Chlorella vulgaris (C. vulgaris) , a fast鄄growing unicellular micro鄄alga, is commonly used as a supplement of food for human and animal consumption. As C. vulgaris readily absorbs metals, this micro鄄algae has also been employed as an important indicator for monitoring the pollution and toxicity of metals in aquatic environments. Due to both natural geological sources as well as anthropogenic sources, the escalating contamination of aquatic environments by metals such as zinc (Zn) is becoming of increasing concern. A limited concentration of Zn is essential for growth of C. vulgaris, but limited knowledge exists concerning toxic impacts of Zn on the alga. The present study investigated various biochemical variables including biomass, the activities of antioxidant enzymes including superoxide dismutase (SOD) and peroxidase (POD) , the intracellular Zn assimilated, and the inducement of Zn鄄MT鄄like proteins in C. vulgaris when the alga was exposed to various Zn 2+ concentrations. Results showed that the growth of C. vulgaris was inhibited by exposure to Zn 2+ at concentrations ranging from 5-100 滋mol l / L. The algal biomass rapidly decreased with increased Zn 2+ exposure concentration. Algal biomass also decreased with increased exposure time to concentrations of Zn 2+ > 10 滋mol / L. The results indicated that the growth of the alga was significantly inhibited by exposure to Zn 2+ ,especially at higher exposure concentrations. The activities of SOD increased with the increase of Zn 2+ exposure concentrations within the ranges of 0-50 滋mol / L, but slight decreases in SOD activity occurred with exposure concentrations of Zn 2+ > 50 滋mol / L. The highest activity of SOD was evident when the alga was exposed to 50 滋mol / L of Zn 2+ , in which the value of SOD activity was two times more than that of the control

No abstract