TABLE 2.
Enterobactin toxicity to E. coli in the presence of Cu and the protective activity of CueO
| Source of spent mediuma | CFUb | Enterobactinc (μM) |
|---|---|---|
| ΔentC strain | >103 | 0 |
| ΔcueO strain | 0 | 57.2 |
| ΔcueO strain + CueOd | >103 | 57.2 |
a
Strains ΔentC, ΔcueO, and W3110 (wild type) were grown to stationary phase in iron-depleted minimal medium with subtoxic concentrations of CuCl2, and the supernatant filter was sterilized.
b
Stationary-phase cultures of E. coli strain W3110 were diluted into fresh minimal medium and, after growth for 2 h, diluted into the respective spent medium, challenged with 5 mM CuCl2 for 15 min, diluted into LB medium, and plated on LB plates.
c
Enterobactin content was determined from the spent supernatant as described in Materials and Methods.
d
Before addition of cells, CueO was added (2 μM final concentration) for 10 min at 37°C.