Effects of addition of chloramphenicol on the growth and ultrastructure of Streptomyces venezuelae.

The effects of adding chloramphenicol before inoculation and during exponential growth of Streptomyces venezuelae (3022a) in fermentors were studied. The responses of the organism during synthesis of chloramphenicol (in a glycerol-serine-lactate medium) were compared with those in media supporting less (glycerol-nutrient broth-yeast extract) or no synthesis (glucosemineral salts). In systems where little or no synthesis of the chloramphenicol occurred, addition of the antibiotic induced micromorphological and ultrastructural abnormalities similar to those reported for sensitive bacteria. There was also an increase in the frequency of mesosomes and electron-light areas. It was suggested that the former may be associated with activity of chloramphenicol hydrolase and the latter with storage and/or excretion of the breakdown product; N-acetyl p-nitro-phenylserinol. When chloramphenicol synthesis occurred, addition of the antibiotic had less effect on the micromorphology or ultrastructure of S. venezuelae as permeability barriers to external chloramphenicol had been established. Electron-light areas were frequent, possibly being associated with storage and excretion of precursors of chloramphenicol.