EVIDENCE FOR THE PHYLOGENETIC HETEROGENEITY OF THE GENUS STREPTOSPORANGIUM

Comparative 16S rDNA/RNA-analyses of five of the fifteen described species of the actinomycete genus Streptosporangium indicate the phylogenetic heterogeneity of the genus. The type species Streptosporangium roseum, Streptosporangium nondiastaticum and Streptosporangium pseudovulgare form a highly related cluster, while Streptosporangium corrugatum is more distantly related. Within the radiation of actinomycete genera these four organisms branch as a sistergroup to the genus Streptomyces. Streptosporangium viridogriseum subsp. viridogriseum was phylogenetically placed within the radiation of the family Pseudonocardiaceae were it branched adjacent to Saccharothrix australiensis. The results confirm previous findings on the heterogeneity of the genus which were based on scanning electon microscopy (Nonomura, 1989) and the electrophoretic mobility of a ribosomal protein (Ochi and Miyadoh, 1992).