UV mutagenesis followed by hydrogen peroxide treatment ameliorates lipid production and omega-3 fatty acids levels in Chlorella sp.

The high potential Chlorella sp. was obtained after the UV mutation which produces higher biomass and lipid content than the wild type. The lipid content and biomass were increased from 34 to 48 % dry cell weight and 1.42 to 1.97 g/L respectively. Further, hydrogen peroxide (H2O2) treatment increased both biomass and lipid content in mutant, whereas wild type did not show any considerable change in both biomass and lipid content. A 3-fold increase in total lipid yield was observed after the H2O2 treatment in mutant when compared to the untreated wild type. H2O2 treatment also altered the fatty acid composition of lipids resulting in enhanced eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. Overall results indicate that the strain improvement of Chlorella sp. by UV mutagenesis and oxidative stress by H2O2 treatment enhances the biomass and lipid content with high amounts of omega-3 fatty acids. Furthermore, the H2O2 treated mutant cells showed upregulation of the important genes involved in the fatty acid synthesis pathway.