Elucidating the Role of Xylose Metabolism Enzymes from Yarrowia lipolytica

The biological production of fuels and chemicals by microorganisms has garnered interest as an alternative to petroleum-derived products. Using lignocellulosic feedstocks enables renewable production without competing for food supplies. However, many industrial microorganisms do not efficiently metabolize xylose and other pentose sugars resulting from lignocellulose hydrolysis. As a result, much effort has focused on engineering microorganisms for efficient xylose utilization. The oleaginous yeast, Yarrowia lipolytica, is capable of accumulating lipids >60% of cell biomass, making it ideal for production of fatty acid-based products. While there are conflicting reports in the literature, our experiments show that Y. lipolytica is unable to utilize xylose as a sole carbon source. Here, we systematically investigated the xylose pathway in Y. lipolytica using synthetic biology and metabolic engineering approaches. Through our efforts, we determined that Y. lipolytica contains a number of enzymes required for xylose metabolism. The elucidation of these endogenous enzymes was confirmed both in vivo and in vitro. The elucidation of functional and non-functional enzymes of the xylose pathway in Y. lipolytica will enable the engineering of robust xylose utilization in this oleaginous host. Finally, we will present our most recent data toward engineering efficient xylose metabolism in Y. lipolytica. As an oleaginous yeast with facile genetic tools, and well defined fermentation characteristics, Y. lipolytica is poised to be important for processing of lignocellulosic feedstocks for sustainable fuels and chemicals.