Compréhension des mécanismes impliqués dans l’activité réductrice et dans les adaptations métaboliques à pH acide de Bacillus cereus : implication des thiols exofaciaux

摘要

Bacillus cereus is a Gram positive bacterium able to adapt and survive to numerous stress, including acid stress or oxydo-reduction potential (Eh) variations. Some adaptations are documeted for each of these two stress. However, the interaction between Eh and pH on B. cereus physiology was never studied. Here, we focus on the impact of Eh variation on the acid resistance of B. cereus, on the metabolic adaptation of these bacteria under low pH and on the interaction of bacterial cells with their redox environement. Results obtained demonstrate that the acid survival of B. cereus was slighlty higher under reductive Eh than under oxdative Eh. Concerning acid adaptations, we observed a major metabolic adjustement for cells cultivated at low pH with an important shift from mixed acid fermentation to butanediolic fermentation. Finally, we demonstrate the importance of exofacials thiols groups in the reductive abilities of B. cereus. All these conclusions will help to better understand the response of B. cereus exposed to acid stress and Eh.