Quorum sensing (QS) as etiological phenomenon: the bacterial paradigm.

Signaling mechanisms that govern physiological and morphological responses to change the cell density are common in bacteria. Quorum sensing is signal transduction processes which involves the production and release of and response to hormone-like molecules (auto-inducers) that accumulate in the external environment as the cell population grows. Quorum sensing is found in a wide variety of bacteria, both Gram-positive and Gram-negative and the spectrum of physiological functions that can be regulated is impressive. Variation in the nature of the extra-cellular signal in the signal detection machinery and in the mechanisms of signal transmission demonstrates the evolutionary adaptability of quorum sensing systems for multiple uses.