ELECTRON MICROSCOPY OF STREPTOMYCES SPORE MORPHOLOGY AND ITS ROLE IN SPECIES DIFFERENTIATION

Abstract
Spore morphology of the streptomycetes was studied by means of electron microscopy to determine the reliability of this feature as a criterion for species differentiation in this genus. Approximately 600 cultures assignable to one or another of some 120 described species or varieties were included in the study. Twenty-five of the species were represented by an average of 14 strains each. Spore of all the streptomycetes studied were found to conform to one of four types[long dash]smooth, warty, spiny or hairy. About one-third of the gray to brownish-spored species had either spiny, warty or hairy spores; the remaining members of this spore color group were smooth-spored. All of the blue to blue-green-spored forms had spiny spores. Those having spore masses in white, or yellow to cream or buff shades had smooth-walled spores. All of the pinkish-cinnamon to pinkish-tan-spored group had smooth spores with the exception of Streptomyces erythraeus, S. purpurascens and two undetermined species which had spiny spores. The size and shape of spores in most species tended to be variable and appeared to be of limited usefulness for taxonomic differentiation. On the other hand, surface configuration of the spores was observed to be a remarkably constant species characteristic and promises to provide a reliable and useful taxonomic aid.