Figure 5.

Amount of pyomelanin produced by biofilms of V. cholerae A1552 wild type and hmgA mutant strains after 1 and 3 days (A). Amount of ROS in the cell-free supernatant of 3 days-old-biofilms of V. cholerae A1552 wild type and hmgA mutant (B). Pyomelanin secreted by the biofilm into the supernatant was measured by optical density (OD _{405 nm}) of the cell-free supernatant obtained from the biofilms. Amount of pyomelanin was then normalised by using the corresponding biofilm biomass measured by CV assays (OD _{490 nm}). Error bars represent the standard deviation of three replicates. Statistical analysis was performed using two-way ANOVA and Sidak's multiple comparisons test (A) and Student's t-test (B). Statistical significance is indicated by ^**, P < 0.001, ^****, P < 0.0001.