Salt at concentrations relevant to meat processing enhances Shiga toxin 2 production in Escherichia coli O157:H7

Harris, Shaun M.; Yue, Wan‐Fu; Olsen, S; Hu, Jia; Means, W.J.; McCormick, Richard J.; Du, Min; Zhu, Mei‐Jun

doi:10.1016/j.ijfoodmicro.2012.09.007

Cited by 28 publications

(26 citation statements)

References 38 publications

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“…RNA concentration was measured by a NanoDrop 2000c spectrophotometer (Thermo Scientific, Waltham, MA), and 500 ng of RNA was reverse transcribed using a QuantiTect reverse transcription kit (Qiagen). We then performed quantitative reverse transcription-PCR (RT-PCR) of selected genes using a CFX96 real-time PCR detection system (Bio-Rad, Hercules, CA) following our published procedure (35). The primers used are listed in Table 1, and 16S rRNA was used as a housekeeping gene.…”

Section: Methodsmentioning

confidence: 99%

“…The resulting supernatant was serial diluted in a phage buffer containing 10 mM CaCl 2 and 5 mM MgSO 4 . The diluent was mixed with 0.9 ml of E. coli MG1655 culture and 5 ml of tempered top agar (0.7% [wt/vol] LB agar supplemented with 10 mM CaCl 2 and 10 mM MgSO 4 ); this mixture was immediately poured onto a bottom layer of agar (1.5% LB agar containing 3 g/ml chloramphenicol) (35). Plates were incubated at 37°C for ϳ36 to ϳ48 h to enumerate PFU.…”

Section: Methodsmentioning

confidence: 99%

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Cinnamon Oil Inhibits Shiga Toxin Type 2 Phage Induction and Shiga Toxin Type 2 Production in Escherichia coli O157:H7

Sheng

Rasco

Zhu

2016

Appl Environ Microbiol

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This study evaluated the inhibitory effect of cinnamon oil against Escherichia coli O157:H7 Shiga toxin (Stx) production and further explored the underlying mechanisms. The MIC and minimum bactericidal concentration (MBC) of cinnamon oil against E. coli O157:H7 were 0.025% and 0.05% (vol/vol), respectively. Cinnamon oil significantly reduced Stx2 production and the stx 2 mRNA expression that is associated with diminished Vero cell cytotoxicity. Consistently, induction of the Stx-converting phage where the stx 2 gene is located, along with the total number of phages, decreased proportionally to cinnamon oil concentration. In line with decreased Stx2 phage induction, cinnamon oil at 0.75؋ and 1.0؋ MIC eliminated RecA, a key mediator of SOS response, polynucleotide phosphorylase (PNPase), and poly(A) polymerase (PAP I), which positively regulate Stx-converting phages, contributing to reduced Stx-converting phage induction and Stx production. Furthermore, cinnamon oil at 0.75؋ and 1.0؋ MIC strongly inhibited the qseBC and luxS expression associated with decreased AI-2 production, a universal quorum sensing signaling molecule. However, the expression of oxidative stress response genes oxyR, soxR, and rpoS was increased in response to cinnamon oil at 0.25؋ or 0.5؋ MIC, which may contribute to stunted bacterial growth and reduced Stx2 phage induction and Stx2 production due to the inhibitory effect of OxyR on prophage activation. Collectively, cinnamon oil inhibits Stx2 production and Stx2 phage induction in E. coli O157:H7 in multiple ways. IMPORTANCEThis study reports the inhibitory effect of cinnamon oil on Shiga toxin 2 phage induction and Shiga toxin 2 production. Subinhibitory concentrations (concentrations below the MIC) of cinnamon oil reduced Stx2 production, stx 2 mRNA expression, and cytotoxicity on Vero cells. Subinhibitory concentrations of cinnamon oil also dramatically reduced both the Stx2 phage and total phage induction in E. coli O157:H7, which may be due to the suppression of RNA polyadenylation enzyme PNPase at 0.25؋ to 1.0؋ MIC and the downregulation of bacterial SOS response key regulator RecA and RNA polyadenylation enzyme PAP I at 0.75؋ or 1.0؋ MIC. Cinnamon oil at higher levels (0.75؋ and 1.0؋ MIC) eliminated quorum sensing and oxidative stress. Therefore, cinnamon oil has potential applications as a therapeutic to control E. coli O157:H7 infection through inhibition of bacterial growth and virulence factors. E scherichia coli O157:H7 is an important foodborne pathogen that is associated with hemorrhagic colitis, hemolytic-uremic syndrome (HUS), and death (1). More than 63,000 cases of foodborne illness are estimated to be caused by E. coli O157:H7 annually in the United States (2). Outbreaks have been associated with ground beef, ready-to-eat salad, cheese, apple juice, and other foods (3-6).Shiga toxin (Stx) is a major virulence factor of E. coli O157:H7. Its production in the gastrointestinal tract in conjunction with other virulence factors induces hemorrhagic colitis, and its entry...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Cinnamon Oil Inhibits Shiga Toxin Type 2 Phage Induction and Shiga Toxin Type 2 Production in Escherichia coli O157:H7

Sheng

Rasco

Zhu

2016

Appl Environ Microbiol

Self Cite

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“…Ingested Stx2 is commonly broken down in the digestive tract; a portion of the ingested Stx could enter the blood stream and causes damage to sensitive organs. Therefore not only viable E. coli O157:H7, which are usually killed during meat thermal processing, is a threat to public health, but also Stx toxins produced by the bacterium are another critical safety risk (Harris et al 2012). Carey et al (2009) evaluated virulence and stress gene expression of E. coli O157:H7 on lettuce using real-time PCR.…”

Section: Discussionmentioning

confidence: 99%

“…Mechanism of Shiga toxins pathogenicity is not well understood precisely (Harris et al 2012). Virulence gene expression investigation in broth or food-like broth models is one of the main problems to investigate in bacterial pathogenicity (Derakhshan et al 2008;Xiang et al 2010;Landau and Shapira 2012).…”

Section: Introductionmentioning

confidence: 99%

Establishment of a Method for Describing stx Genes Expression of E. coli O157:H7 in Ground Beef Matrix during Refrigerated Storage

Mahmoudzadeh

Hosseini

Hedayati

et al. 2015

Journal of Food Safety

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Ingredients and complexity of food matrices are inhibitory factors for gene expression studies of bacterial pathogens directly from food matrix. The aim of this study was to develop a simple and fast method for RNA extraction from ground beef matrix as well as stx genes expression of Escherichia coli O157:H7 by relative quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). Inoculated ground beef samples were kept 7 days in refrigerated storage (4 ± 1C) and bacterial RNA was extracted according to the described method at 0, 2, 5 and 7 days after storage. Results indicate that refrigerated storage temperature decreased gene expression of stx1A (−3.35 relative changes on day 7) and stx2A (−2.9 relative changes on day 7) in ground beef matrix. In the current study, a method requiring minimal equipment and limited interference for RNA extraction from bacteria associated with a meat matrix was evaluated (developed, invested, etc.). Results of the study suggest that the quantitative real-time RT-PCR method could be used as a reliable and sensitive method for gene expression studies. PRACTICAL APPLICATIONSPolymerase chain reaction (PCR), known as a sensitive and specific method, was extensively used for the detection of genes involved in stress and virulence of bacteria. In this way, real-time PCR shows a good sensitivity and diversity for detection and gene expression studies of pathogens. This technique frequently has been used for the study of bacterial behavior in broth or food-like broth models. Complexity of food matrix and presence of proteins, and also other PCR-inhibiting factors, restricted gene expression studies in food matrix. There has been great interest in the survival and pathogenicity of Escherichia coli O157:H7 because it is a great concern of ground meat industry. Shiga toxins (Stx1 and Stx2) as manifest characteristics of E. coli O157:H7 are known as significant virulence factors in the pathogenicity of bacterium so its behavior and gene expression profile in meat matrix and during cold chain were evaluated.

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“…Although there are many physical and chemical factors able to cause this process, including UV irradiation, mitomycin C, high salt concentrations, EDTA, and hydrogen peroxide (Łoś et al 2009;Harris et al 2012;Imamovic and Muniesa 2012), it is not clear whether particular food products can either stimulate or prevent Stx prophage induction. Very recent report on food-related stress demonstrated that particular environmental factors (hydrogen peroxide and acids) could stimulate Stx prophage induction, however, tested stressors, rather than food products, were added to the experimental system (Fang et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Effects of some commonly used drinks on induction of Shiga toxin-converting prophage in Escherichia coli

Pierzynowska

Jasińska

Cyske

et al. 2018

J Consum Prot Food Saf

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Pathogenicity of enterohemorrhagic Escherichia coli (EHEC) strains depends on various virulence factors, like adhesins (including intimin), flagella, type I fimbriae, curli fibers, hemolysins, and agents required for biofilm formation. However, the pathogenicity is highly enhanced by production of Shiga toxins which are encoded by stx genes located in genomes of Shiga toxin-converting (Stx) prophages. Thus, for maximal EHEC virulence, induction of these prophages is necessary. Although various physical and chemical agents causing Stx prophage induction are known, it is not clear whether any food can stimulate this process. Therefore, the aim of this work was to test whether commonly used drinks might enhance Stx prophage induction in E. coli. It was found that 5% Nestea, but not 5% Coca-Cola or 1% ethanol, caused a significant induction of 933W Stx prophage in a bacterial culture in vitro. These results indicate that some commonly used drinks can stimulate Stx prophage induction, potentially enhancing virulence of EHEC. This may have impact on protection of consumers which are infected by these bacteria, and might contribute to choose safe food for such persons.

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Salt at concentrations relevant to meat processing enhances Shiga toxin 2 production in Escherichia coli O157:H7

Cited by 28 publications

References 38 publications

Cinnamon Oil Inhibits Shiga Toxin Type 2 Phage Induction and Shiga Toxin Type 2 Production in Escherichia coli O157:H7

Cinnamon Oil Inhibits Shiga Toxin Type 2 Phage Induction and Shiga Toxin Type 2 Production in Escherichia coli O157:H7

Establishment of a Method for Describing stx Genes Expression of E. coli O157:H7 in Ground Beef Matrix during Refrigerated Storage

Effects of some commonly used drinks on induction of Shiga toxin-converting prophage in Escherichia coli

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