Nocardioides stalactiti sp. nov., isolated from a cave stalactite surface

An aerobic, rod-shaped, Gram-stain-positive, actinobacterial strain, designated 1.0914^T, was isolated from a stalactite sample collected from a cave located in Guizhou Province, southwest PR China. Based on 16S rRNA gene sequence analysis, strain 1.0914^T shared highest similarities values with Nocardioides pelophilus CGMCC 4.7388^T (97.7 %), Nocardioides immobilis CCTCC AB 2017083^T (97.5 %) and Nocardioides silvaticus CCTCC AB 2018079^T (97.3 %) and values lower than 97.0 % to other members of the genus Nocardioides. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain 1.0914^T formed an isolated branch with N. pelophilus CGMCC 4.7388^T, N. immobilis CCTCC AB 2017083^T and N. silvaticus CCTCC AB 2018079^T. The polar lipids contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and one unidentified phospholipid in the cellular membrane. The major fatty acids were identified as iso-C_{16 : 0}, C_{18 : 1} ω9c, C_{17 : 1} ω8c and C_{16 : 0}. The predominant respiratory quinone was MK-8(H₄) and ll-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The genomic DNA G+C content was 71.1 mol%. The orthologous average nucleotide identiy values between N. pelophilus CGMCC 4.7388^T, N. immobilis CCTCC AB 2017083^T, N. silvaticus CCTCC 2018079^T and strain 1.0914^T were 82.3, 81.7 and 81.9 % respectively. DNA-DNA hybridization values between N. pelophilus CGMCC 4.7388^T, N. immobilis CCTCC AB 2017083^T, N. silvaticus CCTCC 2018079^T and strain 1.0914^T were 25.2, 24.6 and 24.5 % respectively. The phylogenetic, phenotypic and chemotaxonomic data supported the classification of strain 1.0914^T as representing a new species of Nocardioides, for which the name Nocardioides stalactiti sp. nov. is proposed. The type strain is 1.0914^T (=CCTCC AB 2018266^T=KCTC 49243^T).