 Hi everyone. Today we are going to discuss about quorum sensing communication system. Quorum sensing is a cell-based communication system that controls the gene expression under the control of cell population density. Basically it controls the expression of various protein at particular cell density. Now let's imagine this is our bacterial cell which produces these small hormone-like molecules. These molecules are known as acyl-homocidine lactone molecules. These molecules play a very important role in signaling system therefore these are known as signaling molecules. These small molecules are received by another bacteria and we can say that there is a cell communication system that is working between these two bacteria which is known as quorum sensing. Now let's discuss the mechanism of quorum sensing. Suppose this is our bacterial cell and it has a lot of different kinds of protein inside it. One of the protein, very important protein is AHL synthase that produces these small molecule and then these small molecules are excreted outside at particular concentration they are received back into the cell and binds to quorum sensing receptor. These receptor with this molecule then binds to DNA and initiates the transcription of various genes. In many bacteria quorum sensing plays very important role in biofilm formation, virulence factor production and cell communication. Let's discuss the structure of AHL molecule. AHL molecule which is a signaling molecule composed of two major components. One homocerine lactone ring and second is fatty acid acyl side chain also known as acyl chain. Quorum sensing controls various important features in bacteria. The first one virulence, second one motility, third one growth, fourth biofilm, fifth protease, sixth elastase and the list is going on and these are really important attributes of bacteria. That was a brief introduction about quorum sensing. Please stay tuned for various exciting topics of basic science series. Thank you and Namaste.