Quorum sensing is a way bacteria “talk” to each other by sending out and detecting special chemical signals called autoinducers. This helps them figure out how many other bacteria are nearby. When there are enough of them, they work together and turn on certain genes, especially ones that use a lot of energy, so their actions have a bigger effect—like releasing toxins or forming a biofilm—only when it really counts.
Quorum sensing (QS) is a mechanism of cell-to-cell communication in bacteria that allows them to detect and respond to population density by producing and responding to signaling molecules called autoinducers.
Processes controlled by QS include
- bioluminescence,
- sporulation,
- competence,
- antibiotic production,
- biofilm formation, and
- virulence factor secretion
Basic Mechanism
Variety of regulatory element and mechanism are present in quorum sensing but they share mostly follwing priciple-
- Autoinducer Synthesis: Bacteria synthesize and release small signaling molecules (autoinducers). Example AHL. At low cell density (LCD), autoinducer diffuse away because of this AI present below detection threshold diffuse away, but at high cell density (HCD), leads local high concentration of AIs, enabling detection and response.
- Accumulation: As the bacterial population increases, the concentration of autoinducers increases in the environment.
- Detection: When a threshold concentration is reached, bacteria detect the autoinducers through receptor proteins. This could be either cytosolic or present in the membrane.
- Gene Regulation: Binding of autoinducer to its receptor triggers a signal transduction cascade, leading to changes in gene expression.
Applications of Quorum Sensing
Medical
- Anti-virulence therapy: Targeting QS pathways instead of killing bacteria.
- Control of biofilm-related infections (e.g., in catheters, implants).
Biotechnology
- Synthetic biology: Engineering QS circuits in microbes.
- Biosensors: Use of QS-regulated genes for detection systems.
Agriculture
- Controlling plant pathogens by quorum quenching.
- Using beneficial bacteria to interfere with QS in harmful microbes.