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 omega 9c, C-17:1 omega 8c and C-16:0. The predominant respiratory quinone was MK-8(H-4) and LL-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The genomic DNA G+C content was 71.1mol%. 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)).