FIG. 1.

Effect of low pH on growth and survival of L. plantarum WCFS1. (A) Percentages of CFU showing growth after pH downshift from pH 5 to pH, determined after plating from liquid culture onto PAO on Gelrite plates at the indicated pH, are shown. (B) Kill curve after pH downshift in liquid culture from pH 5 to 3, assayed by a viable count onto pH 6.5 plates. Open squares, pH downshift for cells at high density; filled squares, pH downshift for cells diluted 100-fold; filled triangles, control cells resuspended to high density in pH 6.5 MRS.