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Rey MDLÁ, Rodriguez Racca A, Rossi Ribeiro L, Dos Santos Cruz F, Cap M, Mozgovoj MV, Cristianini M, Vaudagna SR. High‐pressure processing treatment of beef burgers: Effect on
Escherichia coli
O157 inactivation evaluated by plate count and PMA‐qPCR. J Food Sci 2022; 87:2324-2336. [DOI: 10.1111/1750-3841.16179] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/31/2022] [Accepted: 04/20/2022] [Indexed: 11/27/2022]
Affiliation(s)
- María de los Ángeles Rey
- Instituto Nacional de Tecnología Agropecuaria (INTA) Instituto Tecnología de Alimentos Buenos Aires Argentina
- Instituto de Ciencia y Tecnología de Sistemas Alimentarios Sustentables (UEDD INTA‐CONICET) Buenos Aires Argentina
| | - Anabel Rodriguez Racca
- Instituto Nacional de Tecnología Agropecuaria (INTA) Instituto Tecnología de Alimentos Buenos Aires Argentina
- Instituto de Ciencia y Tecnología de Sistemas Alimentarios Sustentables (UEDD INTA‐CONICET) Buenos Aires Argentina
| | - Luma Rossi Ribeiro
- Department of Food Engineering and Technology, School of Food Engineering University of Campinas (UNICAMP) Campinas Brazil
- Quality and Safety of food and feed, Department of Horticultural Engineering Leibniz Institute for Agricultural Engineering and Bioeconomy Potsdam Germany
| | - Fabiano Dos Santos Cruz
- Department of Food Engineering and Technology, School of Food Engineering University of Campinas (UNICAMP) Campinas Brazil
| | - Mariana Cap
- Instituto Nacional de Tecnología Agropecuaria (INTA) Instituto Tecnología de Alimentos Buenos Aires Argentina
- Instituto de Ciencia y Tecnología de Sistemas Alimentarios Sustentables (UEDD INTA‐CONICET) Buenos Aires Argentina
| | - Marina Valeria Mozgovoj
- Instituto Nacional de Tecnología Agropecuaria (INTA) Instituto Tecnología de Alimentos Buenos Aires Argentina
- Instituto de Ciencia y Tecnología de Sistemas Alimentarios Sustentables (UEDD INTA‐CONICET) Buenos Aires Argentina
| | - Marcelo Cristianini
- Department of Food Engineering and Technology, School of Food Engineering University of Campinas (UNICAMP) Campinas Brazil
| | - Sergio Ramón Vaudagna
- Instituto Nacional de Tecnología Agropecuaria (INTA) Instituto Tecnología de Alimentos Buenos Aires Argentina
- Instituto de Ciencia y Tecnología de Sistemas Alimentarios Sustentables (UEDD INTA‐CONICET) Buenos Aires Argentina
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2
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Prasad A, Gänzle M, Roopesh MS. Antimicrobial activity and drying potential of high intensity blue light pulses (455 nm) emitted from LEDs. Food Res Int 2021; 148:110601. [PMID: 34507746 DOI: 10.1016/j.foodres.2021.110601] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 07/06/2021] [Accepted: 07/08/2021] [Indexed: 01/30/2023]
Abstract
Decontamination of low water activity (aw) foods, like pet foods is a challenging task. Treatment using light emitting diode (LED) is an emerging decontamination method, that can induce photodynamic inactivation in bacteria. The objective of this study was to understand the effect of selected product and process parameters on the antibacterial efficacy of treatment using light pulses of 455 nm wavelength on dry powdered Salmonella and pet foods equilibrated to 0.75 aw. The surface temperature increase, weight loss, and aw decrease in the samples were determined after LED treatments with different doses. S. Typhimurium on pet foods showed better sensitivity to 455 nm LED treatment than the powdered S. Typhimurium. For instance, 455 nm LED treatment with 785.7 J/cm2 dose produced a log reduction of 1.44 log (CFU/g) in powdered S. Typhimurium population compared to 3.22 log (CFU/g) on pet food. The LED treatment was less effective against 5-strain cocktail of Salmonella in low aw pet foods. The treated samples showed significant reduction in weight and aw showing the heating and drying potential of 455 nm LED treatment. Significant lipid oxidation was observed in the treated pet foods. Overall, the dose, treatment time, and sample type influenced the Salmonella inactivation efficacy of 455 nm LED treatment in low aw conditions.
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Affiliation(s)
- Amritha Prasad
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada; College of Bioengineering and Food Science, Hubei University of Technology, Wuhan 430086, China
| | - M S Roopesh
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2R3, Canada.
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3
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Aganovic K, Hertel C, Vogel RF, Johne R, Schlüter O, Schwarzenbolz U, Jäger H, Holzhauser T, Bergmair J, Roth A, Sevenich R, Bandick N, Kulling SE, Knorr D, Engel KH, Heinz V. Aspects of high hydrostatic pressure food processing: Perspectives on technology and food safety. Compr Rev Food Sci Food Saf 2021; 20:3225-3266. [PMID: 34056857 DOI: 10.1111/1541-4337.12763] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 04/02/2021] [Accepted: 04/10/2021] [Indexed: 11/29/2022]
Abstract
The last two decades saw a steady increase of high hydrostatic pressure (HHP) used for treatment of foods. Although the science of biomaterials exposed to high pressure started more than a century ago, there still seem to be a number of unanswered questions regarding safety of foods processed using HHP. This review gives an overview on historical development and fundamental aspects of HHP, as well as on potential risks associated with HHP food applications based on available literature. Beside the combination of pressure and temperature, as major factors impacting inactivation of vegetative bacterial cells, bacterial endospores, viruses, and parasites, factors, such as food matrix, water content, presence of dissolved substances, and pH value, also have significant influence on their inactivation by pressure. As a result, pressure treatment of foods should be considered for specific food groups and in accordance with their specific chemical and physical properties. The pressure necessary for inactivation of viruses is in many instances slightly lower than that for vegetative bacterial cells; however, data for food relevant human virus types are missing due to the lack of methods for determining their infectivity. Parasites can be inactivated by comparatively lower pressure than vegetative bacterial cells. The degrees to which chemical reactions progress under pressure treatments are different to those of conventional thermal processes, for example, HHP leads to lower amounts of acrylamide and furan. Additionally, the formation of new unknown or unexpected substances has not yet been observed. To date, no safety-relevant chemical changes have been described for foods treated by HHP. Based on existing sensitization to non-HHP-treated food, the allergenic potential of HHP-treated food is more likely to be equivalent to untreated food. Initial findings on changes in packaging materials under HHP have not yet been adequately supported by scientific data.
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Affiliation(s)
- Kemal Aganovic
- DIL German Institute of Food Technologies e.V., Quakenbrück, Germany
| | - Christian Hertel
- DIL German Institute of Food Technologies e.V., Quakenbrück, Germany
| | - Rudi F Vogel
- Technical University of Munich (TUM), Munich, Germany
| | - Reimar Johne
- German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | - Oliver Schlüter
- Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Germany.,Alma Mater Studiorum, University of Bologna, Cesena, Italy
| | | | - Henry Jäger
- University of Natural Resources and Life Sciences (BOKU), Wien, Austria
| | - Thomas Holzhauser
- Division of Allergology, Paul-Ehrlich-Institut (PEI), Langen, Germany
| | | | - Angelika Roth
- Senate Commission on Food Safety (DFG), IfADo, Dortmund, Germany
| | - Robert Sevenich
- Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Germany.,Technical University of Berlin (TUB), Berlin, Germany
| | - Niels Bandick
- German Federal Institute for Risk Assessment (BfR), Berlin, Germany
| | | | | | | | - Volker Heinz
- DIL German Institute of Food Technologies e.V., Quakenbrück, Germany
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4
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Rosario AILS, Castro VS, Santos LF, Lisboa RC, Vallim DC, Silva MCA, Figueiredo EES, Conte-Junior CA, Costa MP. Shiga toxin-producing Escherichia coli isolated from pasteurized dairy products from Bahia, Brazil. J Dairy Sci 2021; 104:6535-6547. [PMID: 33741165 DOI: 10.3168/jds.2020-19511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Accepted: 01/28/2021] [Indexed: 11/19/2022]
Abstract
The presence of pathogenic Shiga toxin-producing Escherichia coli (STEC) in dairy products represents a public health concern because of its ability to produce the toxins Stx1 and Stx2, which cause intestinal diseases. Monitoring the stages of milk production and checking dairy products for contamination are crucial steps to ensure dairy safety. This study aimed to report the occurrence of thermotolerant coliforms, E. coli, and STEC strains in pasteurized dairy products and to evaluate the antibiotic resistance profiles, serotypes, and characterizations of the STEC isolates by pulsed-field gel electrophoresis. We obtained a total of 138 pasteurized dairy products from 15 processing plants in Bahia, Brazil, to examine coliforms, E. coli, and STEC strains. We found that 43% of samples (59/138) contained thermotolerant coliforms, and 30% (42/138) did not comply with Brazilian regulations. Overall, 6% (9/138) were positive for E. coli and 4% (5/138) were positive for STEC. We recovered 9 STEC isolates from pasteurized cream (2/9), Minas Padrão cheese (2/9), Minas Frescal cheese (4/9), and ricotta (1/9). All isolates were stx2-positive, and 2 were eae-positive. All isolates were negative for the "big 6" STEC serogroups, belonging instead to serotypes ONT:HNT, ONT:H12, O148:H-, OR:H40, OR:HNT, and O148:HNT. Pulsed-field gel electrophoresis revealed 100% genetic similarity among 3 isolates from 2 different samples produced in the same production facility, which may suggest cross-contamination. As well, we found isolates that were 98% similar but in samples produced in different production facilities, suggesting a mutual source of contamination or a circulating strain. Two STEC strains exhibited resistance to streptomycin. Although the isolates presented a low resistance profile and no strain belonged to the "big 6" pathogenic group, the circulation of stx2-positive STEC strains in ready-to-eat products highlights the importance of epidemiological surveillance inside the Brazilian dairy chain.
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Affiliation(s)
- Anisio I L S Rosario
- Graduate Program in Food Science (PGAli), Faculty of Pharmacy, Federal University of Bahia (UFBA), Salvador, BA, 40170-115, Brazil; Laboratório de Inspeção e Tecnologia de Leite e Derivados (LAITLACTEOS), Federal University of Bahia (UFBA), Salvador, BA, 40170-110, Brazil; Center for Food Analysis (NAL), Technological Development Support, Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-598, Brazil
| | - Vinicius S Castro
- Center for Food Analysis (NAL), Technological Development Support, Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-598, Brazil; Graduate Program in Food Science (PPGCAL), Institute of Chemistry (IQ), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-909, Brazil
| | - Luis F Santos
- Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, Adolfo Lutz Institute, São Paulo, SP, 01246-902, Brazil
| | - Rodrigo C Lisboa
- Laboratório de Zoonoses Bacterianas, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, RJ, 21040-900, Brazil
| | - Deyse C Vallim
- Laboratório de Zoonoses Bacterianas, Oswaldo Cruz Institute, Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, RJ, 21040-900, Brazil
| | - Maurício C A Silva
- Laboratório de Inspeção e Tecnologia de Carnes e Derivados (LABCARNE), Federal University of Bahia (UFBA), Salvador, BA, 40170-110, Brazil
| | - Eduardo E S Figueiredo
- Laboratório de Microbiologia Molecular de Alimentos, Federal University of Mato Grosso (UFMT), Cuiabá, MT, 78060-900, Brazil
| | - Carlos A Conte-Junior
- Center for Food Analysis (NAL), Technological Development Support, Laboratory (LADETEC), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-598, Brazil; Graduate Program in Food Science (PPGCAL), Institute of Chemistry (IQ), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-909, Brazil; Laboratory of Advanced Analysis in Biochemistry and Molecular Biology (LAABBM), Department of Biochemistry, Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-909, Brazil; Graduate Program in Veterinary Hygiene (PPGHV), Faculty of Veterinary Medicine, Fluminense Federal University (UFF), Vital Brazil Filho, Niterói, RJ, 24230-340, Brazil; Graduate Program in Sanitary Surveillance (PPGVS), National Institute of Health Quality Control (INCQS), Oswaldo Cruz Foundation (FIOCRUZ), Rio de Janeiro, RJ, 21040-900, Brazil; Graduate Program in Chemistry (PGQu), Institute of Chemistry (IQ), Federal University of Rio de Janeiro (UFRJ), Cidade Universitária, Rio de Janeiro, RJ, 21941-909, Brazil
| | - Marion P Costa
- Graduate Program in Food Science (PGAli), Faculty of Pharmacy, Federal University of Bahia (UFBA), Salvador, BA, 40170-115, Brazil; Laboratório de Inspeção e Tecnologia de Leite e Derivados (LAITLACTEOS), Federal University of Bahia (UFBA), Salvador, BA, 40170-110, Brazil.
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5
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Li H, Sun X, Liao X, Gänzle M. Control of pathogenic and spoilage bacteria in meat and meat products by high pressure: Challenges and future perspectives. Compr Rev Food Sci Food Saf 2020; 19:3476-3500. [PMID: 33337070 DOI: 10.1111/1541-4337.12617] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/10/2020] [Accepted: 07/19/2020] [Indexed: 01/18/2023]
Abstract
High-pressure processing is among the most widely used nonthermal intervention to reduce pathogenic and spoilage bacteria in meat and meat products. However, resistance of pathogenic bacteria strains in meats at the current maximum commercial equipment of 600 MPa questions the ability of inactivation by its application in meats. Pathogens including Escherichia coli, Listeria, and Salmonelle, and spoilage microbiota including lactic acid bacteria dominate in raw meat, ready-to-eat, and packaged meat products. Improved understanding on the mechanisms of the pressure resistance is needed for optimizing the conditions of pressure treatment to effectively decontaminate harmful bacteria. Effective control of the pressure-resistant pathogens and spoilage organisms in meats can be realized by the combination of high pressure with application of mild temperature and/or other hurdles including antimicrobial agents and/or competitive microbiota. This review summarized applications, mechanisms, and challenges of high pressure on meats from the perspective of microbiology, which are important for improving the understanding and optimizing the conditions of pressure treatment in the future.
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Affiliation(s)
- Hui Li
- Institute of Quality Standard and Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaohong Sun
- College of Food and Biological Engineering, Qiqihar University, Qiqihar, Heilongjiang, China
| | - Xiaojun Liao
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada
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6
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Gautam B, Govindan BN, Gӓnzle M, Roopesh MS. Influence of water activity on the heat resistance of Salmonella enterica in selected low-moisture foods. Int J Food Microbiol 2020; 334:108813. [PMID: 32841809 DOI: 10.1016/j.ijfoodmicro.2020.108813] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 04/23/2020] [Accepted: 08/01/2020] [Indexed: 10/23/2022]
Abstract
Low-moisture foods (LMF with water activity, aw < 0.85) including pet foods and black pepper powder have consistently been associated with foodborne disease caused by Salmonella enterica. Increased heat resistance and prolonged survival at low-moisture conditions, however, remain major challenges to achieve effective inactivation of Salmonella in low-moisture foods. At low water activity (aw) conditions, heat resistance of Salmonella is greatly enhanced when compared to high aw conditions. This study aimed to quantify the effect of aw on the heat resistance of Salmonella enterica in pet food pellets and black pepper powder. Pet food pellets were inoculated with two strains of heat resistant S. enterica and black pepper powder was inoculated with a 5-strain cocktail of Salmonella. Both inoculated food samples were equilibrated at 0.33, 0.54, and 0.75 aw in controlled humidity chambers. Inoculated pet food pellets and black pepper powder in closed aluminum cells were heat treated at specific temperatures for selected times. The results showed that the Weibull model fitted well the inactivation data. At a specific temperature, the rate of inactivation increased with the increase in the aw from 0.33 to 0.75, and the 3-log reduction times decreased for Salmonella in both food samples with the increase in aw. Water adsorption isotherms of pet food pellets and black pepper powder at initial and treatment temperatures were developed to understand the change in aw during heat treatments. The change in aw during heat treatment was dependent on the type of food matrix, which possibly influenced the thermal inactivation of Salmonella in pet food pellets and black pepper powder. The quantitative analysis of heat reduction of Salmonella with respect to aw aids in selection of the appropriate initial aw to develop effective heat treatment protocols for adequate reduction of Salmonella in pet foods and black pepper powder.
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Affiliation(s)
- Bina Gautam
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada
| | - Byju N Govindan
- Department of Entomology, University of Minnesota, 1980 Folwell Avenue, 219 Hodson Hall, St. Paul, MN 55108, USA
| | - Michael Gӓnzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada
| | - M S Roopesh
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta T6G 2P5, Canada.
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7
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Parvin MS, Talukder S, Ali MY, Chowdhury EH, Rahman MT, Islam MT. Antimicrobial Resistance Pattern of Escherichia coli Isolated from Frozen Chicken Meat in Bangladesh. Pathogens 2020; 9:pathogens9060420. [PMID: 32481680 PMCID: PMC7350304 DOI: 10.3390/pathogens9060420] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/23/2020] [Accepted: 05/25/2020] [Indexed: 01/15/2023] Open
Abstract
Escherichia coli is known as one of the most important foodborne pathogens in humans, and contaminated chicken meat is an important source of foodborne infection with this bacterium. The occurrence of extended-spectrum β-lactamase (ESBL)-producing E. coli (ESBL-Ec), in particular, in chicken meat is considered a global health problem. This study aimed to determine the magnitude of E. coli, with special emphasis on ESBL-Ec, along with their phenotypic antimicrobial resistance pattern in frozen chicken meat. The study also focused on the determination of ESBL-encoding genes in E. coli. A total of 113 frozen chicken meat samples were purchased from 40 outlets of nine branded supershops in five megacities in Bangladesh. Isolation and identification of E. coli were done based on cultural and biochemical properties, as well as PCR assay. The resistance pattern was determined by the disc diffusion method. ESBL-encoding genes were determined by multiplex PCR. The results showed that 76.1% of samples were positive for E. coli, of which 86% were ESBL producers. All the isolates were multidrug-resistant (MDR). Resistance to 9-11 and 12-13 antimicrobial classes was observed in 38.4% and 17.4% isolates, respectively, while only 11.6% were resistant to 3-5 classes. Possible extensive drug resistance (pXDR) was found in 2.3% of isolates. High single resistance was observed for oxytetracycline (93%) and amoxicillin (91.9%), followed by ampicillin (89.5%), trimethoprim-sulfamethoxazole, and pefloxacin (88.4%), and tetracycline (84.9%). Most importantly, 89.6% of isolates were resistant to carbapenems. All the isolates were positive for the blaTEM gene. However, the blaSHV and blaCTX-M-2 genes were identified in two ESBL-non producer isolates. None of the isolates carried the blaCTX-M-1 gene. This study provided evidence of the existence of MDR and pXDR ESBL-Ec in frozen chicken meat in Bangladesh, which may pose a risk to human health if the meat is not properly cooked or pickled raw only. This emphasizes the importance of the implementation of good slaughtering and processing practices by the processors.
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Affiliation(s)
- Mst. Sonia Parvin
- Population Medicine and AMR Laboratory, Department of Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh; (M.S.P.); (S.T.); (M.Y.A.)
| | - Sudipta Talukder
- Population Medicine and AMR Laboratory, Department of Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh; (M.S.P.); (S.T.); (M.Y.A.)
| | - Md. Yamin Ali
- Population Medicine and AMR Laboratory, Department of Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh; (M.S.P.); (S.T.); (M.Y.A.)
| | - Emdadul Haque Chowdhury
- Department of Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh;
| | - Md. Tanvir Rahman
- Department of Microbiology and Hygiene, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh;
| | - Md. Taohidul Islam
- Population Medicine and AMR Laboratory, Department of Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh; (M.S.P.); (S.T.); (M.Y.A.)
- Correspondence: ; Tel.: +880-916-7401
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8
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Schultze DM, Couto R, Temelli F, McMullen LM, Gänzle M. Lethality of high-pressure carbon dioxide on Shiga toxin-producing Escherichia coli, Salmonella and surrogate organisms on beef jerky. Int J Food Microbiol 2020; 321:108550. [DOI: 10.1016/j.ijfoodmicro.2020.108550] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/09/2020] [Accepted: 02/05/2020] [Indexed: 11/28/2022]
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9
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Li H, Mercer R, Behr J, Heinzlmeir S, McMullen LM, Vogel RF, Gänzle MG. Heat and Pressure Resistance in Escherichia coli Relates to Protein Folding and Aggregation. Front Microbiol 2020; 11:111. [PMID: 32117137 PMCID: PMC7010813 DOI: 10.3389/fmicb.2020.00111] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 01/17/2020] [Indexed: 01/16/2023] Open
Abstract
The locus of heat resistance (LHR) confers extreme heat resistance in Escherichia coli. This study explored the role of the LHR in heat and pressure resistance of E. coli, as well as its relationship with protein folding and aggregation in vivo. The role of LHR was investigated in E. coli MG1655 and the pressure resistant E. coli LMM1010 expressing an ibpA-yfp fusion protein to visualize inclusion bodies by fluorescence microscopy. The expression of proteins by the LHR was determined by proteomic analysis; inclusion bodies of untreated and treated cells were also analyzed by proteomics, and by fluorescent microscopy. In total, 11 proteins of LHR were expressed: sHSP20, ClpKGI, sHSP, YdfX1 and YdfX2, HdeD, KefB, Trx, PsiE, DegP, and a hypothetical protein. The proteomic analysis of inclusion bodies revealed a differential abundance of proteins related to oxidative stress in strains carrying the LHR. The LHR reduced the presence of inclusion bodies after heat or pressure treatment, indicating that proteins expressed by the LHR prevent protein aggregation, or disaggregate proteins. This phenotype of the LHR was also conferred by expression of a fragment containing only sHSP20, ClpKGI, and sHSP. The LHR and the fragment encoding only sHSP20, ClpKGI, and sHSP also enhanced pressure resistance in E. coli MG1655 but had no effect on pressure resistance of E. coli LMM1010. In conclusion, the LHR confers pressure resistance to some strains of E. coli, and reduces protein aggregation. Pressure and heat resistance are also dependent on additional LHR-encoded functions.
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Affiliation(s)
- Hui Li
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.,Institute of Quality Standard and Testing Technology for Agro-Products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-food Quality and Safety, Ministry of Agriculture, Beijing, China
| | - Ryan Mercer
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Jürgen Behr
- Bavarian Center for Biomolecular Mass Spectrometry, Technical University of Munich, Freising, Germany.,Leibniz-Institute for Food Systems Biology, Technical University of Munich, Freising, Germany
| | - Stephanie Heinzlmeir
- Bavarian Center for Biomolecular Mass Spectrometry, Technical University of Munich, Freising, Germany
| | - Lynn M McMullen
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Rudi F Vogel
- Technical University of Munich - Lehrstuhl fär Technische Mikrobiologie, Freising, Germany
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada.,College of Bioengineering and Food Science, Hubei University of Technology, Wuhan, China
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10
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Andre C, de Jesus Pimentel-Filho N, de Almeida Costa PM, Vanetti MCD. Changes in the composition and architecture of staphylococcal biofilm by nisin. Braz J Microbiol 2019; 50:1083-1090. [PMID: 31456169 DOI: 10.1007/s42770-019-00135-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 08/03/2019] [Indexed: 01/05/2023] Open
Abstract
Bacterial biofilms are involved in various medical infections and food contamination episodes and, for this reason, it is of great importance to developing new strategies of its prevention and control. The subinhibitory concentration of nisin was determined, and its effect against Staphylococcus aureus and Staphylococcus epidermidis biofilms was evaluated. Results obtained by confocal laser microscopy demonstrated morphological changes in the architecture of the structure of biofilms. The main components (polysaccharides, proteins, and extracellular DNA (eDNA)) of the biofilm matrix were determined by spectrophotometry and showed that the formation of staphylococcal biofilms in the presence of nisin results in a less dense matrix structure with modification in its constituents. These results contribute to increase the knowledge of the composition and architecture of the extracellular matrix of biofilms of S. aureus, as well as evidence that the investigation of alternative products to assist in the control and combat of biofilms is a promising strategy.
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Affiliation(s)
- Cleriane Andre
- Departamento de Microbiologia, Universidade Federal de Viçosa, Av. P. H. Rolfs, Viçosa, Minas Gerais, 36570-900, Brazil
| | - Natan de Jesus Pimentel-Filho
- Centro de Ciências da Natureza, Universidade Federal de São Carlos, Rod. Lauri Simões de Barros - SP 189, km 12, Buri, São Paulo, 18290-000, Brazil
| | - Paulo Mafra de Almeida Costa
- Instituto Federal Catarinense - Campus Concórdia, Rod. SC 283, km 8, Concórdia, Santa Catarina, 89703-720, Brazil
| | - Maria Cristina Dantas Vanetti
- Departamento de Microbiologia, Universidade Federal de Viçosa, Av. P. H. Rolfs, Viçosa, Minas Gerais, 36570-900, Brazil.
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de Souza Figueiredo EE, Yang X, Zhang P, Reuter T, Stanford K. Comparison of heating block and water bath methods to determine heat resistance in Shiga-toxin producing Escherichia coli with and without the locus of heat resistance. J Microbiol Methods 2019; 164:105679. [PMID: 31351872 DOI: 10.1016/j.mimet.2019.105679] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 07/24/2019] [Accepted: 07/24/2019] [Indexed: 10/26/2022]
Abstract
This study found variability in the time required for tubes of media in heating block wells to reach 60 °C, resulting in significant effects on heat resistance measurements. To determine the extent that methodology changed heat resistance measurements, we compared the heat resistance of Shiga-toxin producing Escherichia coli (STEC) strains with and without the locus of heat resistance (LHR) using both heating block and water bath methods. A total of 34 strains of STEC were used along with a generic E. coli which has been identified as heat-resistant and used as a positive control. The E. coli strains were incubated in a water bath and a heating block set at 60 °C to determine come up time to 60 °C (T0) and for 6 additional minutes (T6) to calculate the D60 value. After incubation, the colony forming units (CFU) were enumerated and mean log CFU/mL from biological replicates was calculated. To compare reductions from T0 to T6, standard deviations among replicates within heating method and correlation of the D60 values generated across methods were determined using Mixed model and Correlation analyses. Our findings indicate that the method chosen to evaluate heat resistance of E. coli can dramatically influence results as there was not a significant correlation between D60 values for the same isolate determined by water bath and heating block methods. The water bath method generates more reliable and consistent heat resistance data and should be used in future evaluations of heat resistance in E. coli. Moreover, PCR screening for the LHR would only be moderately useful for predicting phenotypic heat-resistance of E. coli. Considering water bath data only, LHR-positive STEC isolates were either moderately heat-resistant (1 to 5 log reduction) or heat-sensitive (> 5 log reduction). As LHR-negative STEC were also moderately heat-resistant, prediction of phenotypic heat resistance from genotype requires further refinement.
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Affiliation(s)
| | - Xianqin Yang
- Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, Lacombe, AB T4L 1W1, Canada
| | - Peipei Zhang
- Agriculture and Agri-Food Canada, Lacombe Research and Development Centre, Lacombe, AB T4L 1W1, Canada
| | - Tim Reuter
- Alberta Agriculture and Forestry, Agriculture Centre, Lethbridge, AB T1J 4V6, Canada
| | - Kim Stanford
- Alberta Agriculture and Forestry, Agriculture Centre, Lethbridge, AB T1J 4V6, Canada.
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Tang KX, Shi T, Gänzle M. Effect of starter cultures on taste-active amino acids and survival of pathogenic Escherichia coli in dry fermented beef sausages. Eur Food Res Technol 2018. [DOI: 10.1007/s00217-018-3130-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Woerner DR, Geornaras I, Martin JN, Belk KE, Acuff GR, Dickson JS. Use of Nonpathogenic Escherichia coli Surrogates as Predictors of the Survival of Nontyphoidal Salmonella, non-O157 Shiga Toxin-Producing Escherichia coli, and Escherichia coli O157 Populations after High Hydrostatic Pressure Processing. J Food Prot 2018; 81:1068-1072. [PMID: 29893583 DOI: 10.4315/0362-028x.jfp-17-385] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Validated surrogates are a useful tool for studying the response of pathogens to food safety interventions, but better surrogates are needed for studies using high pressure processing. Ground beef (85% lean, 15% fat) was inoculated separately with mixed cultures of Escherichia coli O157, non-O157 Shiga toxin-producing E. coli, nontyphoidal Salmonella, and nonpathogenic E. coli surrogate bacteria. The inoculated ground beef was subjected to high hydrostatic pressures of 200, 400, and 600 MPa for 4, 6, and 8 min at each pressure. High pressure processing at 200 MPa reduced the inoculated populations of the pathogenic bacteria by 0.9 to 1.8 log CFU/g, 400 MPa reduced the inoculated populations by 2.5 to 3.6 log CFU/g, and 600 MPa reduced the inoculated populations by 4.5 to 5.6 log CFU/g. The nonpathogenic E. coli surrogates were more resistant to the effects of high pressure processing than were the inoculated pathogen populations. This finding suggests that the nonpathogenic E. coli surrogates could be used as process control indicators for high pressure processing of ground beef to predict a specific level of pathogen reduction. The surviving populations of the potential surrogate bacteria were proportional to the surviving populations of the pathogenic bacteria. The models allow for an estimation of the potential surviving populations of the pathogenic bacteria based on quantitative results of the populations of the surrogate bacteria.
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Affiliation(s)
- Dale R Woerner
- 1 Center for Meat Safety and Quality, Department of Animal Sciences, Colorado State University, 1171 Campus Delivery, Fort Collins, Colorado 80523 (ORCID: http://orcid.org/0000-0002-0761-0720 [J.N.M.])
| | - Ifigenia Geornaras
- 1 Center for Meat Safety and Quality, Department of Animal Sciences, Colorado State University, 1171 Campus Delivery, Fort Collins, Colorado 80523 (ORCID: http://orcid.org/0000-0002-0761-0720 [J.N.M.])
| | - Jennifer N Martin
- 1 Center for Meat Safety and Quality, Department of Animal Sciences, Colorado State University, 1171 Campus Delivery, Fort Collins, Colorado 80523 (ORCID: http://orcid.org/0000-0002-0761-0720 [J.N.M.])
| | - Keith E Belk
- 1 Center for Meat Safety and Quality, Department of Animal Sciences, Colorado State University, 1171 Campus Delivery, Fort Collins, Colorado 80523 (ORCID: http://orcid.org/0000-0002-0761-0720 [J.N.M.])
| | - Gary R Acuff
- 2 Department of Nutrition and Food Science, 2253 TAMU, Texas A&M University, College Station, Texas 77843-2253; and
| | - James S Dickson
- 3 Department of Animal Science, 2372 Kildee, 806 Stange Road, Iowa State University, Ames, Iowa 50011, USA
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Hu M, Gurtler JB. Selection of Surrogate Bacteria for Use in Food Safety Challenge Studies: A Review. J Food Prot 2017; 80:1506-1536. [PMID: 28805457 DOI: 10.4315/0362-028x.jfp-16-536] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Nonpathogenic surrogate bacteria are prevalently used in a variety of food challenge studies in place of foodborne pathogens such as Listeria monocytogenes, Salmonella, Escherichia coli O157:H7, and Clostridium botulinum because of safety and sanitary concerns. Surrogate bacteria should have growth characteristics and/or inactivation kinetics similar to those of target pathogens under given conditions in challenge studies. It is of great importance to carefully select and validate potential surrogate bacteria when verifying microbial inactivation processes. A validated surrogate responds similar to the targeted pathogen when tested for inactivation kinetics, growth parameters, or survivability under given conditions in agreement with appropriate statistical analyses. However, a considerable number of food studies involving putative surrogate bacteria lack convincing validation sources or adequate validation processes. Most of the validation information for surrogates in these studies is anecdotal and has been collected from previous publications but may not be sufficient for given conditions in the study at hand. This review is limited to an overview of select studies and discussion of the general criteria and approaches for selecting potential surrogate bacteria under given conditions. The review also includes a list of documented bacterial pathogen surrogates and their corresponding food products and treatments to provide guidance for future studies.
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Affiliation(s)
- Mengyi Hu
- 1 U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551.,2 Department of Culinary Arts and Food Science, Drexel University, 3141 Chestnut Street, Philadelphia, Pennsylvania 19104-30, USA
| | - Joshua B Gurtler
- 1 U.S. Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Food Safety and Intervention Technologies Research Unit, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038-8551
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Effect of hydrostatic pressure and antimicrobials on survival of Listeria monocytogenes and enterohaemorrhagic Escherichia coli in beef. INNOV FOOD SCI EMERG 2016. [DOI: 10.1016/j.ifset.2016.05.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Li H, Gänzle M. Some Like It Hot: Heat Resistance of Escherichia coli in Food. Front Microbiol 2016; 7:1763. [PMID: 27857712 PMCID: PMC5093140 DOI: 10.3389/fmicb.2016.01763] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/20/2016] [Indexed: 11/13/2022] Open
Abstract
Heat treatment and cooking are common interventions for reducing the numbers of vegetative cells and eliminating pathogenic microorganisms in food. Current cooking method requires the internal temperature of beef patties to reach 71°C. However, some pathogenic Escherichia coli such as the beef isolate E. coli AW 1.7 are extremely heat resistant, questioning its inactivation by current heat interventions in beef processing. To optimize the conditions of heat treatment for effective decontaminations of pathogenic E. coli strains, sufficient estimations, and explanations are necessary on mechanisms of heat resistance of target strains. The heat resistance of E. coli depends on the variability of strains and properties of food formulations including salt and water activity. Heat induces alterations of E. coli cells including membrane, cytoplasm, ribosome and DNA, particularly on proteins including protein misfolding and aggregations. Resistant systems of E. coli act against these alterations, mainly through gene regulations of heat response including EvgA, heat shock proteins, σE and σS, to re-fold of misfolded proteins, and achieve antagonism to heat stress. Heat resistance can also be increased by expression of key proteins of membrane and stabilization of membrane fluidity. In addition to the contributions of the outer membrane porin NmpC and overcome of osmotic stress from compatible solutes, the new identified genomic island locus of heat resistant performs a critical role to these highly heat resistant strains. This review aims to provide an overview of current knowledge on heat resistance of E. coli, to better understand its related mechanisms and explore more effective applications of heat interventions in food industry.
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Affiliation(s)
- Hui Li
- Department of Agricultural, Food and Nutritional Science, University of Alberta, EdmontonAB, Canada
| | - Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, EdmontonAB, Canada
- College of Bioengineering and Food Science, Hubei University of TechnologyHubei, China
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Stress-Induced Evolution of Heat Resistance and Resuscitation Speed in Escherichia coli O157:H7 ATCC 43888. Appl Environ Microbiol 2016; 82:6656-6663. [PMID: 27590820 DOI: 10.1128/aem.02027-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 08/27/2016] [Indexed: 11/20/2022] Open
Abstract
The development of resistance in foodborne pathogens to food preservation techniques is an issue of increasing concern, especially in minimally processed foods where safety relies on hurdle technology. In this context, mild heat can be used in combination with so-called nonthermal processes, such as high hydrostatic pressure (HHP), at lower individual intensities to better retain the quality of the food. However, mild stresses may increase the risk of (cross-)resistance development in the surviving population, which in turn might compromise food safety. In this investigation, we examined the evolution of Escherichia coli O157:H7 strain ATCC 43888 after recurrent exposure to progressively intensifying mild heat shocks (from 54.0°C to 60.0°C in 0.5°C increments) with intermittent resuscitation and growth of survivors. As such, mutant strains were obtained after 10 cycles of selection with ca. 106-fold higher heat resistance than that for the parental strain at 58.0°C, although this resistance did not extend to temperatures exceeding 60.0°C. Moreover, these mutant strains typically displayed cross-resistance against HHP shock and displayed signs of enhanced RpoS and RpoH activity. Interestingly, additional cycles of selection maintaining the intensity of the heat shock constant (58.5°C) selected for mutant strains in which resuscitation speed, rather than resistance, appeared to be increased. Therefore, it seems that resistance and resuscitation speed are rapidly evolvable traits in E. coli ATCC 43888 that can compromise food safety. IMPORTANCE In this investigation, we demonstrated that Escherichia coli O157:H7 ATCC 43888 rapidly acquires resistance to mild heat exposure, with this resistance yielding cross-protection to high hydrostatic pressure treatment. In addition, mutants of E. coli ATCC 43888 in which resuscitation speed, rather than resistance, appeared to be improved were selected. As such, both resistance and resuscitation speed seem to be rapidly evolvable traits that can compromise the control of foodborne pathogens in minimal processing strategies, which rely on the efficacy of combined mild preservation stresses for food safety.
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Parul S, Bist B, Sharma B, Jain U, Yadav JK. A study on association of virulence determinants of verotoxic Escherichia coli isolated from cattle calves. Vet World 2016; 9:915-8. [PMID: 27651684 PMCID: PMC5021845 DOI: 10.14202/vetworld.2016.915-918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/25/2016] [Indexed: 01/07/2023] Open
Abstract
AIM The present study was conducted to find the association among virulence determinants of verotoxic Escherichia coli (VTEC) isolated from cattle calf feces. MATERIALS AND METHODS A total of 216 cattle calf fecal samples were collected aseptically and processed under required conditions for the isolation of E. coli. The isolates were further subjected to multiplex polymerase chain reaction (mPCR) for the detection of virulent genes. All the VTEC isolates were serotyped at the Central Research Institute, Kasauli, Himachal Pradesh. The VTEC isolates were observed for the enterohemolysin production on washed sheep blood agar (wSBA). RESULTS A total of 177 presumptive E. coli were isolated from 216 calf fecal samples revealing an overall prevalence of E. coli to be 81.94%. A total of 32 (14.81%) isolates were detected as VTEC through mPCR. The prevalence of verotoxin genes vt1, vt2, and combination of vt1+vt2 in the VTEC isolates was found to be 12 (37.5%), 14 (43.75%), and 6 (18.75%), respectively. Other virulent genes eaeA and hlyA were found in 6 and 11 VTEC strains with prevalence values of 18.75% and 34.37%, respectively. A total of 13 different O serogroups were revealed in serotyping of 32 VTEC isolates. Out of 32 VTEC strains, only 26 (81.25%) were enterohemolytic on wSBA as they produced the characteristic small, turbid zone of hemolysis around the streaking line. Although enterohemolysin production has been attributed to the presence of hlyA gene, only 11 of 26 enterohemolysin producing VTEC were found to be harboring the hlyA gene (11/26) 42.03%. CONCLUSION The present study concludes that there might be an association between the presence of verotoxin genes and enterohemolysin production in VTEC group of E. coli.
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Affiliation(s)
- Singh Parul
- State Veterinary Hospital, Dhana Teja, Mathura, Uttar Pradesh, India
| | - Basanti Bist
- Department of Veterinary Public Health, College of Veterinary Sciences and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Veterinary Science University, Mathura, Uttar Pradesh, India
| | - Barkha Sharma
- Department of Epidemiology and Preventive Veterinary Medicine, College of Veterinary Sciences and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Veterinary Science University, Mathura, Uttar Pradesh, India
| | - Udit Jain
- Department of Veterinary Public Health, College of Veterinary Sciences and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Veterinary Science University, Mathura, Uttar Pradesh, India
| | - Janardan K. Yadav
- Department of Veterinary Public Health, College of Veterinary Sciences and Animal Husbandry, UP Pandit Deen Dayal Upadhyaya Veterinary Science University, Mathura, Uttar Pradesh, India
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19
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Chen YY, Gänzle MG. Influence of cyclopropane fatty acids on heat, high pressure, acid and oxidative resistance in Escherichia coli. Int J Food Microbiol 2016; 222:16-22. [DOI: 10.1016/j.ijfoodmicro.2016.01.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 01/18/2016] [Accepted: 01/23/2016] [Indexed: 10/22/2022]
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20
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Li H, Garcia-Hernandez R, Driedger D, McMullen LM, Gänzle M. Effect of the food matrix on pressure resistance of Shiga-toxin producing Escherichia coli. Food Microbiol 2016; 57:96-102. [PMID: 27052707 DOI: 10.1016/j.fm.2016.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 01/23/2016] [Accepted: 02/06/2016] [Indexed: 12/18/2022]
Abstract
The pressure resistance of Shiga-toxin producing Escherichia coli (STEC) depends on food matrix. This study compared the resistance of two five-strain E. coli cocktails, as well as the pressure resistant strain E. coli AW1.7, to hydrostatic pressure application in bruschetta, tzatziki, yoghurt and ground beef at 600 MPa, 20 °C for 3 min and during post-pressure survival at 4 °C. Pressure reduced STEC in plant and dairy products by more than 5 logs (cfu/ml) but not in ground beef. The pH affected the resistance of STEC to pressure as well as the post-pressure survival. E. coli with food constituents including calcium, magnesium, glutamate, caffeic acid and acetic acid were treated at 600 MPa, 20 °C. All compounds exhibited a protective effect on E. coli. The antimicrobial compounds ethanol and phenylethanol enhanced the inactivation by pressure. Calcium and magnesium also performed protective effects on E. coli during storage. Glutamate, glutamine or glutathione did not significantly influence the post-pressure survival over 12 days. Preliminary investigation on cell membrane was further performed through the use of fluorescence probe 1-N-phenylnaphthylamine. Pressure effectively permeabilised cell membrane, whereas calcium showed no effects on membrane permeabilisation.
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Affiliation(s)
- Hui Li
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | | | - Darcy Driedger
- Alberta Agriculture and Forestry, Food Processing Development Centre, Leduc, Canada
| | - Lynn M McMullen
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael Gänzle
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada; Hubei University of Technology, School of Food and Pharmaceutical Engineering, Wuhan, China.
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Gänzle M, Liu Y. Mechanisms of pressure-mediated cell death and injury in Escherichia coli: from fundamentals to food applications. Front Microbiol 2015; 6:599. [PMID: 26157424 PMCID: PMC4478891 DOI: 10.3389/fmicb.2015.00599] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/01/2015] [Indexed: 12/12/2022] Open
Abstract
High hydrostatic pressure is commercially applied to extend the shelf life of foods, and to improve food safety. Current applications operate at ambient temperature and 600 MPa or less. However, bacteria that may resist this pressure level include the pathogens Staphylococcus aureus and strains of Escherichia coli, including shiga-toxin producing E. coli. The resistance of E. coli to pressure is variable between strains and highly dependent on the food matrix. The targeted design of processes for the safe elimination of E. coli thus necessitates deeper insights into mechanisms of interaction and matrix-strain interactions. Cellular targets of high pressure treatment in E. coli include the barrier properties of the outer membrane, the integrity of the cytoplasmic membrane as well as the activity of membrane-bound enzymes, and the integrity of ribosomes. The pressure-induced denaturation of membrane bound enzymes results in generation of reactive oxygen species and subsequent cell death caused by oxidative stress. Remarkably, pressure resistance at the single cell level relates to the disposition of misfolded proteins in inclusion bodies. While the pressure resistance E. coli can be manipulated by over-expression or deletion of (stress) proteins, the mechanisms of pressure resistance in wild type strains is multi-factorial and not fully understood. This review aims to provide an overview on mechanisms of pressure-mediated cell death in E. coli, and the use of this information for optimization of high pressure processing of foods.
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Affiliation(s)
- Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
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