Syntrophic interactions driving anaerobic methane oxidation in deep-sea cold seeps revealed by DNA-SIP.

Anaerobic oxidation of methane is a key process reducing methane emissions in oxygen-depleted marine environments such as deep-sea cold seeps. However, the stability and adaptability of microbial interactions driving this process remain poorly understood. Here, we combined stable isotope probing, tracer incubations, and bacterial inhibition experiments to investigate methane-oxidizing communities in sediments from the South China Sea. We found that methane oxidation was sustained by interactions between distinct archaeal and bacterial groups under different electron acceptor conditions. Inhibition experiments revealed tightly coupled microbial partnerships, while community shifts toward alternative metabolic pathways maintained overall methane oxidation rates. These results demonstrate functional redundancy and metabolic flexibility within microbial consortia. Our findings highlighted how dynamic environmental conditions supported multiple overlapping pathways, ensuring stable methane consumption. This work provided insights into the resilience of biogeochemical processes and informs future strategies for methane mitigation.