Submitted to: Journal of Food Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/14/2007
Publication Date: 10/26/2007
Citation: Wedmer, K.W., Soni, K., Hume, M.E., Beier, R.C., Jesuanasan, P., Pillai, S.D. 2007. Identification of poultry meat-derived fatty acids functioning as quorum sensing signal inhibitors of autoinducer-2 (AI-2). Journal of Food Science. 72:M363-368. Interpretive Summary: Autoinducer-2 (AI-2) is a chemical that plays a key role in bacterial cell to cell communication (quorum sensing). Previous research had shown extracts from certain foods inhibit this signaling chemical. Other chemicals that inhibit quorum sensing and contained in poultry meat wash samples were characterized according to their relative size and their ability to mix in water. The inhibitor chemicals were shown to be relatively small that did not mix well with water. They were also shown to be a type of fat called fatty acids. Several fatty acids were identified, quantified, and tested for their ability to inhibit bacterial cell to cell communication. All of the fatty acids inhibited, to relatively medium and high levels, bacterial cell to cell communication. Bacteria treated with the fatty acids did not decrease their ability to grow and increase in numbers. The ability of these fatty acids to modulate quorum sensing in bacteria may offer unique means to control foodborne pathogens and reduce food spoilage caused by contaminating bacteria. The current information is of interest to researchers investigating strategies to reduce foodborne bacteria on foods. Additionally, the information is of interest to researchers and producers seeking alternatives to antibiotics as treatment against bacterial contamination and infection.
Technical Abstract: Autoinducer-2 (AI-2) is a compound that plays a key role in bacterial cell-to-cell communication (quorum sensing). Previous research has shown certain food matrices inhibit this signaling compound. Using the reporter strain, Vibrio harveyi BB170, quorum sensing inhibitors contained in poultry meat wash (PMW) samples were characterized by molecular weight and hydrophobic properties using liquid chromatography systems. Most fractions that demonstrated AI-2 inhibition were 13.7 k Daltons, or less, and had hydrophobic properties. Hexane was used to extract inhibitory compounds from a PMW preparation and the extract was further separated by gas chromatography (GC). Several fatty acids were identified and quantified. Linoleic acid, oleic acid, palmitic acid, and stearic acid were each tested for inhibition at 0.1, 1, and 10 mM concentrations. All samples expressed AI-2 inhibition (ranging from approximately 25 to 99%). Fatty acids, combined in concentrations equivalent to those determined by GC analysis, expressed inhibition at 59.5%, but higher combined concentrations (10- and 100-fold) had inhibition at (84.4% and 69.5%, respectively). The combined fatty acids (100-fold) did not demonstrate a significant decrease in colony plate counts, despite presenting high AI-2 inhibition. These fatty acids, through modulating quorum sensing by inhibition, may offer a unique means to control foodborne pathogens and reduce microbial spoilage.