Anaerobic oxidation of methane: an "active" microbial process

Area of Science:

• Microbial Ecology
• Biogeochemistry
• Environmental Science

Background:

• Anaerobic oxidation of methane (AOM) is a key biological process mitigating methane release into the atmosphere.
• Initially linked to sulfate reduction by anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB).
• AOM is also coupled with denitrification, mediated by specific bacteria and archaea.

Purpose of the Study:

• To review the diverse mechanisms of anaerobic oxidation of methane (AOM).
• To summarize the microbial communities involved in AOM.
• To discuss unresolved questions in AOM research.

Main Methods:

• Literature review of AOM mechanisms and microbial players.
• Analysis of AOM coupling with various electron acceptors.
• Discussion of recent advancements and challenges in the field.

Main Results:

• AOM occurs via sulfate reduction, denitrification, and using manganese or iron as electron acceptors.
• Key microbes include ANME, SRB, Candidatus Methylomirabilis oxyfera, and Candidatus Methanoperedens nitroreducens.
• ANME-1 archaea show methane production capabilities and are found in hypersaline environments.

Conclusions:

• AOM is a multifaceted process with diverse microbial mediators and electron acceptors.
• Further research is needed to clarify the roles of specific microbes and environmental factors in AOM.
• Understanding AOM is critical for predicting methane cycling and its impact on climate change.