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

摘要

Autoinducers are small signaling molecules that mediate intercellularcommunication in microbial populations and trigger coordinated gene expressionvia "quorum sensing". Elucidating the mechanisms that control autoinducerproduction is, thus, pertinent to understanding collective microbial behavior,such as virulence and bioluminescence. Recent experiments have shown aheterogeneous promoter activity of autoinducer synthase genes, suggesting thatsome of the isogenic cells in a population might produce autoinducers, whereasothers might not. However, the mechanism underlying this phenotypicheterogeneity in quorum-sensing microbial populations has remained elusive. Inour theoretical model, cells synthesize and secrete autoinducers into theenvironment, up-regulate their production in this self-shaped environment, andnon-producers replicate faster than producers. We show that the couplingbetween ecological and population dynamics through quorum sensing can inducephenotypic heterogeneity in microbial populations, suggesting an alternativemechanism to stochastic gene expression in bistable gene regulatory circuits.