Fig 2.
Impact of intrinsic aminoglycoside resistance gene knockouts on gentamicin-promoted cytoplasmic membrane depolarization. Cytoplasmic membrane depolarization, as assessed by DIBAC4(3) fluorescence, was measured over time following exposure of wild-type (WT; strain K767) and mutant P. aeruginosa strains to 5 μg/ml of gentamicin (added at time zero). (A) Results of a representative experiment showing increased gentamicin-promoted fluorescence over time. Background fluorescence in the absence of gentamicin is shown for wild-type strain K767 but is representative of all strains, with the exception of the indicated ΔlptA strain. (B) Gentamicin-promoted fluorescence over time for the indicated mutants as a percentage of gentamicin-promoted fluorescence for wild-type strain K767. The data are the mean ± standard deviation of 3 to 4 independent experiments where the fluorescence data were adjusted for the background fluorescence of gentamicin-unexposed cells prior to calculating percentages.