Gayán Elisa, Wang Zhiying, Salvador Maika, Gänzle Michael G, Aertsen Abram
Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada.
Food Res Int. 2023 Feb;164:112280. doi: 10.1016/j.foodres.2022.112280. Epub 2022 Dec 6.
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.
高静水压（HHP）处理是最广泛接受的非热食品加工方法之一，但致病性或腐败性细菌中HHP抗性的发展可能会损害HHP处理食品的安全性和稳定性。因此，绘制食源细菌中HHP抗性发展的可能途径和机制对于预测或防止抗性变体的出现至关重要。虽然RpoS调控的一般应激反应上调是大肠杆菌中增加HHP抗性的既定途径，但先前的研究表明，导致cAMP/CRP活性减弱的突变或易于聚集的TnaA变体可以进化以克服大肠杆菌ΔrpoS突变体的HHP超敏性。在本研究中，进一步的定向进化和遗传分析方法使我们能够证明，由于cAMP/CRP突变体具有更高的HHP抗性，而TnaA突变体具有更快的生长速度，这两种突变体在向HHP抗性进化的大肠杆菌ΔrpoS群体中往往会共同出现并相互竞争。此外，对进化群体的更仔细研究揭示了基于YegW或RppH活性下调的RpoS、cAMP/CRP和TnaA独立的HHP抗性发展途径。
