title: Viable but non-culturable state and toxin gene expression of enterohemorrhagic Escherichia coli O157 under cryopreservation.
abstract: As major food-borne pathogens worldwide, Escherichia coli are capable of toxin production directly causing severe human disease. However, routine methods are incapable of detecting viable but non-culturable (VBNC) bacteria in food products and raw materials, leading to false-negative identification. In this study, VBNC E. coli O157 strains were acquired after cryopreservation at -20 °C, with and without freeze-thawing; morphology was observed to be of shorter rod-shape, and toxin expression remained at relatively high levels. PMA-PCR assay for VBNC detection was also validated. Therefore, these results suggest that VBNC E. coli O157 strains may represent a strong threat to public health and food safety.
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China; Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
authors.forename: Junyan
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Rong
authors.initials: R
authors.lastname: Zhou
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Clinical Pharmacy, College of Pharmacy, University of Tennessee Health Sciences Center, Memphis, TN 38163, USA.
authors.forename: Brian M
authors.initials: BM
authors.lastname: Peters
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Chii-Wann
authors.initials: CW
authors.lastname: Lin
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Tsung-Liang
authors.initials: TL
authors.lastname: Chuang
authors.affiliation: Department of Laboratory Medicine, First Affiliated Hospital of Guangzhou Medical University, Guangzhou 510120, PR China.
authors.forename: Dingqiang
authors.initials: D
authors.lastname: Chen
authors.affiliation: Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, School of Chemical Engineering and Pharmacy, Wuhan Institute of Technology, Wuhan 430073, PR China. Electronic address: xhzhao2006@gmail.com.
authors.forename: Xihong
authors.initials: X
authors.lastname: Zhao
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Xiong
authors.affiliation: College of Food Science and Engineering, South China University of Technology, Guangzhou 510640, PR China; Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA. Electronic address: zhenbo.xu@hotmail.com.
authors.forename: Zhenbo
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Department of Microbial Pathogenesis, School of Dentistry, University of Maryland, Baltimore, MD 21201, USA.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Shirtliff
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics*; D015925:Cryopreservation; D019453:Escherichia coli O157 / Q000166:cytology / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology*; D059022:Food Safety; D006801:Humans; D050296:Microbial Viability; D008855:Microscopy, Electron, Scanning; D016133:Polymerase Chain Reaction
chemical_list: D001427:Bacterial Toxins
keywords: Cryopreservation; E. coli O157; PMA-PCR; Toxin expression; VBNC state