Classification of Streptomyces griseus (Krainsky 1914) Waksman and Henrici 1948 and related species and the transfer of 'Microstreptospora cinerea' to the genus Streptomyces as Streptomyces yanii sp. nov.

A soil actinomycete, strain 80-133(T), with the non-validly published name 'Microstreptospora cinerea', was the subject of a polyphasic study designed to clarify its taxonomic status. Comparative 16S rRNA gene sequence studies indicated that the organism belonged to the genus Streptomyces, a result in line with previous chemotaxonomic and morphological data. The strain belonged to the Streptomyces griseus clade, but could be distinguished from representatives of species assigned to this taxon by using DNA-DNA relatedness and phenotypic data. In light of these findings, it is proposed that the organism should be recognized as a novel species of the genus Streptomyces. The name proposed for this taxon is Streptomyces yanii sp. nov., with isolate 80-133(T) (=AS 4.1146(T)=JCM 3331(T)) as the type strain. It was also shown that representative strains of Streptomyces argenteolus, Streptomyces caviscabies, S. griseus and Streptomyces setonii belong to the same genomic species and have key phenotypic properties in common. It is proposed that S. caviscabies and S. setonii should be considered as later heterotypic synonyms of S. griseus and that S. argenteolus AS 4.1693(T) should also be assigned to this taxon.