Geodermatophilus ruber sp. nov., isolated from rhizosphere soil of a medicinal plant.

A novel actinobacterial strain, designated CPCC 201356(T), was isolated from a rhizosphere soil sample of the medicinal plant Astragalus membranaceus and subjected to a polyphasic taxonomic analysis. Good growth occurred at 20-32 °C, at pH 7.0-7.5 and with 0-1 % (w/v) NaCl. Colonies on R2A and ISP 2 agar were light red to red, round and lacked aerial mycelium; cells adhered to the agar. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant menaquinones were MK-9(H(4)) and MK-9. Polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine and two unknown phospholipids. The major cellular fatty acids were iso-C(16 : 0), iso-C(15 : 0) and C(17 : 1)ω8c. The G+C content of the genomic DNA was 72.8 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain CPCC 201356(T) belonged to the family Geodermatophilaceae and consistently formed a distinct sub-branch with Geodermatophilus obscurus DSM 43160(T). The organism showed 16S rRNA gene sequence similarity of 97.7 % with G. obscurus DSM 43160(T). DNA-DNA hybridization between strain CPCC 201356(T) and G. obscurus DSM 43160(T) was 17.4 %. On the basis of evidence from this polyphasic taxonomic study, a novel species, Geodermatophilus ruber sp. nov., is proposed; the type strain is CPCC 201356(T) (=DSM 45317(T) =CCM 7619(T)).