Event Title

Enterobacteriaceae: Desiccation Survival and Thermal Tolerance of Closely Related Genera

Presentation Type

Poster

Start Date

23-4-2019 12:00 AM

End Date

23-4-2019 12:00 AM

Description

Award for Best Graduate Poster Presentation.

Abstract

Salmonella enteric becomes tolerant to thermal treatments after extended exposure to low water activity. This adaptation raises significant public health concerns as S. enterica is able to survive common thermal food processing. Little is known about other Enterobacteriaceae genera's ability to acquire thermal tolerance after desiccation. S. Typhimurium exposed to dry conditions differentially expresses 719 genes. Among them, two virulence genes (sopD and sseD) were identified to be critical to S. Typhimurium's ability to survive dessication. From these genes, sopD is conserved at the genus level whereas sseD is specific to the species S. enterica. Escherichia coli, a closely related genus within the Enterobacteriaceae family, does not acquire thermotolerance post desiccation. The main objective of this study is to evaluate the survival of Salmonella and closely related genera when they are exposed to high temperatures after enduring dry conditions. This evaluation will provide a concrete scientific basis to advise food safety organizations and thus safeguard public health. Samples were exposed to a dry condition (aw = 0.11) and heated at 85, 90, and 95C. D-values and growth curves were used to quantify the extent to which samples can endure dry conditions and tolerate heat. S. enterica showed the highest resistance to thermal treatment once equilibrated to aw=0.11. S. enterica and C. freundii were found to be significantly better equipped in their ability to recover after thermal treatment and equilibration to dry conditions. The presence of SPI-1 and sopD in S. enterica is crucial to the acquisition of thermal tolerance within the genus Salmonella. This is identified through S. bongori's inability to acquire thermal tolerance. Finally, the acquisition of thermal tolerance is a polyphyletic trait within the Enterobacteriaceae family prompting further investigation into C. fruendii and its ability to acquire thermal tolerance.

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Apr 23rd, 12:00 AM Apr 23rd, 12:00 AM

Enterobacteriaceae: Desiccation Survival and Thermal Tolerance of Closely Related Genera

Award for Best Graduate Poster Presentation.

Abstract

Salmonella enteric becomes tolerant to thermal treatments after extended exposure to low water activity. This adaptation raises significant public health concerns as S. enterica is able to survive common thermal food processing. Little is known about other Enterobacteriaceae genera's ability to acquire thermal tolerance after desiccation. S. Typhimurium exposed to dry conditions differentially expresses 719 genes. Among them, two virulence genes (sopD and sseD) were identified to be critical to S. Typhimurium's ability to survive dessication. From these genes, sopD is conserved at the genus level whereas sseD is specific to the species S. enterica. Escherichia coli, a closely related genus within the Enterobacteriaceae family, does not acquire thermotolerance post desiccation. The main objective of this study is to evaluate the survival of Salmonella and closely related genera when they are exposed to high temperatures after enduring dry conditions. This evaluation will provide a concrete scientific basis to advise food safety organizations and thus safeguard public health. Samples were exposed to a dry condition (aw = 0.11) and heated at 85, 90, and 95C. D-values and growth curves were used to quantify the extent to which samples can endure dry conditions and tolerate heat. S. enterica showed the highest resistance to thermal treatment once equilibrated to aw=0.11. S. enterica and C. freundii were found to be significantly better equipped in their ability to recover after thermal treatment and equilibration to dry conditions. The presence of SPI-1 and sopD in S. enterica is crucial to the acquisition of thermal tolerance within the genus Salmonella. This is identified through S. bongori's inability to acquire thermal tolerance. Finally, the acquisition of thermal tolerance is a polyphyletic trait within the Enterobacteriaceae family prompting further investigation into C. fruendii and its ability to acquire thermal tolerance.