title: Transcriptomic response of Escherichia coli O157:H7 to oxidative stress.
abstract: Chlorinated water is commonly used in industrial operations to wash and sanitize fresh-cut, minimally processed produce. Here we compared 42 human outbreak strains that represented nine distinct Escherichia coli O157:H7 genetic lineages (or clades) for their relative resistance to chlorine treatment. A quantitative measurement of resistance was made by comparing the extension of the lag phase during growth of each strain under exposure to sublethal concentrations of sodium hypochlorite in Luria-Bertani or brain heart infusion broth. Strains in clade 8 showed significantly (P < 0.05) higher resistance to chlorine than strains from other clades of E. coli O157:H7. To further explore how E. coli O157:H7 responds to oxidative stress at transcriptional levels, we analyzed the global gene expression profiles of two strains, TW14359 (clade 8; associated with the 2006 spinach outbreak) and Sakai (clade 1; associated with the 1996 radish sprout outbreak), under sodium hypochlorite or hydrogen peroxide treatment. We found over 380 genes were differentially expressed (more than twofold; P < 0.05) after exposure to low levels of chlorine or hydrogen peroxide. Significantly upregulated genes included several regulatory genes responsive to oxidative stress, genes encoding putative oxidoreductases, and genes associated with cysteine biosynthesis, iron-sulfur cluster assembly, and antibiotic resistance. Identification of E. coli O157:H7 strains with enhanced resistance to chlorine decontamination and analysis of their transcriptomic response to oxidative stress may improve our basic understanding of the survival strategy of this human enteric pathogen on fresh produce during minimal processing.
authors: National Center for Food Safety and Technology, Illinois Institute of Technology, Chicago, Illinois, USA.
authors: Siyun
authors: S
authors: Wang
authors: Kaiping
authors: K
authors: Deng
authors: Sam
authors: S
authors: Zaremba
authors: Xiangyu
authors: X
authors: Deng
authors: Chiahui
authors: C
authors: Lin
authors: Qian
authors: Q
authors: Wang
authors: Mary Lou
authors: ML
authors: Tortorello
authors: Wei
authors: W
authors: Zhang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D024881:Drug Resistance, Bacterial; D019453:Escherichia coli O157 / Q000502:physiology*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018384:Oxidative Stress; D012973:Sodium Hypochlorite / Q000494:pharmacology; D013312:Stress, Physiological
chemical_list: D000900:Anti-Bacterial Agents; D006861:Hydrogen Peroxide; D012973:Sodium Hypochlorite