Alterations in lipidome and metabolome profiles of Nannochloropsis salina in response to reduced culture temperature during sinusoidal temperature and light

Metabolic response to four suboptimal cultivation temperatures was explored in Nannochloropsis salina, with an emphasis on fatty acid and lipid metabolism. Cultures were cultivated in controlled environmental photobioreactors. Physiological performance, characterized by growth rate and photosynthetic output, were reduced at all three cold stress temperatures (5 °C, 10 °C, 15 °C). However, biomass productivity and overall growth for cultures at 20 °C was like that of those grown at the optimal temperature (25 °C). Fatty acid productivity was elevated at all suboptimal temperatures, and both total fatty acid and eicosapentaenoic acid content were statically elevated at 20 °C. Lipid accumulation was observed exclusively in response to cold stress; however, lipid turnover and enrichment in polyunsaturated fatty acids occurred in all temperature variants. In addition, extensive lipid remodeling occurred in both polar and neutral lipid pools, specifically in monogalactosyl diacylglycerol and triacylglycerol pools. While 20 °C is optimal for eicosapentaenoic acid and total fatty acid productivity, cold stress is necessary to induce both productivity and polyunsaturated fatty acid enrichment in triacylglycerol pools.