Dynamic Clustering in Suspension of Motile Bacteria

TL;DR

This study investigates how motile Serratia marcescens bacteria spontaneously form dynamic, long-lived clusters at an air-liquid interface driven by surface-mediated hydrodynamic interactions, affecting local transport processes.

Contribution

It demonstrates the formation and behavior of bacterial clusters at interfaces due to hydrodynamic interactions, revealing their dynamic nature and potential environmental impact.

Findings

Clusters exhibit random translation and counter-clockwise rotation.

Hydrodynamic interactions strongly influence cluster properties.

Clusters alter material and fluid transport near the interface.

Abstract

Bacteria suspension exhibits a wide range of collective phenomena arising from interactions between individual cells. Here we show Serratia marcescens cells near an air-liquid interface spontaneously aggregate into dynamic clusters through surface-mediated hydrodynamic interactions. These long-lived clusters translate randomly and rotate in the counter-clockwise direction; they continuously evolve, merge with others and split into smaller ones. Measurements indicate that long-ranged hydrodynamic interactions have strong influences on cluster properties. Bacterial clusters change material and fluid transport near the interface and hence may have environmental and biological consequences.