Metabolic engineering of Enterobacter aerogenes for 2,3-butanediol production from sugarcane bagasse hydrolysate

Abstract

The pathway engineering of Enterobacter aerogenes was attempted to improve its production capability of 2,3-butanediol from lignocellulosic biomass. In the medium containing glucose and xylose mixture as carbon sources, the gene deletion of pflB improved 2,3-butanediol carbon yield by 40%, while the deletion of ptsG increased xylose consumption rate significantly, improving the productivity at 12 hr by 70%. The constructed strain, EMY-22-galP, overexpressing glucose transporter (galP) in the triple gene knockout E. aerogenes, ldhA, pflB, and ptsG, provided the highest 2,3-butanediol titer and yield at 12 hr flask cultivation. Sugarcane bagasse was pretreated with green liquor, a solution containing Na₂CO₃ and Na₂SO₃ and was hydrolyzed by enzymes. The resulting hydrolysate was used as a carbon source for 2,3-butanediol production. After 72 hr in fermentation, the yield of 0.395g/g sugar was achieved, suggesting an economic production of 2,3-butanediol was possible from lignocellulosic biomass with the metabolically engineered strain.

Keywords: 2,3-Butanediol; Enterobacter aerogenes; Metabolic engineering; Sugarcane bagasse.