FIG. 6.
Ratiometric analysis of membrane potential changes in S. macedonicus cells after acidic lethal challenge with DiBAC4(3). Untreated (a), depolarized (b), and heat-killed (c) mid-log-phase S. macedonicus cells served as controls. Nonadapted (d) or acid-adapted (at pH 5.5 for 30 min) (e) mid-log-phase cells were exposed to pH 3.5 for 15 min. All samples were labeled with DiBAC4(3) and analyzed by flow cytometry. Results are presented as single-parameter histograms of the log ratios of green fluorescence to side scatter. M1, M2, and M3 were defined by the untreated, depolarized, and heat-killed cells' distributions, respectively.