SUPEROXIDE-DISMUTASE PROTECTS AGAINST AEROBIC HEAT-SHOCK IN ESCHERICHIA-COLI

Exposure of a superoxide dismutase-null (sodA sodB) strain of Escheric hia coli to aerobic heat stress (45 to 48 degrees C) caused a profound loss of viability, whereas the same heat stress applied anaerobically had a negligible effect, A superoxide dismutase-competent parental st rain was resistant to the lethal effect of the aerobic heating. It fol lows that aerobic heating imposes an oxidative burden of which O-2(-) must be a major component. This effect is not seen at 53 degrees C, pr esumably because, at this higher temperature, direct thermolability of vital cell components overrides the effect of superoxide radicals.