10.22376/ijpbs.2019.10.1.p1-12 Volume 4 Issue 1 2013 (January - March) Cyanobacteria are autotrophic prokaryotes with excellent antioxidative system that scavenges reactive oxygen species produced during photosynthesis. Superoxide dismutase (SOD) represent the primary defence against oxygen damage. The antioxidative activity of SOD enzymes was determined in cultures of the bloom forming cyanobacteria lessThan i greaterThan Anabaena variabilis lessThan /i greaterThan and lessThan i greaterThan Synechococcus elongates lessThan /i greaterThan . Experimental results depict higher antioxidative activity of SOD enzyme in lessThan i greaterThan S. elongates lessThan /i greaterThan than lessThan i greaterThan A. variabilis. lessThan /i greaterThan The isozymes of SOD in lessThan i greaterThan A lessThan /i greaterThan . lessThan i greaterThan variabilis lessThan /i greaterThan and lessThan i greaterThan S. elongates lessThan /i greaterThan cultures were assayed by negative staining. Two bands were visualised in lessThan i greaterThan S. elongates, lessThan /i greaterThan while one band was seen in lessThan i greaterThan A. variabilis lessThan /i greaterThan . The activity of these bands was insensitive to 2 mM KCN but disappeared when 30% H lessThan sub greaterThan 2 lessThan /sub greaterThan O lessThan sub greaterThan 2 lessThan /sub greaterThan was added to the activity staining solutions. Because Fe-SOD is insensitive to KCN but sensitive to H lessThan sub greaterThan 2 lessThan /sub greaterThan O lessThan sub greaterThan 2 lessThan /sub greaterThan , the bands present were of Fe-SOD. Growth analysis and Pigment profile of cultures was also studied. Screening cyanobacteria for SOD activity can help us in exploring the immense potential of this enzyme as therapeutic enzyme drug. ARCHANA TIWARI AND ANJALI THAKUR Antioxidative enzymes, Cyanobacteria, Superoxide dismutase (SOD). 562-569