Physiological and biochemical responses of dinoflagellate Symbiodinium sp. to the different light intensities

Symbiotic dinoflagellates create valuable bioactive compounds such as carotenoids and lipids, which are used in various industrial fields. However, a small amount of their biomass can be produced by using the suspension- based closed photobioreactors. The present study tried to obtain high lipid and total carotenoid contents from Symbiodinium sp. by creating optimal light intensity conditions using a Twin-layer photobioreactor. In this regard, growth rate, biomass, chlorophyll a concentration, and total carotenoid and lipid contents were examined at the light intensities of 50, 100, and 250 μmol.m−2s−1 for 16 days. Based on the results, biomass productivities ranged from 35.7 to 72.0 g.m-2 at 50 to 250 μmol photons m−2s−1, respectively. In addition, the highest linear growth rates were 2.03, 3.27, and 5.85 g.m−2d−1 at the light intensity of 50, 100, and 250 μmol.m−2s−1 between 12-16 days, respectively. Further, the maximum amount of total carotenoids, chlorophyll a, and total lipid was attained 0.85 and 0.96 g.m^-2, and 27.77% at the light intensity of 250 μmol. m^−2s^−1, respectively. The results represented that the immobilization of algal cells in the photobioreactor biofilm resulted in producing high biomass, total carotenoids, and lipids.