Ethanol production from xylose by ethanol resistant derivatives of Escherichia coli Fbr5 under batch and fed-batch conditions

Residual agricultural biomass represents an untapped resource for renewable fuel production. Ethanol production from lignocellulosic biomass is not economically feasible, in part, due to limitations in biocatalyst performance. Several ethanol resistant derivatives of the ethanologenic strain Escherichia coli FBR5 were isolated. During pilot fermentor studies in a Luria broth medium containing 150 g/L xylose, strains ARL and ANE produced over 50 g/L of ethanol, while FBR5 produces roughly 40 g/L of ethanol. Further fermentations were performed to maximize ethanol concentration. However, high concentrations of xylose inhibited cell growth and ethanol production. Under fed-batch conditions where xylose concentrations were regulated at 100 g/L, ARL produced over 60 g/L ethanol. The fed-batch strategy combined the high ethanol yields and rapid ethanol production observed in batch fermentations with a product stream at a high ethanol concentration. This is an abstract of a paper presented at the 2006 AIChE Annual Meeting (San Francisco, CA 11/12-17/2006).