Modified suspension Ames test for testing proteinaceous substances: An initial step

• Published in: Food and chemical toxicology Vol. 32; no. 12; pp. 1161 - 1166
• Main Authors: Verhagen, H., Bruijntjes-Rozier, G.C.D.M., Coenen, T.M.M., Oosterom, J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.12.1994; New York, NY Elsevier Science
• Subjects: assays; Biological and medical sciences; Chemical mutagenesis; culture media; False Positive Reactions; Medical sciences; Microsomes - drug effects; Mutagenicity Tests - methods; proteins; Proteins - toxicity; Salmonella; Salmonella typhimurium - drug effects; Suspensions; testing; toxicity; Toxicology; DMSO; 2AA; Proteins; Process modification; False positive; Investigation method; Ames test; Mutagenicity testing
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/0278-6915(94)90132-5

The basic Salmonella microsome assay (Ames test) is a valuable primary tool by which to discriminate mutagens from non-mutagens. For a variety of chemical test substances this test is easily conducted according to international guidelines for genotoxicity testing. However, the testing of proteinaceous substances in the basic Ames test may generate false positives owing to the presence of growth-promoting constituents in the test sample, such as histidine or its precursors. It was hypothesized that the growth-promoting capacities of biological test samples might be overcome by testing according to the ‘suspension variant’ of the Ames test, which uses very rich growth conditions thereby overwhelming any growth-enhancing constituents present in a biological test sample. This hypothesis appeared to be correct, although several important modifications had to be made to the suspension assay. The most important aspect of this ‘new suspension Ames test’ appeared to be the plating of overnight regrown bacteria in the poorest way possible (by omitting histidine and nutrient broth from the overlay agar). This study may comprise an initial step in the development of a modified suspension Ames test for testing proteinaceous substances.