Figure 6.

H₂O₂ treatment causes a dose dependent growth reduction of E. coli.

(A) H₂O₂ was added into exponential-phase cultures (OD₅₅₀=0.5) at 0 min to final concentrations indicated in the Figure. The cultures were then immediately dispensed into the wells of a 96-well plate. The plate was incubated with shaking and the OD₅₅₀ was recorded by a plate reader in a time course. Four replicates were read and the mean and standard error were plotted. Note the actual OD₅₅₀ shown is lower than 0.5 initially due to the thinner cultures in the wells than in a regular cuvette. (B) Colony forming unit in OD₅₅₀=0.5 cultures in a time course after addition of H₂O₂ to the indicated final concentrations at 0 min. Colony forming units were determined as described in Materials and methods. The mean and standard error of triplicates were plotted. (C) Colony forming unit in OD₅₅₀=0.01 cultures in a time course after treatment with indicated concentrations of H₂O₂. The mean and standard error of triplicates were plotted.