UC Davis

Engineered microorganisms capable of producing chemical commodities have emerged as sustainable alternatives to petroleum-based manufacturing. Expanded feedstock pools and improved product tolerance are two distinct approaches for improving the sustainability and productivity of microbial systems. Plant biomass sugars, which compete with food resources, are typically employed for most heterotrophic fermentation. Bypassing plants and directly utilizing carbon dioxide (CO2) is a promising alternative. However, biological CO2 fixation is slow and limits microbial growth and production. Regarding tolerance, engineering strategies and synthetic tools have improved the production of many target chemicals. Consequently, product concentrations often exceed the host tolerance threshold. Toxic products can curb titers and require expensive removal strategies, making economically viable microbial production challenging. This works seeks to address these issues by (i) construction of an electrochemical-biological hybrid system to fix CO2 in Escherichia coli and (ii) application of adaptive laboratory evolution (ALE) for improved isobutyl acetate (IBA) tolerance in E. coli. The one pot hybrid system demonstrates the potential for chemical production from CO2 and renewable electricity while the improved tolerance highlights the benefits overcoming product toxicity can have on microbial production.