title: Is the colour of the mature aerial mycelium (spore mass) of streptomycetes a diagnostic key-character of decisive taxonomic importance?
abstract: A white sporulated stable mutant strain (strain No. 66/m) of a Streptomyces sp. belonging to the nigrescens group of the typical grey Streptomyces spp. has been isolated. On the basis of ISP *International Streptomyces Project) criteria strain No. 66/m would be considered a true member of the albus-group of Streptomyces (regarded by some workers as a well separated assemblage of species) all the more so because it fits into this alien group at least in such a degree as into that from which it has originated. Caution is necessary in using the aerial mycelium colour as a distinguishing diagnostic property for establishing large intraspecific groups, series, or even in separating species of Streptomyces.
mesh_terms: D009154:Mutation; D010858:Pigmentation; D013171:Spores, Bacterial; D013302:Streptomyces / Q000145:classification* / Q000235:genetics / Q000502:physiology; D014871:Water Microbiology