Robustness and Precision of Bacterial Quorum Sensing in Fluid Flow

Abstract

Quorum sensing allows bacterial cells to transfer information within populations and make collective measurements about aspects of their surroundings. In this process, quorum sensing molecules diffuse between cells and are therefore exposed to local external forces including advection by fluid flow, a ubiquitous feature of natural and industrial environments. However despite the recent design of experimental systems to test the macroscopic effects of fluid flow on intercellular signaling, the links between microscale genetic circuits and macroscale responses to steady or intermittent flow are not well understood. Here, we develop a theory that explains recent experimental observations by linking population-level spatial and temporal processes to cell-level genetic networks. Our theory predicts that positive feedback in signaling networks acts as a low pass filter that enables cells to respond to the average shear rate of a dynamically changing flow. This suggest that signaling systems with positive feedback act with spatiotemporal robustness in response to changes in fluid flow, whereas systems with negative feedback respond quickly and locally. Our results shed light on how various bacterial signaling systems are adapted to typical physiological environments.