Quorum-Sensing Systems in Pseudomonas

Abstract

Quorum sensing (QS) or cell-to-cell communication is a mechanism used by bacteria to control a broad range of activities in bacteria. The modulation of gene expression by quorum sensing causes phenotypic changes in bacteria leading to their better adjustment to environmental conditions and stress during growth (Turovskiy et al. 2007). Quorum sensing involves the production, secretion, and response to small diffusible signaling molecules also known as autoinducers. Bacteria produce signaling molecules at a basal level during the stationary phase of their growth, and with the increase in cell density, the concentration of the signaling molecule in the environmental medium increases; and on reaching a threshold level, it induces phenotypic effects by regulating quorum-sensing-dependent target gene expression (Czajkowski and Jafra 2009). Quorum sensing is involved mainly in the regulation of virulence, development of genetic competence, transfer of conjugative plasmids, sporulation, biofilm formation, antimicrobial peptide synthesis, and symbiosis (Bai and Rai 2011).