methanogen

Methanogens are a group of anaerobic archaea that produce methane as a metabolic byproduct. These microorganisms are found in various anoxic environments, including aquatic sediments, marshes, landfills, and the digestive tracts of animals. They typically use hydrogen and carbon dioxide as substrates for energy production, but some can utilize other substances like acetate or methylamine.12

Methanogens play a role in the carbon cycle by converting organic materials into methane. This process is crucial in anaerobic decomposition and contributes significantly to global methane emissions. Despite their specialized metabolism and sensitivity to oxygen, methanogens are widespread and define the limits of life in extreme environments.32