Ames Test - This method is used to detect the mutagenic effect of various commercial and pharmaceutical products. Bruce Ames and his associates have developed this sensitive technique, which is rapid and inexpensive and is called as Ames test. Ames procedure involves the use of specially constructed strains of Salmonella typhimurium, which requires histidine amino acid.

Ames test relies on conversion of auxotrophic mutants (his-mutants) back to wild type or prototrophs. The reversion of these auxotrophic mutants to prototrophs either spontaneously or induced by various agents can easily be monitored by placing a known number of mutant cells in a petri plate containing medium supplemented with a trace of growth factor required by the auxotroph (enough to support a few cell divisions but not enough to allow the formation of visible colonies).