Stress response of yeast candida intermedia to Cr(VI)

Stress response of yeast Candida intermedia ZIM 156 exposed to chromium(VI) was investigated. Yeast cells were treated with Cr(VI) in concentrations of 50, 100, 300 and 500 microM in the mid-exponential growth phase. Monitoring of some bioprocess parameters during growth, specifically pO(2), showed that Cr(VI) addition, specifically in concentration of 100 and partially 50 micromol/L, increased metabolism intensity, which is connected to induced stress responses. Furthermore, oxidation of 2',7'-dichlorofluorescin indicated increased intracellular oxidant level, specifically at 100 microM Cr(VI) concentration. Antioxidant defense systems were further investigated. Catalase and superoxide dismutase activity was not increased in the cells exposed to the both Cr(VI) concentrations, which indicate that catalase and superoxide dismutase do not participate in cell defense systems. In contrast intracellular glutathione content in reduced form increased significantly in the cells exposed to 100 micromol Cr(VI)/L. Therefore, we demonstrated that glutathione plays an important role in the stress response of C. intermedia to Cr(VI).