Spatiotemporal monitoring demonstrates prebiotic treatment responses in a periodontal multispecies biofilm model

Abstract

In vitro periodontal model systems are required for further elucidating phenomena behind periodontal pathogenesis and treatment applications. However, most oral biofilm models apply static conditions and are restricted to end-point measurements. This study established a multispecies periodontal model in the drip flow biofilm reactor in order to mimic shear flow in the oral cavity. The design is re-engineered to enable real-time characterization. A community of five bacteria, Streptococcus gordonii-GFPmut3*, Streptococcus oralis-GFPmut3*, Streptococcus sanguinis-pVMCherry, Fusobacterium nucleatum, and Porphyromonas gingivalis-SNAP26 is visualized using two distinct fluorescent proteins and the SNAP-tag. The biofilm in the reactor develops into a spatially uniform, dense and metabolically active biofilm with relative cell abundances similar to those in a healthy individual. Metabolic activity, structural features and bacterial composition of the biofilm remain stable from 3 up to 6 days. As a proof of concept for our periodontal model, the 3-day developed biofilm is exposed to a prebiotic treatment with L-arginine. Multifaceted effects of L-arginine on the oral biofilm were validated by this model setup. L-arginine showed to inhibit growth and co-aggregations of the pathogenic species, and to reduce biofilm thickness and volume. Additionally, L-arginine is metabolized by Streptococcus gordonii-GFPmut3* and Streptococcus sanguinis-pVMCherry, producing high levels of ornithine in the biofilm. In conclusion, our drip flow reactor setup is promising in studying spatiotemporal behavior of a multispecies periodontal community.