Citrullination mediated by PPAD constrains biofilm formation in P. gingivalis strain 381

Deletion of the gene encoding PPAD enhances biofilm formation. a 381 and Δ8820 biomass after 24？h was quantified by staining with safranin. b 24？h biomass of empty vector controls (381 pT-COW and Δ8820 pT-COW) and complemented Δ8820 (Δ8820 pT-C8820) was quantified by staining with safranin. Data in a and b are averages of three independent experiments (n？=？9). Error bars represent the standard deviation. The data in a were analyzed using the Student’s two-tailed t-test. The data in b were analyzed by ANOVA with Bonferroni post tests. *p？<？0.05. c Top-down view of 24？h biofilms stained with SYTO 9 and propidium iodide. d Attached cells 2？h after setting up a biofilm assay stained with SYTO 9 and propidium iodide. Arrows indicate examples of cell–cell aggregates. Scale bar: 50？μ