Lipid extraction from oleaginous yeast cells with very high lipid content, low cell density, and fragile cell wall

The newly developed oleaginous yeast cells behave high lipid content, low cell density, and fragile cell walls, as well as partial cell disruption. To extract the microbial lipid from these very high lipid containing cells, the regular Folch method does not work because the cells are unable to be completely harvested by centrifugation due to the low cell density (lower than broth), and lipid leakage into the broth from broken cells. This study developed a heat-assisted ultrasonic method for direct lipid extraction from the liquid fermentation broth after incubated at 80 °C followed by ultrasonic treatment. The method significantly improved the lipid extraction yield by 12 %-42 % of the very high lipid containing Trichosporon cutaneum cells (45 %-75 %). The method also preserved unsaturated fatty acids more effectively than the modified Folch method. The calculation on cell dry weight and lipid content in cells verified the effectiveness of the method with acceptable derivations. This study offers a simple and reliable method for quantitative measurement of microbial lipids from oleaginous yeast cells with very high lipid content.