Improvement of ethanol productivity during xylose and glucose co-fermentation by xylose-assimilating S. cerevisiae via expression of glucose transporter Sut1

Enhancing the sugar uptake ability of the yeast Saccharomyces cerevisiae is a potentially important factor for efficient ethanol production during fermentation of lignocellulosic biomass. Here, we attempted to express a Pichia stipitis gene encoding a sugar transporter, SUT1, in a xylose-assimilating S. cerevisiae strain that expresses xylose reductase, xylosedehydrogenase and xylulokinase. We next investigated xylose fermentation, glucose fermentation and glucose and xylose co-fermentation using the Sut1-expressing S. cerevisiae strain. Expression of Sut1 in xylose-assimilating S. cerevisiae increased both xylose uptake ability and ethanol productivity during xylose fermentation. Moreover, glucose uptake ability and ethanol productivity during glucose fermentation also increased by expressing of Sut1. The yield of ethanol during xylose and glucose co-fermentation by the Sut1-expressing yeast strain (0.44 g/g-consumed sugar) was significantly higher than that of the parental strain (0.39 g/g-consumed sugar).