Pressure-induced Shape-shifting of Helical Bacteria

TL;DR

This study explores how elastic heterogeneity and pressurization can induce helical shapes in bacteria and elastic cylinders, providing insights into bacterial morphology and potential applications in pressure-controlled actuators.

Contribution

It demonstrates experimentally and theoretically that pressurizing elastic cylinders with reinforced lines can produce helical shapes, influenced by initial angles, revealing a new mechanism for bacterial shape formation.

Findings

Helical morphogenesis can be induced by pressurizing elastic cylinders with reinforced lines.

Steep reinforced angles lead to crooked helices with reduced end-to-end distance.

The properties of the resulting helix depend on the initial helical angle.

Abstract

Many bacterial species are helical in form, including the widespread pathogen H. pylori. Motivated by recent experiments on H. pylori showing that cell wall synthesis is not uniform, we investigate the possible formation of helical cell shape induced by elastic heterogeneity. We show, experimentally and theoretically, that helical morphogenesis can be produced by pressurizing an elastic cylindrical vessel with helical reinforced lines. The properties of the pressurized helix are highly dependent on the initial helical angle of the reinforced region. We find that steep angles result in crooked helices with, surprisingly, reduced end-to-end distance upon pressurization. This work helps to explain the possible mechanisms for the generation of helical cell morphologies and may inspire the design of novel pressure-controlled helical actuators.