Stochastic motility energetics reveals cooperative bacterial swarming in optical tweezers

TL;DR

This study combines optical tweezers and stochastic thermodynamics to analyze the energetics of bacterial swarming, revealing non-equilibrium behaviors and cooperative motility mechanisms at the cluster level.

Contribution

It introduces a novel approach using the Photon Momentum Method and active Brownian modeling to quantify energetic dissipation in bacterial swarms.

Findings

Swarming clusters generate persistent dissipative flows.

Flagellar dynamics break detailed balance and exceed passive friction limits.

Cooperative motility results in dissipative currents overcoming trapping forces.

Abstract

Bacterial flagellar swarming enables dense microbial populations to migrate collectively across surfaces, often resulting in emergent, coordinated behaviors. However, probing the underlying energetics of swarming at the single cluster level remains a challenge. Here, we combine optical tweezers and multiparticle tracking within a stochastic thermodynamic framework to characterize the active motility of confined Proteus mirabilis clusters. Using the Photon Momentum Method to directly measure trapping forces, we show that swarming clusters generate persistent, dissipative flows indicative of non equilibrium stationary motility within confined solenoidal mesostructures. These flagellar rotational dynamics break detailed balance in mesoscopic force space and exceed the limits of passive friction, as evidenced by force velocity correlations and vortex like circulations. By coarse graining cluster trajectories into an active Brownian phase space, we quantify the work performed by bacterial swarms at cooperative coupling to thermal fluctuations, resulting in dissipative Ohmic like currents overcoming conservative trapping. Our findings establish a generalizable approach to quantify collective motility and energetic dissipation in active bacterial clusters, offering new insights into the physical principles governing microbial cooperativity.