FIG. 7.

Survival of preadapted E. coli strains on copper alloy surfaces. E. coli cultures were grown overnight in the presence of nontoxic concentrations of CuCl₂ to induce copper detoxification systems. Washed cells of E. coli wild-type strain W3110 (▪) or its copper-sensitive derivatives GR17 (ΔcopA Δcus ΔcueO) (▴), GR15 (Δcus ΔcueO) (⧫), EC949 (ΔcopA) (+), GR1 (ΔcueO) (X), GR5 (Δcus) (⋄), or W3110 (pPA173) harboring the high-level copper resistance system Pco (•) were streaked on 99.9% copper (A) or “nickel silver” alloy (C75200, maximum of 62% Cu) (B) surfaces and treated as described in the legend for Fig. 1. Shown are averages with standard deviations (error bars) from three independent experiments.