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<OL> <LI> Identify the most promising supernatants of probiotic bacteria (Cell Free Spent Media) for their aptitude to inhibit biofilm formation by L. monocytogenes.
<LI> Identify the most promising supernatants of probiotic bacteria for their aptitude to modulate the agr or prf system of L. monocytogenes (implied in virulence expression) using genetically modified L. monocytogenes strains. These constructs will allow a fast and inexpensive screening of probiotic strains.
<LI> Purify the most promising probiotic supernatants identified in 1. and 2. to allow identification of their active components and to allow their concentration.
<LI> Characterize the effects of purified and concentrated extracts using real-time PCR and microarrays to study aptitude for decreasing virulence gene expression and decreasing stress resistance expression.
<LI> Confirm aptitude of purified and concentrated extracts to decrease biofilm formation and check their ability to decrease invasion of Caco-2 cells
Expected Benefits: <BR>
Identification and purification of active molecules able to decrease the virulence expression of L. monocytogenes or its ability to persist in food-related stress conditions will constitute new and powerful tools to the food industry to control L. monocytogenes but also to pharmaceutical industries to provide better prophylactic and therapeutic treatment to at risk population.
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In addition a better understanding of the virulence mechanisms of this bacterium using quorum sensing will keep Ontario as a leader in this research area