Increasing temperature and sulfate enhances the efficiency of methane abatement in an anaerobic oxidation of methane bioreactor (AOMB) system

Controlling methane emission sources is important for the sustainable application of energy from the deep sea to alleviate methane-induced global warming. The anaerobic oxidation of methane (AOM) process coupled with sulfate reduction (SR) plays a key role in seafloor methane biofiltration. However, the mechanisms for the enhancement of the methane abatement efficiency in an AOM reaction system and the responses of temperature and sulfate concentration remain known. To cover the knowledge gap, this study investigated the enhancement of methane abatement in a self-manufactured AOMB system for 230 days via increasing temperatures and sulfate concentrations. The primary conclusions are as follows: (a) AOM and SR rates were significantly elevated at the conditions of temperature increase (8 to 15 °C) and sulfate addition (+15 mM). (b) Sulfate and temperature were key factors influencing the diversity of archaea and bacterial communities. (c) ANME-2c, ANME-1b, SEEP-SRB1, and Halodesulfovibrio were dominant genera of methane‑sulfur cycling in the system. (d) Functional gene prediction revealed that the coupling of methane oxidation and dissimilatory sulfate reduction was responsible for the methane abatement. Our findings provide new insights into the enhancement of methane abatement efficiency in the deep sea and the application of AOM reaction systems.