Physiological changes induced in four bacterial strains following oxidative stress.

In order to study the behaviour and resistance of bacteria under extreme conditions, physiological changes associated with oxidative stress were monitored using flow cytometry. The study was conducted to assess the maintenance of membrane integrity and potential as well as the esterase activity, the intracellular pH and the production of superoxide anions in four bacterial strains (Ralstonia metallidurans, Escherichia coli, Shewanella oneidensis and Deinococcus radiodurans) following H202 stress (concentrations from 0 to 880 mM). We show that a range of significant physiological alterations occurs when bacteria are challenged with H202 and fluorescent staining methods coupled with flow cytometry are useful for monitoring the changes induced not only by oxidative stress but also by other stresses like temperature, radiation, pressure, pH, etc...