FIG 5.

The role of ClpP1 and ClpP2 in surface adherence. (A) ClpP1 controls the level of adherence after 6 h of incubation, while ClpP2 does not, and both ClpP1 and ClpP2 control levels of adherence after overnight incubation. Cell adherence was measured with crystal violet dye at 37°C in 96-well plates. Values were normalized averages (n = 24) ± SEM. Data were compared to the WT values by ANOVA with Dunnett's post hoc test (***, P < 0.0001; *, P < 0.05; NS, not significant). Comparison of ΔP1 and ΔP1P2 mutants for 6 h of incubation, P = 0.0004. (B) ClpP2 controls microcolony organization, whereas ClpP1 does not. Microcolonies in flow cells were visualized with the LIVE/DEAD BacLight bacterial viability kit and imaged with confocal laser scanning microscopy at ×60 magnification after 72 h of growth in flow cells at 37°C. Replicate images are shown in Fig. S2 in the supplemental material, and results from flow cell experiments with complementation by plasmid expression of ClpP2 are shown in Fig. S3.