The contribution of the σE-regulated putative stress response protein STM1250 to the Salmonella acid tolerance response.

Ellis, Ryan (2023) The contribution of the σE-regulated putative stress response protein STM1250 to the Salmonella acid tolerance response. Masters thesis, University of East Anglia.

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Salmonella are enteric pathogens which frequently infect both humans and animals, resulting in various clinical manifestations. Fundamental to their pathogenesis is the ability of Salmonella to survive in acidic environments experienced throughout the digestive system and inside macrophages. Survival in acidic conditions is credited to several acid tolerance response (ATR) mechanisms, regulated by multiple transcriptional regulators including σE, also a major regulator of the envelope stress response.

The σE-regulated small heat shock proteins (sHsps) IbpA, IbpB, AgsA and the putative stress response protein STM1250, have recently been implicated in Salmonella survival against hydrogen peroxide-associated oxidative stress and the antimicrobial peptide polymyxin B. This same study reported a link between STM1250 and the Salmonella ATR induced by hydrochloric acid. We hypothesised in this study that IbpA, IbpB, AgsA and STM1250 may have unidentified roles in protecting Salmonella against commonly encountered stresses, which may have implications for food safety.

In this study we have corroborated previous findings that STM1250 functions in the initial stages of the Salmonella ATR in the presence of hydrochloric acid. We also established a novel role of STM1250 during the Salmonella ATR in the presence of citric acid. These phenotypic results suggest that STM1250 functions in the Salmonella ATR regardless of environmental factors, enabling potential future structural and functional investigations and studies utilising STM1250 as a therapeutic target for vaccine development.

Investigation into STM1250s importance in the Salmonella ATR during the storage of apple and orange juice identified a trend in which the STM1250 mutant had reduced survival when incubated in these juices, suggesting STM1250s potential implications for Salmonella survival in acidic food products. These initial findings in connection with continued research will facilitate the identification of improved food safety regulations, with more specialised implications for the inactivation of Salmonella specific to the type of food product.

Item Type: Thesis (Masters)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 18 Apr 2024 13:30
Last Modified: 18 Apr 2024 13:30


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