ABSTRACT
In the last few years, signicant progress has been made in understanding the virulence, transmission, survival, stress response, and interactions of food-borne bacteria with other microbiota. However, the knowledge we have about the ecology of food spoilage bacteria and the biochemical mechanisms behind spoilage at the molecular level is considerably less. A number of studies imply that virulence-and spoilage-regulated phenotypes in food-borne bacteria are cell density-dependent phenomenon regulated at the genetic level by the mechanism of quorum sensing. In quorum sensing (QS) or cell-to-cell communication, bacteria produce, detect, and respond to the signaling molecules, also known as autoinducers. Bacteria sense their population density by monitoring the signal molecules in their environment and respond to it by activating or repressing target genes and the expression of certain phenotypes. In this
21.1 Introduction .................................................................................................................................. 399 21.2 Quorum Sensing Systems in Bacteria .......................................................................................... 400
21.2.1 Acylated Homoserine Lactones ....................................................................................... 400 21.2.2 Autoinducer 2 .................................................................................................................. 400 21.2.3 Autoinducer-3/QseC System ............................................................................................ 401 21.2.4 AIP/Agr System ............................................................................................................... 401
21.3 Mechanism of Quorum Sensing in Food-Borne Pathogens ........................................................ 402 21.3.1 E. coli and Salmonella Typhimurium ............................................................................. 402 21.3.2 V. harveyi ......................................................................................................................... 403 21.3.3 Vibrio cholerae ................................................................................................................ 403 21.3.4 Bacillus cereus ................................................................................................................ 404
21.4 Quorum Sensing in Food Spoilage Bacteria ................................................................................ 404 21.5 Biolms in Food Systems ............................................................................................................ 404 21.6 Quorum Sensing Inhibitory Mechanisms .................................................................................... 405
21.6.1 Inhibition of Signal Generation/Degradation.................................................................. 405 21.6.2 Inhibition of Signal Reception/Transduction .................................................................. 406 21.6.3 Nonspecic QS Inhibition ............................................................................................... 406
21.7 Quorum Sensing Inhibitors as Food Preservatives ...................................................................... 407 21.7.1 Synthetic Quorum Sensing Inhibitors ............................................................................. 408 21.7.2 Quorum Quenching by Bacteria ...................................................................................... 408 21.7.3 QS Inhibitors from Food ................................................................................................. 408 21.7.4 Phytochemicals as Quorum Sensing Inhibitors .............................................................. 409
References ...............................................................................................................................................410
