Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2006
Publication Date: 4/20/2006
Citation: Widmer, K.W., Jesudhasan, P., Dowd, S.E., Pillai, S.D. 2006. Gene expression in Salmonella enterica serotype Typhimurium luxS mutant in response to quorum sensing signals and a poultry meat-derived quorum sensing inhibitor using microarray-based studies [abstract]. In: American Society for Microbiology 106th General Meeting Abstracts, May 21-25, 2006, Orlando, Florida. 2006 CDROM. No. P-045. Interpretive Summary:
Technical Abstract: Quorum sensing describes the processes in which bacteria cells produce, secrete, and communicate using chemical signal molecules. There is evidence that these sensing signals, especially AI-2, can influence bacterial gene expression. We have previously shown that food matrices, such as poultry wash (PW), can contain inhibitors that interfere with cell signaling systems. The objective of this study was to understand the expression of Salmonella Typhimurium genes in response to AI-2 in the presence and absence of poultry meat derived inhibitors. DNA spotted microarrays were utilized to determine the gene expression response of a Salmonella Typhimurium luxS mutant (unable to produce AI-2), when treated with purified AI-2 or 'AI-2' cell free cultures (CFS) of a Salmonella Typhimurium wild type, to those combined with PW treatments. The treatments were comprised of 90% Luria Broth combined with 10% (AI-2, AI-2 + PW, CFS, or CFS + PW) of the conditioned treatment. Total RNA was extracted from the S. Typhimurium luxS mutant after culturing the organism in the treated Luria Broth medium for 3 hours. All treatments were compared to a reference S. Typhimurium LT2 strain as a uniform control for the hybridization experiments. Of a total of 1152 genes on the array, 16 genes were differentially expressed (3 up regulated and 13 down regulated) at least 2-fold comparing the purified AI-2 treatment to the combined AI-2 + PW treatment. The AI-2 CFS, when compared to the combined AI-2 CFS + PW treatment, had nearly twice the number of genes differentially expressed (42 genes at least 2-fold), with 26 of the genes up regulated, while 16 were down regulated. All genes differentially expressed were statistically significant (P = 0.05). These results indicate that there is a varied gene expression of Salmonella when comparing purified AI-2 to that of 'AI-2' cell-free cultures when combined with quorum sensing inhibitors derived from a food matrix. The understanding of interaction of these quorum sensing inhibitors with QS signals may help illuminate how certain foods may be susceptible to bacterial colonization, or provide a unique means to control bacterial pathogens in foods.