Mechanisms of bacterial mutagenesis and properties of mutagenesis tester strains.

Bacterial tester strains are available which can detect base pair substitution, frameshift and deletion mutations. I consider possible mechanisms for these types of event. I describe the four main types of DNA repair process operating in Escherichia coli and Salmonella typhimurium and how they may influence mutation: Means of modifying repair processes to increase the sensitivity of tester strains are discussed. The properties of some current strains are briefly described. I comment adversely on forward mutation systems and discuss aspects of the strategy and methodology of mutagenicity testing with bacteria.