Development of commercial yeast strains for efficient lignocellulosic ethanol production

For cost-efficient lignocellulosic ethanol production, enhancing the xylose uptake ability and the tolerance to the hydrolysate inhibitors (e.g. acetic acid, furfural and 5-hydroxymethyl furfural) of yeast strains are the potentially important property. We have been developing the yeast strains by introducing and tuning of each gene expression level encoding the xylose isomerase, pentose phosphate pathway enzymes, and the acetate metabolic pathway enzymes. In addition to enhance the higher xylose consumption and tolerance of inhibitors, evolutionary engineering have been performed to such genetically modified yeast strains.

We evaluated for inserted genes stability and various property of the developing yeast strains. All inserted genes were stably integrated in the genome of the yeast strains. Developed yeast strains showed significantly higher xylose consumption, inhibitors tolerance, and enhancement of ethanol yield. Moreover we confirmed enabling fermentation at large scale, comparatively high temperature, and cell recycling.

In ongoing study, we evaluated the developed yeast strains using various kinds of biomass hydrolysate. The latest scientific results will be presented as well as an update on the strain’s development towards commercial production.