Quorum sensing

Quorum sensing is microbial regulation of gene expression in response to signal molecules that accumulate as a population grows. It coordinates behaviors that are more effective when many cells act together.

Autoinducer: A signaling molecule produced and detected by microbes, often regulating gene expression according to its concentration. Autoinducers accumulate as cells produce them, conveying information about local population density.
Biofilm: A structured community of microorganisms attached to a surface and embedded in a self-produced matrix. Quorum sensing can regulate matrix production and other stages of biofilm development.
Bacterial cell: A single-celled organism whose genetic material is not enclosed in a membrane-bound nucleus. Quorum sensing links the behavior of individual bacterial cells into coordinated population responses.
Gram-positive quorum sensing: Quorum sensing in Gram-positive bacteria, commonly mediated by secreted peptides and membrane-bound receptors. Peptide-based signaling contrasts with the diffusible acyl-homoserine lactones common in Gram-negative models.
LuxI/LuxR quorum-sensing system: A bacterial signaling system in which LuxI produces an acyl-homoserine lactone detected by the LuxR regulator. This model system shows how an accumulating signal activates gene expression in Gram-negative bacteria.
Bacterial virulence: The capacity of bacteria to cause disease through traits that damage or evade a host. Some pathogens use quorum sensing to coordinate toxin production and other virulence traits.
Gene regulation: The control of when, where, and how strongly genes are expressed. Quorum sensing changes behavior by regulating particular genes in response to signals.
AI-2 quorum sensing: Quorum sensing involving autoinducer-2, a signaling molecule produced by diverse bacterial species. AI-2 provides a distinct signaling route often discussed in relation to interspecies communication.
Quorum-sensing threshold: The signal concentration at which quorum-sensing regulation produces a substantial change in gene expression. A threshold converts gradual signal accumulation into a coordinated population-level response.
Bioluminescence: The production of light by living organisms through chemical reactions. The classic Vibrio fischeri system uses quorum sensing to switch on light production at high cell density.

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