Effects of hydrogen peroxide on the motility, catalase and superoxide dismutase of dam and/or seqA mutant of Salmonella typhimurium.

In addition to their role in the virulence attenuation of Salmonella and other pathogens, dam or seqA genes increase the sensitivity towards hydrogen peroxide. The aim of our study is to investigate the effect of H(2)O(2) on the motility, the catalase and superoxide dismutase activities of dam and/or seqA mutants of Salmonella typhimurium. Our findings showed significant differences of the effects of H(2)O(2) on the motility between wild type strain and all of mutants. Hydrogen peroxide changes SOD isoenzyme profile of these mutants by disappearance of Fe-SOD. Concerning the catalase, an increase of its activity was observed in the wild type, dam and seqA mutant. However, H(2)O(2) decreases the activity of this enzyme in the double mutant strain. We can suggest that the dam gene, together with seqA, play a protective role in the oxidative stress response of Salmonella typhimurium.