Nocardia rhizosphaerae sp. nov., a novel actinomycete isolated from the coastal rhizosphere of Artemisia Linn., China

A novel actinomycete, designated strain KLBMP S0043ᵀ, was isolated from the rhizosphere soil of Artemisia Linn. collected from the coastal region of Lianyungang, Jiangsu Province, in east China and was studied in detail for its taxonomic position. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain KLBMP S0043ᵀ is a member of the genus Nocardia. The 16S rRNA gene sequence similarity indicated that strain KLBMP S0043ᵀ is closely related to Nocardia asteroides NBRC 15531ᵀ (97.61 %) and Nocardia neocaledoniensis SBHR OA6ᵀ (97.38 %); similarity to other type strains of the genus Nocardia was found to be less than 97.2 %. The organism has chemical and morphological features consistent with its classification in the genus Nocardia such as meso-diaminopimelic acid as the diagnostic diamino acid in the cell wall peptidoglycan and arabinose and galactose as the diagnostic sugars. The predominant menaquinone was identified as MK-8(H₄ω-cycl). Mycolic acids were detected. The diagnostic phospholipids were found to be diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannosides. The predominant cellular fatty acids were identified as C₁₆:₀, C₁₈:₀, C₁₈:₁ω9c, 10-methyl C₁₈:₀ [tuberculostearic acid (TBSA)] and summed feature 3 (C₁₆:₁ω7c/C₁₆:₁ω6c). The G+C content of the genomic DNA was determined to be 71.4 mol%. The results of DNA–DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of the strain from its most closely related strains. Based on morphological, chemotaxonomic and phylogenetic data, strain KLBMP S0043ᵀ is considered to represent a novel species of the genus Nocardia, for which the name Nocardia rhizosphaerae sp. nov. is proposed. The type strain is KLBMP S0043ᵀ (=CGMCC 4.7204 ᵀ = KCTC 29678ᵀ).