Small mud volcanoes (cold seeps), which are common in the floodplains of northern rivers, are a potentially important, although poorly studied sources of atmospheric methane. Field research on the cold seeps of the Mukhrina River (Khanty-Mansiysk Autonomous okrug, Russia) revealed methane fluxes from these structures to be orders of magnitude higher than from equivalent areas of the mid-taiga bogs. Microbial communities developing around the seeps were formed under conditions of high methane concentrations, low temperatures (3-5 degrees C), and near-neutral pH. Molecular identification of methane-oxidizing bacteria from this community by analysis of the pmoA gene encoding particulate methane monooxygenase revealed both type I and type II methanotrophs (classes Gammaproteobacteria and Alphaproteobacteria, respectively), with predomination of type I methanotrophs. Among the latter, microorganisms related to Methylobacterpsychrophilus and Methylobacter tundripaludum, Crenothrix polyspora (a stagnant water dweller), and a number of methanotrophs belonging to unknown taxa were detected. Growth characteristics of two isolates were determined. Methylobactersp. CMS7 exhibited active growth at 4-10 degrees C, while Methylocystis sp. SB12 grew better at 20 degrees C. Experimental results confirmed the major role ofmethanotrophic gammaproteobacteria in controlling the methane emission from cold river seeps.

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methanotrophs classes gammaproteobacteria river seeps bacteria microorganisms methylobacter tundripaludum crenothrix polyspora a stagnant water methylobacterpsychrophilus volcanoes cold atmospheric pmoa gene particulate methane monooxygenase

S é, Belova I Iu, Oshkin M V, Glagolev E D, Lapshina Sh Sh, Maksiutov S N, Dedysh,.[Methanotrophic bacteria in cold seeps of the floodplains of northern rivers].. 82 (6),732-40.

S é, Belova I Iu, Oshkin M V, Glagolev E D, Lapshina Sh Sh, Maksiutov S N, Dedysh,"[Methanotrophic bacteria in cold seeps of the floodplains of northern rivers]." 82

S é, Belova I Iu, Oshkin M V, Glagolev E D, Lapshina Sh Sh, Maksiutov S N, Dedysh,"[Methanotrophic bacteria in cold seeps of the floodplains of northern rivers]."