Buffer capacity of food components influences the acid tolerance response in Salmonella Typhimurium during simulated gastric passage

Sidsel Henriksen, Tasja Buschhardt, Tina Beck Hansen, Tina Birk, Søren Aabo

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Abstract

Food composition, buffer capacity, and fat and protein content have been shown to effect the gastric acid survival of pathogens (Waterman & Small 1998). In this study, simple food-model substances with different buffer capacities were investigated for their ability to support survival of stationary phase Salmonella Typhimurium during simulated gastric acid passage. We used a computer-controlled fermentor to employ pH changes in synthetic gastric fluid, mimicking the dynamic pH during gastric passage. In order to minimise variation, Salmonella enterica serovar Typhimurium was contained in dialysis tubes, enabling simultaneous testing of biological triplicates under varying conditions. Surprisingly, we found that less buffered media provided higher protection of Salmonella, compared to media with high buffer capacity. By investigating the relative gene expression of rpoS and ompR encoding for two major stationary phase ATR regulators, we found an approx. four-fold increase in expression of ompR and an approx. three-fold increase of rpoS in saline and buffered saline, respectively, after 15 min of gastric acid challenge. The relative expression of these genes, were significantly lower in Brain Heart Infusion Broth having a higher buffer capacity. We suggest this to be associated with a varying ability of Salmonella Typhimurium to mount a stationary phase acid tolerance response (ATR) depending on the buffer capacity of the food vehicle.
Original languageEnglish
Title of host publicationThe Danish Microbiological Society Annual Congress 2014 : Program & Abstracts
Number of pages1
PublisherAmerican Society for Microbiology
Publication date2014
Pages37
Article numberP41
Publication statusPublished - 2014
EventThe Danish Microbiological Society Annual Congress 2014 - Eigtved's Pakhus, Copenhagen, Denmark
Duration: 10 Nov 2014 → …

Conference

ConferenceThe Danish Microbiological Society Annual Congress 2014
LocationEigtved's Pakhus
CountryDenmark
CityCopenhagen
Period10/11/2014 → …

Cite this

Henriksen, S., Buschhardt, T., Hansen, T. B., Birk, T., & Aabo, S. (2014). Buffer capacity of food components influences the acid tolerance response in Salmonella Typhimurium during simulated gastric passage. In The Danish Microbiological Society Annual Congress 2014: Program & Abstracts (pp. 37). [P41] American Society for Microbiology.