Cost-efficient production of cellulosic ethanol requires the microorganism that can co-ferment both hexose and pentose rapidly and that have sufficient tolerance to the inhibitors in pretreated biomass, such as acetic acid and furfural. We have engineered Saccharomyces cerevisie for robust production of ethanol from lignocellulosic biomass by overexpression of the genes that encodes xylose isomerase and native pentose phosphate pathway enzymes. These genes were stably integrated in the genome of S.cerevisiae. To improve ability of ethanol production, we have applied evolutionary engineering and introduced several additional genes from other microorganisms.
As a result, we achieved the rapid consumption of xylose and the high yield of ethanol in the lignocellulosic hydrolysates which contain high concentration of inhibitors. Toyota’s yeast strains (Uz strains) are ready for commercial ethanol production.