Methylomonas stagni sp. nov., a methanotroph of the genus Methylomonas, from a reservoir pond in Korea

A Gram-stain-negative, aerobic, motile, short rod-shaped methanotrophic bacterium, designated CM2 T , was isolated from a reservoir pond in Korea. Cells of strain CM2 T possessed a single polar flagellum, intracytoplasmic membrane stacks characteristic of type I methanotrophs, and contained electron-dense granules. The strain grew only on methane and methanol as carbon and energy sources. Growth occurred at 20–35 °C (optimum, 30 °C), pH 5.5–8.5 (optimum, 6.5) and with 0–0.5% (w/w) NaCl. Phylogenetic analysis based on the 16S rRNA gene sequence placed strain CM2 T within the genus Methylomonas , with sequence similarities to known species ranging from 94.5 to 98.3%. The major cellular fatty acids were C 16:1 and C 14:0 , and the predominant respiratory quinone was ubiquinone-8. The genome of strain CM2 T is 5.06 Mb in size with a G+C content of 56.8 mol%. The digital DNA–DNA hybridization, average nucleotide identity and average amino acid identity values between the genome of strain CM2 T and those of Methylomonas species were 19.2–21.3 %, 73.5–77.5 % and 72.3–76.7 %, respectively. Genome analysis identified genes encoding two distinct particulate forms and one soluble form of methane monooxygenase. Based on a polyphasic characterization, strain CM2 T is considered to represent a novel species of Methylomonas , for which the name Methylomonas stagni sp. nov. is proposed. The type strain is CM2 T (KCTC 8468 T =JCM 36702 T ).