FIG. 1.

Survival of the rpoS, phoP, and fur mutants in the SSC assay. SX 2 (wild type), SX 21 (rpoS), SX 46 (phoP), and SB 270 (fur) strains were grown in minimal EG medium to a mid-logarithmic phase of an OD₆₀₀ of 0.4 (∼2 × 10⁸ CFU/ml). The cultures were adapted at pH 4.4 for 1 h. Acid-adapted cells were washed and resuspended in an equal volume of filter-sterilized SSC. Viable counts were determined at 0, 10, and 20 min for determination of percent survival.