Xylose to ethanol conversion in nature is been done by a few organisms such as yeasts like Scheffersomyces stipitis, an ascomycetous yeast that has been extensively investigated for the fermentation of xylose to ethanol, L-lactic acid for its further polymerization into PLA (Poliy Lactic Acid) and other products from hemicellulose, the second abundant component of cellulosic biomass [5, 6, 7]. Laboratory strains of Schef. stipitis, which are amenable to genetic and physiological manipulation, have been developed by metabolic engineering for xylose utilization [5, 7, 8]. The genome sequence was recently obtained for this yeast and will provide a valuable resource for enhancement of xylose utilization and other industrial attributes by Schef. stipites [8]. Genes from Schef. stipitis have also been introduced into Saccharomyces cerevisiae to enable fermentation of pentoses [5, 7, 8].