D-xylose fermentation by Schizosaccharomyces pombe cloned with xylose isomerase gene

Abstract

Renewable biomass, D-xylose, can be converted to ethanol by microbes which are screened from nature or mutagenesis. An alternative is to develop a genetically modified microorganism which possesses the gene for D-xylose utilization. The plasmid pDB248-XI containing the xylose isomerase gene from Escherichia coli has been cloned to the fission yeast Schizosaccharomyces pombe. A preliminary investigation showed that the modified yeast had the ability to produce ethanol by using D-xylose as substrate. Studies of environmental effects, fermentation limiting factors, and the xylose isomerase gene expression were performed in order to understand the biochemical and physiological characteristics of the modified yeast during D-xylose fermentation. The modified yeast was demonstrated to produce 0.42 g ethanol form 1 g D-xylose under the current situation. However, the studies also indicated that the ethanol yield could be increased through further genetic improvement