Biomass and lipid production of a local isolate Chlorella sorokiniana under mixotrophic growth conditions

• Our local isolate was identified as Chlorella sorokiniana.
• Our isolate exhibited enhanced growth rate and biomass yield under mixotrophy.
• Nitrogen-starved mixotrophic cells show prominent neutral lipid body accumulation.

A local Chlorella sp. isolate with 97% rbcL sequence identity to Chlorella sorokiniana was evaluated in terms of its biomass and lipid production under mixotrophic growth conditions. Glucose-supplemented cultures exhibited increasing growth rate and biomass yield with increasing glucose concentration. Highest growth rate and biomass yield of 1.602 day−1 and 687.5 mg L−1, respectively, were achieved under 2 g L−1 glucose. Nitrogen starvation up to 75% in the 1.0 g L−1 glucose-supplemented culture was done to induce lipid accumulation and did not significantly affect the growth. Lipid content ranges from 20% to 27% dry weight. Nile Red staining showed more prominent neutral lipid bodies in starved mixotrophic cultures. C. sorokiniana exhibited enhanced biomass production under mixotrophy and more prominent neutral lipid accumulation under nitrogen starvation with no significant decrease in growth; hence, this isolate could be further studied to establish its potential for biodiesel production.