FIG 5.

Extracellular CuCl₂ protects both wild-type and ΔrclA E. coli strains against HOCl. Growth curves of E. coli K-12 wild-type (A) and ΔrclA (B) strains in MOPS with the addition of various combinations of HOCl (132 μM) and CuCl₂ (10 μM) (n = 3, ± the SD for each treatment). Time (means ± the SD) for each sample to reach an A₆₀₀ of 0.15 is indicated by vertical dashed lines. Only one of several HOCl concentrations tested is shown for simplicity (see Fig. S5A to C in the supplemental material for lag-phase extension calculations, a summary of all the conditions tested using the growth curve method, and statistics comparing LPE values shown in this figure). (C) Exogenous copper protects both wild-type and ΔrclA E. coli strains from lethal HOCl stress (10 min at 1 mM). Cells were treated as described in Fig. S2C and D.