sp. nov., a methanotroph isolated from a geothermal field in the Republic of Korea.

A Gram-stain-negative, aerobic, non-motile and coccoid methanotroph, strain IM1, was isolated from hot spring soil. Cells of strain IM1 were catalase-negative, oxidase-positive and displayed a characteristic intracytoplasmic membrane arrangement of type I methanotrophs. The strain possessed genes encoding both membrane-bound and soluble methane monooxygenases and grew only on methane or methanol. The strain was capable of growth at temperatures between 15 and 48 °C (optimum, 30-45 °C) and pH values between pH 4.8 and 8.2 (optimum, pH 6.2-7.0). Based on phylogenetic analysis of 16S rRNA gene and PmoA sequences, strain IM1 was demonstrated to be affiliated to the genus . The 16S rRNA gene sequence of this strain was most closely related to the sequences of an uncultured bacterium clone FD09 (100 %) and a partially described cultured sp. GDS2.4 (99.78 %). The most closely related taxonomically described strains were Texas (97.92 %), Bath (97.86 %) and 73a (94.21 %). Strain IM1 shared average nucleotide identity values of 85.93 and 85.62 % with strains Texas and Bath, respectively. The digital DNA-DNA hybridization value with the closest type strain was 29.90 %. The DNA G+C content of strain IM1 was 63.3 mol% and the major cellular fatty acids were C (39.0 %), C 7 (24.0 %), C 6 (13.6 %) and C 5 (12.0 %). The major ubiquinone was methylene-ubiquinone-8. On the basis of phenotypic, genetic and phylogenetic data, strain IM1 represents a novel species of the genus for which the name sp. nov. is proposed, with strain IM1 (=JCM 33941=KCTC 72677) as the type strain.