Methanogens live in anaerobic environments, such as swamps, marshes, cattle rumen, the gut of termites and sewage sludge. These bacteria are chemoautotrophs, which use hydrogen as a source of electrons to reduce carbon dioxide. They emit methane as a waste product of this process.
Methanogens are anaerobic unicellular microorganisms. They are lithotrophs and produce their own energy through the process of methanogenesis. In their habitats, methanogens degrade complex organic molecules and compounds to help recycle elements and nutrients into the ecosystem. In total, they produce approximately 109 tons of methane per year, about half of which escapes into the atmosphere.