Monday, July 25, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Saccharomyces cerevisiae have been widely used in the industries for production of bioethanol from various sources of lignocellulosic biomass. Saccharomyces pastoranius, which is closely related to S.cerevisiae, is also known to produce high levels of ethanol from sugar substrates but is not as widely used. Experiments were conducted to directly compare the two species on xylose. Since neither species can consume xylose, xylose isomerase was added to the media to convert xylose to xylulose, which is consumable by these strains. Both the Saccharomyces strains showed improved growth of about 1.5 times in the presence of xylose isomerase over their growth in its absence. The final cell densities of S.cerevisiae with xylose isomerase were similar to the cell densities observed for S.pastoranius in the absence of xylose isomerase, indicating higher yield for S.pastoranius to S.cerevisiae. Interestingly, the growth profiles for both strains at 80g/L and 40g/L of xylose were very similar indicating that xylose was not inhibitory at these levels. S.pastoranius is a competitive yeast strain for bio-ethanol production and its wider temperature tolerance may prove beneficial.