Differences in Zn and Pb resistance of two ecotypes of the microalga Eustigmatos sp inhabiting metal loaded calamine mine spoils

摘要

Soil-dwelling microalgae as pioneer organisms may play an essential role in degraded post-industrial areas. Zn and Pb resistance of two morphologically identical strains (E120, E5) of the soil microalga Eustigmatos sp. (Eustigmatophyceae) inhabiting two extremely metal polluted calamine mine spoils and Eustigmatos vischeri (Ev) from algal collection was compared. To compare Zn and Pb resistance of algal strains, toxicity parameters (72/96 h-EC50) were determined during their exposure to high Zn (50-800 mu M) and Pb (5-80 mu M) concentrations. Both Zn- and Pb-EC50 values increased as follows: Ev < E5 < E120. The E120 strain from the mine spoil with the highest metal contents appeared to be two times more Zn and Pb resistant (96 h-EC50 = 416 mu M Zn, 39.8 mu M Pb) than E5 strain from the less metal polluted site and 4.7-8.8 times more than Ev. Differences in Zn and Pb accumulation as well as in metal-induced membrane lipid peroxidation were also observed. The present study highlights the evolution of algal ecotypes of high but various Zn and Pb resistance as a result of natural exposure to different metal concentrations in their habitats. The algae of high heavy metal resistance could have a practical application in remediation of contaminated soils of anthropogenic origin.