Nocardioides speluncae sp. nov., a novel actinobacterium isolated from a karstic subterranean environment sample

A novel actinobacterial strain, designated YIM ART13^T, 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 found to aerobic and Gram-stain positive. On the basis of 16S rRNA gene sequence analysis, strain YIM ART13^T was found to be closely related to Nocardioides pakistanensis NCCP 1340^T (96.1% sequence similarity) and is therefore considered to represent a member of the genus Nocardioides. In addition, LL-diaminopimelic acid was identified as the diagnostic diamino acid in the cell wall peptidoglycan. The whole cell sugars were found to be mannose, galactose, glucose and ribose. The major isoprenoid quinone was identified as MK-8(H₄), while the major fatty acids (> 10%) were identified as iso-C_16:0, C_18:1ω9c and C_18:0 10-methyl. The polar lipids were found to contain diphosphatidylglycerol, phosphatidylglycerol phosphatidylinositol and phosphatidylinositol mannoside, an unidentified phospholipid. The genomic DNA G+C content of strain YIM ART13^T was determined from the draft genome sequence to be 70.1 mol%. On the basis of phenotypic, genotypic and phylogenetic data, strain YIM ART13^T represents a novel species of the genus Nocardioides, for which the name Nocardioides speluncae sp. nov. is proposed. The type strain is YIM ART13^T (= KCTC 39593^T = DSM 100493^T).