Streptomyces dioscori sp nov., a Novel Endophytic Actinobacterium Isolated from Bulbil of Dioscorea bulbifera L.

A novel endophytic actinobacterium strain, A217(T), was isolated from the bulbil of Dioscorea bulbifera L. Its taxonomic position was characterized using a polyphasic study. Morphological and chemotaxonomic characteristics of strain A217(T) were consistent with those of members of the genus Streptomyces: long straight to flexuous spore chain; cellular components contained LL-diaminopimelic acid, ribose, and small traces of glucose in whole-cell hydrolysates; MK-9(H-6) and MK-9(H-8) as predominant menaquinones. The patterns of major fatty acids are C-16:0, anteiso-C-15:0, C-15:0, iso-C-14:0, C (16:1)omega 7c, anteiso-C-17:0, and iso-C-17:1 omega 5c. The polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol mannoside, and glycolipid, as well as two unidentified phospholipids, one unidentified aminolipid, and one unidentified aminophospholipid. The DNA G+C content of draft genome is 70.7 mol%. Analysis of the 16S rRNA gene sequence and phylogenetic trees revealed that the isolate was most closely related to S. aurantiacus JCM 4453(T) (99.0%), S. glomeroaurantiacus JCM 4677(T) (99.0%), and S. tauricus JCM 4837(T) (98.8%). The DNA-DNA hybridization values between the strain A217(T) and three reference strains ranged from 34.6% to 51.7%. On the basis of phenotypic and genotypic differentiation from all tested strains, isolate A217(T) is proposed to represent a novel species of the genus Streptomyces, named Streptomyces dioscori sp. nov. The type strain is A217(T) (=CGMCC 4.7415(T)=JCM 32173(T)).