Bending Instability of Rod-shaped Bacteria

TL;DR

This paper investigates how internal pressure influences the bending instability of thin-walled, rod-shaped bacteria, revealing that pressure delays instability onset and proposing a new method to measure bacterial turgor pressure.

Contribution

It provides a theoretical analysis of pressurized rod-shaped bacteria, highlighting the effect of internal pressure on bending instability and introducing a novel pressure inference method.

Findings

Internal pressure significantly delays instability onset.

Bending stiffness has minimal effect on instability.

Proposes a new method to measure bacterial turgor pressure.

Abstract

A thin-walled tube, e.g., a drinking straw, manifests an instability when bent by localizing the curvature change in a small region. This instability has been extensively studied since the seminal work of Brazier nearly a century ago. However, the scenario of pressurized tubes has received much less attention. Motivated by rod-shaped bacteria such as E. coli, whose cell walls are much thinner than their radius and are subject to a substantial internal pressure, we study, theoretically, how this instability is affected by this internal pressure. In the parameter range relevant to the bacteria, we find that the internal pressure significantly postpones the onset of the instability, while the bending stiffness of the cell wall has almost no influence. This study suggests a new method to infer turgor pressure in rod-shaped bacteria from bending experiments.