Cyanobacterial existence is a proof of an effective stress combat system prevalent in them with superoxide dismutases playing a crucial role in this highly successful combat system.SODs are highly valued as therapeutic enzyme drugs'.The book investigates the presence of commercially important enzymes in cyanobacterial isolates followed by detailed investigations for superoxide dismutases from the cyanobacterium, Anabaena variabilis. A.variabilis shows promise for being a potentially useful strain that could be exploited commercially for biotechnological purposes.