THE SOLUBLE METHANE MONOOXYGENASE GENE-CLUSTER OF THE TRICHLOROETHYLENE-DEGRADING METHANOTROPH METHYLOCYSTIS SP STRAIN-M

In methanotrophic bacteria, methane is oxidized to methanol by the enz yme methane monooxygenase (MMO), The soluble MMO enzyme complex from M ethylocystis sp. strain M also oxidizes a wide range of aliphatic and aromatic compounds, including trichloroethylene. In this study, hetero logous DNA probes from the type II methanotroph Methylosinus trichospo rium OE3b were used to isolate soluble MMO (sMMO) genes from the type IP methanotroph Methylocystis sp. strain M. sMMO genes from strain M a re clustered on the chromosome and show a high degree of identity with the corresponding genes from Methylosinus trichosporium OB3b. Sequenc ing and phylogenetic analysis of the 16S rRNA gene from Methylocystis sp. strain M have confirmed that it is most closely related to the typ e II methanotroph Methylocystis parvus OBBP, which, unlike Methylocyst is sp. strain M, does not possess an sMMO. A similar phylogenetic anal ysis using the pmoA gene, which encodes the 27-kDa polypeptide of the particulate MMO, also places Methylocystis sp. strain M firmly in the genus Methylocystis. This is the first report of isolation and charact erization of methane oxidation genes from methanotrophs of the genus m ethylocystis.