Streptosporangium lutulentum sp. nov., Streptosporangium fenghuangense sp. nov. and Streptosporangium corydalis sp. nov., three novel actinobacterial species isolated from National Forest Park of Fenghuang Mountain

Three novel actinobacteria, designated strains NEAU-FSHN1T, NEAU-hd-3T and NEAU-Y6T, were isolated from a stream base, soil adjacent to the stream and a root of Corydalis yanhusuo L, respectively, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic positions of these strains. The three strains were observed to form scant aerial hyphae that differentiated into spherical spore vesicles. The phylogenetic analysis based on the 16S rRNA gene sequences of strains NEAU-FHSN1T, NEAU-hd-3T and NEAU-Y6T showed that the three novel isolates exhibit 99.2 % (NEAU-FHSN1T/NEAU-hd-3T), 99.2 % (NEAU-FHSN1T/NEAU-Y6T) and 99.7 % (NEAU-hd-3T/NEAU-Y6T) 16S rRNA gene sequence similarities with each other and that they are closely related to strains Streptosporangium shengliense NEAU-GH7T (sequence similarities 98.72, 98.85, 98.99 %), Streptosporangium roseum DSM 43021T (98.65, 98.51, 98.58 %) and Streptosporangium album DSM 43023T (98.41, 98.96, 98.89 %). However, the DNA–DNA hybridization values between strains NEAU-FSHN1T, NEAU-hd-3T and NEAU-Y6T were 61.2 % (NEAU-FSHN1T/NEAU-hd-3T), 63.5 % (NEAU-FHSN1T/NEAU-Y6T) and 65.8 % (NEAU-hd-3T/NEAU-Y6T), and the values between the three strains and their close phylogenetic relatives were also below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA–DNA hybridization results, the three strains can be distinguished from each other and their close phylogenetic relatives. Thus, strains NEAU-FHSN1T, NEAU-hd-3T and NEAU-Y6T are concluded to represent three novel species of the genus Streptosporangium, for which the names Streptosporangium lutulentum sp. nov., Streptosporangium fenghuangense sp. nov. and Streptosporangium corydalis sp. nov. are proposed. The type strains are NEAU-FHSN1T (=CGMCC 4.7141T = DSM 46740T), NEAU-Y6T (=CGMCC 4.7150T = DSM 46722T) and NEAU-hd3T (CGMCC 4.7212T = JCM 30058T), respectively.