Development of a Model System to Investigate Oral Antibacterial Technologies

Objectives: The oral cavity is home to over 600 bacterial species which form the oral microbiome, the composition of which is associated with health and disease states. The use of active compounds in oral healthcare products can alter this microbial community. Imbalances (dysbioses) of the oral microbiome are linked to a range of oral pathologies, including dental caries and periodontal disease. Furthermore, cardiovascular disease (Leishman et al., 2010), neurodegeneration (Astafurov et al., 2014), type 2 diabetes (Long et al., 2017)and Alzheimer’s disease (Shoemark and Allen, 2015)have also been linked to oral microbiome dysbiosis. To investigate the links between changes to the oral microbiome, disease and the potential for altering the microbiome through the use of active compounds, we have developed a model system utilising a Centre for Disease Control (CDC) bioreactor.
Methods: CDC bioreactors containing hydroxyapatite disks were used to produce planktonic and biofilm oral communities resembling those of healthy individuals. Bioreactors were inoculated with the pooled saliva of healthy human volunteers and the composition of the biofilms formed on the hydroxyapatite disks was determined through 16S rRNA sequencing over an 8-day time course.
Results: We identified the presence of key oral taxa including Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria and Fusobacteria. The composition of biofilms changed at each timepoint, however no significant differences were observed between independent bioreactor systems, indicating that this methodology is reproducible. In the initial 24-hour colonisation phase the pH dropped to 5.63, however this was followed by a rapid increase to a stable non-cariogenic pH of 6.70.
Conclusions: The development of this model will facilitate standardised assessment of oral healthcare products and active compounds and allow their impact on the oral microbiome to be investigated.