[Action of erythromycin on its own producer in cultivation on broth media]

The effect of erythromycin on the growth, morphogenesis and antibiotic production capacity of the organism producing it or Str. erythreus was studied. Erythromycin was added to the medium in concentrations comparable to the productivity of the organism. It was shown that at the cell level Str. erythreus was highly resistant to its own antibiotic. Still, erythromycin had a significant effect on the developmental cycle of the culture. It inhibited the growth of the mycelium capable of the antibiotic production and induced an increase in reproduction. On long-term subculturing or in the presence of erythromycin the culture showed a pronounced tendency for fragmentation similar to that in proactinomycetes, whereas under the usual conditions the mycelial growth was not disturbed. However, the structure of the septa in Str. erythreus is typical of the streptomycetes. It is concluded that Str. erythreus occupies an intermediate position between Nocardia and Streptomyces.