Identification of Aerobic Methane-Oxidizing Bacteria in Coastal Sediments of the Crimean Peninsula

Methane oxidation rates and diversity of methane-oxidizing microorganisms in the upper sediment layers of the Crimean Peninsula coastal regions (Black Sea) were investigated. Analysis of the 16S rRNA gene sequences revealed microorganisms of the class Gammaproteobacteria, order Methylococcales. At the sites of continuous gas seepage, the percentage of methanotrophs in the bacterial community was high (up to 2.1% of the total read number), which made it possible to detect them by sequencing of the native samples. At the sites of intermittent gas seepage formed during summer and autumn, methanotrophs were minor components of the communities and could be detected only after incubation of the sediment samples in the presence of methane. Low similarity between their 16S rRNA sequences and those of the known methanotrophs indicates that some organisms probably belong to new taxa of the species and genus levels.