Methanogens Harboring in Rice Rhizosphere Reduce Labile Organic Carbon Compounds to Produce Methane Gas

Abstract

Submerged rice paddy soils are one of the major anthropogenic sources of methane (CH4) emission to the atmosphere. Methane is the second most important greenhouse gas after carbon dioxide. Methanogens are strictly anaerobic microorganisms and CH4 is the metabolic end product of those methanogens. Methane is produced by methanogens through multi-step enzyme-mediated process. Methanogens convert labile organic carbon compounds in CH4 and application of organic matter in submerged rice field significantly increased CH4 emission from soil to the atmosphere. The rate of methanogenesis may be determined by quantifying biomarkers namely methyl coenzyme M reductase A (mcrA) gene and coenzyme M (2-mercaptoethane sulphonate) in soil. Nickel ions are present as cofactor in enzymes involved in methanogenesis. Methane emission can be mitigated by application of EDTA at suitable rate in the soil of submerged rice field.