Pseudonocardia rhizophila sp. nov., a novel actinomycete isolated from a rhizosphere soil.

During the course of our research on new actinobacterial sources, a novel actinomycete strain YIM 67013(T) was isolated from rhizosphere soil of Tripterygium wilfordii Hook. f. collected from Yunnan province, south-west China. The strain formed well-differentiated aerial and substrate mycelia, grew in the presence of up to 15% NaCl (optimum, 0-3% NaCl). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YIM 67013(T) belongs to the genus Pseudonocardia, with highest similarity to Pseudonocardia thermophila DSM 43832(T) (97.6%). Sequence similarities between strain YIM 67013(T) and the other Pseudonocardia species ranged from 96.6 to 93.2%. Key morphological and physiological characteristics as well as chemotaxonomic features of strain YIM 67013(T) were congruent with the description of the genus Pseudonocardia. The G+C content of the genomic DNA was 69.7 mol%. Based on comparative analysis of physiological, biochemical and chemotaxonomic data, including low DNA-DNA hybridization results, it is proposed that strain YIM 67013(T) represents a novel species of the genus Pseudonocardia, named Pseudonocardia rhizophila sp. nov. The type strain is YIM 67013(T) (= CCTCC AA 209043(T) = DSM 45381(T)).