Nocardioides euryhalodurans sp. nov., Nocardioides seonyuensis sp. nov. and Nocardioides eburneiflavus sp. nov., isolated from soil

Abstract

Three aerobic, rod-shaped actinobacterial strains, designated MMS17-SY117^T, MMS17-SY207-3^T and MMS17-SY213^T, were isolated from soil and their taxonomic positions were analysed using a polyphasic approach. The isolates showed best growth at 30 °C, pH 7 and 0-1 % (w/v) NaCl. On the basis of 16S rRNA gene sequence similarity, the isolates were affiliated to the genus <i>Nocardioides</i>, and the closest species to MMS17-SY117^T, MMS17-SY207-3^T and MMS17-SY213^T were <i>Nocardioides aestuarii</i> JC2056^T (97.76%), <i>Nocardioides currus</i> IB-3^T (97.41%) and <i>Nocardioides exalbidus</i> RC825^T (98.71%), respectively. Each isolate formed a distinct cluster within the <i>Nocardioides</i> clade in the phylogenetic tree. The orthologous average nucleotide identity and digital DNA-DNA hybridization values were in the range of 74.4-85.7 % and 16.6-39.2 %, respectively, with the type strains of related species. The major polar lipids in all three strains were phosphatidylinositol, phosphatidylglycerol and diphosphatidylglycerol. The predominant fatty acids were iso-C_{16 : 0} and C_{17 : 1} ω8<i>c</i>. MK-8(H₄) was the major isoprenoid quinone and ll-DAP was the major diamino acid. Galactose, glucose and rhamnose were present in the whole-cell hydrolysate, and MMS17-SY213^T also contained mannose and ribose. The DNA G+C contents of MMS17-SY117^T, MMS17-SY207-3^T and MMS17-SY213^T were 72.2, 70.4 and 71.5 mol%, respectively. The phylogenetic, phenotypic and chemotaxonomic data supported the classification of each strain as representing a new species of <i>Nocardioides</i>, for which the names <i>Nocardioides euryhalodurans</i> sp. nov. (MMS17-SY117^T=KCTC 49175^T=JCM 32831^T), <i>Nocardioides seonyuensis</i> sp. nov. (MMS17-SY207-3^T=KCTC 49176^T=JCM 32832^T) and <i>Nocardioides eburneiflavus</i> sp. nov. (MMS17-SY213^T=KCTC 49177^T=JCM 32833^T) are proposed accordingly.