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Methane (CH 4) is one of the most important greenhouse gases and is oxidized by the methanotrophic bacteria in the soil. Present work is an effort to review the available information in this regard and present them in a systematic way. In this review, we concluded that low NH 4 + concentration can be supportive to the methane oxidation and growth of the methanotrophs. However, their high contents suppress the methanotrophic bacteria by inhibiting the enzymes particularly methane monooxygenase (MMO) involved in the methane oxidation. There are a range of the soil and environmental factors such as type of soil and vegetation, methane availability, amount and exposure time of ammonium, and type of methanotrophic community dominating in an ecosystem, which affect the response of the methanotrophic bacteria towards the fertilizer application. However, still there are several gaps in our knowledge as complex interaction of edhapic factors affecting the availability of ammonium is unraveled.

Two methylotrophic strains of Bina coalmine spoil BNV7b and BRV25 were identified based on physiological traits and 16S rDNA sequence as Methylophilus and Methylobacterium species.' The strains exhibited similar carbon utilization but differed in N utilization and their response to the metabolic inhibitors. Methylophilus sp. was less tolerant to salt stress and it viability declined to one tenth within 4 h of incubation in 2M NaCI due to membrane damage and leakage of the intracellular electrolytes as evident from malondiaaldehyde (MDA) assay. In 200 mM NaCI, they exhibited increased superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity while in 500 mM NaCI, enzyme activities declined in Methylophilus sp. and increased in Methylobacterium sp. Among exogenously applied osmoprotectants proline was most efficient; however, polyols (mannitol, sorbitol and glycerol) also supported growth under lethal NaCI concentration.