VOLUME 14 (Supplement)

UV-irradiation mutagenesis of Chlorella vulgaris Beijerinck SP17 to enhance lipid production for potential biodiesel application

Microalgae are considered as ideal and renewable feedstock for biofuel production because they do not pose threats to food security and the environment. Moreover, these strains can produce triacylglycerols (TAGs), a precursor in biodiesel production. However, to further improve the lipid accumulation, genetic engineering of these microorganisms is limited due to lack of candidate genes. Hence, induced mutagenesis presents an alternative for strain improvement. This study showed that ultraviolet (UV)-induced mutations which resulted in the reduced starch production of an indigenous strain of Chlorella vulgaris Beijerinck SP17 led to an increase in lipid production. Indigenous C. vulgaris culture was subjected to induced mutagenesis via UV irradiation. Duration of 10 min UV irradiation was used with the fatality rate of 84% and starch-deficient mutants were selected via negative iodine staining. Selected mutants were grown in upscale and cultured separately in nitrogen-replete (N+) and nitrogen-deplete (N-) conditions to further induce lipid and TAG accumulation. These starch-deficient strains had substantial increase in the production of lipids and TAGs with 58% and 43%, respectively. The N- condition revealed to have induced further synthesis of lipids and TAGs. These demonstrate that connection between lipid and starch biosynthesis pathways may be utilized to improve microalgal strain productivity for biodiesel production.