FIG 7.

Ligand competition tracking experiment between chemoactive and nonchemoactive TlpA ligands. Cultures of the H. pylori PMSS1 WT were grown in BB10 overnight and then back-diluted as described in the legend of Fig. 1. Cultures were mock treated or treated with various concentrations of compounds as indicated. The pH of the cysteine stock was adjusted using NaOH to match the pH of the water used for the untreated control. The cells were immediately filmed, and direction changes were counted over a 3-s swimming period in at least 100 cells per treatment from 3 biological replicates. Repellents increase direction changes, as exemplified by the control repellent HCl, while attractants decrease direction changes, as exemplified by the control attractant dipyridyl. Data are normalized to the values for the untreated control for each strain, as described in Materials and Methods. Error bars represent the standard errors of the means. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (comparisons to the untreated control per strain using two-way ANOVA and Dunnett’s multiple-comparison test).