Ames RAMOS test – Development of a more easy, robust and meaningful mutagenicity assay
The Ames test is one of the most important in vitro mutagenicity tests, which finds its application all over the world. It is based on the back mutation of histidine auxotrophic Salmonella typhimurium strains leading to a growth of these mutants on histidine lacking minimal medium. The more mutagenic a substance is the more mutants will arise. At the department of Biochemical Engineering, this test should get optimized and simplified with help of the RAMOS (Respiration Activity Monitoring System) technology, leading to a more robust test system. This is important in terms of animal rights due to a reduction of S9 fraction (gained from rat liver) as well as expansion of the field of application (e.g. continuous testing of samples or establishment of an online testing system, respectively). Furthermore, the RAMOS technology contributes to a more environmentally friendly and cheaper testing of large amounts of samples.
The conventional Ames test works with the incubation of bacteria on agar plates while the further developed Ames fluctuation test works with liquid cultures in micro titer plates. This fluctuation test has four main advantages: It is less work-intensive, causes less waste and costs and there exist more opportunities to implement online measuring techniques.
The RAMOS technology is perfectly suited for a further optimization of the test since it ensures defined, well-mixed culture conditions, which allow a non-oxygen limited cultivation and the precise measurement of the OTR. The OTR allows conclusions about the growth and metabolism of a culture and thus about the amount of the back mutated bacteria.