Streptosporangium subfuscum sp. nov., isolated from the rhizosphere of marigold (Tagetes erecta L.)

A Gram-stain positive, filamentous bacterial strain, designated strain NEAU-TWSJ13^T, was isolated from the rhizosphere of a marigold (Tagetes erecta L.) plant collected in Heilongjiang Province, northeast China, and characterized using a polyphasic approach. The strain was observed to form abundant aerial hyphae differentiated into spherical sporangia. 16S rRNA gene sequence similarity studies showed that strain NEAU-TWSJ13^T belongs to the genus Streptosporangium, being most closely related to Streptosporangium fragile DSM 43847^T (98.6 %). Phylogenetic analysis of the 16S rRNA gene sequence indicated that it formed a phyletic line with S. fragile DSM 43847^T, Streptosporangium jomthongense NBRC 110047^T (98.4 % 16S rRNA gene similarity) and Streptosporangium violaceochromogenes DSM 43849^T (97.6 % 16S rRNA gene similarity). A combination of DNA–DNA hybridization results and some phenotypic characteristics indicated that strain NEAU-TWSJ13^T can be distinguished from S. fragile DSM 43847^T and S. jomthongense NBRC 110047^T. Moreover, strain NEAU-TWSJ13^T can also be differentiated from S. violaceochromogenes DSM 43849^T and other Streptosporangium species showing high 16S rRNA gene sequence similarity (>98.0 %) by morphological and physiological characteristics. Therefore, it is proposed that strain NEAU-TWSJ13^T represents a novel species of the genus Streptosporangium, for which the name Streptosporangium subfuscum sp. nov. is proposed. The type strain is NEAU-TWSJ13^T ( = CGMCC 4.7146^T = DSM = 46724^T).