EVIDENCE FOR THE PHYLOGENETIC HETEROGENEITY OF THE GENUS STREPTOSPORANGIUM

Comparative 16S rDNA/RNA-analyses of five of the fifteen described spe cies of the actinomycete genus Streptosporangium indicate the phylogen etic heterogeneity of the genus. The type species Streptosporangium ro seum, Streptosporangium nondiastaticum and Streptosporangium pseudovul gare form a highly related cluster, while Streptosporangium corrugatum is more distantly related. Within the radiation of actinomycete gener a these four organisms branch as a sistergroup to the genus Streptomyc es. Streptosporangium viridogriseum subsp. viridogriseum was phylogene tically placed within the radiation of the family Pseudonocardiaceae w ere it branched adjacent to Saccharothrix australiensis. The results c onfirm previous findings on the heterogeneity of the genus which were based on scanning electon microscopy (Nonomura, 1989) and the electrop horetic mobility of a ribosomal protein (Ochi and Miyadoh, 1992).