The antioxidative enzymes catalase and ascorbate peroxidase in toxic bloom forming cyanobacteria play a pioneer role in scavenging free radicals, which are generated as an outcome of photosynthesis and respiration. Ten Bloom forming toxic cyanobacterial strains Synechococcus elongates, Synechocystis aquatalis, Merismopedia glauca, Microcystis aeruginosa, M. aeruginosa (O), Arthrospira (=Spirulina) platensis, Nostoc paludosum, Anabaena iyengarii, A. variabilis and Cylindrospermum muscicola were isolated from natural blooms and purified. The results depict the significant activity of antioxidative enzymes. In A. platensis the activity of catalase (28.7 ± 2.3 mM/min/ìg protein), and Ascorbate peroxidase (1.91±0.12 mM/min/ìg protein) enzyme was maximum. It was also observed that the activity of ascorbate perooxidase was very less compared to activity of catalase. The growth analysis and pigment profile were also studied. Growth measurements revealed that cells attain maximum growth nearly after 15-20 days of inoculation except S. aquatalis, A. platensis and N. paludosum maximum, where optimum growth was achieved after 25th day. Chlorophyll-a content of A.platensis showed maximum concentration (14.47 ± 1.17 mg/L) and minimum concentration in S. elongates (2.30 ± 0.138 mg/L). The concentration of phycobiliproteins was found maximum in A. platensis (2.09 mg/ml). The detection of antioxidative potential of cyanobacterial strains will help to broaden the knowledge about their survival and can pave path for their utilization in biotechnology
