Combinatorial quorum sensing allows bacteria to resolve their social and physical environment

TLDR

Quorum sensing is a widespread bacterial communication system, yet its functional purpose—whether it monitors cell density or environmental factors such as diffusion and flow—remains debated, and the use of multiple signal molecules is not well understood. The study introduces and evaluates a framework showing that bacteria can jointly infer social density and physical mass‑transfer conditions by responding combinatorially to multiple signals with different half‑lives. The authors model bacterial communication as nonadditive responses to multiple signals with distinct half‑lives, enabling simultaneous inference of density and mass‑transfer environments. The results demonstrate that combinatorial quorum sensing is computationally feasible in single‑cell organisms, extending beyond primates.

Abstract

Significance Many bacterial species engage in a form of cell–cell communication known as quorum sensing (QS). Despite great progress in unravelling the molecular mechanisms of QS, controversy remains over its functional role. There is disagreement over whether QS surveys bacterial cell density or rather environmental properties like diffusion or flow, and moreover there is no consensus on why many bacteria use multiple signal molecules. We develop and test a new conceptual framework for bacterial cell–cell communication, demonstrating that bacteria can simultaneously infer both their social (density) and physical (mass-transfer) environment, given combinatorial (nonadditive) responses to multiple signals with distinct half-lives. Our results also show that combinatorial communication is not restricted solely to primates and is computationally achievable in single-celled organisms.