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

A novel endophytic actinobacterium strain, A217T, was isolated from the bulbil of Dioscorea bulbifera L. Its taxonomic position was characterized using a polyphasic study. Morphological and chemotaxonomic characteristics of strain A217T 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(H6) and MK-9(H8) as predominant menaquinones. The patterns of major fatty acids are C16:0, anteiso-C15:0, C15:0, iso-C14:0, C16:1 ω7c, anteiso-C17:0, and iso-C17:1 ω5c. 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 4453T (99.0%), S. glomeroaurantiacus JCM 4677T (99.0%), and S. tauricus JCM 4837T (98.8%). The DNA-DNA hybridization values between the strain A217T and three reference strains ranged from 34.6% to 51.7%. On the basis of phenotypic and genotypic differentiation from all tested strains, isolate A217T is proposed to represent a novel species of the genus Streptomyces, named Streptomyces dioscori sp. nov. The type strain is A217T (= CGMCC 4.7415T = JCM 32173T).