Differentiation of the Vegetative and Sporogenous Phases: The Partially Acid-fast Proactinomycetes

Abstract

About 300 strains of Proactinomycetes isolated from Rothamsted soils and obtained from other sources were examined. Although only 9% were partially acid-fast on immediate test, subcultivation on rich media such as milk or nutrient glucose broth increased the number to 31%. 92 strains were observed continuously for nearly 2 yrs. on a variety of complex media, and were stained at frequent intervals. No evidence was obtained of any "resting spores" or "chlamydospores" in the vegetative mycelia. Since no true spores were observed in the aerial mycelia, in confirma- tion of previous work, the Proactinomycetes in general may be regarded as asporogenous.