Strain and serovar variants ofSalmonella entericaexhibit diverse tolerance to food chain-related stress

Abstract

AbstractNon-TyphoidalSalmonella(NTS) continues to be a leading cause of foodborne illness worldwide. Food manufacturers implement hurdle technology by combining more than one approach to control food safety and quality, including preservatives such as organic acids, refrigeration, and heating. We assessed the variation in survival in stresses of genotypically diverse isolates ofSalmonella entericato identify genotypes with potential elevated risk to sub-optimal processing or cooking. Sub-lethal heat treatment, survival in desiccated conditions and growth in the presence of NaCl or organic acids were investigated.S. Gallinarum strain 287/91 was most sensitive to all stress conditions. While none of the strains replicated in a food matrix at 4°C,S. Infantis strain S1326/28 retained the greatest viability, and six strains exhibited a significantly reduced viability. AS. Kedougou strain exhibited the greatest resistance to incubation at 60°C in a food matrix that was significantly greater thanS. Typhimurium U288, S Heidelberg,S. Kentucky,S. Schwarzengrund andS. Gallinarum strains. Two isolates of monophasicS. Typhimurium, S04698-09 and B54 Col9 exhibited the greatest tolerance to desiccation that was significantly more than for theS. Kentucky andS. Typhimurium U288 strains. In general, the presence of 12mM acetic acid or 14mM citric acid resulted in a similar pattern of decreased growth in broth, but this was not observed forS. Enteritidis, andS. Typhimurium strains ST4/74 and U288 S01960-05. Acetic acid had a moderately greater effect on growth despite the lower concentration tested. A similar pattern of decreased growth was observed in the presence of 6% NaCl, with the notable exception thatS. Typhimurium strain U288 S01960-05 exhibited enhanced growth in elevated NaCl concentrations. An understanding of the molecular basis of phenotypic variation in response to stress has the potential to improve process validation during food challenge tests, improve processing, and result in more reliable risk assessments in the food industry.