[Activation of the alarm response of Escherichia by antibiotics]

The data on the effect of antibiotics suppressing the synthesis of protein on the activation of the SOS-system are presented. The action of tetracycline, chloramphenicol rifampicin and nalidixic acid, a well-known activator of SOS-response, has been studied. The short-term action of inhibitory concentrations and the prolonged action of subinhibitory concentrations of these preparations on the activity of genes rec A and sul A and the induction of the synthesis of phage lambda have been considered. Chloramphenicol and tetracycline, as well as nalidixic acid, have been shown to be capable of activating genes rec A, sul A and synthesis of the phage. The induction of SOS-response has been found to be more pronounced in the short-term action of inhibitory concentrations of antibiotics on bacteria than in the prolonged subinhibitory concentrations.