Anaerobic oxidation of methane (AOM) is a key microbiological process mitigating the release of methane into the atmosphere. AOM coupled to the reduction of manganese oxides was first reported over a decade ago yet the microorganisms responsible and the key mechanisms they employ for this process had not been conclusively demonstrated. In a newly published study by ACE researchers Andy Leu, Simon McIlroy and Gene Tyson, meta-omic studies on a long term enrichment of two novel members of the Methanoperedenaceae revealed the expression of key genes involved in methane oxidation and several shared multi-heme c-type cytochromes (MHCs) that were differentially expressed between these two microorganisms, supporting the use of two different dissimilatory manganese reduction pathways during AOM coupled Mn(IV) reduction. The study expands the known electron acceptors anaerobic methanotrophic (ANME) archaea and importantly demonstrates their role in linking the global carbon and manganese cycles. This has significance to climate change modelling, given it is estimated that 19Tg of manganese is deposited in continental margins each year making it an important global sink for this potent greenhouse gas.
ISME J. 2020 Jan 27. doi: 10.1038/s41396-020-0590-x