Oxidative stress and antioxidant defenses in two green microalgae exposed to copper

The aim of this work was to assess the effects of 1 week copper exposure (6.2, 108, 210 and 414 μM) on Scenedesmus vacuolatus and Chlorella kessleri. The strains showed different susceptibility to copper. Copper content was determined in both strains by total X-ray reflection fluorescence analysis (TXRF). In S. vacuolatus, the increase of medium copper concentration induced an augmentation of protein and MDA content, and a significant decrease in the chlorophyll a/chlorophyll b ratio. S. vacuolatus showed a significant increase of catalase activity in 210 and 414 μM of copper, and a significant increment of SOD activity and GSH content only in 414 μM of copper. On the contrary, C. kessleri did not show significant differences in these parameters between 6.2 and 108 μM of copper. Increased copper in the environment evokes oxidative stress and an increase in the antioxidant defenses of S. vacuolatus.