(380b) Engineering Ethanol Tolerance in Escherichia Coli for Improved Ethanol Production

Recombinant Escherichia coli has been shown to be a potential strain for commercial cellulosic ethanol production with its ability to efficiently convert both pentose and hexose sugars into ethanol. However, native E. coli lacks many desirable traits for bioethanol production, including high tolerance to ethanol. In this work, we have identified genes which confer improved tolerance to ethanol using plasmid-based genomic libraries and selections. The most highly enriched genes identified by microarray were cloned and tested for improved growth with exogenous ethanol (growth rate and minimum inhibitory concentrations). In order to investigate the relationship between improved growth with exogenous ethanol and improved ethanol production, we tested these clones for improved ethanol production with inducible heterologous expression of the Zymomonas mobilis homoethanol production pathway. This E. coli ethanol production strain was constructed with a strong, tightly regulated promoter and the ethanol production cassette was inserted at a genomic region with minimal polar effects. This work identifies promising genetic targets for further ethanol tolerance engineering and provides insight into using genome-wide approaches for strain engineering improved production of inhibitory biofuels.