Nocardioides bizhenqiangii sp. nov. and Nocardioides renjunii sp. nov., isolated from soil and faeces of Tibetan antelope (Pantholops hodgsonii) on the Qinghai-Tibet Plateau.

Abstract

Two novel strain pairs (HM61^T/HM23 and S-34^T/S-58) were isolated from soil and the faeces of Tibetan antelope (Pantholops hodgsonii) collected at the Qinghai-Tibet Plateau of PR China. All four new isolates were aerobic, non-motile, Gram-stain-positive, catalase-positive, oxidase-negative, and short rod-shaped bacteria. The results of phylogenetic analysis based on the full-length 16S rRNA genes and 283 core genomic genes indicated that the four strains were separated into two independent branches belonging to the genus Nocardioides. Strains HM61^T and HM23 were most closely related to Nocardioides pelophilus THG T63^T (98.58 and 98.65 % 16S rRNA gene sequence similarity). Strains S-34^T and S-58 were most closely related to Nocardioides okcheonensis MMS20-HV4-12^T (98.89 and 98.89 % 16S rRNA gene sequence similarity). The G+C contents of the genomic DNA of strains HM61^T and S-34^T were 70.6 and 72.5 mol%, respectively. Strains HM61^T, S-34^T and the type strains of closely related species in the analysis had average nucleotide identity values of 75.4-90.5 % as well as digital DNA-DNA hybridization values between 20.1 and 40.8 %, which clearly indicated that the four isolates represent two novel species within the genus Nocardioides. The chemotaxonomic characteristics of strains HM61^T and S-34^T were consistent with the genus Nocardioides. The major fatty acids of all four strains were iso-C_16 : 0, C_17 : 1  ω8c or C_18 : 1  ω9c. For strains HM61^T and S-34^T, MK-8(H₄) was the predominant respiratory quinone, ll-2,6-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan, and the polar lipids profiles were composed of diphosphatidylglycerol and phosphatidylglycerol. Based on phylogenetic, phenotypic, and chemotaxonomic data, we propose that strains HM61^T and S-34^T represent two novel species of the genus Nocardioides, respectively, with the names Nocardioides bizhenqiangii sp. nov. and Nocardioides renjunii sp. nov. The type strains are HM61^T (=GDMCC 4.343^T=JCM 36399^T) and S-34^T (=CGMCC 4.7664^T=JCM 33792^T).