Bioethanol Fermentation by Robust Recombinant E. Coli FBWHR Using Wood Hemicellulosic Hydrolysate as Substrate

Hemicellulose is a by-product currently under-utilized in the papermaking industry. It is a hetero-carbohydrate polymer, with D-xylose as the major component upon depolymerization. In SUNY-ESF, wood extracts were obtained by extracting sugar maple wood chips with hot water at 160 oC for 120 min. The wood extracts were then concentrated and acid hydrolyzed. Ethanologenic bacteria, E. coli FBR5, had a good performance in pure xylose medium for ethanol production. However, FBR5 was strongly inhibited in dilute sulfuric acid hydrolysate. FBR5 was challenged by wood hemicellulosic hydrolysate in this study. After repeated strain adaptation, a new improved strain: E. Coli fbwhr was obtained. Fermentation experiments indicated that fbwhr was resistant to the toxicity of hydrolysate in the fermentation media of concentrated hydrolysate, and xylose was completely utilized by the strain to produce ethanol. FBWHR was grown in the concentrated hydrolysate without any treatment and yielded 36.8 g/L ethanol.