FIG. 7.

Effect of DCCD on the induction of acid tolerance in S. macedonicus. Prior to lethal challenge, cells were nonadapted (a), acid adapted at pH 5.5 for 60 min, with DCCD being added either 20 min prior to and during the 60 min of acid adaptation (b) or only during the last 40 min of the treatment (c), and acid adapted under the same conditions in the absence of DCCD (d). Percentages (means ± standard deviations) of fluorescent subpopulations, as determined by flow cytometry after cFDA-PI labeling, are presented.