Abstract: The aim of this paper was to examine the effects of selenium on the antioxidant activity of Saccharomyces cerevisiae under cadmium stress. The levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and the activities of important antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and peroxidase (POD) in S. cerevisiae cells were determined. The results obtained showed that cadmium treatment could significantly increase the contents of ROS and MDA in S. cerevisiae (P < 0.01), consequently generating oxidative stress. When a certain amount of exogenous selenium was added to the culture system, the activities of SOD, POD, CAT and GSH-Px were significantly increased (P < 0.01). The content of antioxidant GSH was also increased, enhancing the ability to scavenge ROS and MDA. These results indicated that the addition of exogenous selenium could also antagonize cadmium effects in S. cerevisiae, and this effect was also observed in plants and animals. S. cerevisiae could be used as a model organism for further study to investigate the mechanisms of selenium antagonism towards cadmium toxicity.

Key words: selenium, cadmium, S. cerevisiae, antioxidant enzyme, reactive oxygen species (ROS)