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Detection of the pH-dependent Activity of Escherichia coli Chaperone HdeB In Vitro and In Vivo
Published on: October 23, 2016
Dynamics of high hydrostatic pressure resistance development in RpoS-deficient Escherichia coli
Elisa Gayán1, Zhiying Wang2, Maika Salvador3
1Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
Abstract:
High hydrostatic pressure (HHP) treatment is one of the most widely accepted non-thermal food processing methods, but HHP-resistance development in pathogenic or spoilage bacteria might compromise the safety and stability of HHP-treated foods. Charting the possible routes and mechanisms of HHP resistance development in foodborne bacteria is therefore essential to anticipate or prevent the appearance of resistant variants. While upregulation of the RpoS-governed general stress response is a well-established route for increased HHP resistance in Escherichia coli, previous work revealed that mutations causing attenuated cAMP/CRP activity or aggregation-prone TnaA variants can evolve to overcome the HHP-hypersensitivity of an E. coli ΔrpoS mutant. In this study, further directed evolution and genetic analysis approaches allowed us to demonstrate that both kinds of mutants tend to co-emerge and compete with each other in E. coli ΔrpoS populations evolving towards HHP resistance, because of the higher HHP resistance of cAMP/CRP mutants and the faster growth rate of the TnaA mutants. Moreover, closer scrutiny of evolving populations revealed RpoS, cAMP/CRP and TnaA independent routes of HHP resistance development, based on downregulation of YegW or RppH activity.
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