Bacterial motility and behaviours in viscoelastic materials

Abstract

The motility of Escherichia coli in viscoelastic environments like mucus is essential for understanding its role in infection and nutrient transport. My research focuses on Escherichia coli’s K-12 strain, tested in mucin-rich media derived from porcine stomach, to mimic the viscoelastic conditions these bacteria encounter in biological systems. The motility and behaviour of Escherichia coli in a Newtonian fluid (phosphate-buffered saline, PBS) and a viscoelastic medium (2% mucin) were investigated using video microscopy, mean- squared displacement (MSD) analysis, log-log diffusion scaling, and qualitative observations. The results showed that bacterial motility in both PBS and mucus was significantly different from that in PBS. In addition, bacterial trajectories in both environments showed a significant difference in the mean squared displacement versus time and diffusion exponent (α) approximations, indicating a strong relationship between bacterial movement and the viscosity of the environment. This study provides a method and framework for evaluating bacterial mobility through complex biological media and represents a foundation for future investigations into the mechanical and biochemical parameters ensuring host-pathogen interactions. This work lays the groundwork for better understanding microbial behaviour in host-like environments and ultimately exposing the mechanical hurdles that bacteria must overcome to successfully colonize mucosal surfaces.