Response of the antioxidant systems of the nitrogen fixing cyanobacterium Anabaena doliolum to copper

Different concentrations of copper have been found to produce significant increases in lipid peroxidation, carotenoid contents and activities of antioxidant enzymes like superoxide dismutase and catalase of Anabaena doliolum. In contrast to this, an appreciable decline in the GSH pool and activities of ascorbate peroxidase and glutathione reductase have also been observed. Cu was also found to inhibit chlorophyll a accumulation significantly, although appreciable resumption was observed in cultures supplied with antioxidants exogenously. This study, therefore, suggests that the antioxidant system of this cyanobacterium is not strong enough to withstand copper-induced stress, and this system may show species and stress specific responses.