Mutating Methanogens to Enhance Methane Production in Microbial Electrosynthesis

To address the lack of genetic tools currently hindering the improvement of methanogens with complex metabolic pathways, 60Co-γ irradiation was applied to mutate Methanosarcina barkeri, yielding the efficient strain M600. Transcriptomics revealed significant upregulation of key genes (e.g., Mta, frh, and hdr) involved in ATP synthase in M600, synergistically driving metabolic flux in methane synthesis. Intracellular electron-dense granule levels, cytochrome abundance, and related redox-active substance content increased in the mutant, whereas the surface layer thickness decreased. M600′s free-charge transfer resistance declined by 24.2%, while area capacitance rose by 19.7%, significantly enhancing electron shuttling and transient storage. Consequently, M600′s methane production increased by 99.4% to 10.27 mmol·L–1 in the methylotrophic pathway and by 68.4% to 2.29 mmol·L–1 in the hydrogenotrophic pathway.