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In vitro modelling of tongue derived microbial biofilms and their reponse to treatment

Hewett, Keith Edward

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Keith Edward Hewett


This work concerns the development of a flat plate perfusion model to study biofilms derived from human tongue biota. The model has been derived from a previous sorbarod model, via a flat plate model (used to study wound organisms), to the model described in this thesis. The specific technical objectives were; 1. To measure biofilm pH in real time, 2. To extend VOC analysis by SIFT-MS to six biofilms in parallel and 3. To enable photodynamic interventions and optical monitoring of bioluminescent and non-bioluminescent organisms. The specific scientific objectives were; 1. To validate the model by comparison of in vivo and in vitro case studies, 2. To characterise the in vivo biofilm ecology and compare with ecology in vitro, 3. To compare existing and novel anti-malodour preparations and biofilm disrupting agents (including D-amino acids) and 4. To assess and aid the development of a novel handheld surface plasmon resonance based device for measuring oral volatile compounds.

The results demonstrated that the biofilms transplanted from human donors are stable and reproducible, and that profiles of volatile compounds are retained in the transplanted biofilm, with high and low malodour individuals producing high and low malodour biofilms (profiles are indistinguishable by χ2 analysis at p < 0.1). The model was used to evaluate a novel formulation which was shown to be more effective than similar active compounds and controls (p < 0.05). In a further experiment, exposure of biofilms to D-amino acids during the growth phase was shown to cause significant (P< 0.05) effects onmicrobial and EPS composition compared with controls.

Finally, the model in conjunction with SIFT-MS has been used to assess the performance of a novel surface plasmon resonance based biosensor. This biosensor has been shown to distinguish high and low malodour biofilms both in vitro and in vivo.

In conclusion it has been demonstrated that the flat plate perfusion system is a stable, reproducible and accurate model covering many of the main aspects of a real tongue biofilm, and it has many advantages when compared with other published biofilm models.

Thesis Type Thesis
APA6 Citation Hewett, K. E. In vitro modelling of tongue derived microbial biofilms and their reponse to treatment. (Thesis). University of the West of England. Retrieved from


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