Response of the Antioxidant Systems of the Nitrogen Fixing Cyanobacterium Cylindrospermum sp. to Lead Stress

Cyanobacteria Cylindrospermum sp. as biofertilizer for rice cultivation has a beneficial effect on crop productivity and maintenance of soil fertility. A study was undertaken under controlled laboratory conditions, to study the influence of different concentrations of lead (0, 25, 50, 75, 100 and 125 μM) on the growth, lipid peroxidation (MDA), peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and proline of cyanobacterium Cylindrospermum sp. Lead stress caused negative impact on growth (Dry weight) of Cylindrospermum sp. and the damaging effect was further increased by enhanced lipid peroxidation probably because of generation of reactive oxygen species. To explore the survival stretegies of cyanobacterium under Pb stress enzymatic antioxidants SOD, POD, CAT and non enzymatic antioxidant proline was studied. A general induction of SOD, POD and proline was observed. In contrast to this CAT activity was reduced after 50 μM Pb. This study may be helpful in biological indication of lead toxicity in cyanobacteria.