(288g) Characterize and Release Biological Constraints for Lignocellulose Bioconversion

Although conversion of lignocellulosic biomass into value-added fuels and chemicals by microbial processes offers a sustainable route to replace petroleum-based chemicals, intrinsic biological constraints in microbial hosts limit production metrics and inhibit the economic viability of lignocellulosic refineries. The native regulatory mechanisms at the transcriptional and biochemical levels to maintain homeostasis often limit hyperproduction of fermentation products, especially for nonnative products. In addition, cellular transport across the cytoplasmic membrane for substrate import and product export also represents potential bottlenecks for bioproduction. Characterization of these intrinsic regulatory constraints leads to new metabolic engineering strategies to deregulate transcriptional and metabolic controls for lignocellulose bioconversion. We have discovered effective engineering strategies to release carbon catabolite repression and mitigate allosteric regulation in Escherichia coli for more efficient conversion of lignocellulosic sugar mixtures into renewable bioproducts. Meanwhile, we have initiated a thorough investigation of E. coli native cellular export systems of short-chain organic acids that are produced as renewable bioproducts to debottleneck potential product export constraints.