FIG 1 .

Contribution of K⁺ uptake to the generation of S. aureus proton motive force. Wild-type S. aureus (blue lines) and its isogenic ΔktrC mutant (red lines) were inoculated to an OD₆₀₀ of 0.2 in K⁻TB with (filled symbols) and without (empty symbols) 10 mM supplemental KCl at pH 6.0 (A to D), 7.3 (E to H), and 8.6 (I to L). Immediately following inoculation and each hour after, OD₆₀₀ (A, E, and I), intracellular and extracellular pH (ΔpH) (B, F, and J), and transmembrane electrical potential (ΔΨ) (C, G, and K) were measured and subsequently calculated. The total proton motive force was calculated from these values (PMF) (D, H, and L). Results generated using pH 6.0 media are averages from four biological replicates (n = 4) acquired from two independent experiments with the standard deviations shown. Results generated using pH 7.3 and 8.6 media are averages from at least three independent experiments with the standard deviations shown.