Effect of heavy metal stress on proline, malondialdehyde, and superoxide dismutase activity in the cyanobacterium Spirulina platensis-S5

This study investigated toxic impacts of lead, copper, and zinc over a concentration gradient of 0.05–0.20 mg/L on proline, malondialdehyde (MDA), and superoxide dismutase (SOD) in the cyanobacterium Spirulina platensis-S5. Despite a reduction in growth of the test microorganism, its MDA, SOD, and proline contents increased under the heavy metal stress, corresponding to the concentration of the metal ion in the culture medium. Increased amount of MDA was indicative of formation of free radicals in the test microorganism under heavy metals stress(es), while increased levels of SOD and proline pointed to the occurrence of a scavenging mechanism.