Batch experiments demonstrating a two-stage bacterial process coupling methanotrophic and heterotrophic bacteria for 1-alkene production from methane

Methane (CH 4 ) is a sustainable carbon feedstock source for aerobic CH 4 -oxidizing bacteria (methanotrophs) to produce value-added chemicals. Under substrate-limited (e.g., CH 4 , oxygen and nitrogen) conditions, CH 4 oxidation results in the production of various short-chain organic acids and platform chemicals. These CH 4 -derived products could be broadened by utilizing them as a feedstock for heterotrophic bacteria. As a proof of concept, a two-stage system for CH 4 abatement and 1-alkene production was developed in this study. Types I and II methanotrophs, i.e., Methylobacter tundripaludum SV96 and Methylocystis rosea SV97, respectively, were investigated in batch tests under different CH 4 and air supplementation schemes. CH 4 oxidation under either microaerobic or aerobic conditions induced the production of formate, acetate, succinate, and malate in M. tundripaludum SV96, accounting for 4.8-7.0% of consumed CH 4 -carbon while M. rosea SV97 produced the same compounds except for malate, and with lower efficiency than M. tundripaludum SV96, accounting for 0.7-1.8% of consumed CH 4 -carbon For the first time, the organic acids-rich spent media of methanotrophs were successfully used for 1-alkene production using engineered Acinetobacter baylyi ADP1 ‘ tesA-undA cells. The highest yield of 1-undecene was obtained from spent medium of M. tundripaludum SV96 at 68.9 ± 11.6 μmol mol C substrate −1 .