FIG. 4.

Oxidative stress assays with S. mutans UA159 grown under aerobic or anaerobic conditions. For hydrogen peroxide killing (A), aerobically or anaerobically grown cells were harvested and suspended in BHI containing 0.2% hydrogen peroxide for 30, 60, or 90 min. The growth rate of S. mutans under 0.001% hydrogen peroxide (B) or 25 mM paraquat (C) was monitored using a Bioscreen C system to analyze the ability of cells to withstand oxidative stress under aerobic or anaerobic conditions. Data presented here are representative of at least three independent experiments.