Anti-Oxidative Response of Cyanobacterium Anabaena sp. strain PCC 7120 to Arsenite (As(III))

Abstract

Arsenite (As(III)) induced changes were investigated in the diazotrophic cyanobacterium Anabaena PCC 7120. The cells of Anabaena sp. strain PCC 7120 exposed to As(III) produced H₂O₂ and its production increased with increase in As(III) concentration. As a part of resistant mechanism and also to counteract the deleterious effect of H₂O₂, the cells of Anabaena sp. strain PCC 7120 produced more ascorbate peroxidase (APx) whose level also increased in response to As(III) concentrations. The increase in APx activity was directly proportional to the increase in H₂O₂ production and maximum APx activity was recorded at 40 ppm of As(III). In contrast, glutathione reductase (GR) activity decreases with increase in As(III) concentrations and attained its minimum level at 40 ppm of As(III). Lipid peroxidation increased with increase in As(III) concentration and maximum peroxidation (which was about two fold higher than that of the untreated control cells) was recorded at 40 ppm of As(III). Exposure of the Anabaena sp. strain PCC 7120cells to As(III) has also resulted in a significant increase in ascorbate and dehydro-ascorbate contents which was about 6.44 and 1.97 fold higher than that of the untreated control cells, respectively at 40 ppm of As(III).