Abstract
The umu-test is based on measuring the activity of j9-galactosidase induced as a SOS-response against DNAdamaging agents (≅carcinogens and mutagens) in Salmonella typhimurium TA1535/pSK1002. The test system is very useful for detecting and monitoring the carcinogens and the mutagens in air, because it is simple, rapid and inexpensive. However, the conventional umu-test has some problems on measuring the colored sample, such as airborne particulate extract, and on the sensitivity. The present authors have developed an improved method as follows:
1) For the improvement of accuracy, test mixture without enzymatic reaction was used as a reference solution for the measurement of UV-absorbance in β-galactosidase activity assay. 2) Reincubation of the diluted overnight culture, which was carried out with conventional method, was omitted. 3) Bacterial solution of lower concentration showed higher sensitivity than that of the conventional method. Furthermore, 6 polynuclear aromatic hydrocarbons and 10 nitro compounds, some of which were found in air, were assayed in this improved method, and the results were compared to the results of the Ames test. Significantcorrelation was obtained from their results between both method.
