Nocardia aurea sp. nov., a novel actinobacterium isolated from a karstic subterranean environment

A novel actinobacterium, designated strain SYSU K10002T, was isolated from a soil sample collected from a karst cave in Xingyi county, Guizhou province, south-western China. The taxonomic position of the strain was investigated using a polyphasic approach. Cells of the strain were aerobic and Gram-stain-positive. On the basis of 16S rRNA gene sequence similarities and phylogenetic analysis, strain SYSU K10002T was most closely related to the type strains of Nocardiaaltamirensis NBRC 108246T (99.0 % sequence similarity) and Nocardiatenerifensis NBRC 101015T (98.8 %) and is therefore considered to represent a member of the genus Nocardia . DNA–DNA hybridization values between strain SYSU K10002T and the closely related type strains of the genus Nocardia were less than 70 %. In addition, meso-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The whole-cell sugars were arabinose, ribose and galactose. The major isoprenoid quinone was MK-8(H4,ω-cycl), while the major fatty acids (>10 %) were C16 : 0, C18 : 1ω9c and C18 : 0 10-methyl. The polar lipids contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified glycolipid. Mycolic acids were present. The genomic DNA G+C content of strain SYSU K10002T was 67.4 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU K10002T represents a novel species of the genus Nocardia , for which the name Nocardia aurea sp. nov. is proposed. The type strain is SYSU K10002T (=KCTC 39849T=DSM 103986T).