Analysis of the growth of wild-type, spy1236 knockout, and complemented strains cultured in acidic (pH 6.0) media in an atmosphere containing 5% CO
. The CFU/ml after 23 h, broth culture of wild-type strain 1529 and its derived strains are shown. Viable counts were performed on BHI-Y and sheep blood agar plates. At least three independent experiments were performed and they always yielded essentially the same results. The error bars indicate the standard error of the mean.