Sequence-Based Differentiation of Strains in the Streptomyces cyaneus Species-Group

In an extensive numerical phenetic survey, a numberof blue, red and gray spored streptomycete strainswere grouped together as Streptomyces cyaneusspecies-group, a taxon which encompasses strainsknown to produce antitumor antibiotics, notably anthracyclines.In the present investigation these and relatedstreptomycetes were the subject of morphological and16S rRNA sequencing studies designed to clarify theirtaxonomic relationships. It is evident from these resultsthat the Streptomyces cyaneus species-group encompassesmisclassified strains and members of severaldistinct species. However, some of the red-sporedstrains (e.g. Streptomyces janthinus ISP 5206T,Streptomyces roseoviolaceus ISP 5277T andStreptomyces violatus ISP 5209T) formed a distinctclade. In contrast, most of the blue and gray-sporedstrains showed much less sequence homologybetween and with one another and were scatteredthroughout the 16S rRNA Streptomyces tree. Theimproved classification of this group of streptomycetesprovides an essential basis for establishing their industrialand economical significance.