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M. W. GRIFFITHS, Dept. of Food Science, Univ. of Guelph, Canadian Research Institute for Food Safety, 43 McGilvray St., Guelph, ON N1G 2W1, Canada Bacteria talk to each other and the implications of this are becoming apparent to food microbiologists. This communication occurs at several levels; intraspecies (like talking to like), interspecies (communication among bacteria of different species and genera), and bacteria-host (communication with mammalian cells). This communication is achieved by the production of small molecules (termed autoinducers), which, when present at sufficient concentrations, trigger a variety of cellular responses. Thus, bacterial numbers must reach a certain level (quorum) to generate the critical concentration of these signaling molecules. This has led to the term quorum sensing to describe this phenomenon. Quorum sensing allows bacteria to co-ordinate their behaviour in response to changes in their environment. These responses include adaptation to availability of nutrients, for example through the synthesis of extracellular enzymes to scavenge nutrients or through the formation of biofilms. In Gram negative bacteria, the main signaling molecules are acyl homoserine lactones. However, a single bacterial species can use more than one signal molecule, and it may respond to each molecule in a different way. Interspecies communication in Gram negative bacteria is mediated through the production of autoinducer-2 (AI-2). Disruption of these signaling pathways may offer an approach to prevent biofilm formation in food processing plants and to improve the shelf-life of foods.
Session 42, Control of quorum sensing signals and antimicrobial effects on foods
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |