Reversing methanogenic archaea to mitigate anthropogenic methane emissions and generate value-added products

Nearly 1000 Tg of the greenhouse gas methane are produced annually in diverse anaerobic biospheres. While methanotrophs naturally control atmospheric release by consuming methane, uncontrolled anthropogenic emissions contribute an estimated 20% of global methane emissions. Leveraging methanotrophs offers a process that complements nature in balancing the global methane budget. In this article, we present an engineered anaerobic system employing Methanosarcina acetivorans, in which Fe(III)-dependent reversal of methanogenesis enables methane consumption and conversion into value-added products. The implementation of electron-redirection strategies combined with growth-arrested resting cells led to a marked increase in methane conversion efficiency. This process was sustained for 48 days in a pilot-scale reactor system using resting cells under continuous methane feeding, with periodic regeneration of Fe(III) from Fe(II) via controlled micro-aeration. Our findings establish a foundational platform for developing advanced technologies aimed at mitigating point-source methane emissions, offering a promising approach to counteract anthropogenic contributions to global warming.