Ethanolic fermentation of xylose with Saccharomyces cerevisiae harboring the Thermus thermophilus xylA gene, which expresses an active xylose (glucose) isomerase

The Thermus thermophilus xylA gene encoding xylose (glucose) isomerase was cloned and expressed in Saccharomyces cerevisiae under the control of the yeast PGK1 promoter. The recombinant xylose isomerase showed the highest activity at 85 degrees c with a specific activity of 1.0 U mg(-1). A new functional metabolic pathway in S. cerevisiae with ethanol formation during oxygen-limited xylose fermentation was demonstrated. Xylitol and acetic acid were also formed during the fermentation.