Nocardioides ochotonae sp. nov., Nocardioides campestrisoli sp. nov. and Nocardioides pantholopis sp. nov., isolated from the Qinghai-Tibet Plateau

Six Gram-stain-positive, aerobic and irregular-rod-shaped actinobacteria (ZJ1313(T), ZJ1307, MC1495(T), Y192, 603(T) and X2025) were isolated from the Qinghai-Tibet Plateau of China and were characterized using a polyphasic taxonomic method. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the six new strains formed three distinct clusters within the genus Nocardioides, and strains ZJ1313(T) and ZJ1307 were most closely related to N. solisilvae JCM 31492(T) (16S rRNA gene sequence similarity, 98.0%), MC1495(T) and Y192 to N. houyundeii 78(T) (98.5 %), and 603(T) and X2025 to N. dokdonensis JCM 14815(T) (97.6%). The digital DNA-DNA hybridization values of strains ZJ1313(T), MC1495(T) and 603(T) among each other and with type strains of their closest relatives were all below the 70% cut-off point, but values within each pair of new strains were all higher than the threshold. The major fatty acids of these strains were iso-C-16:0, C-17:1 omega 8c or C-18:1 omega 9c. MK-8(H-4) was the predominant respiratory menaquinone and LL-2,6-diaminopimelic acid was the diagnostic diamino acid. All the strains shared diphosphatidylglycerol (predominant), phosphatidylglycerol, phosphatidylcholine and phosphatidylinositol as the common polar lipids, with minor difference in the types of unidentified phospholipids, glycolipids and lipids. The G+C contents based on genomic DNA of strains ZJ1313(T), MC1495(T) and 603(T) were 72.5, 72.1 and 73.2 mol%, respectively. The above results suggested that strain pairs ZJ1313(T)/ZJ1307, MC1495(T)/Y192 and 603(T)/X2025 represent three new species of genus Nocardioides, for which the names Nocardioides ochotonae sp. nov. (ZJ1313(T)=GDMCC 4.177(T)=KCTC 49537(T)=JCM 34185(T)), Nocardioides campestrisoli sp. nov. (MC1495(T)=GDMCC 4.176T=KCTC 49536(T)=JCM 34307(T)) and Nocardioides pantholopis sp. nov. (603(T)=CGMCC 4.7510(T)=DSM 106494(T)) are proposed accordingly.

Automated summary

In this study, six new actinobacteria strains were isolated from the Qinghai-Tibet Plateau of China and characterized using a taxonomic approach. The results revealed that these strains represent three new species within the genus Nocardioides.