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

Symbiotic dinoflagellates produce bioactive valuable compounds such as carotenoids and lipids used in various industrial fields. However, a small amount of their biomass can be produced with a suspension-based closed photobioreactors. In the present study, we attempted to obtain a high lipid and total carotenoid contents from Symbiodinium sp. by creating optimal light intensity conditions using a Twin-layer photobioreactor. The growth rate, biomass, chlorophyll a concentration, as well as total carotenoid and lipid contents were examined at the light intensities of ۵۰, ۱۰۰ and ۲۵۰ μmol m-۲ s-۱ for ۱۶ days. Based on the results, biomass productivities ranged from ۳۵.۷, to ۷۲.۰ g m-۲ at ۵۰ and ۲۵۰ µmol photons m-۲ s-۱, respectively. The highest linear growth rates were obtained ۲.۰۳, ۳.۲۷, and ۵.۸۵ g m−۲ d−۱ between ۱۲ and ۱۶ days at light intensity of ۵۰, ۱۰۰, and ۲۵۰ μmol m−۲ s−۱, respectively. The highest values of total carotenoids, chlorophyll a, and percentage of total lipid were ۰.۸۵ g m-۲, ۰.۹۶ g m-۲, and ۲۷.۷۷% at light intensity of ۲۵۰ μmol m-۲ s-۱, respectively. The findings proved that immobilization of algal cells in the photobioreactor biofilm resulted in high production of biomass and total carotenoids and lipids.

Keywords:

Biomass , Chlorophyll a , Total carotenoids , Total lipids , Twin-layer Photobioreactor , Symbiotic alga