Salinity manipulation as an effective method for enhanced starch production in the marine microalga Tetraselmis subcordiformis

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.