Nocardiopsis sinuspersici sp. nov., isolated from sandy rhizospheric soil

Abstract

A polyphasic taxonomic study of a halotolerant bacterium, isolated from sandy rhizospheric soil in Sarbandar, Persian Gulf, Iran, revealed that strain HM6(T) represents a novel species within the genus Nocardiopsis. Results of the 16S rRNA gene sequence comparison revealed that strain HM6(T) clustered with strains of the genus Nocardiopsis, showing the highest degree of 16S rRNA gene sequence similarity to Nocardiopsis quinghaiensis (99.2 %), Nocardiopsis aegyptia (98.5 %) and Nocardiopsis halotolerans (98.3 %). However, DNA-DNA hybridization studies with these type strains revealed less than 39.6 % similarity. Rather than genotypic differences, there are some phenotypic discrepancies between strain HM6(T) and closely related species of the genus Nocardiopsis. Main morphological and chemotaxonomical features of strain HM6(T) include: (i) growth characteristics, i.e. the formation of a scant light-yellow to white aerial mycelium and the typical zig-zag form of the hyphae, which fragment during ageing into smooth rod-shaped spores; (ii) the presence of meso-diaminopimelic acid and glucose plus ribose in whole-cell hydrolysates; (iii) the presence of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and phosphatidylinositol, together with three unknown Nocardiopsis-specific phospholipids (close to diphosphatidylglycerol in position) in polar lipid extracts; (iv) the presence of the major menaquinones MK-10(H₀), MK-10(H₂) and MK-9(H₀) in the non-polar fraction; (v) the presence of iso/anteiso-branched plus 10-methyl-branched fatty acids, showing the diagnostic combination for species of the genus Nocardiopsis of iso-16 : 0 (31.1 %), anteiso-17 : 0 (19.2 %), 10-methyl-17 : 0 (5.8 %) and tuberculostearic acid (8.8 %); and (vi) the absence of mycolic acids. Analysis of the 16S rRNA gene sequence revealed that strain HM6(T) represents a distinct taxon within the genus Nocardiopsis. Based upon genotypic and phenotypic differences from other members of the genus, a novel species, Nocardiopsis sinuspersici sp. nov., is proposed. The type strain is HM6(T) (=UTMC 00102(T) =DSM 45277(T) =CCUG 57624(T)).