methanogenic bacteria and the reactions they use to survive

One of a group of primitive micro-organisms, the Archaea. They give off methane gas as a by-product of their metabolism, and are common in sewage treatment plants and hot springs, where the temperature is high and oxygen is absent. Archaeons were originally classified as bacteria, but were found to be unique in 1996 following the gene sequencing of the deep-sea vent Methanococcus jannaschii.