Nocardioides endophyticus sp nov and Nocardioides conyzicola sp nov., isolated from herbaceous plant roots

Two Gram-stain-positive, non-motile, non-spore-forming, rod-shaped actinobacterial strains were isolated from the surface-sterilized roots of mugwort (Artemisia princeps) and horse-weed (Conyza canadensis), and subjected to taxonomic characterization. 16S rRNA gene sequence analysis indicated that the isolates, designated MWE 3-5(T) and HWE 2-02(T), should be placed in the genus Nocardioides of the family Nocardioidaceae. The strains were closely related to Nocardioides hankookensis DS-30(T), which exhibited 16S rRNA gene sequence similarity values of 97.99 and 99.09% with strains MWE 3-5(T) and HWE 2-02(T), respectively. The genome relatedness of N. hankookensis DS-30(T) with strain MWE 3-5(T) was 35.8%, and that with strain HWE 2-02(T) was 36.4%, whereas that between the two isolates was 43.2%. Strains MWE 3-5T and HWE 2-02(T) possessed MK-8(H-4) as the major isoprenoid quinone, and LL-diaminopimelic acid in the cell-wall peptidoglycan. The main fatty acids were iso-C-16:0, iso-C-17:0 and C-18:1 omega 9c for strain MWE 3-5(T) and iso-C-(16:0), 10-methyl C-18:0 and C-18:1 omega 9c for strain HWE 2-02T. Based on phenotypic, genotypic and phylogenetic studies, the following two novel species are proposed: Nocardioides endophyticus sp. nov. (type strain, MWE 3-5(T)=KCTC 29122(T)=JCM 18532(T)) and Nocardioides conyzicola sp. nov. (type strain, HWE 2-02(T)=KCTC 29121(T)=JCM 18531(T)).