9/18/2016 Bacterial Cellular Communication Quorum Sensing Communication via small chemical molecules to coordinate Two different gene regulation activities as a population instead of as single cells mechanisms 1.Quorum sensing -population size Low Cell Dersity High Cell Density 2.Signal transduction-environment 飞 Tw-Cop Bacterial Quorum Sensing ⊙a LNI CDABE6 autoirduction Two-Component Signal Transduction response to environmental stress/stimuli Role of Quorum sensing in Food Microbiology Speculated that QS has a role in food spoilage Not much data to support this Signal molecules are found in food products such as milk,chicken soup, bean sprouts Components of food may mimic or alter Phasphorylated response QS signaling systems Modulates gene Probiotics may inhibit QS signaling 99/18/2016 9 Bacterial Cellular Communication • Two different gene regulation mechanisms 1. Quorum sensing – population size 2. Signal transduction - environment 33 Quorum Sensing Communication via small chemical molecules to coordinate activities as a population instead of as single cells Low Cell Density Hi h C ll D nsit High Cell Density Light luxR luxI C D A B E G LuxR LuxR LuxI Acyl-ACP SAM luxR luxI C D A B E G LuxI LuxR unstable inactive Luciferase autoinduction 34 Two-Component Signal Transduction response to environmental stress / stimuli Signal does not diffuse across the membrane Kinase transmits signal across the membrane via a conformational change Modulates gene expression in respone to the environment Phosphorylated response regulator activates gene expression 35 Role of Quorum sensing in Food Microbiology • Speculated that QS has a role in food spoilage • Not much data to support this • Signal molecules are found in food products such as milk, chicken soup, bean sprouts • Components of food may mimic or alter QS signaling systems • Probiotics may inhibit QS signaling 36