Even microbiologists believed for centuries that bacteria are solitary organisms; but new discoveries have a different story to tell.

Pioneering studies on bacterial communication started with a phenomenon observed in the bioluminescent marine bacteria, Vibrio fischeri. Naturally, this species of bacteria resides inside the light-producing organs of bobtail squid. When grown in cultured conditions in the laboratory, it was found that these are only able to produce light when their population is dense. This finding suggested that these bacteria may be producing signals that enable them to sense their “quorum” or population density in the culture medium. This hypothesis was proven by the isolation and purification of the supposed signal molecule and when further molecular mechanisms of this signaling system were elucidated. This communication system in bacteria came to be known as quorum sensing.

Quorum sensing is now one of the hot topics of research in microbiology having been known that most, if not all, bacteria utilize a communication system similar to that of V. fischeri. Even more interesting is the fact that quorum sensing actually regulates and governs the expression of important behaviors or phenotypes in bacteria. For instance, it was found that it controls the production of proteins used by many disease-causing bacteria during infection and invasion of their hosts. The disruption of this communication system was therefore found to be effective in fighting diseases caused by bacteria, especially those that are resistant to antibiotics.