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<p>Pathogenic <i>Escherichia coli</i> (<i>E. coli</i>) O157:H7 poses a major threat to food safety. Non-thermal physical technologies offer antibacterial effects while preserving food quality. The outer membrane of <i>E. coli</i> acts as a key structural and permeation barrier, limiting the antibacterial efficacy of non-thermal technologies. However, the differences in the structure and composition changes of outer membrane induced by ultrasound (US), ultraviolet (UV), intense pulsed light (IPL), and electron beam irradiation (EBI) treatmentsremain unclear. Plate counting showed that UV (5.7&#xa0;mJ/cm<sup>2</sup>) and EBI (0.5&#xa0;kGy) reduced <i>E. coli</i> O157:H7 by 5.41 ± 0.53 and 6.10 ± 0.21 log CFU/mL, respectively, whereas US (9&#xa0;min) and IPL (1&#xa0;min) reduced only 0.63 ± 0.09 and 1.73 ± 0.11 log CFU/mL, respectively. Fluorescent probe analyses indicated that non-thermal treatments significantly increased outer membrane permeability, while exerting limited effects on outer membrane fluidity. In addition, UV and EBI treatments induced depolarization of the outer membrane potential, whereas US treatment was associated with membrane hyperpolarization. SDS-PAGE analysis revealed alterations in LPS and OMPs profiles following non-thermal treatments, including possible Lipid A palmitoylation, protein aggregation, and degradation. RT-qPCR showed that US caused the largest transcriptional changes in selected OMP genes. Collectively, these results provide insight into the bacterial inactivation effect of different non-thermal physical technologies and their impact on membrane functional properties and compositions, offering a theoretical basis for optimizing non-thermal treatment conditions and further mechanistic investigations.</p>

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Inactivation of Escherichia coli O157:H7 by Non-thermal Physical Treatments and its Influence on Outer Membrane Properties and Composition

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • Zhehao Yang,
  • Xinhui Zhang,
  • Qiao He,
  • Mingming Guo

摘要

Pathogenic Escherichia coli (E. coli) O157:H7 poses a major threat to food safety. Non-thermal physical technologies offer antibacterial effects while preserving food quality. The outer membrane of E. coli acts as a key structural and permeation barrier, limiting the antibacterial efficacy of non-thermal technologies. However, the differences in the structure and composition changes of outer membrane induced by ultrasound (US), ultraviolet (UV), intense pulsed light (IPL), and electron beam irradiation (EBI) treatmentsremain unclear. Plate counting showed that UV (5.7 mJ/cm2) and EBI (0.5 kGy) reduced E. coli O157:H7 by 5.41 ± 0.53 and 6.10 ± 0.21 log CFU/mL, respectively, whereas US (9 min) and IPL (1 min) reduced only 0.63 ± 0.09 and 1.73 ± 0.11 log CFU/mL, respectively. Fluorescent probe analyses indicated that non-thermal treatments significantly increased outer membrane permeability, while exerting limited effects on outer membrane fluidity. In addition, UV and EBI treatments induced depolarization of the outer membrane potential, whereas US treatment was associated with membrane hyperpolarization. SDS-PAGE analysis revealed alterations in LPS and OMPs profiles following non-thermal treatments, including possible Lipid A palmitoylation, protein aggregation, and degradation. RT-qPCR showed that US caused the largest transcriptional changes in selected OMP genes. Collectively, these results provide insight into the bacterial inactivation effect of different non-thermal physical technologies and their impact on membrane functional properties and compositions, offering a theoretical basis for optimizing non-thermal treatment conditions and further mechanistic investigations.