Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 12, 2008
Publication Date: May 16, 2008
Citation: Bearson, B.L., Casey, T., Lee, I. 2008. Escherichia coli O157:H7 glutamate- and arginine-dependent acid resistance systems protect against oxidative stress during extreme acid challenge. Proceedings of 48th Microbiology Society of Korea Annual Meeting & 2008 International Symposium on Microbiology, May 15-16, 2008, Daejeon, Korea. p. 210. Technical Abstract: To investigate the protection that several known Escherichia coli O157:H7 acid resistance systems provide against oxidative stress, the addition of diamide or hydrogen peroxide were used concomitant with acid challenge at pH 2.5 to determine bacterial survival. Diamide and hydrogen peroxide both decreased the acid resistance of E. coli O157:H7 during challenge at pH 2.5 for acid resistance system 1 (AR1, stationary-phase induced) in a dose-dependent manner. In contrast, both the glutamate- (AR2) and arginine- (AR3) dependent acid resistance systems provided significant protection against diamide- and hydrogen peroxide-induced oxidative stress during pH 2.5 acid challenge. Oxidative stress protection during acid challenge required gadC and adiA for the glutamate- and arginine-dependent acid resistance systems, respectively. In addition, maximal protection against oxidative stress in the presence of glutamate required a low external pH (pH 2.5), since pH 5.5 did not protect. This study demonstrates that the glutamate- and arginine-dependent acid resistance systems of E. coli O157:H7 can simultaneously protect against oxidative stress during extreme acid challenge.