A SUPEROXIDE-DISMUTASE MIMIC PROTECTS SODA SODB ESCHERICHIA-COLI AGAINST AEROBIC HEATING AND STATIONARY-PHASE DEATH

Superoxide appears to be a major cause of stationary-phase death and h eat kill. In support of this conclusion are the following observations : (a) Stationary-phase death was apparent in the sodA sodB, but not in the superoxide dismutase (SOD)-competent parental strain; (b) Station ary phase death in the sodA sodB strain was dioxygen-dependent; (c) A manganic porphyrin, which catalyzes the dismutation of superoxide, pro tected the sodA sodB strain against stationary-phase death; (d) Heatin g the sodA sodB strain to 42 degrees C caused a loss of viability not seen with the SOD-competent parental strain and preventable by the man ganic porphyrin. Exposure to aerobic conditions induced antibiotic res istance in the sodA sodB, but not in the parental strain and the manga nic porphyrin prevented that induction. This again indicates its abili ty to substitute for SOD in Escherichia coli. (C) 1995 Academic Press, Inc.