Geodermatophilus nigrescens sp. nov., isolated from a dry-hot valley

A novel actinomycete, designated as strain YIM 75980(T), was isolated from a soil sample collected from a dry-hot river valley in Dongchuan county, Yunnan province, south-west China and was subjected to polyphasic taxonomic characterization. The organism produced circular, smooth, red to black coloured colonies comprising coccoid-shaped cells. Colonies on agar medium lacked mycelia and cells adhered to the agar. Strain YIM 75980(T) contained meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan and contained galactose, arabinose and glucosamine as the main sugars in the whole-cell hydrolysates. The predominant menaquinone was MK-9 (H(4)) and the major fatty acids were iso-C(15:0), iso-C(16:0) and C(16:0). The DNA G + C content of strain YIM 75980(T) was 73.1 mol%. Phylogenetic analyses based on 16S rRNA gene sequences clearly showed that strain YIM 75980(T) formed a distinct clade within the genus Geodermatophilus and was closely related to Geodermatophilus obscurus DSM 43160(T) (level of similarity, 97.9%). Furthermore, the result of DNA-DNA hybridization between strain YIM 75980(T) and G. obscurus 43160(T) demonstrated that this isolate represented a different genomic species in the genus Geodermatophilus. Moreover, the physiological and biochemical data showed the differentiation of strain YIM 75980(T) from its closest phylogenetic neighbour. Therefore, it is proposed that strain YIM 75980(T) represents a novel species of the genus Geodermatophilus, for which the name Geodermatophilus nigrescens sp. nov. is proposed. The type strain is YIM 75980(T) (=CCTCC AA 2011015(T) =JCM 18056(T)).