Biotransformation of antibiotics. I. Acylation of chloramphenicol by spores of Streptomyces griseus isolated from the egyptian soil.

Abstract

Incubation of spores, washed mycelium or whole cultures of a Streptomyces sp. with chloramphenicol resulted in the loss of in vitro bioactivity of the antibiotic. Gas chromatographic estimation of an appropriate extract revealed that > 95% of the antibiotic was inactivated under the specified conditions. The spores inactivated chloramphenicol in an inorganic buffer solution or in distilled water without the addition of carbohydrate or external co-facter. Addition of certain C sources to the spores showed a pronounced effect on the chloramphenicol transformation process and on the relative concentration of the inactivated products. Time-course studies on the spore-catalyzed chloramphenicol transformation activity showed a maximum activity at 12 h incubation. Addition of glucose or acetate at this point maintained maximum activity. The transformation products were identified as: chloramphenicol-1-acetate; chloramphenicol-3-acetate; chloramphenicol-3-propionate; chloramphenicol-3-isobutyrate; chloramphenicol-3-butyrate; and chloramphenicol-3-isovalerate, by techniques of TLC, CPC, gas chromatography, UV, IR, mass spectometry and NMR. The microbial characteristics of the isolated strain include the formation of flexuous gray aerial mycelium with smooth to rough spores, irregular in size. It is an H2S and melanin former, non-chromogenic and was inhibited by a streptomycin-producing strain of S. griseus. The organism was identified as a strain of subspecies of S. griseus (Krainsky 1914) Waksman and Henrici (1948).