Microbispora clausenae sp. nov., an endophytic actinobacterium isolated from the surface-sterilized stem of a Thai medicinal plant, Clausena excavala Burm. f.

An endophytic actinobacterium, strain CLES2 T , was discovered from the surface-sterilized stem of a Thai medicinal plant, Clausena excavala Burm. f., collected from the Phujong-Nayoa National Park, Ubon Ratchathani Province, Thailand. The results of a polyphasic taxonomic study identified this strain as a member of the genus Microbispora and a Gram-stain-positive, aerobic actinobacterium. It had well-developed substrate mycelia, which were non-motile and possessed paired spores. A phylogenetic evaluation based on 16S rRNA gene sequence analysis placed this strain in the family Streptosporangiaceae , being most closely related to Microbispora bryophytorum NEAU-TX2-2 T (99.4 %), Microbispora camponoti 2C-HV3 T (99.2 %), Microbispora catharanthi CR1-09 T (99.2 %) and Microbispora amethystogenes JCM 3021 T and Microbispora fusca NEAU-HEGS1-5 T (both at 99.1 %). The major cellular fatty acid of this strain was iso-C 16 : 0 and major menaquinone was MK-9(H 4 ). The polar lipid profile of strain CLES2 T contained diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylinositol and phosphatidylinositol dimannosides. These chemotaxonomic data confirmed the affiliation of strain CLES2 T to the genus Microbispora . The DNA G+C content of this strain was 70 mol%. Digital DNA-DNA hybridization and average nucleotide identity blast values between strain CLES2 T and M. catharanthi CR1-09 T were 62.4 and 94.0 %, respectively. The results of the polyphasic study allowed the genotypic and phenotypic differentiation of strain CLES2 T from its closest species with valid names. The name proposed for the new species is Microbispora clausenae sp. nov. The type strain is CLES2 T (=DSM 101759 T =NRRL B-65340 T ).