Combined Effect of Copper and Cadmium on Heavy Metal Ion Bioaccumulation and Antioxidant Enzymes Induction in Chlorella vulgaris

The relationships between metal uptake and antioxidant enzyme activities or a response to membrane lipid peroxidation (i.e., malondialdehyde production) in Chlorella vulgaris exposed to Cu and Cd compounds singly and in combination were investigated. The results showed that bioaccumulation of a single metal was influenced by the presence of the other metal. The activities of superoxide dismutase and peroxidase increased to more than fivefold of the control after exposure to Cu(1.5 mu M) alone or to Cu(1.5 mu M) with Cd mixtures. Malondialdehyde levels in C. vulgaris also increased to approximately twofold of the control after exposure to high concentration of Cu(1.5 mu M) alone or to Cu and Cd mixtures. However, Cd alone did not significantly increase the levels of antioxidant enzymes or malondialdehyde.