Systems metabolic engineering of Escherichia coli improves co-conversion of lignocellulose-derived sugars

Currently microbial conversion of lignocellulose-derived glucose and xylose to biofuels is hindered by the fact that most microbes (including Escherichia coli , Saccharomyces cerevisiae , and Zymomonas mobilis ) preferentially consume glucose first and consume xylose slowly after glucose is depleted in lignocellulosic hydrolysates. In this study, we developed Escherichia coli strains that simultaneously utilize glucose and xylose in lignocellulosic biomass hydrolysate using genome-scale models and adaptive laboratory evolution. We designed and constructed E. coli strains that co-utilize glucose and xylose, and adaptively evolved them to improve glucose and xylose utilization. Whole-genome resequencing of the evolved strains found relevant mutations in metabolic and regulatory genes, and we investigated the mutations’ involvement in sugar co-utilization. The developed strains showed significantly improved co-conversion of sugars in lignocellulosic biomass hydrolysates, and they provide a promising platform for producing next-generation biofuels.