A two-staged bacterial process coupling methanotrophic and heterotrophic bacteria for 1-alkene production from methane

Abstract

Methane (CH4) is a sustainable carbon feedstock source for aerobic CH4-oxidizing bacteria (methanotrophs) to produce value-added chemicals. Under O2-limiting conditions, CH4 oxidation results in the production of various short-chain organic acids and platform chemicals. However, these CH4-derived products are still limited to C2-C6 and could be extended by utilizing them as a feedstock for heterotrophic bacteria. A two-stage system for CH4 abatement and 1-alkene production was developed in this study. Gamma- and alphaproteobacterial methanotrophs, i.e. Methylobacter tundripaludum SV96 and Methylocystis rosea SV97, respectively, were investigated in batch tests under different gas supplementation schemes. Under O2 limiting conditions (O2/CH4 molar ratio ~0.3), M. tundripaludum SV96 could potentially produce formate, acetate, succinate, and malate, accounted for ~7.4% of mol-CH4 consumed. For the first time, the organic acids-rich spent media derived from O2 limited-methanotrophic cultivation were successfully used for 1-alkene production using engineered Acinetobacter baylyi ADP1 (‘tesA-undA) cells.