TEMPERATURE SHIFT-INDUCED CHANGES IN THE ANTIOXIDANT ENZYME-SYSTEM OFCYANOBACTERIUM SYNECHOCYSTIC PCC-6803

The 24 h effect of low (20-degrees-C) and high (43-degrees-C) temperat ure on the antioxidant enzyme activities and lipid peroxidation was in vestigated in intact cells of the cyanobacterium Synechocystis PCC 680 3 grown at 36-degrees-C. At low temperature treated cells, the superox ide dismutase, catalase and glutathione peroxidase activities were sig nificantly higher and the protein content lower than in high temperatu re treated cells. The increase of hydroxyl free radical level and malo nyldialdehyde formation, when algal cells were exposed to low temperat ure, were due to the stimulated production of superoxide radicals O2- and hydrogen peroxide (H2O2).