Elastohydrodynamic synchronization of rotating bacterial flagella

TL;DR

This paper demonstrates that bacterial flagella synchronize through an elastohydrodynamic mechanism, with the synchronization rate depending on elastic compliance, providing new insights into bacterial motility.

Contribution

It introduces a rigorous coarse-grained model showing bacterial flagella naturally synchronize via elastohydrodynamics, a novel mechanism compared to prior models.

Findings

Synchronization rate peaks at intermediate elastic compliance

Bacterial flagella synchronize to zero phase difference

Elastohydrodynamics plays a key role in bacterial flagella coordination

Abstract

To rotate continuously without jamming, the flagellar filaments of bacteria need to be locked in phase. While several models have been proposed for eukaryotic flagella, the synchronization of bacterial flagella is less well understood. Starting from a reduced model of flexible and hydrodynamically-coupled bacterial flagella, we rigorously coarse-grain the equations of motion using the method of multiple scales, and hence show that bacterial flagella generically synchronize to zero phase difference via an elastohydrodynamic mechanism. Remarkably, the far-field rate of synchronization is maximized at an intermediate value of elastic compliance, with surprising implications for bacteria.