Flagella-induced transitions in the collective behavior of confined microswimmers

TL;DR

This study presents a physical model showing how reduced flagellar activity in confined microswimmers causes a transition from turbulent swimming to aggregation, shedding light on biofilm formation mechanisms.

Contribution

It introduces an idealized model linking flagellar activity to collective behavior transitions in confined microswimmers, highlighting hydrodynamic interactions as a key factor.

Findings

Decreasing flagellar activity triggers a transition to clustering.

Hydrodynamic interactions influence collective behavior.

Results have implications for understanding biofilm initiation.

Abstract

Bacteria exist in a free-swimming state or in a sessile biofilm state. The transition from free-swimming to sessile mode is characterized by changes in gene expression which alter, among others,the mechanics of flagellar motility. In this paper, we propose an idealized physical model to investigate the effects of flagellar activity on the hydrodynamic interactions among a population of microswimmers. We show that decreasing flagellar activity induces a hydrodynamically-triggered transition in confined microswimmers from turbulent-like swimming to aggregation and clustering. These results suggest that the interplay between flagellar activity and hydrodynamic interactions provides a physical mechanism for coordinating collective behaviors in confined bacteria, with potentially profound implications on biofilm initiation.