A new sensitive test based on yeast cells for studying environmental pollution

Different tests based on yeast cells were developed for determination of mutagenic/carcinogenic action; however, they all showed lower sensitivity compared to bacterial tests, the main reason for this being the limited permeability of yeast cells. We found that general permeability of Saccharomyces cerevisiae cells can be increased by mutation and on this basis we developed a more sensitive test. The aim of this study was to prove the applicability of our test, called D7ts1, in environmental studies. Soil, water and air samples were taken during 1998 from regions in Bulgaria with declared low, average or high pollution levels and investigated for presence of mutagenic/carcinogenic activities in the bacterial test of Ames, the yeast D7 test of Zimmermann and our new D7ts1 test. Results obtained evidenced the following conclusions: (1) the usage of D7ts1 test instead of D7 test permits a clearer measurement of positive samples and detects mutagenic/carcinogenic activities undetectable by D7 test; (2) all samples with positive Ames test were positive in the D7ts1 test; however, some samples, clearly positive in the D7ts1, were negative in the Ames test; therefore, the simultaneous usage of D7ts1 and Ames tests in environmental studies is advantageous because it detects dangers for the human health activities to which bacterial cells do not respond; and (3) regions in Bulgaria declared clean were found to be polluted; particularly troubled are the whole-year positive data in the three tests for air samples from a 'clean' region.