The first psychrophilic obligate methanotroph was isolated from the tundra soil in the Polar Ural. The organism has an optimal temperature range of 3.5-degrees-10-degrees-C, but at 20-degrees-C the growth is minimal. The cells of the metanotroph are Gram-negative cocci resembling Methylococcus in appearance but of low G + C content (G + C = 45.6 mol%). Membranes are arranged into bundles of vesicular discs. Gas vesicles are formed at the temperature range of 7-degrees-20-degrees-C, and the number of cells with vesicles increases with the temperature. Only methane or methanol serves as substrate for growth in the mineral salt medium. Psychrophilic methanotrophs might be important components of a microbial gas filter in the tundra region.