Electron shuttles facilitate anaerobic methane oxidation coupled to nitrous oxide reduction in paddy soil

Anaerobic oxidation of methane (AOM) coupled with simultaneous consumption of nitrous oxide (N2O) has been recently reported, but the underlying coupling mechanism remains unclear. Here, we investigated N2O-mediated AOM in paddy soil under amendment of electron shuttles (anthraquinone-2,6-disulphonate and methylviologen). Sixty-day anaerobic incubation showed that N2O-mediated AOM occurred in paddy soil, and that electron shuttles stimulated AOM coupled to N2O reduction. Approximate 60% of (CH4)-C-13-C was converted into soil organic matter in paddy soil during anaerobic oxidation. Our results suggest that electron shuttles may play important roles in mitigating the emission of greenhouse gases (CH4 and N2O) and increasing organic matter in paddy soils.