Metabolic Enhancement for Improved Conversion of Lignocellulosic Ethanol

A robust system of biocatalyst is key to the efficient conversion of lignocellulose to bioethanol. In this paper, three metabolic enhancement strategies (transfer of desirable foreign genes, carbon flux redirection, and co-culture of metabolically complementing strains) were applied for improved conversion of lignocellulosic ethanol. The transformation of heterologous xylose reductase gene into Saccharomyces cerevisiae resulted in no significant improvement. The knockout of the pyruvate formate lyase gene in Escherichia coli redirected the carbon flux and enhanced ethanol production. The co-culture of S. cerevisiae and E. coli KO11 significantly improved ethanol conversion relative to single culture. In conclusion, co-culture may be the most efficient and cost-effective way for improving conversion of lignocellulosic ethanol.