Since the emergence of life on our

Since the emergence of life on our planet, anaerobic methane metabolism, including methanogenesis and methane oxidation, has been a crucial element in the Earth’s carbon cycle1, and both processes are key to the global methane budget. Methanogenic archaea produce ~500–600Tg of methane per year2, whereas anaerobic methane-oxidizing archaea (ANME) oxidize a large portion of methane within the seafloor before it reaches the water column3,4. The metabolic pathways of methane formation and anaerobic oxidation of methane are largely identical, as both contain exclusively C1-compound-transforming enzymes that were described originally in the methanogenesis pathway5–7.