FIG. 4.

Effect of prior pH conditioning on the survival of the wild-type S. mutans LT11 and the mutant BH97LC in TYEG following a 3-h exposure to pH 3.0. Log-phase cells growing at pH 7.5 were transferred to fresh TYEG medium buffered at pH 6.0 to 3.5 and incubated at 37°C for 2 h prior to acidification to pH 3.0. The control cells (pH 7.5) were similarly treated. Error bars, standard deviations.