A potent lipid producing isolate of Epicoccum purpurascens AUMC5615 and its promising use for biodiesel production

摘要

Oils of oleaginous microorganisms are a powerful alternative to vegetable oils for biodiesel production. In this study, the fungus Epicoccum purpurascens AUMC5615 isolated from Egypt showed a potent high lipid content (80% lipid) when grown on 4% sucrose in submerged culture under continuous illumination. Under dark submerged conditions the lipid content has drastically decreased to 12%. In light static conditions, the lipid content was 70%; however, the net lipid yield was significantly lower than that of light submerged cultures because of the decrease in growth under light static conditions in comparison to light submerged cultures. Under dark static conditions the lipid content of the fungus has declined to 30%. These results indicate that light plays a crucial role in the lipid accumulation whereas submersion enhances the growth of the fungus. Concomitantly, the highest yield of carotenoids was obtained under light submerged conditions followed respectively by light static, dark submerged and dark static. This synchronized increase in carotenoids content might be implicated in protecting the high lipid pools in the fungus from perox-idation. Growing the fungus on 4% of crude molasses resulted in a net lipid production of 26.8 g per liter under light submerged conditions. The determination of fatty acids by GC/MS revealed that the major constituents are four saturated fatty acids, hexadecanoic, n-decanoic, dodecanoic and octadecanoic acids. These saturated fatty acids would give valuable stability properties of such fungal biodiesel. The current investigation opens the scope for the possible use of this promising fungal isolate in biodiesel production.