Electrochemically coupled CH 4 and CO 2 consumption driven by microbial processes.

The chemical transformations of methane (CH 4 ) and carbon dioxide (CO 2 ) greenhouse gases typically have high energy barriers. Here we present an approach of strategic coupling of CH 4 oxidation and CO 2 reduction in a switched microbial process governed by redox cycling of iron minerals under temperate conditions. The presence of iron minerals leads to an obvious enhancement of carbon fixation, with the minerals acting as the electron acceptor for CH 4 oxidation and the electron donor for CO 2 reduction, facilitated by changes in the mineral structure. The electron flow between the two functionally active microbial consortia is tracked through electrochemistry, and the energy metabolism in these consortia is predicted at the genetic level. This study offers a promising strategy for the removal of CH 4 and CO 2 in the natural environment and proposes an engineering technique for the utilization of major greenhouse gases.