Meiothermus roseus sp. nov., a thermophilic bacterium isolated from a geothermal area

Two closely related thermophilic bacterial strains, designated YIM 71031T and YIM 71039, were isolated from a hot spring in Tengchong county, Yunnan province, south-western China. The novel isolates were observed to be Gram-negative, aerobic, rod-shaped and yellow-pigmented bacteria. The strains were found to be able to grow at 37–65 °C, pH 6.0–9.0 and with a NaCl tolerance up to 1.0 % (w/v). Phylogenetic analysis based on 16S rRNA gene sequences placed these two isolates in the genus Meiothermus. They were found to be closely related to Meiothermus timidus DSM 17022T (98.6 % similarity), and formed a cluster with this species. The predominant menaquinone was identified as MK-8 and the major fatty acids (>10 %) as anteiso-C15:0, iso-C15:0, anteiso-C17:0, iso-C16:0 and C16:0. The genomic DNA G+C contents of strains YIM 71031T and YIM 71039 were determined to be 64.0 and 65.4 mol%, respectively. DNA–DNA hybridizations showed low values between strains YIM 71031T and YIM 71039 and their closely related neighbour M. timidus DSM 17022T. Morphological phylogenetic and chemotaxonomic results suggest that strains YIM 71031T and YIM 71039 are representatives of a new species within the genus Meiothermus, for which the name Meiothermus roseus sp. nov. is proposed. The type strain is YIM 71031T (=KCTC 42495T =NBRC 110900T).