Differential expression of the outer membrane protein W (OmpW) stress response in enterohemorrhagic Escherichia coli O157:H7 corresponds to the viable but non-culturable state

During an outbreak of enterohemorrhagic Escherichia coli (EHEC) O157, we showed previously that food isolates were resistant to oxidative stress, while patient isolates were sensitive to it. Because food isolates increased stress-sensitivity after mouse passage, this change most likely occurred duri...

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Bibliographic Details
Published in:Research in microbiology 2008-11, Vol.159 (9-10), p.709-717
Main Authors: Asakura, Hiroshi, Kawamoto, Keiko, Haishima, Yuji, Igimi, Shizunobu, Yamamoto, Shigeki, Makino, Sou-ichi
Format: Article
Language:English
Subjects:
Animals
Bacterial Outer Membrane Proteins - genetics
Bacterial Outer Membrane Proteins - metabolism
Bacteriology
Biological and medical sciences
Culture Media
EHEC O157
Escherichia coli
Escherichia coli O157 - genetics
Escherichia coli O157 - growth & development
Escherichia coli O157 - metabolism
Escherichia coli Proteins - genetics
Escherichia coli Proteins - metabolism
Food Microbiology
Fundamental and applied biological sciences. Psychology
Gene Expression Regulation, Bacterial
Heat-Shock Response
Humans
Mice
Microbiology
Miscellaneous
Molecular Sequence Data
Outer membrane protein W (OmpW)
Oxidative Stress
Salmon - microbiology
Sequence Analysis, DNA
Viable but non-culturable (VBNC) state
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Summary:During an outbreak of enterohemorrhagic Escherichia coli (EHEC) O157, we showed previously that food isolates were resistant to oxidative stress, while patient isolates were sensitive to it. Because food isolates increased stress-sensitivity after mouse passage, this change most likely occurred during passage through patients. Here we demonstrate that the phenotypic change occurring during mouse passage correlates with the stress response of outer membrane protein W (OmpW) in EHEC O157 strains. Upon induction of oxidative stress, OmpW was highly expressed only in the stress-sensitive MP37 strain, obtained by mouse passage of food strain F2, but not in the F2 strain. Western blotting confirmed that expression of OmpW was induced in the viable but non-culturable (VBNC) state. Deletion of ompW in the MP37 strain increased recovery from dormancy, while overexpression of OmpW in the F2 strain decreased recovery when exposed to oxidative stress, suggesting that high levels of OmpW sensitize the bacteria to stress. DNA alignment revealed that the class I integron (int1I) fragments flanking the ompW gene are oriented in opposite directions between stress-resistant and -sensitive strains. All stress-sensitive strains induced ompW under stress. We propose that the different stress response of OmpW was introduced by genetic alteration during in vivo passage.
ISSN:0923-2508
1769-7123
DOI:10.1016/j.resmic.2008.08.005