Location: Bioenergy ResearchTitle: Enhancement of xylose utilization from corn stover by a recombinant bacterium for ethanol production Author
Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/2015
Publication Date: 8/1/2015
Publication URL: http://handle.nal.usda.gov/10113/62174
Citation: Saha, B.C., Qureshi, N., Kennedy, G.J., Cotta, M.A. 2015. Enhancement of xylose utilization from corn stover by a recombinant Escherichia coli strain for ethanol production. Bioresource Technology. 190:182-188. Interpretive Summary: Any lignocellulosic biomass, upon pretreatment and enzymatic hydrolysis, generates a mixture of sugars such as glucose, xylose and arabinose. The recombinant E. coli strain FBR5 can convert all these sugars to ethanol. However, the fermentation becomes slower due to repression by glucose and arabinose on the utilization of xylose. In this paper, we have demonstrated that xylose utilization can be enhanced by using substrate selective inoculum preparation and manipulation of simultaneous saccharification and fermentation. This information will be useful to develop more efficient process technology for production of ethanol from lignocellulosic feedstock.
Technical Abstract: Effects of substrate-selective inoculum prepared by growing on glucose, xylose, arabinose, GXA (glucose, xylose, arabinose, 1:1:1) and corn stover hydrolyzate (dilute acid pretreated and enzymatically hydrolyzed, CSH) on ethanol production from CSH by a mixed sugar utilizing recombinant Escherichia coli (strain FBR5) were investigated. The initial ethanol productivity was faster for the seed grown on xylose followed by GXA, CSH, glucose and arabinose. Arabinose grown seed took the longest time to complete the fermentation. Delayed saccharifying enzyme addition in simultaneous saccharification and fermentation of dilute acid pretreated CS by the recombinant E. coli strain FBR5 allowed the fermentation to finish in a shorter time than adding the enzyme simultaneously with xylose grown inoculum. Use of substrate selective inoculum and fermenting pentose sugars first under glucose limited condition helped to alleviate the catabolite repression of the recombinant bacterium on ethanol production from lignocellulosic hydrolyzate.