Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 2/6/2007
Publication Date: 5/21/2007
Citation: Sirsat, S.A., Dowd, S.E., Chalova, V.I., Muthaiyan, A., Ricke, S.C. 2007. Effect of temperature stress on gene expression of Salmonella Typhimurium [abstract]. 107th American Society for Microbiology General Meeting, May 21-25, 2007, Toronto, Canada. Abstract No. P-106. Interpretive Summary:
Technical Abstract: Environmental stressors including pH, nutrient starvation, high osmolarity, oxidative stress, and temperature fluctuations regulate the expression of the virulence genes. Hot water used for carcass decontamination in the meat industry is a potential stressor that may regulate virulence gene expression of Salmonella enterica serotype Typhimurium. Previous studies have shown the role of heat shock protein in attachment of Salmonella to intestinal epithelial cells. The objective of this study was to evaluate the effect of heat shock on genes expression in Salmonella Typhimurium ATCC 14028. Overnight grown isolates of Salmonella Typhimurium were inoculated into fresh LB and grown at 30 deg C to an OD600 of 0.4. Using 3 biological replications for each treatment, separate aliquots of these cultures were then exposed to one of four treatments that included: 42 deg C for 10 min and 30 min and 48 deg C for 10 min and 30 min. Cells were immediately collected into RNA protect bacteria reagent, RNA extracted, and microarray analyses performed (24 arrays). The arrays were analyzed to obtain genes consistently regulated on every array, not taking into account exposure time or temperature. Compared to controls exposed at 30 deg C, there were significant differences (P < 0.01; FDR < 0.05) in the comparative expression of > 300 genes (fold regulation > 2.0). Induced genes mapped to functional clusters related to sigma-70, transcriptional regulation, DNA damage repair, fimbia, and protein folding. Repressed genes mapped to functional clusters related to flagella biosynthesis, motility, DNA polymerase activity, cold shock, and porins. Fur, rpoS, SPI genes pipA and pipB, and fimbia genes were shown to be upregulated 2 fold compared to control. Fimbria gene products are responsible for the ability to adhere epithelial cells which is the first step of invasion and infection for Salmonella. The Salmonella Pathogenicity Island (SPI) genes are involved in the ability of Salmonella to cause infection in hosts. In conclusion, pathogen interventions used as hurdles to eliminate pathogen contamination and growth may influence the pathogenic responses of surviving pathogens.