant stirring and an initial biomass concentration of 0.03 g L−1. The biomass weights from ten lighting conditions consisting of blue and red LEDs of different compositions were evaluated in relation to the algal productivity and the chlorophyll a, total carotenoid and phycocyanin contents. The best results were obtained using LEDs that had a 70% red and 30% blue composition and a light intensity of 100 μE m−2 s−1, leading to an average biomass productivity of 0.148 g L−1d−1 and average concentrations of 21.35 μg mL−1, 5.45 μg mL−1 and 167.98 μg mL−1 of chlorophyll a, carotenoids and phycocyanin, respectively, in the given culture volume.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.012
      Issue No: Vol. 31 (2018)
  • High-throughput system for quantifying and characterizing homologous
           recombination in Chlamydomonas reinhardtii
    • Authors: Hussam Hassan Nour-Eldin; Elizabeth A. Specht; Joseph Ostrand; Kevin T.D. Hoang; Prema S. Karunanithi; Stephen P. Mayfield
      Pages: 167 - 172
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Hussam Hassan Nour-Eldin, Elizabeth A. Specht, Joseph Ostrand, Kevin T.D. Hoang, Prema S. Karunanithi, Stephen P. Mayfield
      In the green alga Chlamydomonas reinhardtii, introduced DNA fragments predominantly insert randomly into the nuclear genome by non-homologous recombination (NHR), often resulting in highly variable phenotypes between transformants. Homologous recombination (HR) can occur in C. reinhardtii but at very low frequency, and is often accompanied by insertions, deletions, and/or rearrangements at the recombination site. To benchmark the frequency and characterize the nature of HR integrations in C. reinhardtii, we developed a system for detecting and characterizing HR events that includes three intact markers and one split marker as well a novel design element: utilizing a long intron as the homology region. In this study we demonstrate that this system meets the following criteria: accommodates high-throughput screening; provides a high-fidelity phenotype for detecting HR without false positives from reversion or locus heterogeneity; allows and captures both single- and double-crossover HR events; reports HR and NHR rates from a single transformation; and allows characterization of imprecise recombination or rearrangement at the integration site. Using this system we reproducibly determined the HR rate in our recipient strain of C. reinhardtii and characterized a number of recombinants by restriction digests and sequencing of PCR amplified recombination junctions to show that both double and single crossover events were recovered and that integration occurred both via perfect and imperfect (i.e. accompanied by insertions, deletions, and rearrangements) HR. This system is valuable for systematically testing approaches for increasing HR efficiency and accuracy.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.005
      Issue No: Vol. 31 (2018)
  • An in situ method for synthesis of magnetic nanomaterials and efficient
           harvesting for oleaginous microalgae in algal culture
    • Authors: Pei-Rui Liu; Zi-Yu Yang; Yu Hong; Yang-Long Hou
      Pages: 173 - 182
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Pei-Rui Liu, Zi-Yu Yang, Yu Hong, Yang-Long Hou
      An in situ approach for magnetic nanomaterial synthesis and harvesting of oleaginous Chlorella sp. HQ in an algal culture was explored. Fe-based nanomaterials were synthesized by an in situ reduction reaction using NaBH4 and FeCl3∙6H2O in an algal culture. The various reactant molar ratios and the reaction system of a water solution or an algal culture determined the different formation pathways of magnetic nanomaterials. With the optimal reactant molar ratio of 2:1, this in situ magnetic harvesting method obtained a high harvesting efficiency in a broad pH and temperature range and different algal concentration levels with cost of $505 US per ton of algal biomass harvested. During this in situ process, the algal antioxidant defense system efficiently eliminated the cellular reactive oxygen species caused by nanomaterials via catalase and superoxide dismutase. Fatty acid methyl ester composition analysis indicated that the Fe-based nanomaterials affected the relative contents of several components, but the predominant types were still palmitic acid (C16:0), linoleic acid (C18:2) and γ-linoleic acid (C18:3), which were suitable for biofuel production. Additionally, the recycled cultivation medium maintained normal algal cell growth within 18 days after the biomass had reached the harvesting level. This novel in situ method has promising potential for the harvest of oleaginous microalgae with good biocompatibility.
      Graphical abstract image

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.013
      Issue No: Vol. 31 (2018)
  • Overexpression of acetyl-CoA synthetase (ACS) enhances the biosynthesis of
           neutral lipids and starch in the green microalga Chlamydomonas reinhardtii
    • Authors: Rocío Rengel; Richard T. Smith; Richard P. Haslam; Olga Sayanova; Marta Vila; Rosa León
      Pages: 183 - 193
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Rocío Rengel, Richard T. Smith, Richard P. Haslam, Olga Sayanova, Marta Vila, Rosa León
      Genetic engineering can be the solution to achieve the economically feasible production of microalgal based biofuels and other bulk materials. A good number of microalgal species can grow mixotrophically using acetate as carbon source. Moreover, experimental evidence suggests that the biosynthesis of acetyl-CoA could be a limiting step in the complex multifactor-dependent biosynthesis of acylglycerides and point to acetyl-CoA synthetase (ACS) as a key enzyme in the process. In order to test this hypothesis we have engineered the model chlorophyte Chlamydomonas reinhardtii to overexpress the endogenous chloroplastic acetyl-CoA synthetase, ACS2. Expression of the ACS2 encoding gene under the control of the strong constitutive RBCS2 promoter in nitrogen-replete cultures resulted in a 2-fold increase in starch content and 60% higher acyl-CoA pool compared to the parental line. Under nitrogen deprivation, the Cr-acs2 transformant shows 6-fold higher levels of ACS2 transcript and a 2.4-fold higher accumulation of triacylglycerol (TAG) than the untransformed control. Analysis of lipid species and fatty acid profiles in the Cr-acs2 transformant revealed a higher content than the parental strain in the major glycolipids and suggests that the enhanced synthesis of triacylglycerol in the transformant is not achieved at the expense of membrane lipids, but is due to an increase in the carbon flux towards the synthesis of acetyl-CoA in the chloroplast. These data demonstrate the potential of engineering the chloroplastic ACS to increase the carbon flux towards the synthesis of fatty acids as an alternative strategy to enhance the biosynthesis of lipids in microalgae.
      Graphical abstract image

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.009
      Issue No: Vol. 31 (2018)
  • Techno-economic analysis of milking of Botryococcus braunii for renewable
           hydrocarbon production
    • Authors: Sofia Chaudry; Parisa A. Bahri; Navid R. Moheimani
      Pages: 194 - 203
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Sofia Chaudry, Parisa A. Bahri, Navid R. Moheimani
      Microalgal biofuel has the potential to address two major global issues; 1) fulfill the rising energy demand of the world and 2) mitigate the increasing global warming by CO2 sequestration. Botryococcus braunii is a unique alga producing high hydrocarbon contents which can be hydrocracked into high quality fuel. However, there is a lack of interest on the use of B. braunii for biofuel production due to its slow growth rate, an influencing parameter in determining the economics of conventional algal fuel production process. Non-destructive extraction (milking) of B. braunii hydrocarbons is a process which enables the alga to reproduce the hydrocarbons reducing the requirement of fast growth of this alga for biofuel production. This study targets to establish a techno-economics of B. braunii milking to analyze its potential for the renewable hydrocarbon production. The minimum sales price (MSP) to achieve a 10% rate of return was estimated to be US$3.20 L−1 of B. braunii hydrocarbons for the base case scenario. The extraction efficiency and the hydrocarbon contents were found to be the major economy drivers of the process as a result of the additional sensitivity analysis performed to identify the most economic influencing parameters. The MSP has the potential of significant reduction (down to US$1.45 L−1) if a B. braunii with higher hydrocarbon contents is identified as long as the selected strain is suitable for milking and the higher non-destructive extraction efficiency is achieved. A resource assessment comparison was also made to evaluate the significance of the repetitive extraction versus the single extraction. The milking has the clear advantage over the conventional single extraction regarding resource consumption and the cost of the process.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.011
      Issue No: Vol. 31 (2018)
  • Growth rates and photon efficiency of Chlorella vulgaris in relation to
           photon absorption rates under different LED-types
    • Authors: Johannes Bialon; Thomas Rath
      Pages: 204 - 215
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Johannes Bialon, Thomas Rath
      A general model was developed that depicts the long-term growth profiles of Chlorella vulgaris batch cultures under different light intensities of white LED light. The model equation reflects the growth with a time delay of second order at different light intensities by changing only one parameter of the entire equation. This model was applied to the data of short-term batch cultures at different incident light intensities of white, blue, green and red LEDs and growth rates were calculated. Models for the growth rates depending on the photon absorption rates for the different LED-types were developed. Photon absorption rates can be determined for other photobioreactor systems, hence the growth rates of Chlorella vulgaris in other reactor systems can be calculated using the newly developed models. At photon absorption rates up to 2.5 Einstein L−1 d−1, C. vulgaris yielded the highest growth rates under red LEDs. At higher photon absorption rates, white light led to the highest growth rates. Green and blue LEDs yielded similar growth rates which were consistently lower than the growth rates under white and red LEDs. Maximum photon efficiency of ~130 absorbed photons per fixed CO2 was reached under red LEDs.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.007
      Issue No: Vol. 31 (2018)
  • Selection of microalgae with potential for cultivation in
           surfactant-stabilized foam
    • Authors: María Vázquez; Juan L. Fuentes; Adriana Hincapié; Inés Garbayo; Carlos Vílchez; María Cuaresma
      Pages: 216 - 224
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): María Vázquez, Juan L. Fuentes, Adriana Hincapié, Inés Garbayo, Carlos Vílchez, María Cuaresma
      Recently, microalgal cultivation in liquid foams has been developed. Compared to the traditional systems, this concept is expected to offer advantages such as increased mass transfer and reduced biomass harvesting costs and water consumption. However, there is limited information, thus far, on the microalgal performance in foam-bed photobioreactors. Therefore, this study was aimed at comparing the foaming properties of six algal strains to identify the criteria that could be broadly employed for assessing the microalgal potential for cultivation in a foam-bed photobioreactor. The microalgal strains investigated were selected based on their different nature and potential uses. All the microalgal strains could not naturally produce stable foam, thus necessitating the use of a surfactant. To investigate the differences in the foaming properties of the selected microalgae, the natural surfactant, bovine serum albumin, was employed. Factors such as culture age, algal hydrophobicity, and biomass concentration differently influenced the key foaming properties (foamability, microalgal partitioning, and foam stability) depending on the microalgal strain. In conclusion, the assessment of the foaming properties of microalgal strains together with their inherent growth characteristics revealed large differences in the potentiality of microalgae to be cultivated in a foam-bed photobioreactor. In particular, among the microalgal strains tested, the commercial strains Chlorella sorokiniana, Nannochloropsis gaditana, and Scenedesmus obliquus showed the highest potentiality for cultivation in foam. Overall, the following criteria could be broadly applied to select suitable microalgae for cultivation in a foam-bed photobioreactor: high or moderate foamability of the microalga-surfactant suspension, and microalgal partitioning, stability of the foam formed, and robustness and fast growth of the strains.
      Graphical abstract image

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.006
      Issue No: Vol. 31 (2018)
  • Characterization of 3-ketoacyl-coA synthase in a nervonic acid producing
           oleaginous microalgae Mychonastes afer
    • Authors: Yong Fan; Cheng Yuan; Yi Jin; Guang-Rong Hu; Fu-Li Li
      Pages: 225 - 231
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Yong Fan, Cheng Yuan, Yi Jin, Guang-Rong Hu, Fu-Li Li
      Nervonic acid (C24:1, Δ15), a monounsaturated long chain fatty acid, is a major component of mammalian neural tissue. Lack of nervonic acid in human usually leads to neurological disorder. Recently, production of nervonic acid from plant for pharmaceutical, nutraceutical, and functional food received increasing attention. We have previously isolated a microalgal strain Mychonastes afer HSO-3-1, which can accumulate approximately 6% of nervonic acid and <0.5% of erucic acid in triacylglycerol. In this study, the full length of 3-ketoacyl-coA synthase gene MaKCS, encoding the first component of fatty acid elongation complex, was cloned and expressed in Saccharomyces cerevisiae BY4741 under the control of GAL1 promoter. S. cerevisiae harboring pYC230-Gal-MaKCS resulted in the production of 1.5% nervonic acid in total lipid. The expression of KCS gene in M. afer was found to be induced under stress conditions such as nitrogen deficiency and high light, which was revealed by real-time PCR analysis. MaKCS was demonstrated to be able to extend very long chain monounsaturated fatty acids including nervonic acid, which provides insights into how nervonic acid is synthesized in microalgae.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.017
      Issue No: Vol. 31 (2018)
  • Light-dependent kinetic model for microalgae experiencing
           photoacclimation, photodamage, and photodamage repair
    • Authors: Levi Straka; Bruce E. Rittmann
      Pages: 232 - 238
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Levi Straka, Bruce E. Rittmann
      Microalgae naturally are exposed to changing light conditions. While a higher light intensity can promote a faster growth rate, it also can cause photodamage that leads to a temporary or semi-permanent decline in growth rate. We developed a model of photosynthetic growth including photoacclimation, reversible photodamage to photosystem II (PSII), and more severe photodamage to photosystem I (PSI). Phototrophic biomass optimizes its photosynthetic machinery to the light intensity it is experiencing; this is captured in the model by photoacclimation, in which photodamage to PSII caused by absorbed light is balanced by repair. However, repair of PSII photodamage can be overwhelmed by increases of light outside the photoacclimated condition, and this leads to severe PSII photodamage that slows the cells' specific growth rate. Furthermore, very large increases in light intensity can lead to photodamage to PSI, which is semi-permanent in that it can take days to weeks to repair. Our model captures all these phenomena. Example model outputs demonstrate the importance of each phenomenon for increases and decreases in light intensity from the photoacclimated state.
      Graphical abstract image

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.022
      Issue No: Vol. 31 (2018)
  • Simple and efficient method for extraction of C-Phycocyanin from dry
           biomass of Arthospira platensis
    • Authors: Hrishikesh A. Tavanandi; Rochak Mittal; Jampani Chandrasekhar; K.S.M.S. Raghavarao
      Pages: 239 - 251
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Hrishikesh A. Tavanandi, Rochak Mittal, Jampani Chandrasekhar, K.S.M.S. Raghavarao
      Conventional methods for primary extraction can extract only 50–60% of the total C-phycocyanin (C-PC) present in a given biomass because of the resistance offered by the cell membrane for its disruption. Current practice for extraction of C-PC is from wet biomass of Arthospira platensis, which is highly perishable. Drying of biomass increases the shelf life and helps the small scale industries as the need for considerable space and expertise for cultivation of biomass is avoided. However, dry biomass was reported to be unsuitable for C-PC extraction due to its higher resistance to cell disruption. So, the main objective of the current study is to develop a method for primary extraction of C-PC from dry biomass of A. platensis. Practically such reports are scarce. Conventional methods such as homogenization, maceration, freezing and thawing were attempted besides ultrasonication. A presoaking step (0–150 min) of biomass introduced prior to extraction has significantly increased the efficiency of all the extraction methods. Standardization of process parameters such as solid-liquid ratio (1:6, 1:8 and 1:10) and processing time was carried out besides amplitude (10–70%) and time (0–3.0 min) of ultrasonication. When ultrasonication was employed in combination with the conventional primary extraction methods, significant synergy was observed. Ultrasonication in combination with ‘Freezing and thawing’ resulted in 30% increase (maximum) in extraction efficiency over ‘freezing and thawing’ alone. Among all the methods employed, ‘ultrasonication + freezing and thawing’ resulted in the highest extraction efficiency of 92% followed by ‘ultrasonication + maceration’ (83.45%). Studies on extraction kinetics and energy requirement are also carried out. In any given primary extraction method, colour measurements showed a qualitative correlation of the extraction efficiency of C-PC with the extent of discoloration of spent biomass. These synergistic methods can be applied for extraction of biomolecules from other microalgae.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.008
      Issue No: Vol. 31 (2018)
  • Evaluation of secretion reporters to microalgae biotechnology: Blue to red
           fluorescent proteins
    • Authors: João Vitor Dutra Molino; João Carlos Monteiro de Carvalho; Stephen Mayfield
      Pages: 252 - 261
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): João Vitor Dutra Molino, João Carlos Monteiro de Carvalho, Stephen Mayfield
      Efficient protein secretion could potentially be exploited for improving the performance of heterologous protein expression system. However, efficient protein secretion depends on numerous factors that are not always known, and rapid development of protein secretion depends on efficient reporters. This study aimed to compare the secretion efficiency of seven fluorescent proteins (FPs)—mTagBFP, mCerulean, Emerald, CrGFP, cOFP, tdTomato, and mCherry—which are photoactive across the visible light spectrum in the microalgal expression system, Chlamydomonas reinhardtii. To fully compare the efficiency of FPs, three expression vectors—a non-secreting vector used as a control and two secreting vectors employing arylsulfatase 1 (ARS1) signal peptide—were used. Up to 94 transformants for each construct were evaluated to better determine the secretion detection efficiency and variability of each FP construct. Fluorescence measurements of all FPs in the whole culture and supernatant were conducted using a microplate reader. Furthermore, we observed fluorescence of six FPs, among the seven tested, in the secretory pathway by confocal fluorescence microscopy. The results indicated that orange and red FPs are the most suitable for this photosynthetic pigment-rich organism, but the FP reporter for secretion should be selected carefully, since some may be deleteriously modified, as observed in the case of tdTomato, in our study. Overall, cOFP and mCherry performed admirably with a high fluorescence signal to noise ratio (S/N > 6) for all constructs as compared to that of the wild type auto-fluorescence, and showed a high positive rate of transformants (>75%). This FP may play an important role in protein secretion studies, supporting the development of this potential expression system based on microalgae.
      Graphical abstract image

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.018
      Issue No: Vol. 31 (2018)
  • Metabolic engineering of fatty acid biosynthesis in Chlorella vulgaris
           using an endogenous omega-3 fatty acid desaturase gene with its promoter
    • Authors: Md Nor Norashikin; Saw Hong Loh; Ahmad Aziz; Thye San Cha
      Pages: 262 - 275
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Md Nor Norashikin, Saw Hong Loh, Ahmad Aziz, Thye San Cha
      This study demonstrated the overexpression of omega-3 fatty acid desaturase (ω-3 FAD) gene under the control of its endogenous promoter and to elucidate its effect on fatty acid biosynthesis pathway in transgenic Chlorella vulgaris. Two stable transgenic lines (Ch-TL1 and Ch-TL2) were selected and cultured under nitrate-replete and nitrate-deficient BBM culture conditions, respectively to determine the growth, biomass production, total oil content, fatty acid composition and the expression level of four fatty acid biosynthetic genes of the transgenic C. vulgaris. Results revealed that both transgenic lines and wild-type displayed similar growth patterns. Higher biomass production and total oil content were recorded for both transgenic lines that were cultured under nitrate-deficient condition. The ω-3 FAD gene expression was consistently up-regulated in Ch-TL2 in all culture conditions which led to higher α-linolenic acid (C18:3n3) content. Similarly, the expression of β-ketoacyl ACP synthase I (KAS I), stearoyl-ACP desaturase (SAD) and omega-6 desaturase (ω-6 FAD) genes were also up-regulated in Ch-TL2. However, the accumulation of palmitic (C16:0), stearic (C18:0), oleic (C18:1) and linoleic (C18:2) acids were found to be differentially regulated at either transcriptional or post-transcriptional levels. PCR-base genome walking of Ch-TL2 genomic DNA successfully elucidated the integration sites and flanking regions of the inserted vector cassette. These findings provide valuable insight that could pave way for further genetic improvement of the C. vulgaris for various downstream applications.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.020
      Issue No: Vol. 31 (2018)
  • Heterogeneous expression of human PNPLA3 triggers algal lipid accumulation
           and lipid droplet enlargement
    • Authors: Xiang Wang; Wei Wei; Nian-Jing Li; Wasiqi Yuan; Yu Ding; Wei-Dong Yang; Jie-Sheng Liu; Srinivasan Balamurugan; Hong-Ye Li
      Pages: 276 - 281
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Xiang Wang, Wei Wei, Nian-Jing Li, Wasiqi Yuan, Yu Ding, Wei-Dong Yang, Jie-Sheng Liu, Srinivasan Balamurugan, Hong-Ye Li
      Microalgal metabolic engineering holds great promise for algal biofuels. However, identification of the key lipid metabolic target remains challenging due to its complex regulation. In this study, we advocated an alternative strategy that potentially rewired lipid metabolism by unprecedented mechanisms. PNPLA3, a human protein associated with non-alcoholic fatty liver disease (NAFLD), was firstly tested in microalgae for enhancing lipid accumulation. HsPNPLA3 was synthesized with a site mutation (I148M) and expressed in a model diatom Phaeodactylum tricornutum. Heterogeneous HsPNPLA3-I148M was successfully integrated, transcribed and expressed. Lipidomic analyses revealed that HsPNPLA3-I148M significantly elevated TAG content by 1.55-fold in algae, while algal growth and photosynthetic rate were not impaired. Fatty acid profile showed that content of C16:0, C18:1 and C20:4 was increased by 1.43-, 4.18- and 4.3-fold, respectively, which implied that HsPNPLA3-I148M might regulate the fatty acid substrate preference. Overall, the findings demonstrated that human PNPLA3 played a potential role in elevating TAG accumulation by regulating lipogenic enzymes and provide unprecedented insights into its functional significance.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.019
      Issue No: Vol. 31 (2018)
  • Life history determinants of the susceptibility of the blood alga
           Haematococcus to infection by Paraphysoderma sedebokerense
    • Authors: Céline C. Allewaert; Noreen Hiegle; Martina Strittmatter; Reinhoud de Blok; Tiago Guerra; Claire M.M. Gachon; Wim Vyverman
      Pages: 282 - 290
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Céline C. Allewaert, Noreen Hiegle, Martina Strittmatter, Reinhoud de Blok, Tiago Guerra, Claire M.M. Gachon, Wim Vyverman
      Haematococcus pluvialis is currently cultivated at large scale for its ability to produce high amounts of the high value keto-carotenoid astaxanthin when encysted. Mass cultivation of this species is threatened by the destructive blastocladialean fungus, Paraphysoderma sedebokerense Boussiba, Zarka and James, responsible for the fast collapse of Haematococcus populations. Given the difficulty of maintaining pathogen-free production systems and the lack of treatment options, the selection and development of resistant Haematococcus strains could potentially present an effective and efficient method to control infection. In the present work, we examined the host specificity of P. sedebokerense (strain PS1) through quantitative phenotyping of 44 Haematococcus strains in a laboratory-controlled infectivity assay. We determined the growth and photosynthetic activity of strains in the presence and absence of PS1 over time (using Chl a in vivo fluorescence) and quantified the degree of infection through the intensity of fluorescence after staining with Wheat Germ Agglutinin (WGA)-Fluorescein, which labels PS1 without interfering with Haematococcus. The measurements were converted into three infectivity proxies, allowing comparisons amongst strains. Eventually, microscopy was performed to check the life stage of Haematococcus upon infection. Strains of Haematococcus clearly exhibited different levels of susceptibility against PS1 as determined by the three proxies. These were not related to phylogenetic background, nor the sampling origin of the strains. Amongst ten strains with low susceptibility, five occurred as flagellated state cultures, while others were palmelloid and/or aplanospore dominated. In addition, in a long-term selection experiment, we showed that susceptibility to PS1 of a highly sensitive H. pluvialis strain decreased through the dominance of flagellated phenotypes over several generations of infection. While providing considerable expansion of the relation between PS1 and Haematococcus our study opens the possibility for selection and development of resistant strains.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.015
      Issue No: Vol. 31 (2018)
  • Over-accumulation of astaxanthin in Haematococcus pluvialis through
           chloroplast genetic engineering
    • Authors: Janeth I. Galarza; Javier A. Gimpel; Verónica Rojas; Bertha O. Arredondo-Vega; Vitalia Henríquez
      Pages: 291 - 297
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Janeth I. Galarza, Javier A. Gimpel, Verónica Rojas, Bertha O. Arredondo-Vega, Vitalia Henríquez
      The carotenoid biosynthesis pathway of Haematococcus pluvialis has been genetically modified to overproduce astaxanthin, a red pigment of high commercial value. The endogenous phytoene desaturase coding sequence (pds) has been codon optimized and overexpressed in the chloroplast of H. pluvialis under the control of the psbA promoter/UTR. After biolistic transformation and selection, PDS mRNA and protein were detected in transformants. Astaxanthin accumulated up to 67% higher in transformed strains than in wild-type upon induction with high light intensity and nitrogen depletion. This is the first report of plastid transformation of a microalgae with its endogenous pds nuclear gene.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.024
      Issue No: Vol. 31 (2018)
  • Identification of harmful protozoa in outdoor cultivation of Chlorella and
           the use of ultrasonication to control contamination
    • Authors: Yao Wang; Yingchun Gong; Lili Dai; Milton Sommerfeld; Chengwu Zhang; Qiang Hu
      Pages: 298 - 310
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Yao Wang, Yingchun Gong, Lili Dai, Milton Sommerfeld, Chengwu Zhang, Qiang Hu
      Contaminating organisms in mass cultivation present one of the major challenges that must be overcome for successful commercialization of algal biofuels. The present study identified a range of contaminating organisms in Chlorella cultures cultivated in outdoor raceway ponds at the Arizona Center for Algae Technology and Innovation (Mesa, AZ). Nineteen organisms or Operational Taxonomic Units (OTU) in the Chlorella culture were identified by a combination of microscopic observation and 18S rRNA denaturing gradient gel electrophoresis (DGGE). More detailed analyses identified these contaminating organisms as 2 fungi, 7 flagellates, 3 amoebae, 4 ciliates, 1 rotifer, and 2 large insects. Among them Poterioochromonas sp., a small flagellate, appeared to be one of the most harmful causing culture collapse. In order to control Poterioochromonas sp., various operational parameters and application strategies of ultrasonic treatment were investigated. During sixteen-day consecutive Chlorella cultivation in batch mode, the ultrasonication conditions of 6 L min−1 flow rate with the power of 495 W at 100% amplitude and a treatment frequency of once for 1 h every day, was proven to be the most effective in preventing Poterioochromonas outbreak in Chlorella culture with volume of 60 L. The above ultra-sonication method was also effective at destroying an unknown fungus, an amoeba (Acanthocystis sp.), and ciliates (a member of the family Orchitophryidae). Our findings can serve as a technical foundation for the application of ultrasonication to control some of the contaminating microorganisms in mass cultivation of microalgae including Chlorella.

      PubDate: 2018-02-25T00:56:52Z
      DOI: 10.1016/j.algal.2018.02.002
      Issue No: Vol. 31 (2018)
  • Numerical analysis of the effects of air on light distribution in a bubble
           column photobioreactor
    • Authors: Christopher McHardy; Giovanni Luzi; Christoph Lindenberger; Jose R. Agudo; Antonio Delgado; Cornelia Rauh
      Pages: 311 - 325
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Christopher McHardy, Giovanni Luzi, Christoph Lindenberger, Jose R. Agudo, Antonio Delgado, Cornelia Rauh
      Light distribution inside photobioreactors (PBR) is a crucial parameter for the determination of growth of phototropic microorganisms and reactor productivity. In order to compute the light propagation inside PBR, scattering due to the presence of microorganisms is often neglected, since it is difficult to measure experimentally and it is not trivial to handle numerically. Moreover, absorption is usually assumed constant, but it is affected by the concentration of microorganisms and the presence of gas bubbles. In the present contribution we study how the flow hydrodynamics and local gas fractions inside a bubble column PBR affect the light distribution. First, we perform numerical simulations of a bubble column flow at different gas superficial velocities. Afterwards, we use instantaneous air volume fractions to calculate the effective scattering and absorption coefficient of the mixture, as well as the effective scattering phase function. Finally, we compute the polychromatic light distribution inside the PBR by means of a Lattice-Boltzmann solver. On the one hand, we find that gas bubbles affect both spatial distribution and magnitude of the light intensity field and their impact increases at higher gas superficial velocity. On the other hand, we also observe that the biomass counteracts these effects already at concentrations less than 1 kg/m3 so that the role of the gas phase on light fields seems to be of minor importance in PBR.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.016
      Issue No: Vol. 31 (2018)
  • Comparative energetics of carbon storage molecules in green algae
    • Authors: Zaid M. McKie-Krisberg; Lieve M.L. Laurens; Andy Huang; Jürgen E.W. Polle
      Pages: 326 - 333
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Zaid M. McKie-Krisberg, Lieve M.L. Laurens, Andy Huang, Jürgen E.W. Polle
      Several members of the green algae possess the ability to produce lipids and/or high value compounds in significant quantities. While for several of these green algal species induction of increased lipid production has been shown, and cultivation of species for high value molecules occurs at production scale, the molecular mechanisms governing over-accumulation of molecules synthesized from isoprenoid precursors, carotenoids, for example, have received far less attention. Here, we present a calculation of the required ATP equivalencies per carbon atom and reducing power equivalencies as NADH/NADPH (NAD(P)H) per carbon atom for the isoprenoid molecules β-carotene (C40), astaxanthin (C40), and squalene (C30). We compared energetic requirements of carbohydrates, triacylglycerol, and isoprenoid molecules under a gradient of conditions of cellular stress. Our calculations revealed slightly less ATP and NAD(P)H equivalency per carbon atom between triacylglycerol and the three isoprenoid molecules. Based on our results, we propose that the driving force for differences in accumulation patterns of carotenoids vs. triacylglycerols in algal cells under stress is largely dependent on the presence and regulation of bypass mechanisms at metabolic junction bottlenecks, like pyruvate dehydrogenase (PDH), within particular species. We provide a discussion of several molecular mechanisms that may influence carbon partitioning within different groups of green algae, including metabolic inhibition through accumulation of specific substrates related to ATP and reducing equivalent production (NAD(P)H) as well as cellular compartmentalization. This work contributes to the ongoing discussion of cellular homeostatic regulation during stress, as well as the potential mechanisms driving long-term carbon storage as it relates to energy and redox states within the algal cell.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.01.018
      Issue No: Vol. 31 (2018)
  • An empirical process model to predict microalgal carbon fixation rates in
    • Authors: Bojan Tamburic; Christian R. Evenhuis; Joseph R. Crosswell; Peter J. Ralph
      Pages: 334 - 346
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Bojan Tamburic, Christian R. Evenhuis, Joseph R. Crosswell, Peter J. Ralph
      An empirical process model was developed to infer the instantaneous net photosynthesis and carbon fixation rates from continuous pH and dissolved oxygen measurements during microalgal cultivation in photobioreactors. The model is based on the physical and chemical processes that govern the relationship between inorganic carbon supplied to a microalgal culture and the organic carbon fixed into microalgal biomass, with a particular focus on carbonate chemistry and mass transfer. Bayesian statistics were used to estimate the uncertainty in state variables, such as pH, net photosynthesis rate, and bicarbonate ion concentration, based on the constraints imposed by prior knowledge about these variables. The model was verified by batch-culturing the chlorophyte microalga Chlorella vulgaris in a photobioreactor under both bicarbonate-replete and bicarbonate-limiting conditions in order to test its predictive ability under different operational settings. The replicate photobioreactors were set up to simulate a scaled-down vertical cross-section of a typical raceway pond. This model could be used to test the activity and efficiency of carbon concentrating mechanisms in different microalgal species. It also provides a detailed understanding of how the rate of photosynthesis depends on dissolved inorganic carbon concentration, which could lead to better management of carbon supply in large-scale microalgal cultivation facilities.
      Graphical abstract image

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.014
      Issue No: Vol. 31 (2018)
  • Techno-economic evaluation of microalgae harvesting and dewatering systems
    • Authors: F. Fasaei; J.H. Bitter; P.M. Slegers; A.J.B. van Boxtel
      Pages: 347 - 362
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): F. Fasaei, J.H. Bitter, P.M. Slegers, A.J.B. van Boxtel
      Microalgal biomass is processed into products by two main process steps: 1) harvesting and dewatering; and 2) extraction, fractionation and conversion. The performance of unit operations for harvesting and dewatering is often expressed in qualitative terms, like “high energy consumption” and “low in operational cost”. Moreover, equipment is analysed as stand-alone unit operations, which do not interact in a chain of operations. This work concerns a quantitative techno-economic analysis of different large-scale harvesting and dewatering systems with focus on processing cost, energy consumption and resource recovery. Harvesting and dewatering are considered both as a single operation and as combinations of sequential operations. The economic evaluation shows that operational costs and energy consumption are in the range 0.5–2€·kg−1 algae and 0.2–5kWh·kg−1 of algae, respectively, for dilute solutions from open cultivation systems. Harvesting and dewatering of the dilute systems with flocculation results in the lowest energy requirement. However, due to required chemicals and loss of flocculants, these systems end at the same cost level as mechanical harvesting systems. For closed cultivation systems the operational costs decrease to 0.1–0.6€·kg−1 algae and the energy consumption to 0.1–0.7kWh·kg−1 algae. For all harvesting and dewatering systems, labour has a significant contribution to the total costs. The total costs can be reduced by a high level of automation, despite the higher associated investment costs. The analysis shows that a single step operation can be satisfactory if the operation reaches high biomass concentrations. Two-step operations, like pressure filtration followed by spiral plate technology or centrifugation, are attractive from an economic point of view, just as the operation chain of flocculation followed by membrane filtration and a finishing step with spiral plate technology or centrifugation.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2017.11.038
      Issue No: Vol. 31 (2018)
  • Exploring the potential of high-density cultivation of cyanobacteria for
           the production of cyanophycin
    • Authors: Luca Lippi; Lars Bähr; Arne Wüstenberg; Annegret Wilde; Ralf Steuer
      Pages: 363 - 366
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Luca Lippi, Lars Bähr, Arne Wüstenberg, Annegret Wilde, Ralf Steuer
      Photoautotrophic cyanobacteria and microalgae offer significant potential for the renewable synthesis of high-value products. As yet, however, the productivity of phototrophic cultures is limited due to the low cell densities that are typically obtained in current pilot scale photobioreactors. Here, we explore the use of ultrahigh-density cultivation of cyanobacteria for the production of cyanophycin, a non-ribosomally synthesized biopolymer of high biotechnological interest. We demonstrate that ultrahigh-density cultivation using a two-tier vessel with membrane-mediated CO2 supply yields a cyanophycin content per cellular dry weight similar to previously reported values, while the volumetric productivity per culture volume is significantly increased. Already after 96 h of cultivation, the engineered production strain BW86 reached up to 1 g cyanophycin per liter culture, approximately a 4-fold increase over the previously reported maximal yield obtained after 12 days of cultivation. Under phosphate-limiting growth conditions, the wild-type strain Synechcocystis sp. PCC 6803 accumulates up to 0.6 g cyanophycin per L culture. Our results demonstrate that ultrahigh-density cultivation is a suitable strategy towards the development of viable phototrophic production processes for cyanophycin and possibly other products of interest.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.028
      Issue No: Vol. 31 (2018)
  • Full-scale validation of an algal productivity model including nitrogen
    • Authors: Quentin Béchet; Noémie Coulombier; Christophe Vasseur; Thomas Lasserre; Loic Le Dean; Olivier Bernard
      Pages: 377 - 386
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Quentin Béchet, Noémie Coulombier, Christophe Vasseur, Thomas Lasserre, Loic Le Dean, Olivier Bernard
      Accurate predictions of algal productivity under nutrient-limiting conditions are needed to assess the economics of full-scale algal cultivation for the developing markets of food, feed, and at longer term, green chemistry and biofuel. In particular, predicting pigments production from micro-algae is a critical milestone in the assessments of high-value chemicals production from micro-algae. This study validates a mathematical model predicting algal biomass productivity in outdoor raceway ponds under nitrogen-limiting conditions. The model was first validated from experimental data collected during Dunaliella salina cultivation in indoor photobioreactors and accounts for the impact of light, temperature, and nitrogen concentration on algal productivity (overall accuracy on algal concentration of ±2.7 mg L−1, N = 48). The model was then validated against data collected in outdoor raceway ponds over a period of 2 years, representing a total of 111 days of cultivation. Biomass and extracellular nitrogen concentrations predictions were accurate within ±0.055 g L−1 (N = 69) and ±0.0024 g L−1 (N = 26), respectively. Model inaccuracies were mostly due to measurement errors and uncertainties on model inputs. Measured carotenoids concentrations were found proportional to the biomass concentrations in the outdoor raceway ponds. By coupling this linear correlation to the productivity model, predicted carotenoids concentrations were in good agreement with experimental data (accuracy within ±0.0046 g L−1, N = 55). The mathematical model developed in this study has therefore the potential to refine previous assessments of algal cultivation for biofuels and pigments production.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.010
      Issue No: Vol. 31 (2018)
  • The impact of day length on cell division and efficiency of light use in a
           starchless mutant of Tetradesmus obliquus
    • Authors: G. Mitsue León-Saiki; Tània Cabrero Martí; Douwe van der Veen; René H. Wijffels; Dirk E. Martens
      Pages: 387 - 394
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): G. Mitsue León-Saiki, Tània Cabrero Martí, Douwe van der Veen, René H. Wijffels, Dirk E. Martens
      Large scale microalgal production will be primarily done under natural sunlight conditions, where microalgae will be exposed to diurnal cycles of light and dark (LD) and to differences in the length of both periods (photoperiod). Tetradesmus obliquus (formerly known as Scenedesmus obliquus), a strain with potential for biofuel production, and the starchless mutant slm1 were grown under 3 different LD periods: 16:8 h, 14:10 h and 12:12 h. Cell division started a fix number of hours after the light went on (sunrise), independently of the length of the photoperiod. For the wild-type, cell division started approximately 14 h after the beginning of the day and occurred mainly at night. For the starchless mutant slm1, timing of cell division was also independent of the photoperiod length (starting 10–12 h after sunrise). However, as opposed to the wild-type, cell division always started during the day. For both strains, growth rate increased with increased length of the light period. The slm1 mutant is capable of surviving long dark periods (up to 12 h) despite the lack of starch. In general, the slm1 mutant has a lower photosynthetic efficiency than the wild-type, with the 12:12 h LD resulting into even less efficiency than the other two LD cycles.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.027
      Issue No: Vol. 31 (2018)
  • First insight on interactions between bacteria and the marine diatom
           Haslea ostrearia: Algal growth and metabolomic fingerprinting
    • Authors: Alexandra Lépinay; Vincent Turpin; Florence Mondeguer; Quentin Grandet-Marchant; Hervé Capiaux; Régis Baron; Thierry Lebeau
      Pages: 395 - 405
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Alexandra Lépinay, Vincent Turpin, Florence Mondeguer, Quentin Grandet-Marchant, Hervé Capiaux, Régis Baron, Thierry Lebeau
      A first insight on the interactions between bacteria isolated from monospecific cultures of the marine diatom Haslea ostrearia and this microalgae is described in this work. From 28 bacterial isolates, the maximal growth rate and the maximal cell concentration were on average 58% and 27% higher (max. 67% for isolate B22). Isolates B5, B10 (both Saccharospirillum sp.) and B22 (Rhodobacter sp.) were the most efficient. The geographical origin of H. ostrearia from which bacteria were isolated had no impact on the algal growth performances, and a given bacterial isolate led to the same algal growth irrespective of the geographical origin of H. ostrearia. To explain the results obtained, a comprehensive integrative strategy was conducted that analyzed the variations in the thousands of metabolites present in our culture extracts. Beyond a holistic view in which all organic substances of natural origin derived from the metabolism of a living organism were analyzed, we focussed on metabolites specific to each partner of the bacteria-H. ostrearia co-cultures, and relating to a particular biological function. To this end, a high throughput analytical technique, mass spectrometry was used, along with uni- and multivariate association statistical methods. Metabolic fingerprinting (untargeted approach) enabled compounds specific to each association to be identified, especially those concerning the positive bacterial effect on the growth of H. ostrearia.

      PubDate: 2018-03-06T12:34:47Z
      DOI: 10.1016/j.algal.2018.02.023
      Issue No: Vol. 31 (2018)
  • Microalgal dewatering using a polyamide thin film composite forward
           osmosis membrane and fouling mitigation
    • Authors: Jing Ye; Quan Zhou; Xuezhi Zhang; Qiang Hu
      Pages: 421 - 429
      Abstract: Publication date: April 2018
      Source:Algal Research, Volume 31
      Author(s): Jing Ye, Quan Zhou, Xuezhi Zhang, Qiang Hu
      In this study, the dewatering of Scenedesmus acuminatus suspensions using a polyamide thin film composite (TFC) forward osmosis (FO) membrane with enhanced surface shearing was investigated. The influence of the draw solution (DS) concentration and microalgal properties were studied, and a fouling mitigation method using mechanical shearing was developed. S. acuminatus suspension dewatering by the same FO membrane was repeated 8 times to test the membrane's recoverability and durability. The results showed that the membrane flux and the concentration of magnesium chloride DS presented a non-linear relationship. In addition, membrane flux did not increase once the DS concentration increased to 2 mol L−1, when serious fouling occurred. However, the membrane flux was significantly improved by mechanical shearing across the membrane surface. At shear rate of 4 (1000 rpm), a 2 mol L−1 MgCl2 solution resulted in an average flux as high as 25.9 L m−2 h−1 during the dewatering of a 1.0 g L−1 microalgal suspension. Microalgal cells and algogenic organic matter (AOM) were tested to determine the membrane fouling mechanism. The results showed that the microalgal cells and AOM resulted in 15.4% and 9.4% water flux loss in 1 h, respectively, whereas the combination of microalgal cells and AOM resulted in 24.7% water flux loss. After dewatering for 8 h, microalgal suspensions were concentrated 20 times, and the average membrane flux was 23.3 L m−2 h−1. In addition, most of the membrane fouling was reversible by simple hydraulic flushing; the pure water flux remained more than 97% of original pure water flux after 8 repeated dewatering processes, which demonstrated the potential application of FO in microalgal dewatering.
      Graphical abstract image

      PubDate: 2018-03-18T15:48:21Z
      DOI: 10.1016/j.algal.2018.02.003
      Issue No: Vol. 31 (2018)
  • The physiology of Chlorella vulgaris grown in conventional and biodigested
           treated vinasses
    • Authors: Camila Candido; Ana Teresa Lombardi
      Pages: 79 - 85
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Camila Candido, Ana Teresa Lombardi
      Conventional and biodigested vinasses are organic and nutrient rich residues from the sugar cane alcohol industry. Their disposal in running waters and soils are controlled due to their eutrophication potential. Using it as algal culture medium, lower costs and residue remediation can be achieved. Here, we report on the physiology of Chlorella vulgaris grown in 60% conventional and 80% biodigested treated vinasses in 6days experiments. Cell densities, chlorophyll a concentrations and pulse amplitude modulated (PAM) fluorometry were used for culture monitoring. Maximum and operational quantum yields, photochemical (qP) and non-photochemical quenchings (qN and NPQ) and rapid light response curves were determined and efficiency of light use (α) and light saturation (IK) obtained for all treatments. The results showed that C. vulgaris grew better in vinasse (1.5–1.6d−1) than in controls (0.9–1.2d−1). PAM fluorometry showed that, despite the increased algal growth in vinasses, photosynthesis was higher in controls than in the residues, supporting that C. vulgaris used organic carbon as energy source. We suggest that the high competitiveness of the microalgae was due to its ability to grow mixotrophically in the residue even though heterotrophic contaminants were present. A reduction of the vinasses eutrophication potential was obtained after the microorganisms' growth. This study is a contribution to the knowledge of microalgae photosynthetic physiology in organic rich residues, information that can help improve algal biomass production in residues at the same time that performs its remediation.

      PubDate: 2018-01-10T10:44:49Z
      DOI: 10.1016/j.algal.2018.01.005
      Issue No: Vol. 30 (2018)
  • Quantification of heterotrophic bacteria during the growth of
           Synechocystis sp. PCC 6803 using fluorescence activated cell sorting and
    • Authors: Yun Zhou; Everett Eustance; Levi Straka; YenJung Sean Lai; Siqing Xia; Bruce E. Rittmann
      Pages: 94 - 100
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Yun Zhou, Everett Eustance, Levi Straka, YenJung Sean Lai, Siqing Xia, Bruce E. Rittmann
      The presence of heterotrophic bacteria in microalgal cultures can dilute the microalgal content of the harvested biomass, compete for nutrients, and be associated with culture crashes. Being able to detect and quantify heterotrophic bacteria would be of high value for monitoring culture health and reducing deleterious effects. Here, we developed and applied a new method that combines flow cytometry (FC) and fluorescence activated cell sorting (FACS) for the quantification of heterotrophic bacteria in cultures of the cyanobacterium Synechocystis sp. PCC 6803. Particles not containing chlorophyll – heterotrophic bacteria and cell debris – were separated from mixed cultures using FACS based on autofluorescence of Synechocystis. Heterotrophic bacteria were differentiated from cell debris using FC with SYTOX green fluorescence. Using microscopy, we verified that FACS was able to quantify heterotrophic bacteria in Synechocystis cultures effectively. Applying these methods to batch cultures of Synechocystis showed that the count proportions of heterotrophic bacteria were significant (3–13%) and that depletion of inorganic P in the culture favored Synechocystis over heterotrophic bacteria, but led to more cell lysis.
      Graphical abstract image

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2018.01.006
      Issue No: Vol. 30 (2018)
  • Fluorescence activated cell-sorting principles and applications in
           microalgal biotechnology
    • Authors: Hugo Pereira; Peter S.C. Schulze; Lisa Maylin Schüler; Tamára Santos; Luísa Barreira; João Varela
      Pages: 113 - 120
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Hugo Pereira, Peter S.C. Schulze, Lisa Maylin Schüler, Tamára Santos, Luísa Barreira, João Varela
      Microalgal biotechnology has gained increasing attention over the last few decades as a next-generation driver for obtaining food, feed and biofuels and to carry out bioremediation of effluents and CO2 mitigation. Flow cytometry (FC) and fluorescence-activated cell sorting (FACS) have recently acquired outstanding importance in the development of high-throughput methodologies. For example, bioprospecting novel species using FACS widened the current portfolio of available strains for drug discovery and biomass production in large-scale production systems. Moreover, FACS has recently prompted several approaches for the effective improvement of microalgal strains by means of genetic engineering, serial selection and random mutagenesis. In the upcoming years, routine implementation of FC and FACS is expected to further bring forward the field of microalgal biotechnological research as occurred with mammalian cells in biomedical sciences. This review highlights the recent developments of FACS applications to different biotechnological goals, as well as the principles and details of FACS-based microalgal analysis. In addition, the future perspectives of novel and innovative approaches of FACS applications in microalgal biotechnology are suggested and discussed.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2017.12.013
      Issue No: Vol. 30 (2018)
  • Discovery and characterization of Synechocystis sp. PCC 6803
           light-entrained promoters in diurnal light:dark cycles
    • Authors: Allison Werner; Katelyn Oliver; Alexander Dylan Miller; Jacob Sebesta; Christie A.M. Peebles
      Pages: 121 - 127
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Allison Werner, Katelyn Oliver, Alexander Dylan Miller, Jacob Sebesta, Christie A.M. Peebles
      Cyanobacteria are photosynthetic bacteria employed for production of valuable chemicals using sunlight and atmospheric carbon dioxide as substrates. Industrial production in outdoor facilities exposes cyanobacteria to daily light:dark (LD) cycles of sunlight availability. Strain engineers need genetic tools suited for diurnal LD cycles to maximize production in these conditions, but tools for engineering in diurnal LD cycles are extremely limited. Here, we discover native Synechocystis sp. PCC 6803 promoters which provide light-entrained expression in 12-hour light:12-hour dark (12:12) LD cycles. Promoters were characterized using bacterial luciferase bioluminescent promoter probes and RT-qPCR. P hliC , P rbp1 , P slr0006 , and P sigA provide light-entrained expression in 12:12 LD cycles when expressed from the slr0168 chromosomal neutral site. None of the promoters provided free-running oscillations in continuous light (CL) following diurnal LD entrainment, but growth in CL resulted in constant mid-level bioluminescence. Transcripts from P rbp1 , P slr0006 , and P sigA increased significantly following the onset of light, whereas transcripts from P hliC exhibited no oscillations in 12:12 LD cycles. Furthermore, P hliC bioluminescence induction at the onset of light increased at higher light intensities. Overall, our work provides additional genetic engineering tools for cyanobacterial strains for chemical production in diurnal LD cycles.

      PubDate: 2018-02-03T14:13:46Z
      DOI: 10.1016/j.algal.2017.12.012
      Issue No: Vol. 30 (2018)
  • Inside Front Cover - Editorial Board Page/Cover image legend if applicable
    • Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30

      PubDate: 2018-02-03T14:13:46Z
  • Nitrogen uptake by the macro-algae Cladophora coelothrix and Cladophora
           parriaudii: Influence on growth, nitrogen preference and biochemical
    • Authors: Michael E. Ross; Katharine Davis; Rory McColl; Michele S. Stanley; John G. Day; Andrea J.C. Semião
      Pages: 1 - 10
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Michael E. Ross, Katharine Davis, Rory McColl, Michele S. Stanley, John G. Day, Andrea J.C. Semião
      The capacity of macro-algae to remove nutrients means they have the potential to concomitantly bioremediate polluted waters and generate exploitable biomass. The influence of different nitrogen (N) regimes on growth, biochemical composition and bioremediation capacity was studied for two species of the macro-alga Cladophora. These were incubated in media containing four single N sources, ammonium (NH4 +), nitrite (NO2 −), nitrate (NO3 −) and urea (CO(NH2)2), each with four nitrogen/phosphorous (N/P) ratios, followed by equimolar dual mixtures of these N sources at two selected N/P ratios. There were clear differences in growth between species, depending upon the nutrient regime. In every instance, the daily growth rate (DGR) of Cladophora parriaudii (4.75–11.2%) was higher than that of Cladophora coelothrix (3.98–7.37%) with significance when either NO2 − (p =0.025) or urea (p =0.002) were the employed N form. Differences in algal productivity were reflected in the corresponding N-uptake, whereby C. parriaudii consistently removed more N than C. coelothrix. There were significant differences in growth (p =0.005) when C. parriaudii was cultivated in a single and multi-N source medium: NH4 + was preferentially removed from the medium, whereas urea was typically removed secondarily. However, the presence of urea in the medium enhanced the uptake of the other co-existing N forms and resulted in an increased DGR and yielded a biomass rich in carbohydrates. The relative composition of C. parriaudii varied depending upon N/P ratio of the medium, with the final proportion of protein and carbohydrate ranging from 5 to 15% and 36 to 54% per unit dry weight, respectively. Results from this study demonstrated that algal strain selection is key to treating waste-streams with specific N profiles. Additionally, the biochemical profile of the biomass produced is dependent on the alga and the N regime, providing the potential for designing processes with specific properties and products.

      PubDate: 2017-12-19T18:07:20Z
      DOI: 10.1016/j.algal.2017.12.005
      Issue No: Vol. 30 (2017)
  • Comparing EPA production and fatty acid profiles of three Phaeodactylum
           tricornutum strains under western Norwegian climate conditions
    • Authors: Pia Steinrücken; Siv Kristin Prestegard; Jeroen Hendrik de Vree; Julia E. Storesund; Bernadette Pree; Svein Are Mjøs; Svein Rune Erga
      Pages: 11 - 22
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Pia Steinrücken, Siv Kristin Prestegard, Jeroen Hendrik de Vree, Julia E. Storesund, Bernadette Pree, Svein Are Mjøs, Svein Rune Erga
      Microalgae could provide a sustainable alternative to fish oil as a source for the omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, growing microalgae on a large-scale is still more cost-intensive than fish oil production, and outdoor productivities vary greatly with reactor type, geographic location, climate conditions and microalgae species or even strains. The diatom Phaeodactylum tricornutum has been intensively investigated for its potential in large-scale production, due to its robustness and comparatively high growth rates and EPA content. Yet, most research have been performed in southern countries and with a single commercial P. tricornutum strain, while information about productivities at higher latitudes and of local strains is scarce. We examined the potential of the climate conditions in Bergen, western Norway for outdoor cultivation of P. tricornutum in flat panel photobioreactors and cultivated three different strains simultaneously, one commercial strain from Spain (Fito) and two local isolates (M28 and B58), to assess and compare their biomass and EPA productivities, and fatty acid (FA) profiles. The three strains possessed similar biomass productivities (average volumetric productivities of 0.20, 0.18, and 0.21gL−1 d−1), that were lower compared to productivities reported from southern latitudes. However, EPA productivities differed between the strains (average volumetric productivities of 9.8, 5.7 and 6.9mgL−1 d−1), due to differing EPA contents (average of 4.4, 3.2 and 3.1% of dry weight), and were comparable to results from Italy. The EPA content of strain Fito of 4.4% is higher than earlier reported for P. tricornutum (2.6–3.1%) and was only apparent under outdoor conditions. A principal component analysis (PCA) of the relative FA composition revealed strain-specific profiles. However, including data from laboratory experiments, revealed more significant differences between outdoor and laboratory-grown cultures than between the strains, and higher EPA contents in outdoor grown cultures.

      PubDate: 2017-12-19T18:07:20Z
      DOI: 10.1016/j.algal.2017.12.001
      Issue No: Vol. 30 (2017)
  • Isolation and biochemical characterisation of two thermophilic green algal
           species- Asterarcys quadricellulare and Chlorella sorokiniana, which are
           tolerant to high levels of carbon dioxide and nitric oxide
    • Authors: Prachi Varshney; John Beardall; Sankar Bhattacharya; Pramod P. Wangikar
      Pages: 28 - 37
      Abstract: Publication date: March 2018
      Source:Algal Research, Volume 30
      Author(s): Prachi Varshney, John Beardall, Sankar Bhattacharya, Pramod P. Wangikar
      Atmospheric levels of carbon dioxide (CO2) and nitric oxide (NO) have been on the rise ever since the beginning of industrialisation. A significant fraction of this increase can be attributed to the emissions from stationary sources such as thermal power plants and steel plants. While there has been an impetus in recent times towards sequestration of these greenhouse gases at source, current technologies are not commercially viable. In this context, microalgae-mediated CO2 capture and utilization has attracted attention, although several technological challenges remain to be addressed. Importantly, this process will require algal strains that grow fast and are tolerant to high light, temperature and flue gases. The majority of the reported algal strains fail in at least one of these requirements. On account of this, we have isolated two novel green algal strains, which have been identified as Asterarcys quadricellulare and Chlorella sorokiniana, from water bodies that are located in and around a steel plant in India. These are relatively fast-growing strains with specific growth rates of up to 0.06h−1 and 0.1h−1, respectively. Furthermore, these strains can tolerate high temperatures of up to 43°C, high light intensity and high CO2 and NO levels. When exposed to high CO2 levels, 55–71% of the dry cell weight comprised of carbohydrates. Additionally, exposure to NO gas along with CO2 led to an enhanced lipid accumulation of 44%–46% of dry biomass. The high lipid content makes these strains valuable feedstock in biodiesel production, and the high carbohydrate content makes the lipid extracted biomass an attractive source of carbon for biochemical conversion to ethanol. We believe that these strains are promising and ready to be tested with real flue gases under outdoor conditions.

      PubDate: 2017-12-26T18:17:05Z
      DOI: 10.1016/j.algal.2017.12.006
      Issue No: Vol. 30 (2017)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
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