Growth Response of Clostridium perfringens to Oxidative Stress
Résumé
The sensitivity of Clostridium perfringens strain 13 to oxygen and its toxic derivatives was investigated in a new, defined medium (MMP). Exponentially growing cells in MMP medium were very sensitive to exposure to air by vigorous shaking. When exposed to air, the cells survived only 1hour and then rapidly died. Addition of cysteine, ascorbic acid, or yeast extract to the medium significantly increased vegetative cell survival without inducing sporulation. The level of toxicity of peroxyl and hydroperoxyl radicals, generated by H2O2, t-butyl hydroperoxide or ethanol, was very similar with and without air exposure. By contrast, plumbagin or menadione, which generate superoxide radicals in the presence of oxygen, caused high levels of cell death only in aerobiosic culture. Growth-arrested cells were more resistant to H2O2and to redox-cycling agents than were exponentially growing cells, but the resistance required de novo synthesis of proteins. An adaptive response to oxidative stress was also suggested by the higher level of cell resistance to H2O2and to ethanol when cells were pretreated with sublethal doses of these oxidants.