.3, 9.5 and 17.2%, respectively. F106X produced 18.2% less glycerol from a glucose–xylose mixture medium than FB3X, whereas no glycerol production was detected in these four strains when grown on a xylose medium. In addition, the xylitol production and ethanol yield in strain F106X did not differ significantly. These results suggested that the improvement in ethanol production in strain F106X was mainly due to increased xylose consumption