Review on Methanogenesis and its Role

Abstract

Methane (CH4 ) is the second major gas, next to CO2 , responsible for the warming of environment and ozone layer depletion. It is a potent greenhouse gas with a global warming potential 25 times more than carbon dioxide. Methanogenesis is the biological production of methane mediated by anaerobic microorganisms from the domain Archaea commonly called methanogens. These methanogens are different from bacteria and eukarya as they lack peptidoglycan in their cell wall, which is present in bacteria and eukarya. Methane is produced by three major pathways on the basis of substrate utilized for methane production: hydrogenotropic, acetoclastic and methylotropic. Out of these, hydrogenotropic and acetoclastic are the two predominant pathways. There are two major sources of methane; namely, natural and anthropogenic. The natural sources include wetlands, termites and oceans, whereas, the common anthropogenic sources are fossil fuel transport and distribution, livestock, rice fields, and landfills. Among anthropogenic sources of methanogenesis, livestock which is ruminal methanogenesis is the major and it contribute to global warming and gross energy feed intake loss about 10-12%. The role of methanogenesis to ruminant animals is to remove hydrogen (H2 ) from the rumen. Methanogenesis can also beneficially exploit to treat organic wastes to produce useful compounds and methane that can be collected as biogas.