Effects of D-valine on periodontal or peri-implant pathogens: Porphyromonas gingivalis biofilm

Background: When presented with a surface or an interface, bacteria often grow as biofilms in which cells are held together by an extracellular matrix. Biofilm formation on implants is an initiating factor for their failure. Porphyromonas gingivalis is the primary etiologic bacteria of initiation and progression of periodontal disease. This microorganism is also the risk factor of many systemic diseases, such as cardiovascular disease, diabetes, and pulmonary infection. To date, no medication that can remove such biofilm has been accepted for clinical use. D-valine (D-val) can reportedly inhibit the formation of biofilm and/or trigger the scattering of mature biofilm. Accordingly, this study investigated the effects of D-val on single-species P. gingivalis biofilms in vitro. Methods: P. gingivalis grown in brain heart infusion culture with or without D-val was inoculated in 24-or 96-well plates. After incubation for 72 hours, biomass via crystal violet staining, extracellular polysaccharide production by biofilms, and scanning electron microscopy (SEM) were used to determine the D-val concentration that can effectively prevent P. gingivalis biofilm formation. Results: Experimental results showed that D-val effectively inhibited biofilm formation at concentrations >= 50 mM (mMol/L), and that D-val inhibition increased with increased concentration. Moreover, at high concentrations, the bacterial form changed from the normal baseball form into a rodlike shape. D-val also notably affected extracellular polysaccharide production by P. gingivalis. Conclusions: D-val can inhibit P. gingivalis biofilm formation, and high concentrations can affect bacterial morphology.