Optimal census by quorum sensing

TL;DR

This paper investigates how feedback mechanisms in bacterial quorum sensing can enhance the information bacteria obtain about their local cell density, potentially improving their environmental sensing capabilities.

Contribution

It introduces a quantitative framework showing feedbacks can increase information transmission in quorum sensing, enabling bacteria to distinguish more density ranges.

Findings

Feedbacks can increase information transmission about cell density.

Bacteria can resolve up to two additional density ranges with feedbacks.

Feedback mechanisms enhance environmental sensing in multi-agent systems.

Abstract

Quorum sensing is the regulation of gene expression in response to changes in cell density. To measure their cell density, bacterial populations produce and detect diffusible molecules called autoinducers. Individual bacteria internally represent the external concentration of autoinducers via the level of monitor proteins. In turn, these monitor proteins typically regulate both their own production and the production of autoinducers, thereby establishing internal and external feedbacks. Here, we ask whether feedbacks can increase the information available to cells about their local density. We quantify available information as the mutual information between the abundance of a monitor protein and the local cell density for biologically relevant models of quorum sensing. Using variational methods, we demonstrate that feedbacks can increase information transmission, allowing bacteria to resolve up to two additional ranges of cell density when compared with bistable quorum-sensing systems. Our analysis is relevant to multi-agent systems that track an external driver implicitly via an endogenously generated signal.