Epsilon Archive for Student Projects

Abstract

Under the premise of high energy price with estimated petroleum crisis, biodiesel extracted from plant oil, animal fat and microorganisms is considered as a promising replacement for fossil raw material. However, the increasing price of animal feeding and decreasing tillable land for oil plants have brought great difficulty to achieve biodiesel from feedstock plant oil and animal fat.
In this study, four oleaginous yeasts including Lipomyces lipofer, Lipomyces starkeyi, Rhodotorula glutinis and Yarrowia lipolytica were compared for their lipid accumulating productivity in different carbon sources: glucose, xylose and a mixture of both glucose and xylose. According to the experimental results, Rhodotorula glutinis had the highest lipid yield in both glucose sole carbon source and mixed sugar in shake flask test. Lipomyces starkeyi was able to utilize xylose as sole carbon source to accumulate lipid with highest yield in shake flask test. In comparison with Lipomyces lipofer, Lipomyces starkeyi had higher lipid yield in both shake flask test and fermentation bioreactors. Yarrowia lipolytica could not utilize xylose sole carbon source and its lipid yield was the lowest one when compared to other three oleaginous yeasts. During fermentation in the bioreactor test, lipid content of Lipomyces lipofer showed a maximum, later the lipid content decreased. A similar peak of lipid content was observed in the fermentation test in bioreactor of Lipomyces starkeyi, but after a temporary decrease the lipid content increased again. Lipid content reached its highest amount at early stationary phase and decreased may be due to lipid remobilization.