Effect of chloramphenicol on the survival of Escherichia coli irradiated with ultraviolet light.

Chloramphenicol is known to inhibit protein synthesis in different microorganisms without affecting the syntheses of nucleic acids (Gale and Folkes, 1953; Wisseman et al., 1954; Aronson and Spiegelman, 1958). Harold and Ziporin (1958) and Drakulic and Errera (1959) reported that the treatment of Escherichia coli with chloramphenicol immediately after ultraviolet irradiation prevented the resumption of deoxyribonucleic acid (DNA) synthesis. Doudney and Haas (1958) showed that a considerable recovery of colony forming ability in ultraviolet irradiated E. coli strain B occurred after irradiation in the absence of nitrogen source or in the presence of chloramphenicol. A similar observation was reported by Gillies and Alper (1959). Contrary to such observations, a different response to the same antibiotic was encountered when one employed several other strains of E. coli; the ultraviolet irradiated bacteria may die when they are held in media containing chloramphenicol. The nature and the mechanism of this phenomenon is the subject of this paper.