An Improved Bacterial Test System for the Detection and Classification of Mutagens and Carcinogens

TLDR

The lipopolysaccharide coating of Salmonella typhimurium normally blocks mutagen penetration into the cell membrane. The authors present improved Salmonella tester strains and adjunct assays for highly sensitive and convenient detection of mutagens. The improved tester strains carry an rfa mutation producing a deficient lipopolysaccharide, and the authors also employ deep rough strains with or without DNA excision repair to compare mutagenic killing and forward mutagenesis. The four Salmonella strains effectively detect diverse mutagens and carcinogens, the presented assays are highly sensitive and convenient, and the specificity of frameshift mutagenesis is clarified.

Abstract

We previously described a set of four strains of Salmonella typhimurium designed for detecting the various types of mutagens, and showed their utility in detecting a wide variety of carcinogens as mutagens. The lipopolysaccharide that normally coats these bacteria is a barrier to penetration of mutagens to the cell membrane. The set of tester strains has been improved by adding a mutation ( rfa: deep rough) that results in a deficient lipopolysaccharide. The techniques for using these strains for detecting mutagens are presented and the tests are shown to be extremely sensitive and convenient. The specificity of frameshift mutagenesis is clarified. As adjuncts to the test with the four strains, we describe a test that compares mutagenic killing in deep rough strains with and without DNA excision repair, and a test using forward mutagenesis in a deep rough strain lacking excision repair.