Mutagenicity Testing Services
EBPI Analytics offers a large selection of traditional Ames tests to meet any research requirement. There are multiple options offered for these assays, and clients can choose from different bacterial strains, developed for specific sensitivities to mutation type. We also offer both Salmonella and E. coli test bacteria which allows standardization of our assays to previously established test protocols depending on client requirements. Clients can also choose between three assay methods including a standard plate assay, fluctuation test, and a modified ISO procedure. The assay choices promote flexibility depending on personal preference, budget, application, or experimental design. We also offer optional addition of S9 fraction rat liver extracts to metabolically bioactivate genotoxins, which increases the number of mutagenic compounds detected by the Ames assays.
EBPI Analytics also offers three testing methods for our mutagenicity assays that can be chosen depending on application and budget.
Standard Ames Test Procedure
For the standard Ames test, the bacterial strains are pre-exposed to the test compound for 100 minutes in the presence or absence of the S9 fraction. The reaction mixture is then poured onto an agar plate. The agar plate contains biotin and a minimal amount of histidine. The bacteria are able to undergo a few rounds of cell division before the histidine runs out. After an incubation period of 2-3 days, the colonies are counted and tabulated as the number of revertants per plate. Comparisons are made between growth in the control and exposed plates.
- Uses 2 mL of sample (small sample sizes)
- Quantification is simple (counting)
- Concentration of samples may be required
- Most widely used mutagenic test and used as the industry standard.
Modified ISO Procedure
This procedure uses a modification of the Ames fluctuation assay. Bacterial strains are pre-exposed to differing concentrations of the mutagenic compounds with a growth media in suspension for 100 minutes. Each dilution is run in triplicate. The samples are then transferred, mixed with a reversion solution and plated onto a 96 well plate. The samples are incubated for 2-3 days and the number of revertant colonies (individual wells) are counted by colorimetric analysis.
- Uses small sample size
- Bacterial concentration is checked by optical density (ensures log growth phase)
- Quantification is simple and fluctuation test scoring is quick and easy
- Assay is more sensitive than the plate-incorporation assay
- Utilizes pre-exposure period to enhance bacterial uptake
- More consistent exposure concentration during auxotrophic growth phases
- Concentration may be required and exposure time may be extended to increase the uptake and positive results.
This is the simplest procedure of the three Ames assays and utilizes the fluctuation assay procedure. The test solution is mixed directly with the bacterial strains and the reaction mixture and the entire solution is allowed to incubate for 3 to 5 days at 37 °C. The plates are removed and revertant colonies are counted by colorimetric changes.
- Large sample sizes (17.5 mL, ideal for waste water treatments)
- No pre-exposure period, exposure and uptake occurs over the duration of the test.
- No concentration of the sample is necessary
- Assay is more sensitive than the plate incorporation assays
- Exposure concentration is kept consistent during auxotrophic growth phase