Sensitivity of S. agalactiae to H2O2. The wild-type strain, NEM316 (▴), the sodA mutant, NEM1640 (■), and the complemented strain, NEM1641 (●) were grown and treated with H2O2 as described in Materials and Methods. Exponential-phase cells were exposed to 20 mM H2O2 for 30, 60, or 120 min at 37°C. Viability was determined by plating on BHI agar. Error bars represent the standard deviations of three independent experiments.