Scientists have recently found that an archaebacteria belonging to the phylum Lokiarchaeota can be grown only in co-culture along with a Methanobacterium and another aerobic proteobacterium. The archaeon catabolizes amino acids that are secreted out from the Methanobacterium, producing formate. The formate released from the archaeon is utilized by the Methanobacterium as an energy source. The proteobacterium, by scav