Description of a new strain of Streptomonospora nanhaiensis and reclassification of Streptomonospora halotolerans as a later heterotypic synonym of Streptomonospora nanhaiensis

A novel actinomycete, designated strain NEAU-YY374, was isolated from root of wheat and a polyphasic taxonomic study was carried out. 16S rRNA gene sequence analysis indicated that strain NEAU-YY374 was closely related to Streptomonospora halotolerans NEAU-Jh2-17T (99.3 %) and Streptomonospora nanhaiensis 12A09T (98.6%). Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain NEAU-YY374 formed a stable clade with S. halotolerans NEAU-Jh2-17T and S. nanhaiensis 12A09T in trees generated with two algorithms. Key morphological and chemotaxonomic properties also confirmed the affiliation of strain NEAU-YY374 to the genus Streptomonospora . The differences of DNA G+C contents among these three strains were all less than 1 %, and the digital DNA-DNA hybridization and the average nucleotide identity values were higher than the circumscription thresholds of species and subspecies, clearly indicating that the three strains should belong to the same species. Therefore, we concluded that strain NEAU-YY374 is a new strain of S. nanhaiensis . Meanwhile, S. halotolerans should be reclassified as a later heterotypic synonym of S. nanhaiensis according to the priority of publication and validation of the name.