Genome-based reclassification of Streptosporangium sandarakinum Kämpfer et al. 2013 as a later heterotypic synonym of Streptosporangium nondiastaticum Nonomura and Ohara 1969 (Approved Lists 1980)

A comparison of 16S rRNA gene sequences between Streptosporangium sandarakinum GW-12028 T and Streptosporangium nondiastaticum IFO 13990 T revealed a sequence similarity of 98.8%. The genus Streptosporangium includes 33 species with validly published names. The type strains S. sandarakinum GW-12028 T (=DSM 45763 T =LMG 27062 T ) and S. nondiastaticum IFO 13990 T (=ATCC 27101 T =DSM 43848 T =JCM 3114 T =KCTC 9434 T =NBRC 13990 T =VKM Ac-1299 T ) were both isolated from soil. Whole-genome data were used to clarify the taxonomic assignment of these two closely related Streptosporangium species. Overall genomic relatedness index analyses indicated that S. sandarakinum GW-12028 T and S. nondiastaticum IFO 13990 T shared average nucleotide identity and digital DNA–DNA hybridization values >95% and >70%, respectively, exceeding the thresholds for bacterial species delineation. Additionally, S. sandarakinum GW-12028 T and S. nondiastaticum IFO 13990 T displayed near-identical phenotypic and chemotaxonomic profiles. Based on the 16S rRNA gene phylogenetic tree and the core-genome phylogenomic trees, S. sandarakinum GW-12028 T and S. nondiastaticum IFO 13990 T phylogenetically form a separate, tight cluster apart from other Streptosporangium species. Based on this combined evidence, S. sandarakinum Kämpfer et al . 2013 is proposed as a later heterotypic synonym of S. nondiastaticum Nonomura and Ohara 1969.