Nils Heine (Hannover, DE), Dr. Maria Leilani Torres-Mapa (Hannover, DE), Professor Janina Bahnemann (Augsburg, DE), Professor Thomas Scheper (Hannover, DE), Professor Alexander Heisterkamp (Hannover, DE), Prof. Dr. Meike Stiesch (Hannover, DE), Dr. Katharina Nikutta-Doll (Hannover, DE)
Abstract text (incl. figure legends and references)
Introduction
The human mouth contains a diverse microbiome. Solid surfaces inside the oral cavity, like teeth or implants, are almost constantly populated by multispecies bacterial biofilms. Initially commensal and harmless to oral health, the species distribution inside these biofilms can shift to a pathogenic state and cause severe infections. To develop, test, and verify systems for early detection and treatment of this biofilm dysbiosis, complex in-vitro models are required.
Objectives
The objective of this study is to establish and validate a reproducible in-vitro model for oral biofilm dysbiosis using five clinically relevant bacterial species and a saliva flow-simulating flow chamber system.
Materials & methods
Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar, Fusobacterium nucleatum, and Porphyromonas gingivalis were added to a flow chamber system to form multispecies biofilms on titanium samples placed in flow chambers. After 24 h, the bacterial suspension was replaced with sterile medium to allow further development only of the initially formed biofilm under flow for 20 more days. Flow velocity was set to 100 µL/min and the system was kept at 37 °C and anaerobic conditions. The pH value of the medium leaving the flow chambers was constantly monitored. At different time points, samples were taken out for analysis via fluorescent staining and microscopy as well as qRT-PCR.
Results
After 6 days, a change in species distribution started, with the relative amount of commensal bacteria decreasing. The decrease of commensal bacteria was preceded by an increase in pH, following the initial drop after exponential growth.
Conclusion
To validate diagnostic tools and therapeutics for associated infections, reproducible in-vitro models of complex biologic systems like multi-species bacterial communities are required. In this study, we presented an approach to obtain such a model for oral biofilm dysbiosis, based on the natural shift over time.