Streptomyces salinomycinicus sp. nov. and reclassifications of Streptomyces rubiginosus, Streptomyces niveoruber, Streptomyces griseomycini, Streptomyces roseoviolaceus, Streptomyces violaceochromogenes and Streptomyces virens

Salinomycin is a polyether ionophore discovered from a streptomycete strain designated 80614 (=DSM 41398=NBRC 107858), and the producer has been published as Streptomyces albus . In this study, the taxonomic position was investigated using a polyphasic approach. The 16S rRNA gene sequence of S. albus 80614 showed similarities of 99.8 and 98.8% to those of ‘ Streptomyces physcomitrii ’ LD120 ^T and Streptomyces levis NBRC 15423 ^T , respectively, as the closest, but the similarity to S. albus NBRC 13014 ^T was only 96.1%. S. albus 80614 was not close to S. albus NBRC 13014 ^T and rather formed a clade with ‘ S. physcomitrii ’ LD120 ^T in the phylogenetic tree based on 16S rRNA gene sequences. The digital DNA–DNA hybridization (dDDH) values were 67.8, 23.3 and 21.6% to ‘ S. physcomitrii ’ LD120 ^T , S. levis JCM 6924 ^T and S. albus NBRC 13014 ^T , respectively. The average nucleotide identity based on MUMmer (ANIm) was 96.5% between S. albus 80614 and ‘ S. physcomitrii ’ LD120 ^T . These dDDH and ANIm values were below the thresholds, 70 and 96.7% for bacterial and streptomycetal species delineation, respectively. The strain was differentiated from these three referenced species in major phenotypic characteristics such as spore morphology, NaCl tolerance and carbon source utilization. Therefore, Streptomyces salinomycinicus sp. nov. was proposed for the strain. This new species included S. albus ZD11, S. albus BK3-25, Streptomyces sp. SCSIO ZS0520, ‘ S. physcomitrii ’ NPDC020937 and ‘ S. physcomitrii ’ NPDC020938. Additionally, Streptomyces rubiginosus is reclassified as a later heterotypic synonym of Streptomyces pseudogriseolus ; Streptomyces niveoruber as a later heterotypic synonym of Streptomyces griseoviridis ; Streptomyces griseomycini as a later heterotypic synonym of Streptomyces griseostramineus ; Streptomyces roseoviolaceus as a later heterotypic synonym of Streptomyces violaceus ; Streptomyces violaceochromogenes as a later heterotypic synonym of Streptomyces collinus ; and Streptomyces virens as a later heterotypic synonym of Streptomyces calvus .