Figure 3

Biofilm predation by HI biofilm predation mutants (BPM). Ten HI biofilm predation mutants (BPM-5, 14, 15, 6, 7, 13, 20, 28, 37, 8), HI transposon insertion mutants (HI-Ra, HI-Rb) and HI mutant A (HI-A) were grown and used for the following assays: (A) Plaque predation assays. The above samples were spotted on a thick lawn of host cells (pre-treatment). Images were taken 48 hr post-inoculation. Each experiment was carried out three times, with three replicates for each treatment, yielding similar results- representative images are shown here. (B) Biofilm predation assays. E. coli biofilms were developed for 18 hrs in 96 well microtiter plates (pre-treatment), followed by 48 hr exposure to various treatments then rinsed and stained with CV. Each experiment was carried out three times, with 24 wells for each treatment, yielding similar results. (C) Quantification of biofilm biomass. Samples were added to a developed E. coli biofilm. Forty-eight hours later the dishes were rinsed, stained with CV and the amount of CV staining was quantified at OD₆₀₀ for each time point. Each value represents the mean of 12 wells from one representative experiment. Error bars indicate standard errors. Each experiment was carried out three times yielding similar results. The difference in biofilm reduction between the biofilm reducing mutants (BPM-5, 14, 15, 6, 7, 13, 20, 28, 37, 8), DDNB control, and the treatments which were able to reduce the pre-developed biofilm (HI-A, HI-Ra, HI-Rb) was statistically significant (P < 0.001).