Molecular detection of methanotrophic bacteria in the hot springs of the Uzon caldera, Kamchatka

Abstract

867 Microbial communities inhabiting such extreme ecosystems as continental volcanogenic hot springs are of considerable interest for both basic and applied biotechnological studies. The currently available data on methanotrophs from hightemperature habitats are scarce (1). The validly described species of thermo� philic and thermotolerant methanotrophic bacteria include members of the genera Methylothermus (2, 3), Methylococcus (4), and Methylocaldum (5, 6). The microbial communities inhabiting hightemperature springs of Kamchatka are of great interest to Russian scientists (7); however, the data on the microorgan� isms utilizing methane and/or other C1 compounds are fragmentary. Acidothermophilic methaneoxidiz� ing representatives of the phylum Verrucomicrobia were isolated from the acidic hot springs of Kam� chatka (pH 3.5) (8). Methaneoxidizing activity was detected by the radioisotope method in the silt sam� ples collected from the springs of the Vostochnoe Field of the Uzon Caldera, with the temperature not exceeding 60°C (Pimenov, unpublished data). There is, however, no data on the presence of methanotrophs in other hot springs of Kamchatka. Thus, the goal of the present work was to detect aerobic methanotrophic bacteria in the sediments of the hot springs of the Uzon caldera using two molecu� lar biological techniques: fluorescent in situ hybridiza� tion (FISH) and analysis of the pmoA gene encoding the β subunit of the particulate methane monooxyge� nase.