Lipid accumulation in Lipomyces starkeyi mutants cultured in sago media

Afizul Safwan, Azahari (2020) Lipid accumulation in Lipomyces starkeyi mutants cultured in sago media. Masters thesis, Universiti Malaysia Sarawak (UNIMAS).

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Abstract

With the imminent depletion of natural resources, the search for alternatives for diesel has been an ongoing issue in the scientific world. Biodiesel feedstock, such as microbial oil, can be generated from fungi, yeast and algae. However, suitable environment must be provided to ensure optimal growth for efficient production of microbial oil. In this study, two different growth media, yeast malt broth (YMB) and Wild medium were tested for the growth of Lipomyces starkeyi ATCC 12659 and its mutant strains. The mutant strains tested were L. starkeyi MV-01 and L. starkeyi MV-05. L. starkeyi ATCC 12659 produced 8.62 g/L biomass in YMB and 8.51 g/L in Wild media (1.3% difference). A significantly higher yield was recorded for L. starkeyi MV-01 when grown in YMB (9.16 g/L), compared to Wild media (6.44 g/L). As for L. starkeyi MV-05, a lower biomass yield was recorded when grown in YMB (9.62 g/L) than when grown in Wild medium (11.23 g/L). L. starkeyi ATCC 12659 was found to accumulate lipid up to 27.78% (w/w) of its biomass at 8.07 g/L. L. starkeyi MV-01 accumulated lipid at 22.46% (w/w) of its biomass at 7.82 g/L and L. starkeyi MV-05 showed a peak lipid accumulation of 25.89% (w/w) at 8.60 g/L. When grown in sago effluent, L. starkeyi ATCC 12659 efficiently hydrolyzed starch to lipid at 35.04% (w/w) (9.47 g/L) of its dry biomass. L. starkeyi MV-01 was able to produce lipid at 33.62% (w/w) (8.03 g/L) of its dry biomass while L. starkeyi MV-05 converted starch to lipid at 34.11% (w/w) at 9.80 g/L dry biomass. Further studies that focuses on optimizing the cultivation conditions such as the types of carbon sources, carbon to nitrogen ratio, aeration inside the fermentation broth, pH and temperature can be conducted as these attributes greatly affect the microbial lipid yield. These include can greatly. In conclusion, parental strain L. starkeyi showed the highest amount of lipid accumulated when compared with its mutant strains for both sago starch and sago effluent substrate.

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