Figure 2.

Generation time with polyamines, as a function of pH. E. coli was grown aerobically at 37°C in LBK buffered at pH 5.5, 7.0, or 8.5, with or without 1 mM spermine or 10 mM spermidine. Overnight cultures were diluted 1000-fold, and growth rates were measured between OD₆₀₀ values of 0.1 and 0.2. Error bars represent SEM (N = 3).