Role of in vivo passage on the environmental adaptation of enterohemorrhagic Escherichia coli O157:H7: cross-induction of the viable but nonculturable state by osmotic and oxidative stresses.
In an enterohemorrhagic Escherichia coli (EHEC) O157:H7 outbreak caused by salted salmon roe that occurred in Japan, 1998, a food isolate (F2) was NaCl-resistant and a patient isolate (P5) was sensitive to NaCl. We show here that hydrogen peroxide, like NaCl, induced a significant loss of culturability in P5. The BacLight assay suggested that the EHEC O157:H7 entered a viable but nonculturable (VNC) state. We used the passage through mice in an attempt to model this transition in phenotype. Mouse-passaged isogenic variants of F2 became NaCl- and oxidation-sensitive, entered the nonculturable state in response to either of these stresses, and could be resuscitated by sodium pyruvate. Since the expression of RpoS in response to these stresses correlated with the isolates' culturabilities, we concluded that in vivo passage negatively modulated RpoS expression, and the subsequent stress exposure induced the VNC state in the EHEC O157:H7 isolates.
Asakura
Hiroshi
H
Division of Biomedical Food Research, National Institute of Health Sciences, Kami-yoga 1-18-1, Setagaya-ku, Tokyo 158-8501, Japan. hasakura@nihs.go.jp
Igimi
Shizunobu
S
Kawamoto
Keiko
K
Yamamoto
Shigeki
S
Makino
Sou-Ichi
S
D000085:Acetates / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics; D004777:Environment; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006358:Hot Temperature; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D050296:Microbial Viability / Q000187:drug effects; D009997:Osmotic Pressure / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D012692:Serial Passage; D012808:Sigma Factor / Q000235:genetics; D012965:Sodium Chloride / Q000494:pharmacology; D014466:Ultraviolet Rays
D000085:Acetates; D001426:Bacterial Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D012965:Sodium Chloride; D006861:Hydrogen Peroxide