Question

which organism produces methane gas

Answer 1

methane gas is performed by bacteria under anoix conditions

Answer 2

Methanogenesis or biomethanation is the formation of methane by microbes known as methanogens. Organisms capable of producing methane have been identified only from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although many live in close association with anaerobicbacteria.