Methanotrophic bacteria, methanotrophy and methane oxidation in soil and rhizosphere

Abstract

Methane (CH₄ ), a chemically as well as radiatively active trace gas, affects the oxidation capacity of the troposphere and radiation budget of the earth. The sources of methane production have been relatively well identified. Free hydroxyl radicals (OH) in the atmosphere comprise a major sink of methane. Additional sink is constituted by gram-negative, aerobic methanotrophic bacteria occurring in the soil and rhizosphere of aquatic macrophytes which consume substantial amounts of CH₄. Six genera of methanotrophs have been identified, all use methane or methanol as the sole source of carbon and energy. Rates of methane oxidation in nature due to the biological activity of these bacteria are highly variable and depend on several factors. This communication presents a brief review of the biology and ecology of CH₄ oxidation, and includes a cross-section of values reported for CH₄ consumption under field and laboratory conditions.