FIG. 7.

Comparison of EDF production levels of various E. coli strains. E. coli strains MC4100relA⁺, K-38, MG1655, and W3110 were grown to mid-logarithmic phase (OD₆₀₀ of 0.6) as described in the legend to Fig. 2. Supernatants of these untreated dense cultures (NT) were obtained (see legend to Fig. 2), and their activities were quantified (see Materials and Methods) (A). Supernatants were also obtained from cultures of the parallel strains harboring pQE-mazF in which MazF was overproduced (+MazF), which were grown in M9 medium with added ampicillin to mid-logarithmic phase, and mazF was induced (see the legend to Fig. 4) (B). Finally, supernatants were obtained and EDF activities were quantified (see Materials and Methods). After incubation without shaking at 37°C for 10 min, rifampin (10 μg/ml) was added, and the culture was incubated without shaking at 37°C for an additional 10 min. For the rest of the experiment, see the legend to Fig. 2.