Simultaneous accumulation of lipid and carotenoid in freshwater green microalgae Desmodesmus subspicatus LC172266 by nutrient replete strategy under mixotrophic condition

Production of biofuel by microalgae can become economically viable if other high-value commercial products such as carotenoid are simultaneously produced. This study aimed at enhancement of lipid and carotenoid productivity by an oleaginous microalga sp. Desmodesmus subspicatus LC172266 by supplementing Nitrogen sources to BG 11 medium under batch or fed batch mixotrophic condition. Optimum urea supplement (0.2 gL−1) to BG 11 medium enhanced carotenoid content of the D. subspicatus by about 3.7 fold (3.02±0.002 mgg−1 cell) and 3.0 fold (3.86±0.001 mgg−1 cell) using glucose or glycerol as organic carbon sources, respectively. Also, lipid productivity was enhanced by about 2.0 (0.07817±0.0028 gL−1day−1) (0.265±0.006 gg−1 cell) and 2.5 (0.08426±0.0008 gL−1day−1) (0.285±0.02 gg−1 cell) fold. Fed-batch cultivation with glucose at a feed rate of 0.5 gL−1 per day enhanced both carotenoid and lipid productivities of D. subspicatus by 34% and 45%, respectively, after eight days of mixotrophic cultivation.