Separation and Identificaiton of Microbial Lipids From Oleaginous Microorganism As Biodiesel Feedstock

Oleaginous yeasts are microorganisms that accumulate high lipids up to over 56% of dry cell mass, and can be used as a feedstock for biodiesel production. However, determination of the oil contents in the fatty cells by lipid extraction places a great role in the research on microbial lipids. The most commonly accepted method of lipid extraction in the laboratory uses chloroform, methanol and water as solvents. In the performance of the method, a lot of  solvent is needed and the operation is difficult to handle, and the repetition is not high.  The purpose of this experiment is to find a new method that is much easier and simpler for extracting lipid from oleaginous yeast grown on glucose or xylose as the sole carbon and energy source.  In the experiments, several lipid extraction methods were investigated to determine the effectiveness of the method in terms of  lipid recovery and composition. One method is the gravimetrical Bligh-Dyer method using water, methanol and chloroform as solvent. The second method evaluated  used tert-butyl methyl ether or hexane as the solvent instead of chloroform. Since the terminal objective is to produce biodiesel, following extraction, the lipids have to be transesterified to fatty acid methyl ester (FAME). Therefore, in-situ transesterification of the fatty cells was also studied, where the lipids were extracted and transesterified simultaneously. The results showed that all the methods are effective to extract the lipids from the R. glutinis grown on glucose or xylose. In terms of the FAME yield based on cell mass, difference among the three methods is negligible. While using MTBE as solvent, the process is easier to operate.