The Ames Salmonella/microsome mutagenicity assay

The Ames Salmonella/microsome mutagenicity assay (Salmonella test; Ames tes t) is a short-term bacterial reverse mutation assay specifically designed t o detect a wide range of chemical substances that can produce genetic damag e that leads to gene mutations. The test employs several histidine dependen t Salmonella strains each carrying different mutations in various genes in the histidine operon. These mutations act as hot spots for mutagens that ca use DNA damage via different mechanisms. When the Salmonella tester strains are grown on a minimal media agar plate containing a trace of histidine, o nly those bacteria that revert to histidine independence (his(+)) are able to form colonies. The number of spontaneously induced revertant colonies pe r plate is relatively constant. However, when a mutagen is added to the pla te, the number of revertant colonies per plate is increased, usually in a d ose-related manner. The Ames test is used world-wide as an initial screen to determine the muta genic potential of new chemicals and drugs. The test is also used for submi ssion of data to regulatory agencies for registration or acceptance of many chemicals, including drugs and biocides. International guidelines have bee n developed for use by corporations and testing laboratories to ensure unif ormity of testing procedures. This review provides historical aspects of how the Ames was developed and d etailed procedures for performing the test, including the design and interp retation of results. (C) 2000 Elsevier Science B.V. All rights reserved.