Quorum Sensing – How bacteria communicate

November 18, 2022

Quorum sensing is a phenomenon found in bacteria. Individual cells coordinate their behavior according to the density of their population. This allows for change in gene expression in response to changes in cell-population density.
Simply put, quorum sensing enables bacteria to “communicate” with one another. It also allows them to coordinate their activities. Think of this as the equal of our global cell phone network service. Except that it happened well before human beings evolved on planet earth. But you might ask, why do microbiota need quorum sensing and what do they use it for?
One important role of quorum sensing is the regulation of microbiota itself. The microbiota is the collection of all microorganisms that live within a host. These include bacteria, viruses, fungi and protozoa.
The human gut microbiota, for example, plays an important role in digestion, immune function, and metabolism. In order for the microbiota to function properly, it is important that the different types of bacteria are able to communicate with one another. Quorum sensing then relies on the production and detection of small molecules known as autoinducers. Autoinducers are secreted by bacteria and diffused throughout the surrounding environment. When the concentration of autoinducers reaches a threshold level, this triggers a change in gene expression within the bacteria. This change in gene expression results in the coordinated behavior of the bacterial population.
For example, quorum sensing has been shown to regulate the production of virulence factors by pathogenic bacteria. Virulence factors are proteins or other molecules that enable bacteria to cause disease. In many cases, virulence factors are only produced when the bacterium is part of a large population; this allows pathogenic bacteria to avoid detection and destruction by the immune system when they are present in low numbers. Once sufficient numbers have amassed, however, quorum sensing allows pathogenic bacteria to coordinately produce virulence factors and cause disease.

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