Anisotropic Diffusion Model of Communication in 2D Biofilm

TL;DR

This paper develops a 2D anisotropic diffusion model for bacterial communication within biofilms, analyzing how molecular signals propagate differently depending on biofilm structure and position, with implications for faster environmental response.

Contribution

It introduces a novel 2D anisotropic diffusion model for biofilm communication and validates it with simulations, highlighting effects of anisotropy on signal propagation.

Findings

Anisotropic diffusion causes higher peaks when transmitter is off-center.

Propagation speed is inversely related to biofilm size and diffusion coefficient.

Symmetry results in similar diffusion for isotropic and anisotropic cases.

Abstract

A biofilm is a microbial city. It consists of bacteria embedded in an extracellular polymeric substance (EPS) that functions as a protective barrier. Quorum sensing (QS) is a method of bacterial communication, where autoinducers (AIs) propagate via diffusion through the EPS and water channels within the biofilm. This diffusion process is anisotropic due to varying densities between the EPS and water channels. This study introduces a 2D anisotropic diffusion model for molecular communication (MC) within biofilms, analyzing information propagation between a point-to-point transmitter (TX) and receiver (RX) in bounded space. The channel impulse response is derived using Green's function for concentration (GFC) and is validated with particle-based simulation (PBS). The outcomes reveal similar results for both isotropic and anisotropic diffusion when the TX is centrally located due to symmetry. However, anisotropic conditions lead to greater diffusion peaks when the TX is positioned off-center. Additionally, the propagation of AIs is inversely proportional to both overall biofilm size and and diffusion coefficient values. It is hypothesized that anisotropic diffusion supports faster responses to hostile environmental changes because signals can propagate faster from the edge of the biofilm to the center.