TY - JOUR
T1 - Growth, lipid production and metabolic adjustments in the euryhaline eustigmatophyte Nannochloropsis oceanica CCALA 804 in response to osmotic downshift
AU - Pal, Dipasmita
AU - Khozin-Goldberg, Inna
AU - Didi-Cohen, Shoshana
AU - Solovchenko, Alexei
AU - Batushansky, Albert
AU - Kaye, Yuval
AU - Sikron, Noga
AU - Samani, Talya
AU - Fait, Aaron
AU - Boussiba, Sammy
N1 - Funding Information:
Acknowledgments This research was financially supported by the European Commission's Seventh Framework Program for Research and Technology Development (FP7), project GIAVAP, Grant No. 266401. DP and AB acknowledge support from the Albert Katz International School for Desert Studies at BGU. AS acknowledges partial financial support from the Ministry of Science and Education of the Russian Federation (contract no. 14.515.11.0026), Russian Foundation of Basic Research, and “Skolkovo” Scientific Fund.
PY - 2013/9/1
Y1 - 2013/9/1
N2 - We investigated the effects of osmotic downshift induced by the transfer of Nannochloropsis oceanica CCALA 804 from artificial seawater medium (27 g L -1 NaCl) to the same medium without NaCl or freshwater modified BG-11 medium (mBG-11) as a function of photosynthetically active radiation (170, 350, or 700 μmol photon m-2 s-1). Alterations in growth, total fatty acid (FA) content and FA composition of individual lipid classes, and in relative contents of metabolites relevant to osmotic adjustments were studied. Cells displayed remarkable tolerance to the osmotic downshift apart from some swelling, with no substantial lag or decline in cell division rate. Biomass accumulation and chlorophyll a content were enhanced upon downshifting, especially under the highest irradiance. The highest chlorophyll a and eicosapentaenoic acid (EPA) biomass and culture contents were determined in the cultures grown in mBG-11. Two days after transfer to 0 g L-1 NaCl, the proportion in total acyl lipids of the major chloroplast galactolipid monogalactosyldiacylglycerol, a major depot of EPA, increased twofold, along with a modest change in the proportion of digalactosyldiacylglycerol (DGDG). EPA percentage decreased in DGDG and increased in the extraplastidial lipid phosphatidylethanolamine. Metabolite profiling by GC-MS analysis revealed a sharp decrease in metabolites potentially involved in osmoregulation, such as mannitol and proline, while proline-cycle intermediates and some free sugars increased. The stress-induced polyamine spermidine decreased ca. one order of magnitude, while its catabolic product - the non-protein amino acid γ-amino butyric acid - increased twofold, as did the stress-related sugars trehalose and talose. Biochemical mechanisms governing osmotic plasticity and implications for optimization of EPA production by N. oceanica CCALA 804 under variable cultivation conditions are discussed.
AB - We investigated the effects of osmotic downshift induced by the transfer of Nannochloropsis oceanica CCALA 804 from artificial seawater medium (27 g L -1 NaCl) to the same medium without NaCl or freshwater modified BG-11 medium (mBG-11) as a function of photosynthetically active radiation (170, 350, or 700 μmol photon m-2 s-1). Alterations in growth, total fatty acid (FA) content and FA composition of individual lipid classes, and in relative contents of metabolites relevant to osmotic adjustments were studied. Cells displayed remarkable tolerance to the osmotic downshift apart from some swelling, with no substantial lag or decline in cell division rate. Biomass accumulation and chlorophyll a content were enhanced upon downshifting, especially under the highest irradiance. The highest chlorophyll a and eicosapentaenoic acid (EPA) biomass and culture contents were determined in the cultures grown in mBG-11. Two days after transfer to 0 g L-1 NaCl, the proportion in total acyl lipids of the major chloroplast galactolipid monogalactosyldiacylglycerol, a major depot of EPA, increased twofold, along with a modest change in the proportion of digalactosyldiacylglycerol (DGDG). EPA percentage decreased in DGDG and increased in the extraplastidial lipid phosphatidylethanolamine. Metabolite profiling by GC-MS analysis revealed a sharp decrease in metabolites potentially involved in osmoregulation, such as mannitol and proline, while proline-cycle intermediates and some free sugars increased. The stress-induced polyamine spermidine decreased ca. one order of magnitude, while its catabolic product - the non-protein amino acid γ-amino butyric acid - increased twofold, as did the stress-related sugars trehalose and talose. Biochemical mechanisms governing osmotic plasticity and implications for optimization of EPA production by N. oceanica CCALA 804 under variable cultivation conditions are discussed.
KW - EPA
KW - Euryhaline microalga
KW - MGDG
KW - Nannochloropsis
KW - Osmolyte
KW - Salinity
KW - TFA
UR - http://www.scopus.com/inward/record.url?scp=84883554283&partnerID=8YFLogxK
U2 - 10.1007/s00253-013-5092-6
DO - 10.1007/s00253-013-5092-6
M3 - Article
AN - SCOPUS:84883554283
SN - 0175-7598
VL - 97
SP - 8291
EP - 8306
JO - Applied Microbiology and Biotechnology
JF - Applied Microbiology and Biotechnology
IS - 18
ER -