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Lina Juana Dolch, Camille Rak, Giorgio Perin, Guillaume Tourcier, Richard Broughton, Marina Leterrier, Tomas Morosinotto, Frédérique Tellier, Jean-Denis Faure, Denis Falconet, Juliette Jouhet, Olga Sayanova, Frederic Beaudoin, Eric Marechal
Nannochloropsis species are oleaginous eukaryotes containing a plastid limited by four membranes, deriving from a secondary endosymbiosis. In Nannochloropsis, thylakoid lipids including monogalactosyldiacylglycerol (MGDG) are enriched in eicosapentaenoic acid (EPA). The need for EPA in MGDG is not understood. Fatty acids are de novo synthesized in the stroma, then converted into very-long-chain polyunsaturated fatty acids at the ER. The production of MGDG relies therefore on an EPA supply from the ER to the plastid, following an unknown process...
November 28, 2016: Plant Physiology
C Safi, G Olivieri, R P Campos, N Engelen-Smit, W J Mulder, L A M van den Broek, L Sijtsma
A mild biorefinery process was investigated on the microalga Nannochloropsis gaditana, to obtain an enriched fraction of water soluble proteins free from chlorophyll. After harvesting, a 100g.L(-1) solution of cells was first subjected to cell disruption by either high-pressure homogenization (HPH) or enzymatic treatment (ENZ). HPH resulted in a larger release of proteins (49%) in the aqueous phase compared to the Alcalase incubation (35%). In both cases, an ultrafiltration/diafiltration (UF/DF) was then performed on the supernatant obtained from cell disruption by testing different membrane cut-off (1000kDa, 500kDa and 300kDa)...
November 18, 2016: Bioresource Technology
Kenneth Wei Min Tan, Huixin Lin, Hui Shen, Yuan Kun Lee
Certain species of microalgae are natural accumulators of lipids, while others are more inclined to store starch. However, what governs the preference to store lipids or starch is not well understood. In this study, the microalga Dunaliella tertiolecta was used as a model to study the global gene expression profile regulating starch accumulation in microalgae. D. tertiolecta, when depleted of nitrogen, produced only 1% of dry cell weight (DCW) in neutral lipids, while starch was rapidly accumulated up to 46% DCW...
November 16, 2016: Scientific Reports
Chongchong Wu, Ye Xiao, Weiguo Lin, Jiaquan Li, Saisai Zhang, Junying Zhu, Junfeng Rong
An effective cell disruption method, including alkaline pretreatment and subsequent enzymatic treatment, was established to break cell walls and extract lipid from Nannochloropsis sp. A synergistic effect was found between alkaline pretreatment and enzymatic treatment. The combination of commercialize enzymes (cellulase, protease, lysozyme, and pectinase) achieved higher lipid yield compared with a single enzyme application. With the compromise between economic feasibility and lipid yield, the optimum reaction conditions were obtained with alkaline pretreatment at pH 10...
October 22, 2016: Bioresource Technology
Benjamin H J Yap, Simon A Crawford, Raymond R Dagastine, Peter J Scales, Gregory J O Martin
Nitrogen deprivation (N-deprivation) is a proven strategy for inducing triacylglyceride accumulation in microalgae. However, its effect on the physical properties of cells and subsequently on product recovery processes is relatively unknown. In this study, the effect of N-deprivation on the cell size, cell wall thickness, and mechanical strength of three microalgae was investigated. As determined by analysis of micrographs from transmission electron microscopy, the average cell size and cell wall thickness for N-deprived Nannochloropsis sp...
October 24, 2016: Journal of Industrial Microbiology & Biotechnology
David Bína, Zdenko Gardian, Miroslava Herbstová, Radek Litvín
Photosystem I (PSI) is a multi-subunit integral pigment-protein complex that performs light-driven electron transfer from plastocyanin to ferredoxin in the thylakoid membrane of oxygenic photoautotrophs. In order to achieve the optimal photosynthetic performance under ambient irradiance, the absorption cross section of PSI is extended by means of peripheral antenna complexes. In eukaryotes, this role is played mostly by the pigment-protein complexes of the LHC family. The structure of the PSI-antenna supercomplexes has been relatively well understood in organisms harboring the primary plastid: red algae, green algae and plants...
October 12, 2016: Photosynthesis Research
Carolina Shene, Yusuf Chisti, Daniela Vergara, César Burgos-Díaz, Mónica Rubilar, Mariela Bustamante
The marine microalga Nannochloropsis oculata is a potential source of eicosapentaenoic acid (EPA, C20:5n3) and carotenoids for use in functional foods and nutraceuticals. Mixotrophic culture of N. oculata using glycerol was examined as a possible way of increasing the biomass and metabolite productivity relative to a pure photoautotrophic culture in modified f/2 medium. The effect of CO2 supply was also tested. EPA production in semi-continuous culture with and without glycerol and CO2 was evaluated. The effects of glycerol supplementation and light/dark cycling on the production of the biomass and EPA are reported for cultures conducted at a constant pH controlled using CO2...
October 8, 2016: Journal of Biotechnology
M Sendra, D Sánchez-Quiles, J Blasco, I Moreno-Garrido, L M Lubián, S Pérez-García, A Tovar-Sánchez
Given the large numbers of sunbathers on beaches, sunscreen compounds are being released into the coastal aquatic environment in significant amounts. Until now the effect of these potential pollutants on microbiota has been not well-known. Phytoplankton is a key component of the microbiota community. It forms the basis of the aquatic trophic networks, and any change in the natural population of phytoplankton can affect the structure of aquatic biota. This paper describes an experiment performed outdoors (in natural sunlight conditions including ultraviolet radiation (UVR) and with UVR blocked) on mixed microalgae populations (four species from different key marine taxonomic groups, Nannochloropsis gaditana, Chaetoceros gracilis, Pleurochrysis roscoffensis and Amphidinium carterae), for three days, exposed to a range of concentrations of three commercial sunscreens (with variable TiO2 concentrations: highest concentration for sunscreen C, followed by sunscreen A; and sunscreen B did not contain TiO2 in its composition)...
October 4, 2016: Environment International
A K Upadhyay, S K Mandotra, N Kumar, N K Singh, Lav Singh, U N Rai
The present study was conducted with microalga Nannochloropsis sp. to evaluate its tolerance responses and biofuel perspectives under different arsenic regime (0-1000μM As(III)). Results showed that optimal biomass (61.00±3.72mg/L/d) and lipid productivity (20.27mg/L/d) were obtained in culture treated with 100μM As(III) in comparison to other treatments. In addition, fatty acid profile of alga was in accordance with European biodiesel standards (EN 14214), which reflects good oxidative stability of oil...
December 2016: Bioresource Technology
Fang Guo, Jing Zhao, Lusi A, Xiaoyi Yang
The aim of this work is to compare the life cycle assessments of low-N and normal culture conditions for a balance between the lipid content and specific productivity. In order to achieve the potential contribution of lipid content to the life cycle assessment, this study established relationships between lipid content (nitrogen effect) and specific productivity based on three microalgae strains including Chlorella, Isochrysis and Nannochloropsis. For microalgae-based aviation fuel, the effects of the lipid content on fossil fuel consumption and greenhouse gas (GHG) emissions are similar...
December 2016: Bioresource Technology
N F Santos-Sánchez, R Valadez-Blanco, B Hernández-Carlos, A Torres-Ariño, P C Guadarrama-Mendoza, R Salas-Coronado
Despite microalgae recently receiving enormous attention as a potential source of biodiesel, their use is still not feasible as an alternative to fossil fuels. Recently, interest in microalgae has focused on the production of bioactive compounds such as polyunsaturated fatty acids (PUFA), which provide microalgae a high added value. Several considerations need to be assessed for optimizing PUFA production from microalgae. Firstly, a microalgae species that produces high PUFA concentrations should be selected, such as Nannochloropsis gaditana, Isochrysis galbana, Phaeodactylum tricornutum, and Crypthecodinium cohnii, with marine species gaining more attention than do freshwater species...
October 2016: Applied Microbiology and Biotechnology
Alessandro Alboresi, Clotilde Le Quiniou, Sathish K N Yadav, Martin Scholz, Andrea Meneghesso, Caterina Gerotto, Diana Simionato, Michael Hippler, Egbert J Boekema, Roberta Croce, Tomas Morosinotto
Photosystem I (PSI) is a pigment protein complex catalyzing the light-driven electron transport from plastocyanin to ferredoxin in oxygenic photosynthetic organisms. Several PSI subunits are highly conserved in cyanobacteria, algae and plants, whereas others are distributed differentially in the various organisms. Here we characterized the structural and functional properties of PSI purified from the heterokont alga Nannochloropsis gaditana, showing that it is organized as a supercomplex including a core complex and an outer antenna, as in plants and other eukaryotic algae...
September 13, 2016: New Phytologist
Sanjaya Lama, Koenraad Muylaert, Tika Bahadur Karki, Imogen Foubert, Rita K Henderson, Dries Vandamme
Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species...
November 2016: Bioresource Technology
Jia-Wen Chen, Wan-Jun Liu, Dong-Xiong Hu, Xiang Wang, Srinivasan Balamurugan, Adili Alimujiang, Wei-Dong Yang, Jie-Sheng Liu, Hong-Ye Li
Oleaginous microalgae hold great promises for biofuel production. However, commercialization of microalgal biofuels remains impracticable due to lack of suitable industrial strain with high growth rate and lipid productivity. Engineering of metabolic pathways is a potential strategy for the improvement of microalgal strains for the production of lipids and also value-added products in microalgae. Malonyl CoA-acyl carrier protein transacylase (MCAT) has been reported to be involved in fatty acid biosynthesis...
August 30, 2016: Biotechnology and Applied Biochemistry
Qintao Wang, Yandu Lu, Yi Xin, Li Wei, Shi Huang, Jian Xu
Microalgae are promising feedstock for biofuels yet mechanistic probing of their cellular network and industrial strain development have been hindered by lack of genome-editing tools. Nannochloropsis spp. are emerging model microalgae for scalable oil production and carbon sequestration. Here we established a CRISPR/Cas9-based precise genome-editing approach for the industrial oleaginous microalga Nannochloropsis oceanica, using nitrate reductase (NR; g7988) as example. A new screening procedure that compares between restriction enzyme-digested nested PCR (nPCR) products derived from enzyme-digested and not-digested genomic DNA of transformant pools was developed to quickly, yet reliably, detect genome-engineered mutants...
August 19, 2016: Plant Journal: for Cell and Molecular Biology
Haifeng Geng, Mary B Tran-Gyamfi, Todd W Lane, Kenneth L Sale, Eizadora T Yu
Open microalgae cultures host a myriad of bacteria, creating a complex system of interacting species that influence algal growth and health. Many algal microbiota studies have been conducted to determine the relative importance of bacterial taxa to algal culture health and physiological states, but these studies have not characterized the interspecies relationships in the microbial communities. We subjected Nanochroloropsis salina cultures to multiple chemical treatments (antibiotics and quorum sensing compounds) and obtained dense time-series data on changes to the microbial community using 16S gene amplicon metagenomic sequencing (21,029,577 reads for 23 samples) to measure microbial taxa-taxa abundance correlations...
2016: Frontiers in Microbiology
David Bína, Karel Bouda, Radek Litvín
Eustigmatophyte algae represent an interesting model system for the study of the regulation of the excitation energy flow due to their use of violaxanthin both as a major light-harvesting pigment and as the basis of xanthophyll cycle. Fluorescence induction kinetics was studied in an oleaginous marine alga Nannochloropsis oceanica. Nonphotochemical fluorescence quenching was analyzed in detail with respect to the state of the cellular xanthophyll pool. Two components of nonphotochemical fluorescence quenching (NPQ), both dependent on the presence of zeaxanthin, were clearly resolved, denoted as slow and fast NPQ based on kinetics of their formation...
August 2, 2016: Photosynthesis Research
Tipawan Thawechai, Benjamas Cheirsilp, Yasmi Louhasakul, Piyarat Boonsawang, Poonsuk Prasertsan
Oleaginous microalgae Nannochloropsis sp. was selected as potential strain for CO2 mitigation into lipids and pigments. The synergistic effects of light intensity and photoperiod were evaluated to provide the adequate light energy for this strain. The saturation light intensity was 60μmol·photon·m(-2)s(-1). With full illumination, the biomass obtained was 0.850±0.16g·L(-1) with a lipid content of 44.7±1.2%. The pigments content increased with increasing light energy supply. Three main operating factors including initial cell concentration, CO2 content and gas flow rate were optimized through Response Surface Methodology...
November 2016: Bioresource Technology
Madhusree Mitra, Freny Shah, S V Vamsi Bharadwaj, Shailesh Kumar Patidar, Sandhya Mishra
The eicosapentaenoic acid rich marine eustigmatophyte Nannochloropsis oceanica was grown in wastewaters sampled from four different industries (i.e. pesticides industry, pharmaceutical industry, activated sludge treatment plant of municipality sewage and petroleum (oil) industry). Under the wastewater based growth conditions used in this study, the biomass productivity ranged from 21.78±0.87 to 27.78±0.22mgL(-1)d(-1) in relation to freeze dried biomass, while the lipid productivity varied between 5.59±0...
October 2016: Bioresource Technology
Andrea Meneghesso, Diana Simionato, Caterina Gerotto, Nicoletta La Rocca, Giovanni Finazzi, Tomas Morosinotto
Nannochloropsis is an eukaryotic alga of the phylum Heterokonta, originating from a secondary endosymbiotic event. In this work, we investigated how the photosynthetic apparatus responds to growth in different light regimes in Nannochloropsis gaditana. We found that intense illumination induces the decrease of both photosystem I and II contents and their respective antenna sizes. Cells grown in high light showed a larger capacity for electron transport, with enhanced cyclic electron transport around photosystem I, contributing to photoprotection from excess illumination...
September 2016: Photosynthesis Research
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