FIG 8.

Exogenous linearized enterobactin protects ΔmacAB mutant cells from hydrogen peroxide-mediated killing. An overnight culture of the ΔmacAB mutant was subcultured at 1/100 in peroxide-containing LB (black circles) or in the same media additionally supplemented with enterobactin monomer (gray open squares), enterobactin dimer (gray open upward-pointing triangles), enterobactin trimer (open circles), and enterobactin (gray open downward-pointing triangles) and incubated at 37°C with aeration. Aliquots were collected hourly, serially diluted, and plated for CFU enumeration. Data are presented as mean survival results from at least three independent experiments. Asterisks indicate significance in Student’s t test with P values of <0.05.