Exposure of Salmonella enterica serovar typhimurium to three humectants used in the food industry induces different osmoadaptation systems

Sarah Finn, Lisa Rogers, Kristian Händler, Peter McClure, Alejandro Amézquita, Jay C.D. Hinton, Séamus Fanning*

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Citations (Scopus)
195 Downloads (Pure)


Common salt (NaCl) is frequently used by the food industry to add flavor and to act as a humectant in order to reduce the water content of a food product. The improved health awareness of consumers is leading to a demand for food products with reduced salt content; thus, manufacturers require alternative water activity-reducing agents which elicit the same general effects as NaCl. Two examples include KCl and glycerol. These agents lower the water activity of a food matrix and also contribute to limit the growth of the microbiota, including foodborne pathogens. Little is currently known about how foodborne pathogens respond to these water activity-lowering agents. Here we examined the response of Salmonella enterica serovar Typhimurium 4/74 to NaCl, KCl, and glycerol at three time points, using a constant water activity level, compared with the response of a control inoculum. All conditions induced the upregulation of gluconate metabolic genes after 6 h of exposure. Bacteria exposed to NaCl and KCl demonstrated the upregulation of the osmoprotective transporter mechanisms encoded by the proP, proU, and osmU (STM1491 to STM1494) genes. Glycerol exposure elicited the downregulation of these osmoadaptive mechanisms but stimulated an increase in lipopolysaccharide and membrane protein-associated genes after 1 h. The most extensive changes in gene expression occurred following exposure to KCl. Because many of these genes were of unknown function, further characterization may identify KCl-specific adaptive processes that are not stimulated by NaCl. This study shows that the response of S. Typhimurium to different humectants does not simply reflect reduced water activity and likely involves systems that are linked to specific humectants.

Original languageEnglish
Pages (from-to)6800-6811
Number of pages12
JournalApplied and Environmental Microbiology
Issue number19
Early online date24 Jul 2015
Publication statusPublished - Oct 2015

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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