From local defects to shear-organized biofilms in tonsillar crypts via computational simulations

TL;DR

This paper presents a biophysical simulation framework explaining how mechanical interactions in tonsillar crypts lead to persistent, organized biofilm structures, advancing understanding of their spatial localization and long-term behavior.

Contribution

It introduces a novel biophysical model combining defect nucleation and shear instability to explain biofilm organization in crypts.

Findings

Coexistence of defect nucleation and shear instability produces organized biofilm structures.

Simulations show only combined mechanisms yield persistent, localized interface features.

Absence of either mechanism results in diffuse, unstructured biofilm dynamics.

Abstract

Biofilms in human tonsillar crypts show long term persistence with episodic dispersal that current biochemical and microbiological descriptions do not fully explain, particularly with respect to spatial localization. We introduce a biophysical framework in which tonsillar biofilm dynamics arise from the interaction between two mechanical phenomena: a Kosterlitz Thouless type defect nucleation process and a Kelvin Helmholtz type shear driven interfacial instability. Crypt geometry is modeled as a confined, heterogeneous environment that promotes mechanically persistent surface defects generated by growth induced compression. Tangential shear associated with breathing and swallowing selectively amplifies these defects, producing organized surface deformations. Numerical simulations show that only the coexistence of both mechanisms yields localized, propagating, and persistent interface structures, whereas their absence leads to diffuse, unstructured dynamics.