Unification of the Genera Streptoverticillum and Streptomyces, and Amendation of Streptomyces Waksman and Henrici 1943, 339 AL

Abstract

Summary 40 strains of 37 species of the genera Streptomyces and Streptoverticillium were subjected to phylogenetic analyses. The degree of intra-cluster relationships, determined by DNA-DNA hybridization for phenetic clusters A21 and F61 (as defined by Williams et al., 1983), varies widely, with lower values ranging at a level found for intercluster relationships. Comparison of partial 16S rRNA sequences of 17 strains indicates that all organisms are members of one of the several phylogenetically defined lines of descent of the order Actimomycetales . Organisms do not cluster according to their allocation into different genera but certain members of Streptomyces are more closely related to streptoverticillia than they are to members of their genus. Clusters defined by numerical phenetic analyses also emerge in the rRNA-based phylogenetic study. The high degree of phenetic, chemotaxonomic and phylogenetic similarities between members of Streptomyces and Streptoverticillium justifies unification of the two genera in an amended genus Streptomyces .