Methane is produced as a metabolic byproduct in anoxic conditions by methanogenic microorganisms belongs to Archaea.
Methanogen has an unusual type of metabolism,because they use H2/CO2, formate,methylated C1 compounds or acetate as energy and carbon sources for growth. Methane production is occurs in two ways either by means of cleavage of acetic acid molecules to generate carbon dioxide and methane or by reduction of carbon dioxide with hydrogen