Synergistic dynamics of light, photoperiod and chemical stimulants influences biomass and lipid productivity in Chlorella singularis (UUIND5) for biodiesel production

Microalgae have emerged as a potential alternative for the production of many useful compounds like protein, carbohydrate and lipid. Lipid-rich microalgae are important and rich source for alternative energy production. In order to commercially utilize microalgae for energy production, the lipid productivity should be enhanced. Keeping in view the above-mentioned potentials of microalgae, in the present study, we have attempted to display the role of chemical stimulants and light in the growth and lipid production of the microalgae Chlorella singularis (UUIND5). During the present investigations, effect of varying photoperiods and different types of lights and chemical stimulants, viz. CaCl2 and kinetin on growth rate and lipid production, was studied. The maximum growth rate recorded was 166 +/- 0.3 mg/L/d, when 0.80 g/l CaCl2 and 0.5 mg/l kinetin were added to Bold's basal medium. C. singularis was then cultivated in this medium for 14 days under sunlight +LED (10-h sunlight + 14-h LED light) at photoperiod 24-h light/0-h dark. The maximum lipid yield 30.2% of dry wt. was obtained under sunlight +LED. Further, the gas chromatography analysis also showed the presence of fatty acid methyl esters (FAME). FAMEs profile was analyzed according to ASTM D6751 specification. Thus, it was concluded that sunlight +LED at 24-h light/0-h dark (100 mu mol photons m(-2) s(-1)) photoperiod with CaCl2 and kinetin is an effective strategy to boost lipid productivity in C. singularis (UUIND5).