Figure 6.

Effect of cell-free supernatants (A), H₂O₂ (B) and catalase (C) on grazing resistance to A. castellanii. The cell-free supernatant of 3-days-old V. cholerae biofilms were added to 3-days-old biofilms at a concentration of 50% in fresh VNSS and incubated with A. castellanii for 3 days. Biofilm biomass was determined by CV staining. Experiments were run in triplicate and repeated three times on different days. Error bars represent the standard deviation of three replicates. Statistical analysis was performed using one-way ANOVA and Dunnett's multiple comparisons test comparing all to the WT (A), Student's t-test (B) and two-way ANOVA and Sidak's multiple comparisons test (C). Statistical significance is indicated by ^*, P < 0.05; ^***, P < 0.001 and ^****, P < 0.0001 and Ns, not significant.