Microalgal starch is considered a promising feedstock for bioethanol production. The biomass and starch accumulation in the marine microalga Tetraselmis subcordiformis were characterized under different salinities in response to nitrogen repletion (+N) or depletion (-N) at high irradiance (HI) or low irradiance (LI). Under favorable nutritional conditions (HI+N), biomass accumulation was seldom affected under 20% normal salinity, though starch accumulation were somewhat reduced. Increased salinity impaired overall biomass and starch accumulation, though it led to a temporary starch accumulation at initial cultivation phase. Under nitrogen deprivation, decreased salinity strengthened biomass and starch accumulation regardless of irradiance. The highest starch content of 58.2% dry weight and starch productivity of 0.62 g L(-1) d(-1) were obtained under HI-N with 20% normal salinity. Decreased salinity combined with -N generated moderate stress to facilitate starch accumulation. Salinity manipulation can be effectively applied for enhanced starch production in marine microalgae.
Keywords: +N; ASW; ASW–N; CEF; Chl; DW; HI; Irradiance; LI; NPQ; Nitrogen deprivation; PS I; PS II; ROS; Salinity; Starch; Tetraselmis subcordiformis; artificial seawater; chlorophyll; cyclic electron flow; dry weight; energy-dependent non-photochemical quenching; high irradiance; low irradiance; nitrogen deprivation; nitrogen repletion; nitrogen-deprived artificial seawater; non-photochemical quenching; photosystem I; photosystem II; qE; reactive oxygen species; −N.
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