Electromethanogenesis underpins the methane production in a Tibetan wetland
En palabras de los autores
Wetlands are a significant source of methane, a potent greenhouse gas that contributes to global warming. Acetate and H2/CO2 are generally considered the dominant precursors for methane formation, while H2, generally considered as the electron donor, is considerably lower in wetlands. This work investigated alternative reductive mechanisms of methanogenesis in the soil microcosms of Zoige wetland on Tibetan Plateau. Carbon monoxide inhibition of hydrogenase combined with isotope tracing experiments indicated only 2.9%-12.5% of the wetland H2 was used in methanogenesis. Electron shuttles (biochar and magnetite) promoted methane production, and electrochemical experiments detected current generation from bacteria and current consumption coupled to methane production, confirming that electromethanogenesis occurred in the Zoige wetland and contributed 27.7%-50.9% of CH4 production. Moreover, electromethanogenesis exhibited 2.6-16.1-fold higher CO2- and methanol-reductive methanogenic efficiencies than using H2. Uncultured Rice Cluster Ⅱ methanogens and a family of H2-dependent methylotrophic methanogen called Methanomassiliicoccaceae were enriched in electrochemical microcosms. Remarkably, oxidized anthraquinone-2,6-disulfonate decreased methane production. This work verifies the role of electromethanogenesis in a Tibetan wetland and provides a potential strategy for reducing methane emission. Direct interspecies electron transfer drives methane production in Tibetan wetlands and is more efficient than H2-dependent methanogenesis, shown using CO-inhibited microcosms, isotope tracing, electrochemistry, and electron-shuttle amendments.
Apareció: viernes, 25 de septiembre. Communications Earth & Environment. Revista con revisión por pares.