title: Effects of chemical and low-temperature treatments and adaption on the responses of virulence factor genes and outer membrane proteins in Escherichia coli O157:H7.
abstract: BACKGROUND
  In the years after the discovery of this pathogen, Escherichia coli O157:H7 has become increasingly prominent, and outbreaks have been reported in many areas.
  
  
  METHODS
  In the current study, we determined the expressions of virulent factor genes shiga-like toxin II (stxII) and E. coli attaching and effacing (eaeA), in strains that were isolated from cattle feces and a clinical case in Taiwan. In addition, the effects of chemical and low-temperature stresses and adaptions on the expressions of virulent factor genes were investigated. Furthermore, the outer membrane proteins of acid-adapted E. coli O157:H7 TWC01 (TWC01) was separated using two-dimensional electrophoresis, and proteins were identified using mass spectrometry in order to illustrate the changes in protein expression after adaption.
  
  
  RESULTS
  Expressions of stxII and eaeA in the TWC01 isolated from a clinical case were higher than those in two strains isolated from cattle feces, and both organic and inorganic acid stresses and adaptions enhance the expression of genes encoding virulent factors in strains. In addition, the outer membrane proteins of TWC01 were regulated under hydrochloric acid adaption, indicating induction of acid tolerance and enhancement adhesion in TWC01. Lactic acid treatment of TWC01 resulted in downregulation of channel protein and adherence-related protein expressions.
  
  
  CONCLUSIONS
  The results of this study are helpful in understanding the resistance of locally isolated TWC01 to chemical and low-temperature stresses, and improving the control of this pathogen.
authors.affiliation: Department of Food Science, Fu Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Da-Hao
authors.initials: DH
authors.lastname: Huang
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Cardinal Tien Hospital, New Taipei City, Taiwan.
authors.forename: Kun
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Food Science, Fu Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Chihwei P
authors.initials: CP
authors.lastname: Chiu
authors.affiliation: Department of Biochemical Science and Technology, National Taiwan University, Taipei City, Taiwan.
authors.forename: Tzu-Ming
authors.initials: TM
authors.lastname: Pan
authors.affiliation: Department of Food Science, Fu Jen Catholic University, New Taipei City, Taiwan. Electronic address: tytsai@mail.fju.edu.tw.
authors.forename: Tsung-Yu
authors.initials: TY
authors.lastname: Tsai
mesh_terms: D018829:Adhesins, Bacterial / Q000096:biosynthesis*; D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000187:drug effects* / Q000235:genetics; D002417:Cattle; D003080:Cold Temperature; D015180:Electrophoresis, Gel, Two-Dimensional; D019453:Escherichia coli O157 / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D005243:Feces / Q000382:microbiology; D005650:Fumarates / Q000494:pharmacology; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology; D019344:Lactic Acid / Q000494:pharmacology; D022641:Shiga Toxin 2 / Q000096:biosynthesis*; D012973:Sodium Hypochlorite / Q000494:pharmacology; D037521:Virulence Factors / Q000235:genetics
chemical_list: D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D005650:Fumarates; D022641:Shiga Toxin 2; D037521:Virulence Factors; C073819:eaeA protein, E coli; D019344:Lactic Acid; C032005:fumaric acid; D012973:Sodium Hypochlorite; D006851:Hydrochloric Acid
keywords: Escherichia coli O157:H7; Escherichia coli attaching and effacing; gene expression of shiga-like toxin II; reverse transcription multiplex TaqMan polymerase chain reaction; two-dimensional electrophoresis