The simultest approach for testing mutagens in the Salmonella Microtitre fluctuation assay

Abstract

The concept of combining several histidine-dependent Salmonella strains in a single test, the SIMULTEST, has been applied to the microtitre fluctuation test. The activity of five mutagens was determined in strains TA97, TA98, TA100, and TA102 individually as well as in a SIMULTEST mixture. All five compounds were mutagenic in the SIMULTEST, demonstrating the utility of this time and labour-saving approach of combining strains for testing with this method. The microtitre fluctuation SIMULTEST results were quantitatively comparable to those of the SIMULTEST Salmonella/microsome plate test. The microtitre fluctuation test compared with the plate incorporation assay generally showed more favourable "sensitivity" and "quantity" indices in that four of the five chemicals tested in the fluctuation test were mutagenic at lower doses than in the plate test.

The micro‐Ames test: A direct comparison of the performance and sensitivities of the standard and 24‐well plate versions of the bacterial mutation test

“…This may explain why the test is usually performed in only two strains, i.e., TA98 and either TA100 or “TAMix”, which is a mixture of specific base‐pair mutation sensitive Salmonella strains [Kamber et al, ]. Pooling several strains has also been suggested as a screening strategy for both plate incorporation and fluctuation test systems [Nestmann et al, , McPherson and Nestmann , Gee et al, ] although there are doubts about the use of mixed strains including lack of knowledge of the final proportions of the bacterial strains, their potential interaction, and their sensitivities compared to the individual strains. Several screens employ the standard strains and the same principles as the pour plate methods described in OECD guideline 471 but in a multi‐well format. In this case, all the components of the test are the same but are utilized in proportionately smaller amounts.…”