How Bacteria Communicate? Know about Bacterial Quorum Sensing

WHAT IS QUORUM SENSING?

- Jay Prakash Yadav, Pankaj Dhaka and Deepthi Vijay

Figure 1: An overview of population dependent quorum sensing among bacteria

Quorum sensing (QS) is a cell-to-cell communication system in bacteria. It occurs due to the production, secretion, and sensing of extracellular molecules or signals called as autoinducers (AIs). The AIs take parts in many physiological metabolic processes of cells, such as bioluminescence, biofilm formation, bacterial virulence, antibiotic production, motility, sporulation, etc. The process of QS starts whenever bacterial cell number increases beyond a particular point, known as threshold concentration. The signal molecules (AIs) interact with the bacterial receptors in the process of cell-to-cell communication (Figure 1).

HOW WAS QUORUM SENSING DISCOVERED?

Quorum sensing was first described in1970, by Kenneth Nealson, Terry Platt, and J. Woodland Hastings in the bioluminescent marine bacterium- Vibrio fischeri through the identification of “autoinducing” activity in the high-density bacterial cell medium. Initially, they ascribed this conditioning of medium is due to the growing population of cells and termed this phenomenon as “autoinduction”.

WHEN DO BACTERIA USE QUORUM SENSING?

From public health perspective, the bacterial QS signaling play important roles in biofilm formation, antimicrobial resistance, and bacterial virulence. These phenomena occur due to production, release, and detection of extracellular signal molecules (autoinducers). These molecules allow cells to coordinate gene expression based on bacterial cell density in the outer cell environment.

Biofilm formation: