FIG. 1.

C. jejuni remains viable and helically shaped after a 20-min exposure to MH-MES medium at pH 4.5. (A) C. jejuni NCTC 11168 was grown to exponential phase in biphasic MH medium and exposed to MH-MES medium at pH 4.5. Samples were withdrawn after 0, 2, 4, 12, 16, and 20 min for viable count determination. Values from seven independent experiments are represented as the percent survival (with 100% being the number of viable cells present at time zero). Error bars denoting the standard errors of the means are present but are too small to be seen. (B) Scanning electron micrographs of C. jejuni prior to (0 min) and after (20 min) exposure to MH-MES medium at pH 4.5. Size bars, 1 μm. Cells from samples taken 2, 4, 12, and 16 min after acid shock were indistinguishable from those shown. mag, magnification.