FIG. 1.

Acid and base shift growth curves. B. subtilis strain AG174 cultures grown overnight in unbuffered LBK were diluted 500-fold and grown at 37°C in LBK (50 mM HOMOPIPES) adjusted to pH 6.0 (•) or pH 8.5 (○) until an OD₆₀₀ of 0.3. The culture at pH 6.0 was then diluted 10-fold into medium at pH 6.0 (•) and at pH 8.5 (▾). The original culture at pH 8.5 was diluted 10-fold into medium at pH 8.5 (○) and at pH 6.0 (▿). Diluted cultures were incubated for 2.5 h. The average of three biological replicates is shown for each condition. Error bars represent SEM.