Antioxidant modulation in response to selenium induced oxidative stress in unicellular cyanobacterium Synechococcus elongatus PCC 7942

A unicellular cyanobacterium Synechococcus elongatus PCC 7942 was exposed to various concentrations of SeO42–. A growth supportive effect was seen at 50 µM concentration of SeO42− whereas 50% growth retardation was observed at 200 µM of SeO42−. Selenium (Se) stress at 200 µM SeO42− induced the formation of reactive oxygen species such as superoxide radical (O2•–), hydrogen peroxide (H2O2) and malondialdehyde (MDA). Modifications in antioxidant enzyme levels, namely, superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), glutathione reductase (GR), glutathione peroxidase (GPX) and isozyme patterns were also examined. This article outlines the synergistic action of antioxidant components on Se toxicity in S. elongatus PCC 7942. Key words: Antioxidant, reactive oxygen species, selenium, Synechococcus elongatus PCC 7942, toxicity.