Quorum Sensing Circuits in the Communicating Mechanisms of Bacteria and Its Implication in the Biosynthesis of Bacteriocins by Lactic Acid Bacteria: a Review.

It is well established that bacteria communicate between each other by using different mechanisms; among which, quorum sensing (QS) is the best known one. Indeed, intra- and intercellular communications of microorganisms, as well as the regulation of metabolism and reaction to the surrounding environmental conditions, are carried out by using different signaling molecules. N-Acyl homoserine lactones control the QS in Gram-negative bacteria, while Gram-positive bacteria use communicating peptides. These compounds, by diffusing through the bacterial membrane cell from the extracellular medium, directly or indirectly control the expression of specific genes that induce bacteria to react to their surrounding environment and stressing agents. In the case of lactic acid bacteria and bifidobacteria which are widely used in the dairy industry, QS is of extreme importance for their survival and the extent of their activity in the dairy matrix. Moreover, it is also via QS that these bacteria synthesize various antimicrobial agents such as bacteriocins. The aim of this review is to highlight the quorum sensing circuits involved in the communicating mechanisms of bacteria with emphasis on current applications of QS in lactic acid bacteria. More particularly, the implication of QS in the biosynthesis of bacteriocins by lactic acid bacteria will be detailed.