The role of body rotation in bacterial flagellar bundling

TL;DR

This paper demonstrates that the counter-rotation of the bacterial cell body alone can cause flagellar bundling during chemotaxis, without requiring the swirling flows from individual filaments, highlighting a key mechanical aspect of bacterial motility.

Contribution

It reveals that cell body counter-rotation is sufficient for flagellar bundling, providing a new understanding of the mechanics behind bacterial swimming behavior.

Findings

Counter-rotation of the cell body can induce flagellar bundling

Resistive-force theory explains bundling without filament swirling flows

Cell body rotation alone influences bacterial motility mechanisms

Abstract

In bacterial chemotaxis, E. coli cells drift up chemical gradients by a series of runs and tumbles. Runs are periods of directed swimming, and tumbles are abrupt changes in swimming direction. Near the beginning of each run, the rotating helical flagellar filaments which propel the cell form a bundle. Using resistive-force theory, we show that the counter-rotation of the cell body necessary for torque balance is sufficient to wrap the filaments into a bundle, even in the absence of the swirling flows produced by each individual filament.