Fig. 2.

The E. coli Δldt3 strain is hypersensitive to EDTA. Wild-type and mutant E. coli strains grown to stationary phase in LB medium were pelleted and washed twice with 50 mM Tris pH 8.0. (a, c) Cells were resuspended in either 50 mM Tris pH 8.0 (Tris, control) or 50 mM Tris pH 8.0, 1 mM EDTA (EDTA). (b) Cells were resuspended in either 50 mM Tris pH 8.0, 1 mM EDTA (EDTA) or 50 mM Tris pH 8.0, 1 mM EDTA, 8 mM MgSO₄ (EDTA, MgSO₄). All cell suspensions were incubated at 37 °C for 4.5 h and plated onto LB agar for viability at 90 min intervals. (c) Wild-type and Δldt3 strains with the pCA24N plasmid expressing the ybiS (ybiS⁺) or the vector control (vc). Δlpp, Braun’s lipoprotein mutant; Δldt2, ΔynhBΔycbB; Δldt3, ΔerfKΔybiSΔycfS. Data are plotted as the viable counts at each time point divided by the viable counts at time zero on a log₁₀ scale. Data were analysed using Student’s t-test. *P-values ≤0.05 were significant. Error bars, ±S.D.