Enantiopure meso-2,3-butanediol production by metabolically engineered Saccharomyces cerevisiae expressing 2,3-butanediol dehydrogenase from Klebsiella oxytoca.

2,3-Butanediol (2,3-BDO) is a functional C4 compound with various industrial applications. It exists as three isomers, and racemic mixtures can be produced through chemical synthesis and fermentation using natural producers. In this study, Saccharomyces cerevisiae was engineered to produce enantiopure meso-2,3-BDO by eliminating BDH1 encoding (2 R,3 R)-butanediol dehydrogenase and introducing budC coding for acetoin reductase from Klebsiella oxytoca. The resulting strain produced 69.2 g/L of enantiopure meso-2,3-BDO production with a productivity of 1.5 g meso-2,3-BDO/L•h using cassava hydrolysates. Furthermore, improved titer and productivity of meso-2,3-BDO were achieved by resolving C2-auxotrophy. To decrease the acetoin accumulation, the budC gene was stably and strongly expressed throughout the chromosomal integration. The resulting strain produced 171 g/L of meso-2,3-BDO with 0.49 g meso-2,3-BDO /g glucose, which is 99.8 % of theoretical yield and a productivity of 1.8 g meso-2,3-BDO/L•h. These results will help facilitate the commercial production of enantiopure meso-2,3-BDO using the GRAS strain.