Quorum Sensing and its Correlation with Virulence Factors

Quorum sensing (QS) is cell to cell signaling mechanism that enables bacteria collectively control gene expression in response to their population density, or it is bacterial communicate with one another using chemical signals. There are three types of signaling molecules: Acyl-homoserinelactonase (AHLs), Auto-inducer peptides (AIPs) and Autoinducer-2 (AI-2). Q.S was first observed and described in bioluminescence bacterium V.fischeri.In V. fischeri, several kinds of quorum sensing system were identified. At first, lux system was found and regulates the luciferase operon and light production. LuxIwas isolated as an AHL synthase while LuxR was isolated as a transcriptional activator of the luciferase operon. At low cell density, LuxOrepresses LitR, which is a positive regulator of the expression of LuxR. Quorum quenching (QQ) refers to the mechanism by which bacterial communication can be interrupted, or it is the process of preventing QS by disrupting the signaling.The first major QS-disrupting strategy that has been studied is the interference with the detection of the AIs and the second one is the inactivation/degradations of the signal molecules.