Ecological feedback in quorum-sensing microbial populations can induce heterogeneous production of autoinducers

TL;DR

This paper presents a theoretical model demonstrating that ecological feedback in quorum-sensing microbial populations can lead to heterogeneous autoinducer production, independent of stochastic gene expression.

Contribution

It introduces a novel mechanism where ecological and population dynamics coupling induces phenotypic heterogeneity in autoinducer production.

Findings

Ecological feedback can cause heterogeneity in autoinducer production.

Non-producers replicate faster than producers.

Phenotypic heterogeneity arises without stochastic gene expression.

Abstract

Autoinducers are small signaling molecules that mediate intercellular communication in microbial populations and trigger coordinated gene expression via "quorum sensing". Elucidating the mechanisms that control autoinducer production is, thus, pertinent to understanding collective microbial behavior, such as virulence and bioluminescence. Recent experiments have shown a heterogeneous promoter activity of autoinducer synthase genes, suggesting that some of the isogenic cells in a population might produce autoinducers, whereas others might not. However, the mechanism underlying this phenotypic heterogeneity in quorum-sensing microbial populations has remained elusive. In our theoretical model, cells synthesize and secrete autoinducers into the environment, up-regulate their production in this self-shaped environment, and non-producers replicate faster than producers. We show that the coupling between ecological and population dynamics through quorum sensing can induce phenotypic heterogeneity in microbial populations, suggesting an alternative mechanism to stochastic gene expression in bistable gene regulatory circuits.