Synthetic Methylotrophy: Engineering Escherichia coli for Methanol Utilization and Metabolite Production
Methylotrophy is the ability of microorganisms to utilize one carbon compounds such as methane and methanol as growth and energy sources. The recent discovery of large natural gas reserves has prompted considerable interest in utilizing methane or methanol as a substrate or co-substrate with sugars in the industrial fermentation of fuels and chemicals. Increased biomass and product yields are expected from methane and methanol since both are more reduced than sugars. Native methylotrophs are poor industrial microorganisms since many are strict aerobes, produce few metabolites and lack genetic tools. Therefore, the development of synthetic methylotrophy is of considerable interest. Herein, we describe the development of Escherichia coli as a platform microorganism for methanol metabolism. By incorporating native methylotrophic genes, we demonstrate the ability of E. coli to metabolize methanol into biomass and metabolites. We further discuss how to overcome the challenges involved in synthetic methylotrophy, including unfavorable methanol oxidation, carbon conservation and regulatory limitations. We also discuss the importance of the pentose phosphate pathway during methanol metabolism in E. coli and its regulatory tuning for optimal methanol assimilation. Finally, we provide data demonstrating the use of methanol as a substrate for cell growth, energy generation and metabolite production in E. coli.
SUPPORTED by the US DOE ARPA-E agency through contract no. DE-AR0000432.