Ocean margin sediments are an extensive reservoir of methane, but methane release from these settings to the atmosphere is only a minor component of the global atmospheric methane budget, because of subsurface consumption by the anaerobicoxidation of methane (AOM). In this study, a combined geochemical and metagenomic approach was adopted to provide insight on the microbial communities responsible for AOM in diffusive methane settings and to investigate the effects of AOM on the sediment solid phase.