Dynamics of Physiological Changes of Shiga Toxin-Producing <i>Escherichia coli</i> O157:H7 on Romaine Lettuce During Pre-Processing Cold Storage, and Subsequent Effects on Virulence and Stress Tolerance
If lettuce is contaminated in the field, Shiga toxin-producing <i>E. coli</i> (STEC) O157:H7 can survive through the distribution chain. Prolonged cold storage during transportation may impact pathogen physiology, affecting subsequent stress survival and virulence. Greenhouse-grown Romai...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
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| Series: | Applied Microbiology |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2673-8007/5/2/45 |
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| Summary: | If lettuce is contaminated in the field, Shiga toxin-producing <i>E. coli</i> (STEC) O157:H7 can survive through the distribution chain. Prolonged cold storage during transportation may impact pathogen physiology, affecting subsequent stress survival and virulence. Greenhouse-grown Romaine lettuce, inoculated with three STEC O157:H7 strains, was harvested after 24 h and stored at 2 °C for 5 d following 4 h at harvest temperature (9 °C or 17 °C). Culturable, persister, and viable but non-culturable (VBNC) cells were quantified. Virulence was evaluated using <i>Galleria mellonella</i> and acid tolerance at pH 2.5 and tolerance to 20–25 ppm free chlorine were quantified. Colder harvest temperature (9 °C) before cold storage led to greater transformation of STEC O157:H7 into dormant states and decreased virulence in most cases. Increasing length of cold storage led to decreased virulence and acid tolerance of STEC O157:H7 on lettuce, while having no significant effect on chlorine tolerance. These findings highlight that entry of STEC O157:H7 into dormant states during harvest and transportation at cold temperatures leads to decreased stress tolerance and virulence with increasing cold storage. Changes in STEC O157:H7 physiology on lettuce during cold storage can be integrated into risk assessment tools for producers, which can assist in identifying practices that minimize risk of STEC O157:H7 from consumption of lettuce. |
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| ISSN: | 2673-8007 |