<i>E. coli</i> survives at pH lower than pH 2.0.

<p>Overnight cultures of <i>E. coli</i> K-12 strain W3110 were grown in LBK 100 mM MES pH 5.0. These cultures were exposed to medium at pH 1.2; 1.6;and 2.0, respectively, for two hours. Dilutions from exposed cells were completed as in <b>Fig. 1</b>. Strains were exposed in autoclave-sterilized medium (light bars) and in filtered medium (dark bars). Error bars indicate SEM (n = 5 or 6).