Flagella bending affects macroscopic properties of bacterial suspensions

TL;DR

This paper presents a PDE model showing how bacterial flagella bending influences suspension viscosity and enables bacteria to escape wall entrapment, highlighting the role of flagella flexibility in bacterial flow interactions.

Contribution

The study introduces a PDE model that links flagella bending to macroscopic suspension properties without relying on tumbling behavior.

Findings

Flagella bending reduces effective viscosity in dilute suspensions.

Bacterial flagella buckling can facilitate escape from wall entrapment.

Flexible flagella influence bacteria's interaction with flow and obstacles.

Abstract

To survive in harsh conditions, motile bacteria swim in complex environment and respond to the surrounding flow. Here we develop a PDE model describing how the flagella bending affects macroscopic properties of bacterial suspensions. First, we show how the flagella bending contributes to the decrease of the effective viscosity observed in dilute suspension. Our results do not impose tumbling (random re-orientation) as it was done previously to explain the viscosity reduction. Second, we demonstrate a possibility of bacterium escape from the wall entrapment due to the self-induced buckling of flagella. Our results shed light on the role of flexible bacterial flagella in interactions of bacteria with shear flow and walls or obstacles.