Figure 2.

Effect of acetic acid (left hand panels) and sorbic acid (right hand panels) on growth (A,E), intracellular pH (B,F), ATP (C,G), and ADP (D,H) levels of BY4741. Growing cultures were exposed to 0 mM (■ and white bars), 40 mM HA or 1 mM HS (◦ and gray bars), and 70 mM HA or 2 mM HS (▲ and dark gray bars) at t = 0. pH_i data are presented as ratio of fluorescence emission upon excitation at 390 nm and 470 nm (R_390/470) while the relevant pH_i values derived from the calibration curves are also indicated. Data presented are the average of three independent cultivations and error bars represent standard deviation. An asterisk indicates significance of the difference between acid exposed and control cultures at the same time point (two-tailed t-test; P < 0.05).