Forsten Eva, Finger Maurice, Scholand Theresa, Deitert Alexander, Kauffmann Kira, Büchs Jochen
AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
AVT - Biochemical Engineering, RWTH Aachen University, Aachen, Germany.
Sci Total Environ. 2023 Dec 20;905:167035. doi: 10.1016/j.scitotenv.2023.167035. Epub 2023 Sep 12.
The Ames test is one of the most applied tools in mutagenicity testing of chemicals ever since its introduction by Ames et al. in the 1970s. Its principle is based on histidine auxotrophic bacteria that regain prototrophy through reverse mutations. In the presence of a mutagen, more reverse mutations occur that become visible as increased bacterial growth on medium without histidine. Many miniaturized formats of the Ames test have emerged to enable the testing of environmental water samples, increase experimental throughput, and lower the required amounts of test substances. However, most of these formats still rely on endpoint determinations. In contrast, the recently introduced Ames RAMOS test determines mutagenicity through online monitoring of the oxygen transfer rate. In this study, the oxygen transfer rate of Salmonella typhimurium TA100 during the Ames plate incorporation test was monitored and compared to the Ames RAMOS test to prove its validity further. Furthermore, the Ames RAMOS test in 96-well scale is newly introduced. For both the Ames plate incorporation and the Ames RAMOS test, the influence of the inoculum cell count on the negative control was highlighted: A lower inoculum cell count led to a higher coefficient of variation. However, a lower inoculum cell count also led to a higher separation efficiency in the Ames RAMOS test and, thus, to better detection of a mutagenic substance at lower concentrations.
自20世纪70年代艾姆斯等人引入以来，艾姆斯试验一直是化学物质致突变性测试中应用最广泛的工具之一。其原理基于组氨酸营养缺陷型细菌，这些细菌通过回复突变恢复原养型。在诱变剂存在的情况下，会发生更多的回复突变，这表现为在不含组氨酸的培养基上细菌生长增加，从而变得可见。艾姆斯试验出现了许多小型化形式，以能够测试环境水样、提高实验通量并降低所需的测试物质用量。然而，这些形式中的大多数仍然依赖终点测定。相比之下，最近引入的艾姆斯RAMOS试验通过在线监测氧传递速率来确定致突变性。在本研究中，监测了鼠伤寒沙门氏菌TA100在艾姆斯平板掺入试验期间的氧传递速率，并与艾姆斯RAMOS试验进行比较，以进一步证明其有效性。此外，新引入了96孔规模的艾姆斯RAMOS试验。对于艾姆斯平板掺入试验和艾姆斯RAMOS试验，均强调了接种细胞计数对阴性对照的影响：较低的接种细胞计数导致较高的变异系数。然而，较低的接种细胞计数在艾姆斯RAMOS试验中也导致较高的分离效率，因此能够在较低浓度下更好地检测诱变物质。
