Bacterial communities often synthesize and embed themselves in a sticky polymer matrix known as a biofilm which provides a safe environment protected from many environmental stresses. As Steve Atkinson describes in this article in Microbiology Today, for this mode of living to be successful the members of the community need to communicate:
When the first bacteria were observed with a microscope, it must have been something of a leap of faith to believe they were living organisms, let alone consider that they were not behaving as individuals, but were in fact co-operating in a coordinated community where cell-to-cell communication plays an integral part in their life cycle. As early as 1905, Erwin Frink Smith, in his manuscript Bacteria in relation to plant disease was astute enough to comment that ‘a multiple of bacteria are stronger than a few’, but it was not until the early 1990s that the concept of bacterial cell-to-cell communication actually gained credence within the microbiological community with the discovery that bacteria employ chemical signals (pheromones) to communicate, and so coordinate population-wide behaviour with changes in environmental conditions. The concept of bacterial cell-to-cell signalling, usually referred to as quorum sensing (QS), has now been observed in a wide variety of Gram-positive and Gram-negative plant and animal pathogens, including those responsible for important human diseases. It is also noteworthy that QS systems are not limited to prokaryotes, but have also been described in eukaryotes such as yeast.