Figure 1.

Effect of WOA pre-exposure on acid entry. The rate of acidification (A,C) and pHi reduction after 1 min (B,D) caused by 20 mM acetic acid (A,B) or 1.2 mM sorbic acid (C,D), in control cultures (no pre-exposure) and culture pre-exposed to 45 mM of HA (A,B) or 1 mM of HS (C,D). The same experiment was performed in the presence (black) and absence (gray) of glucose. Data presented are the average of three independent cultivations and error bars represent standard deviations. An asterisk indicates significance of the difference between control and pre-adapted cultures, or between conditions indicated with a marker (two-tailed t-test; ^*p < 0.05; ^**p < 0.01; ^***p < 0.001).