Nocardioides dubius sp. nov., isolated from an alkaline soil

A Gram-positive, rod- or coccus-shaped bacterial strain, KSL-104^T, was isolated from an alkaline soil from Korea and its taxonomic position was investigated by a polyphasic approach. Strain KSL-104^T grew optimally at pH 7.0-8.0 and 30 °C. It was characterized chemotaxonomically as having a cell-wall peptidoglycan type based on LL-2,6-diaminopimelic acid with MK-8(H₄) as the predominant menaquinone. The major fatty acid was iso-C_16:0 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The DNA G+C content was 70.6 mol%. A neighbour-joining phylogenetic tree based on 16S rRNA gene sequences revealed that strain KSL-104^T joined the cluster comprising Nocardioides jensenii and Marmoricola aurantiacus. The cellular fatty acid profile of strain KSL-104^T was different from that of M. aurantiacus. Strain KSL-104^T and the type strain of N. jensenii exhibited a 16S rRNA gene sequence similarity value of 97.1% and a mean DNA-DNA relatedness value of 13%. Levels of 16S rRNA gene sequence similarity between strain KSL-104^T and the type strains of other Nocardioides species were in the range 94.0-96.5%. On the basis of phenotypic, phylogenetic and genetic data, strain KSL-104^T (=KCTC 9992^T=JCM 13008^T) represents a novel species of the genus Nocardioides, for which the name Nocardioides dubius sp. nov. is proposed.