Despite being an anaerobe, Fn exhibits a relatively high oxygen tolerance.52 We next evaluated the ability of our asymmetric coculture system to coculture gingival epithelial cells with more oxygen-sensitive anaerobes, such as Porphyromonas gingivalis (Pg).53 As an oral pathogen, Pg is closely related to the progression of periodontitis.16,54 We hypothesized that using an oral bacterium with significantly lower oxygen tolerance would rigorously test whether oxygen leakage and diffusion through the cell monolayer into the apical chamber adversely impact bacterial viability. This evidence concerns the gene FN1 and periodontitis.