Figure 4.

The sensitivity of WT M2 A. nosocomialis strain and its derivatives deficient in katE, katG, both katE and katG to H₂O₂. The A. nosocomialis strains were cultured overnight, and then grown for 5 hours in fresh medium. Bacteria were adjusted according to their optical densities and seeded into soft agar on tryptic soy broth medium containing 1.5% agar. Hydrogen peroxide (2%, 10 µl) was spotted onto sterilized dry filter discs of 8-mm diameter. The plates were incubated at 37°C overnight. The halos were photographed and diameters of the halos were measured using a digital caliper. A. Halo formation caused by H₂O₂ on lawn containing different A. nosocomialis strains. Representative images are shown. B. Diameters of the halos caused by H₂O₂ for distinct A. nosocomialis strains. Bars are means ± standard error from 5 independent experiments. *, p<0.05, compared to the parental M2 strain. †, p<0.05, compared to the ΔkatG strain. Student’s t-test was used for comparison.