INDUCTION OF A MUTANT PROPHAGE-LAMBDA IN ESCHERICHIA-COLI - RAPID SCREENING-TEST FOR CARCINOGENS

The induction of prophage λ and its mutant, λcIts857, by a number of water-soluble substances, carcinogens and noncarcinogens, has been investigated with the object of developing a suitable screening test for carcinogens and of assessing the sensitivity of repressors to inducing agents. By the use of measurements of endolysin activity in place of plaque assays, induction may be estimated more simply and quickly. While prophage λ is inducible only by certain carcinogens, λcIts857 is inducible, without exceptions, by all the carcinogens tested. Some carcinogens require prior metabolic activation to be effective. Most noncarcinogens are noninducing toward both strains. The prophage λcIts857 induction test appears to be a simple, quick, and sensitive method for the screening of carcinogens. It can detect carcinogens that do not induce the wild-type prophage λ, and, in some cases, is even more sensitive than the Ames Salmonella/microsome test. © 1979.