Nocardioides nematodiphilus sp. nov., isolated from rhizosphere of Arabidopsis thaliana

An actinobacterial strain, designated R-N-C8(T), was isolated from the rhizosphere soil of Arabidopsis thaliana collected in Yunnan Province, south-west China. Based on the results of 16S rRNA gene sequence analysis, strain R-N-C8(T) had highest similarity to Nocardioides terrae CGMCC 1.7056(T) (96.5%), Nocardioides opuntiae KCTC 19804(T) (96.3%) and Nocardioides currus IB-3(T) (96.1%), and lower than 96.0% similarity to other members of the genus Nocardioides. Phylogenetic trees based on 16S rRNA gene sequences indicated that strain R-N-C8(T) formed an isolated branch with N. terrae CGMCC 1.7056(T) and N. opuntiae KCTC 19804(T). The polar lipids contained phosphatidylglycerol, diphosphatidylglycerol, one unidentified phosphoglycolipid and four unidentified phospholipids in the cellular membrane. The major fatty acids were identified as iso-C-16:0, anteiso-C-17:0, iso-C-17:0, summed feature 9 (iso-C-17:1 omega 9c and/or C-16:0 10-methyl) and iso-C-15 :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 70.9mol%. The orthologous average nucleotide identiy values between N. terrae CGMCC 1.7056(T), N. currus IB-3(T) and strain R-N-C8(T) were 77.1 and 75.1%, respectively. DNA-DNA hybridization values between N. terrae CGMCC 1.7056(T), N. currus IB-3(T) and strain R-N-C8(T) were 20.7 and 19.9% respectively. Data from phenotypic and genotypic analyses supported that strain R-N-C8T represents a new species of Nocardioides, for which the name Nocardioides nematodiphilus sp. nov. is proposed. The type strain is R-N-C8(T) (=CGMCC 1.18723(T)= KCTC 49528(T)).