FIG. 5.

UTI89 Δhfq is hypersensitive to the cationic peptide polymyxin B. Equal numbers of CFU of UTI89 and its mutant derivatives were subcultured in LB broth with or without 1.0 or 5.0 μg of polymyxin B/ml, as indicated. After shaking at 37°C for 1.5 h, bacterial titers (in CFU per milliliter) in triplicate samples were determined by plating serial dilutions. The graph shows the means for each sample set ± standard deviations. These experiments were repeated three times, with similar results.