1
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Brar J, Novoa-Rama E, Corkran S, Juneja VK, Kroft B, Singh M. Predictive modeling of thermal inactivation of non-O157 Shiga toxin-producing Escherichia coli in ground beef with varying fat contents. Food Res Int 2023; 174:113481. [PMID: 37986491 DOI: 10.1016/j.foodres.2023.113481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 11/22/2023]
Abstract
A mathematical model to predict the thermal inactivation of non-O157 Shiga toxin-producing Escherichia coli (STEC) in ground beef was developed, with temperature and fat content of ground beef as controlling factors. Survival curves for a cocktail of non-O157 STEC strains in ground beef at four temperatures (55, 60, 65, and 68 °C) and six fat levels (5, 10, 15, 20, 25, and 30%) were generated. Nine primary models-log-linear, log-linear with tail, biphasic, sigmoidal, four-factor sigmoidal, Baranyi, Weibull, mixed Weibull, and Gompertz-were tested for fitting the survival curves. Primary modeling analysis showed the Weibull model had the highest accuracy factor and Akaike's weight, making it the best-fitting model. The parameters of the Weibull model were estimated using a nonlinear mixed, and response surface modeling was used to develop a second-order polynomial regression to estimate the impact of fat in ground beef and cooking temperature on the heat resistance of non-O157 STEC strains. The secondary model was successfully validated by comparing predicted lethality (log10 CFU/g) with the observed values for ground beef containing 10 and 27% fat at 58 and 62 °C. Process lethality obtained from experimental data was within the prediction interval of the predictive model. The developed model will assist the food industry in estimating the appropriate time and temperature required for cooking ground beef to provide adequate protection against STEC contaminants.
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Affiliation(s)
- Jagpinder Brar
- Department of Food Science, Purdue University, West Lafayette, IN 47906
| | - Estefania Novoa-Rama
- Department of Food Science and Technology, University of Georgia, Athens, GA 30602
| | - Sydney Corkran
- Department of Food Science, Purdue University, West Lafayette, IN 47906
| | - Vijay K Juneja
- US Department of Agriculture - Eastern Regional Research Center, Wyndmoor, PA 19038
| | - Brenda Kroft
- Department of Food Science and Technology, University of Georgia, Athens, GA 30602
| | - Manpreet Singh
- Department of Food Science and Technology, University of Georgia, Athens, GA 30602.
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2
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Gayán E, Wang Z, Salvador M, Gänzle MG, Aertsen A. Dynamics of high hydrostatic pressure resistance development in RpoS-deficient Escherichia coli. Food Res Int 2023; 164:112280. [PMID: 36737893 DOI: 10.1016/j.foodres.2022.112280] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/17/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
High hydrostatic pressure (HHP) treatment is one of the most widely accepted non-thermal food processing methods, but HHP-resistance development in pathogenic or spoilage bacteria might compromise the safety and stability of HHP-treated foods. Charting the possible routes and mechanisms of HHP resistance development in foodborne bacteria is therefore essential to anticipate or prevent the appearance of resistant variants. While upregulation of the RpoS-governed general stress response is a well-established route for increased HHP resistance in Escherichia coli, previous work revealed that mutations causing attenuated cAMP/CRP activity or aggregation-prone TnaA variants can evolve to overcome the HHP-hypersensitivity of an E. coli ΔrpoS mutant. In this study, further directed evolution and genetic analysis approaches allowed us to demonstrate that both kinds of mutants tend to co-emerge and compete with each other in E. coli ΔrpoS populations evolving towards HHP resistance, because of the higher HHP resistance of cAMP/CRP mutants and the faster growth rate of the TnaA mutants. Moreover, closer scrutiny of evolving populations revealed RpoS, cAMP/CRP and TnaA independent routes of HHP resistance development, based on downregulation of YegW or RppH activity.
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Affiliation(s)
- Elisa Gayán
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium
| | - Zhiying Wang
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Maika Salvador
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, 4-10 Ag/For Centre, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven, Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001 Leuven, Belgium.
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3
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Saricaoglu B, Gültekin Subaşı B, Karbancioglu-Guler F, Lorenzo JM, Capanoglu E. Phenolic compounds as natural microbial toxin detoxifying agents. Toxicon 2023; 222:106989. [PMID: 36509264 DOI: 10.1016/j.toxicon.2022.106989] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 11/29/2022] [Accepted: 12/01/2022] [Indexed: 12/13/2022]
Abstract
Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.
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Affiliation(s)
- Beyza Saricaoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Büşra Gültekin Subaşı
- Hafik Kamer Ornek Vocational School, Sivas Cumhuriyet University, 58140, Sivas, Turkey
| | - Funda Karbancioglu-Guler
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey
| | - Jose Manuel Lorenzo
- Centro Tecnológico de La Carne de Galicia, Parque Tecnológico de Galicia, Avd. Galicia nº 4, San Cibrao das Viñas, 32900 Ourense, Spain; Universidade de Vigo, Área de Tecnoloxía dos Alimentos, Facultade de Ciencias, 32004 Ourense, Spain
| | - Esra Capanoglu
- Department of Food Engineering, Faculty of Chemical and Metallurgical Engineering, Istanbul Technical University, 34469, Maslak, Istanbul, Turkey.
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4
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Manafi L, Aliakbarlu J, Dastmalchi Saei H. Susceptibility of
Salmonella
serotypes isolated from meat and meat contact surfaces to thermal, acidic, and alkaline treatments and disinfectants. Food Sci Nutr 2023; 11:1882-1890. [PMID: 37051333 PMCID: PMC10084953 DOI: 10.1002/fsn3.3221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 12/13/2022] [Accepted: 12/28/2022] [Indexed: 01/11/2023] Open
Abstract
The present study was conducted to evaluate the response of 29 Salmonella isolates to exposure to thermal (60°C for 2 min), acidic (pH 2.9 for 30 min), and alkaline (pH 11 for 60 min) treatments and investigate the susceptibility of the isolates and their biofilms to disinfectants. The reductions of Salmonella isolates populations subjected to each treatment were analyzed according to their isolation source, serotype, antibiotic resistance pattern, and biofilm formation ability. Median reductions for all of Salmonella isolates populations after thermal, acidic, and alkaline treatments were 1.8, 2.1, and 0.7 log CFU/ml, respectively. The isolates behavior under stress conditions were not related to their isolation source, serotype, or biofilm formation ability. The median reduction after alkaline treatment in non-MDR (multidrug- resistant) isolates populations was significantly (p < .05) higher than MDR isolates. The median reduction in biofilms of moderate biofilm producers by disinfectants was significantly (p < .05) higher than that of strong biofilm producers. In conclusion, Salmonella isolates showed the highest susceptibility to acidic treatment and MDR isolates were more resistant to alkaline treatment than non-MDR ones. The current study also revealed that the strong biofilm producer isolates were more resistant to disinfectants than moderate biofilm producers. This study facilitated the understanding of the relationship between Salmonella characteristics (isolation source, serotype, antibiotic resistance pattern, and biofilm formation ability) and its susceptibility to thermal, acidic, and alkaline treatments and disinfectants. The findings are helpful for the prevention and control of Salmonella.
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Affiliation(s)
| | | | - Habib Dastmalchi Saei
- Faculty of Veterinary Medicine, Department of Microbiology Urmia University Urmia Iran
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5
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Fang Y, Brückner LL, McMullen LM, Gänzle MG. Transduction of stx2a mediated by phage (Φ11-3088) from Escherichia coli O104:H4 in vitro and in situ during sprouting of mung beans. Int J Food Microbiol 2022; 383:109952. [PMID: 36191491 DOI: 10.1016/j.ijfoodmicro.2022.109952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Revised: 09/19/2022] [Accepted: 09/23/2022] [Indexed: 12/29/2022]
Abstract
Escherichia coli O104:H4 strain 11-3088 encoding Stx2a is epidemiologically related to the foodborne outbreak associated with sprouts in Germany, 2011. Sprouting provides suitable conditions for bacterial growth and may lead to transduction of non-pathogenic strains of E. coli with Stx phages. Although transduction of E. coli by Stx phages in food has been documented, data on the phages from E. coli O104:H4 is limited. This study determined the host range of the bacteriophage Φ11-3088 from E. coli O104:H4 using E. coli O104:H4 ∆stx2::gfp::ampr and demonstrated phage transduction during sprouting. The Φ11-3088∆stx transduced 5/45 strains, including generic E. coli, pap-positive E. coli O103:H2, ETEC, and S. sonnei. The expression level of Φ11-3088∆stx differed among lysogens upon induction. Of the 3 highly induced lysogens, the lytic cycle was induced in E. coli O104:H4∆stx2::gfp::ampr and O103:H2 but not in S. sonnei. E. coli DH5α was the only strain susceptible to lytic infection by Φ11-3088∆stx. To explore the effect of drying and rehydration during seed storage and sprouting on phage induction and transduction, mung beans inoculated with the phage donor E. coli O104:H4∆stx2::gfp::ampr (8 log CFU/g) were dried, rehydrated, and incubated with the phage recipient E. coli DH5α (7 log CFU/g) for 96 h. Sprouted seeds harbored about 3 log CFU/g of putative lysogens that acquired ampicillin resistance. At the end of sprouting, 71 % of putative lysogens encoded gfp, confirming phage transduction. Overall, stx transfer by phages may increase the cell counts of STEC during sprouting by converting generic E. coli to STEC.
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Affiliation(s)
- Yuan Fang
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Luisa Linda Brückner
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Lynn M McMullen
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael G Gänzle
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada.
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6
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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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7
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Enhanced high hydrostatic pressure lethality in acidulated raw pet food formulations was pathogen species and strain dependent. Food Microbiol 2022; 104:104002. [DOI: 10.1016/j.fm.2022.104002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/30/2022] [Accepted: 02/03/2022] [Indexed: 12/12/2022]
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8
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Genetic Determinants of Stress Resistance in Desiccated Salmonella enterica. Appl Environ Microbiol 2021; 87:e0168321. [PMID: 34586905 DOI: 10.1128/aem.01683-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteric pathogens, including Salmonella, are capable of long-term survival after desiccation and resist heat treatments that are lethal to hydrated cells. The mechanisms of dry-heat resistance differ from those of wet-heat resistance. To elucidate the mechanisms of dry-heat resistance in Salmonella, screening of the dry-heat resistance of 108 Salmonella strains, representing 39 serotypes, identified the 22 most resistant and the 8 most sensitive strains for comparative genome analysis. A total of 289 genes of the accessory genome were differently distributed between resistant and sensitive strains. Among these genes, 28 proteins with a putative relationship to stress resistance were selected for to quantify relative gene expression before and after desiccation and expression by solid-state cultures on agar plates relative to cultures growing in liquid culture media. Of these 28 genes, 15 genes were upregulated (P < 0.05) after desiccation or by solid-state cultures on agar plates. These 15 genes were cloned into the low-copy-number vector pRK767 under the control of the lacZ promoter. The expression of 6 of these 15 genes increased (P < 0.05) resistance to dry heat and to treatment with pressure of 500 MPa. Our finding extends the knowledge of mechanisms of stress resistance in desiccated Salmonella to improve control of this bacterium in dry food. IMPORTANCE This study directly targeted an increasing threat to food safety and developed knowledge and targeted strategies that can be used by the food industry to help reduce the risk of foodborne illness in their dry products and thereby reduce the overall burden of foodborne illness. Genomic and physiological analyses have elucidated mechanisms of bacterial resistance to many food preservation technologies, including heat, pressure, disinfection chemicals, and UV light; however, information on bacterial mechanisms of resistance to dry heat is scarce. Mechanisms of tolerance to desiccation likely also contribute to resistance to dry heat, but this assumption has not been verified experimentally. It remains unclear how mechanisms of resistance to wet heat relate to dry-heat resistance. Thus, this study will fill a knowledge gap to improve the safety of dry foods.
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9
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Effects of high-pressure carbon dioxide on microbial quality and germination of cereal grains and beans. J Supercrit Fluids 2021. [DOI: 10.1016/j.supflu.2021.105272] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Kamal SM, Simpson DJ, Wang Z, Gänzle M, Römling U. Horizontal Transmission of Stress Resistance Genes Shape the Ecology of Beta- and Gamma-Proteobacteria. Front Microbiol 2021; 12:696522. [PMID: 34295324 PMCID: PMC8290217 DOI: 10.3389/fmicb.2021.696522] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/07/2021] [Indexed: 01/25/2023] Open
Abstract
The transmissible locus of stress tolerance (tLST) is found mainly in beta- and gamma-Proteobacteria and confers tolerance to elevated temperature, pressure, and chlorine. This genomic island, previously referred to as transmissible locus of protein quality control or locus of heat resistance likely originates from an environmental bacterium thriving in extreme habitats, but has been widely transmitted by lateral gene transfer. Although highly conserved, the gene content on the island is subject to evolution and gene products such as small heat shock proteins are present in several functionally distinct sequence variants. A number of these genes are xenologs of core genome genes with the gene products to widen the substrate spectrum and to be highly (complementary) expressed thus their functionality to become dominant over core genome genes. In this review, we will present current knowledge of the function of core tLST genes and discuss current knowledge on selection and counter-selection processes that favor maintenance of the tLST island, with frequent acquisition of gene products involved in cyclic di-GMP signaling, in different habitats from the environment to animals and plants, processed animal and plant products, man-made environments, and subsequently humans.
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Affiliation(s)
- Shady Mansour Kamal
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
| | - David J Simpson
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Zhiying Wang
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Michael Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Ute Römling
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solna, Sweden
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11
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Hu Z, Xiao Y, Wang B, Jin TZ, Lyu W, Ren D. Combined treatments of low dose irradiation with antimicrobials for inactivation of foodborne pathogens on fresh pork. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.107977] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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12
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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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13
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González-Angulo M, Serment-Moreno V, Clemente-García L, Tonello C, Jaime I, Rovira J. Assessing the pressure resistance of Escherichia coli O157:H7, Listeria monocytogenes and Salmonella enterica to high pressure processing (HPP) in citric acid model solutions for process validation. Food Res Int 2021; 140:110091. [PMID: 33648306 DOI: 10.1016/j.foodres.2020.110091] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 12/22/2020] [Accepted: 12/26/2020] [Indexed: 10/22/2022]
Abstract
Despite the commercial success of high pressure processing (HPP) in the juice industry, some regulatory agencies still require process validation. However, there is a lack of consensus on various aspects regarding validation protocols, including the selection of representative strains to be used in challenge tests. This study characterized the variable response of Escherichia coli O157:H7 (34 strains), Listeria monocytogenes (44 strains) and Salmonella enterica (45 strains) to HPP, and identified potential candidates to use in process validation. Stationary phase cells were submitted to 500 MPa for 1 min at 10 °C in model solutions consisting of tryptic soy broth + 0.6% yeast extract (TSBYE) adjusted to pH 4.5 and 6.0 with citric acid. At pH 6.0, pressure resistance widely varied between species and within strains of the same species. E. coli O157:H7 and L. monocytogenes were the most pressure resistant and showed high variability at strain level, as the total count range given by minimum and maximum counts spread between 2.0 and 6.5 log10 CFU/ml. S. enterica was the least resistant pathogen with more than 82% of the isolates displaying non-detectable counts after HPP. Recovery through storage at 12 °C was also variable for all pathogens, but eventually most strains recovered with median counts on day 14 between 8.3 and 8.9 log10 CFU/ml. For pH 4.5 solutions, 26 E. coli O157:H7 strains displayed survivors after HPP but did not adapt, registering non-detectable counts in the next sampling dates. None of the L. monocytogenes and S. enterica strains survived HPP or incubation at pH 4.5 (<2.0 log10 CFU/ml), suggesting that citric acid at 4.16 g/l is a safe barrier for pathogen control under moderate HPP conditions. Principal component and cluster analyses served to propose strain cocktails for each species based on their pressure resistant and adaptation phenotypes. Additionally, S. enterica was identified as less pressure resistant and less prone to recover following HPP than E. coli O157:H7 and L. monocytogenes, so its relevance in process validation for juices should be questioned. Future work will validate the proposed strain cocktails on real food systems.
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Affiliation(s)
- Mario González-Angulo
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain; University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain.
| | - Vinicio Serment-Moreno
- Hiperbaric USA Corporation, Department of Applications and Food Processing, 2250 NW 84(th) Avenue, 101, Miami, FL 33122, United States
| | - Laura Clemente-García
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain
| | - Carole Tonello
- Hiperbaric, S.A., Department of Applications and Food Processing, C/ Condado de Treviño, 6, 09001 Burgos, Spain
| | - Isabel Jaime
- University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain
| | - Jordi Rovira
- University of Burgos, Department of Biotechnology and Food Science, Faculty of Sciences, Pza. Misael Bañuelos s/n, 09001 Burgos, Spain
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14
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Yang P, Rao L, Zhao L, Wu X, Wang Y, Liao X. High pressure processing combined with selected hurdles: Enhancement in the inactivation of vegetative microorganisms. Compr Rev Food Sci Food Saf 2021; 20:1800-1828. [PMID: 33594773 DOI: 10.1111/1541-4337.12724] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/28/2020] [Accepted: 01/21/2021] [Indexed: 12/15/2022]
Abstract
High pressure processing (HPP) as a nonthermal processing (NTP) technology can ensure microbial safety to some extent without compromising food quality. However, for vegetative microorganisms, the existence of pressure-resistant subpopulations, the revival of sublethal injury (SLI) state cells, and the resuscitation of viable but nonculturable (VBNC) state cells may constitute potential food safety risks and pose challenges for the further development of HPP application. HPP combined with selected hurdles, such as moderately elevated or low temperature, low pH, natural antimicrobials (bacteriocin, lactate, reuterin, endolysin, lactoferrin, lactoperoxidase system, chitosan, essential oils), or other NTP (CO2 , UV-TiO2 photocatalysis, ultrasound, pulsed electric field, ultrafiltration), have been highlighted as feasible alternatives to enhance microbial inactivation (synergistic or additive effect). These combinations can effectively eliminate the pressure-resistant subpopulation, reduce the population of SLI or VBNC state cells and inhibit their revival or resuscitation. This review provides an updated overview of the microbial inactivation by the combination of HPP and selected hurdles and restructures the possible inactivation mechanisms.
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Affiliation(s)
- Peiqing Yang
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
| | - Lei Rao
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
| | - Liang Zhao
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
| | - Xiaomeng Wu
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
| | - Yongtao Wang
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
| | - Xiaojun Liao
- College of Food Science and Nutritional Engineering, National Engineering Research Center for Fruit and Vegetable Processing, Key Laboratory of Fruit and Vegetable Processing of Ministry of Agriculture and Rural Affairs, Beijing Key Laboratory for Food Non-Thermal Processing, China Agricultural University, Beijing, 100083, China
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15
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Sabillón L, Stratton J, Rose D, Eskridge K, Bianchini A. Effect of high‐pressure processing on the microbial load and functionality of sugar‐cookie dough. Cereal Chem 2020. [DOI: 10.1002/cche.10377] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Luis Sabillón
- Department of Food Science and Technology University of Nebraska‐Lincoln Lincoln NE USA
- Department of Family and Consumer Sciences New Mexico State University Las Cruces NM USA
| | - Jayne Stratton
- Department of Food Science and Technology University of Nebraska‐Lincoln Lincoln NE USA
- The Food Processing Center University of Nebraska‐Lincoln Lincoln NE USA
| | - Devin Rose
- Department of Food Science and Technology University of Nebraska‐Lincoln Lincoln NE USA
- Department of Agronomy and Horticulture University of Nebraska‐Lincoln Lincoln NE USA
| | - Kent Eskridge
- Department of Statistics University of Nebraska‐Lincoln Lincoln NE USA
| | - Andréia Bianchini
- Department of Food Science and Technology University of Nebraska‐Lincoln Lincoln NE USA
- The Food Processing Center University of Nebraska‐Lincoln Lincoln NE USA
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16
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Gayán E, Van den Bergh B, Michiels J, Michiels CW, Aertsen A. Synthetic reconstruction of extreme high hydrostatic pressure resistance in Escherichia coli. Metab Eng 2020; 62:287-297. [PMID: 32979485 DOI: 10.1016/j.ymben.2020.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 12/17/2022]
Abstract
Although high hydrostatic pressure (HHP) is an interesting parameter to be applied in bioprocessing, its potential is currently limited by the lack of bacterial chassis capable of surviving and maintaining homeostasis under pressure. While several efforts have been made to genetically engineer microorganisms able to grow at sublethal pressures, there is little information for designing backgrounds that survive more extreme pressures. In this investigation, we analyzed the genome of an extreme HHP-resistant mutant of E. coli MG1655 (designated as DVL1), from which we identified four mutations (in the cra, cyaA, aceA and rpoD loci) causally linked to increased HHP resistance. Analysing the functional effect of these mutations we found that the coupled effect of downregulation of cAMP/CRP, Cra and the glyoxylate shunt activity, together with the upregulation of RpoH and RpoS activity, could mechanistically explain the increased HHP resistance of the mutant. Using combinations of three mutations, we could synthetically engineer E. coli strains able to comfortably survive pressures of 600-800 MPa, which could serve as genetic backgrounds for HHP-based biotechnological applications.
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Affiliation(s)
- Elisa Gayán
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
| | - Bram Van den Bergh
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium; VIB Center for Microbiology, Flanders Institute for Biotechnology, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Jan Michiels
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium; VIB Center for Microbiology, Flanders Institute for Biotechnology, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Chris W Michiels
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium
| | - Abram Aertsen
- Department of Microbial and Molecular Systems, KU Leuven. Faculty of Bioscience Engineering, Kasteelpark Arenberg 20, 3001, Leuven, Belgium.
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17
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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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18
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Are Antimicrobial Interventions Associated with Heat-Resistant Escherichia coli on Meat? Appl Environ Microbiol 2020; 86:AEM.00512-20. [PMID: 32303544 DOI: 10.1128/aem.00512-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 04/14/2020] [Indexed: 01/01/2023] Open
Abstract
Decontamination practices, which often involve thermal treatments, are routinely performed in beef packing plants and have generally improved the safety of meat in North America. We investigated whether Escherichia coli in the beef production chain is becoming more heat resistant due to those treatments. Cattle isolates (n = 750) included seven serogroups (O157, O103, O111, O121, O145, O26, and O45) which were collected between 2002 and 2017. Beef plant isolates (n = 700) from carcasses, fabrication equipment, and beef products were included. Heat resistance was determined in Luria-Bertani broth at 60°C and by PCR screening for the locus of heat resistance (LHR). The decimal reduction for E. coli at 60°C (D 60ºC values) ranged from 0 to 7.54 min, with 97.2% of the values being <2 min. The prevalence of E. coli with D 60ºC values of >2 min was not significantly different (P > 0.05) among cattle and meat plant isolates. E. coli from equipment before sanitation (median, 1.03 min) was more heat resistant than that after sanitation (median, 0.9 min). No significant difference in D 60ºC values was observed among E. coli isolates from different years, from carcasses before and after antimicrobial interventions, or from before and during carcass chilling. Of all isolates, 1.97% harbored LHR, and the LHR-positive isolates had greater median D 60ºC values than the LHR-negative isolates (3.25 versus 0.96 min). No increase in heat resistance in E. coli was observed along the beef production chain or with time.IMPORTANCE The implementation of multiple hurdles in the beef production chain has resulted in substantial improvement in the microbial safety of beef in Canada. In this study, we characterized a large number of Escherichia coli isolates (n = 1,450) from various sources/stages of beef processing to determine whether the commonly used antimicrobial interventions would give rise to heat-resistant E. coli on meat, which in turn may require alternatives to the current control of pathogens and/or modifications to the current cooking recommendations for meat. The findings show that the degree and rate of heat resistance in E. coli did not increase along the production chain or with time. This furthers our understanding of man-made ecological niches that are required for the development of heat resistance in E. coli.
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19
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Dos Santos Rosario AIL, da Silva Mutz Y, Castro VS, da Silva MCA, Conte-Junior CA, da Costa MP. Everybody loves cheese: crosslink between persistence and virulence of Shiga-toxin Escherichia coli. Crit Rev Food Sci Nutr 2020; 61:1877-1899. [PMID: 32519880 DOI: 10.1080/10408398.2020.1767033] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
General cheese manufacturing involves high temperatures, fermentation and ripening steps that function as hurdles to microbial growth. On the other hand, the application of several different formulations and manufacturing techniques may create a bacterial protective environment. In cheese, the persistent behavior of Shiga toxin-producing Escherichia coli (STEC) relies on complex mechanisms that enable bacteria to respond to stressful conditions found in cheese matrix. In this review, we discuss how STEC manages to survive to high and low temperatures, hyperosmotic conditions, exposure to weak organic acids, and pH decreasing related to cheese manufacturing, the cheese matrix itself and storage. Moreover, we discuss how these stress responses interact with each other by enhancing adaptation and consequently, the persistence of STEC in cheese. Further, we show how virulence genes eae and tir are affected by stress response mechanisms, increasing either cell adherence or virulence factors production, which leads to a selection of more resistant and virulent pathogens in the cheese industry, leading to a public health issue.
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Affiliation(s)
- Anisio Iuri Lima Dos Santos Rosario
- Postgraduate Program in Food Science, Faculty of Pharmacy, Universidade Federal da Bahia, Salvador, Brazil.,Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
| | - Yhan da Silva Mutz
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil
| | - Vinícius Silva Castro
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Maurício Costa Alves da Silva
- Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
| | - Carlos Adam Conte-Junior
- Postgraduate Program in Food Science, Chemistry Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Food Technology, Faculty of Veterinary, Universidade Federal Fluminense, Niterói, Brazil.,National Institute for Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Marion Pereira da Costa
- Postgraduate Program in Food Science, Faculty of Pharmacy, Universidade Federal da Bahia, Salvador, Brazil.,Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechnics of Veterinary, Universidade Federal da Bahia, Salvador, Brazil
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20
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Xu A, Scullen O, Sheen S, Liu Y, Johnson JR, Sommers CH. Inactivation of extraintestinal pathogenic E. coli suspended in ground chicken meat by high pressure processing and identification of virulence factors which may affect resistance to high pressure. Food Control 2020. [DOI: 10.1016/j.foodcont.2019.107070] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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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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22
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Yang X, Tran F, Klassen MD. Heat resistance in
Escherichia coli
and its implications on ground beef cooking recommendations in Canada. J Food Saf 2020. [DOI: 10.1111/jfs.12769] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Xianqin Yang
- Agriculture and Agri‐Food Canada Lacombe Research and Development Centre Lacombe Alberta Canada
| | - Frances Tran
- Agriculture and Agri‐Food Canada Lacombe Research and Development Centre Lacombe Alberta Canada
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23
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Antunes P, Novais C, Peixe L. Food-to-Humans Bacterial Transmission. Microbiol Spectr 2020; 8:10.1128/microbiolspec.mtbp-0019-2016. [PMID: 31950894 PMCID: PMC10810214 DOI: 10.1128/microbiolspec.mtbp-0019-2016] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Indexed: 12/17/2022] Open
Abstract
Microorganisms vehiculated by food might benefit health, cause minimal change within the equilibrium of the host microbial community or be associated with foodborne diseases. In this chapter we will focus on human pathogenic bacteria for which food is conclusively demonstrated as their transmission mode to human. We will describe the impact of foodborne diseases in public health, the reservoirs of foodborne pathogens (the environment, human and animals), the main bacterial pathogens and food vehicles causing human diseases, and the drivers for the transmission of foodborne diseases related to the food-chain, host or bacteria features. The implication of food-chain (foodborne pathogens and commensals) in the transmission of resistance to antibiotics relevant to the treatment of human infections is also evidenced. The multiplicity and interplay of drivers related to intensification, diversification and globalization of food production, consumer health status, preferences, lifestyles or behaviors, and bacteria adaptation to different challenges (stress tolerance and antimicrobial resistance) from farm to human, make the prevention of bacteria-food-human transmission a modern and continuous challenge. A global One Health approach is mandatory to better understand and minimize the transmission pathways of human pathogens, including multidrug-resistant pathogens and commensals, through food-chain.
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Affiliation(s)
- Patrícia Antunes
- Faculdade de Ciências da Nutrição e Alimentação, Universidade do Porto, Porto, Portugal
| | - Carla Novais
- Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
| | - Luísa Peixe
- Faculdade de Farmácia, Universidade do Porto, Porto, Portugal
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24
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Buzrul S. High hydrostatic pressure inactivation of microorganisms: A probabilistic model for target log-reductions. Int J Food Microbiol 2019; 309:108330. [PMID: 31493566 DOI: 10.1016/j.ijfoodmicro.2019.108330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 07/08/2019] [Accepted: 08/25/2019] [Indexed: 01/25/2023]
Abstract
A probabilistic model based on logistic regression was developed for a target log reduction of microorganisms inactivated by high hydrostatic pressure. Published inactivation data of Salmonella Typhimurium in broth for 4 and 5 log reductions, and Escherichia coli in buffer and carrot juice for 5 log reduction were used. The probabilities of achieving 4 or 5 log reductions for S. Typhimurium in broth and 5 log reduction for E. coli in buffer and carrot juice could be calculated at different pressure, temperature and time levels. The fitted interfaces of achieving/not achieving the target log reduction were consistent with the experimental data. Although the reliability of the predictions of the developed models could be questioned due to strain variation and different food matrix, a validation study has demonstrated that the developed models could be used to predict the target log reduction of these microorganisms at different pressure, temperature and time levels. This study has indicated that the probabilistic modeling for target log reductions can be useful tool for HHP inactivation of microorganisms, but further studies could be performed with several other factors such as pH and water activity of the food, concentration of certain additives as well as initial number of bacteria present in the food.
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Affiliation(s)
- Sencer Buzrul
- Department of Food Engineering, Konya Food and Agriculture University, Konya, Turkey.
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25
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Hu Z, Rohde A, McMullen L, Gänzle M. Effect of sodium chloride and chitosan on the inactivation of heat resistant or Shiga-toxin producing Escherichia coli during grilling of burger patties. Int J Food Microbiol 2019; 308:108308. [PMID: 31466020 DOI: 10.1016/j.ijfoodmicro.2019.108308] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 08/19/2019] [Accepted: 08/20/2019] [Indexed: 11/25/2022]
Abstract
Cattle are a reservoir for enterohemorrhagic Escherichia coli (EHEC), and ground beef is a major vehicle for human infection with EHEC. Heat resistance of E. coli, including EHEC, is impacted by NaCl and other additives. This study aimed to evaluate the effect of NaCl and other additives on the heat resistance of E. coli in beef patties. E. coli AW1.7ΔpHR1(pLHR) with the locus of heat resistance (LHR), E. coli AW1.7ΔpHR1(pRK767) without LHR, or a 5-strain cocktail of EHEC were inoculated (107-108 CFU/g) into ground beef (15% fat) with NaCl (0-3%), marinade, carvacrol (0.1%), potassium lactate (3%) or chitosan (0.1%) following different protocols. Patties were grilled immediately, or stored in sterile bags for two days at 4 °C prior to grilling to a core temperature of 71 °C. Cell counts of LHR-positive E. coli AW1.7ΔpHR1(pLHR) were higher than that of the isogenic LHR-negative E. coli AW1.7ΔpHR1(pRK767) by >3 log10 (CFU/g) after cooking. Addition of 3% NaCl increased survival of E. coli AW1.7ΔpHR1(pRK767) and the EHEC cocktail while cell counts of the heat resistant strains were not changed. A protective effect of NaCl was not observed with E. coli AW1.7ΔpHR1(pRK767) or EHEC if cells of E. coli were cooled to 4 °C prior to mixing with cold meat and NaCl, indicating that the response of E. coli to osmotic shock contributes to this effect. Chitosan enhanced the thermal destruction of LHR-positive E. coli AW1.7ΔpHR1(pLHR) in ground beef stored at 4 °C for 2 days, while marinade, carvacrol, or potassium lactate had no such effect, indicating that chitosan can be characterized as an effective hurdle concept to reduce the potential risk of LHR-positive pathogen to meat safety.
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Affiliation(s)
- Ziyi Hu
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Alina Rohde
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Lynn McMullen
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael Gänzle
- University of Alberta, Dept. of Agricultural, Food and Nutritional Science, Edmonton, Canada; Hubei University of Technology, College of Bioengineering and Food Science, Wuhan, PR China.
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26
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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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27
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Home style frying of steak and meat products: Survival of Escherichia coli related to dynamic temperature profiles. Int J Food Microbiol 2019; 300:53-63. [PMID: 31048092 DOI: 10.1016/j.ijfoodmicro.2019.03.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 02/15/2019] [Accepted: 03/29/2019] [Indexed: 11/24/2022]
Abstract
Microbial survival of heating and cross-contamination are the two transmission routes during food preparation in the consumers' kitchen that are relevant for QMRA (Quantitative Microbial Risk Assessment). The aim of the present study was to extend the limited amount of data on microbial survival during real-life preparation of meat and meat products and to obtain accessory temperature data that allow for a more general (product unspecific) approach. Therefore survival data were combined with extensive measurements of time- and location dependent temperature using an infrared camera for the surface and buttons for the inside of the product, supplemented with interpolation modelling. We investigated the survival of heating of Escherichia coli O111:H2 in beefsteak, hamburgers (beef and 50% beef 50% pork (HH)), meatballs (beef and HH) and crumbs (HH). For beefsteak, survival as a whole is dominated by the sides, giving a log reduction of 1-2 (rare), 3-4 (medium) and 6-7 (done). Limited measurements indicated that done preparation gave 5-6 log reduction for crumbs and at least 8-9 log for the other products. Medium preparation gave a higher reduction in hamburgers (2-4 log) than in meatballs (1-2 log) and in beef (3-4) than in HH (2-3) hamburgers. In general, our 'done' results give larger inactivation than found in literature, whereas 'rare' and 'medium' results are similar. The experiments resulted in two types of curves of D70/z-values, dependent on product, doneness and for beefsteaks sides vs. top/bottom. One type of curve agrees reasonably with literature D70/z estimates from isothermal temperature experiments, which supports using these estimates for home style cooking QMRA calculations. In case of the other type of curve, which is mainly found for (near) surface contamination in close contact with the pan, these literature estimates cannot be applied. We also applied a simplified approach, assuming thermal inactivation is dominated by the highest temperatures reached. The time duration of this highest temperature gives accessory D-values which prove to fit with isothermal temperature literature data, thus suggesting application of such data for QMRA is possible by this approach also, which is less labor intensive both in terms of measurements and modelling. In real life, variability in product properties and preparation styles is large. Further studies are needed to analyze the effect on survival, preferably focusing on determining the essential variables. More variation in heating time will allow for estimating D70/z point estimates rather than curves representing possible sets of D70/z-values.
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Identification of novel genes involved in high hydrostatic pressure resistance of Escherichia coli. Food Microbiol 2019; 78:171-178. [DOI: 10.1016/j.fm.2018.10.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 09/19/2018] [Accepted: 10/21/2018] [Indexed: 12/16/2022]
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Hu ZY, Balay D, Hu Y, McMullen LM, Gänzle MG. Effect of chitosan, and bacteriocin – Producing Carnobacterium maltaromaticum on survival of Escherichia coli and Salmonella Typhimurium on beef. Int J Food Microbiol 2019; 290:68-75. [DOI: 10.1016/j.ijfoodmicro.2018.10.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/16/2018] [Accepted: 10/03/2018] [Indexed: 10/28/2022]
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Gill A, Tamber S, Yang X. Relative response of populations of Escherichia coli and Salmonella enterica to exposure to thermal, alkaline and acidic treatments. Int J Food Microbiol 2019; 293:94-101. [PMID: 30677561 DOI: 10.1016/j.ijfoodmicro.2019.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 01/09/2019] [Accepted: 01/14/2019] [Indexed: 02/06/2023]
Abstract
We evaluated the relative response of generic Escherichia coli (GEC), Shiga toxin-producing E. coli (STEC) and Salmonella enterica to heat, alkaline or acid treatments. GEC included strains from carcasses (n = 24) and trim (n = 25) at a small beef plant where no decontamination interventions are used and at a large plant where multiple decontamination interventions are used (carcass n = 25 and trim n = 25). STEC strains belonging to nine serogroups, included isolates from cattle (n = 53), beef (n = 16) and humans (n = 44). S. enterica strains belonging to 29 serotypes, included isolates from humans (n = 30), poultry (n = 26), pork (n = 10) and beef (n = 33). Strains were grown in Brain Heart Infusion (BHI) broth and subjected to the following treatments: 60 °C for 2 min, 5% lactic acid (pH 2.9) for 1 h at 4 °C, or NaOH (pH 11.0) for 2 h at 4 °C. Median log reductions of the GEC populations after heat, alkaline and acid treatment ranged from 2.3 to 3.8, 0.7 to 2.2 and 0.7 to 1.2 log CFU/mL, respectively. No statistically significant difference in reductions was observed between carcass GEC or trim GEC from the large or small plant, except for a greater reduction in trim GEC from the small plant. Median reductions of the STEC populations ranged from 3.3 to 3.5, 0.0 to 0.6, and 0.3 to 0.5 log CFU/mL after heat, alkaline and acid treatment, respectively. The median reductions were not dependent upon isolation source, except between STEC cattle and human isolates after alkaline treatment, where the reduction of the former was higher by 0.6 log unit. For the Salmonella populations, median log reductions ranged from 3.5 to 4.0, 1.7 to 2.4 and 3.7 to 4.1 log CFU/mL after heat, alkaline and acid treatment, respectively. The reductions were not isolation source related. The median log reductions were in the order GEC < STEC < Salmonella after heat treatment and STEC < GEC < Salmonella after alkaline or acid treatment. Overall, the relative response of GEC, STEC and Salmonella in the model system suggests that exposure to heat or pH-based decontamination interventions in meat plants is not associated with increased resistance among E. coli strains in these environments, and total E. coli counts on beef can be indicative of treatment efficacy for the control of Salmonella by heat, lactic acid and alkaline treatment and for the control of STEC subjected to heat.
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Affiliation(s)
- Alexander Gill
- Bureau of Microbial Hazards, Health Products and Food Branch, Health Canada, 251 Sir Frederick Banting Driveway, P.L. 2204E, Ottawa, ON K1A-0K9, Canada
| | - Sandeep Tamber
- Bureau of Microbial Hazards, Health Products and Food Branch, Health Canada, 251 Sir Frederick Banting Driveway, P.L. 2204E, Ottawa, ON K1A-0K9, Canada
| | - Xianqin Yang
- Agriculture and Agri-Food Canada Lacombe Research and Development Centre, 6000 C & E Trail, Lacombe, Alberta T4L 1W1, Canada.
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Inactivation of Escherichia coli O157:H7 by ozone in different substrates. Braz J Microbiol 2018; 50:247-253. [PMID: 30637637 DOI: 10.1007/s42770-018-0025-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 07/01/2018] [Indexed: 10/27/2022] Open
Abstract
Ozone has a broad antimicrobial spectrum and each microorganism species has inherent sensitivity to the gas. The objective of this study was to evaluate the effect of ozone gas on Escherichia coli O157:H7 inoculated on an organic substrate, and the efficacy of ozonated water in controlling the pathogen. For the first experiment, E. coli O157:H7 (ATCC® 43890™) was inoculated in milk with different compositions and in water, which was ozonated at concentrations of 35 and 45 mg L-1 for 0, 5, 15, and 25 min. In the second experiment, water was ozonated at 45 mg L-1 for 15 min. E. coli O157:H7 was exposed for 5 min to the ozonated water immediately after ozonation, and after storage for 0.5, 1.0, 1.5, 3.0, and 24 h at 8 °C. The results showed that the composition of the organic substrate interfered with the action of ozone on E. coli O157:H7. In lactose-free homogenized skim milk, reductions of 1.5 log cycles were obtained for ozonation periods of 25 min at the concentrations tested. Ozonated water was effective in inactivating of E. coli O157:H7 in all treatments. The efficiency of ozone on E. coli O157:H7 is influenced by the composition of the organic substrates, reinforcing the need for adequate removal of organic matter before sanitization. Furthermore, refrigerated ozonated water stored for up to 24 h is effective in the control of E. coli O157:H7.
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Zhang LX, Simpson DJ, McMullen LM, Gänzle MG. Comparative Genomics and Characterization of the Late Promoter pR' from Shiga Toxin Prophages in Escherichia coli. Viruses 2018; 10:v10110595. [PMID: 30384416 PMCID: PMC6266700 DOI: 10.3390/v10110595] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 10/26/2018] [Accepted: 10/27/2018] [Indexed: 02/02/2023] Open
Abstract
Shiga-toxin producing Escherichia coli (STEC) causes human illness ranging from mild diarrhea to death. The bacteriophage encoded stx genes are located in the late transcription region, downstream of the antiterminator Q. The transcription of the stx genes is directly under the control of the late promoter pR’, thus the sequence diversity of the region between Q and stx, here termed the pR’ region, may affect Stx toxin production. Here, we compared the gene structure of the pR’ region and the stx subtypes of nineteen STECs. The sequence alignment and phylogenetic analysis suggested that the pR’ region tends to be more heterogeneous than the promoter itself, even if the prophages harbor the same stx subtype. Furthermore, we established and validated transcriptional fusions of the pR’ region to the DsRed reporter gene using mitomycin C (MMC) induction. Finally, these constructs were transformed into native and non-native strains and examined with flow cytometry. The results showed that induction levels changed when pR’ regions were placed under different regulatory systems. Moreover, not every stx gene could be induced in its native host bacteria. In addition to the functional genes, the diversity of the pR’ region plays an important role in determining the level of toxin induction.
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Affiliation(s)
- Ling Xiao Zhang
- Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
| | - David J Simpson
- Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
| | - Lynn M McMullen
- Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
| | - Michael G Gänzle
- Department of Agriculture, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada.
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Daqu Fermentation Selects for Heat-Resistant Enterobacteriaceae and Bacilli. Appl Environ Microbiol 2018; 84:AEM.01483-18. [PMID: 30120119 DOI: 10.1128/aem.01483-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 08/15/2018] [Indexed: 11/20/2022] Open
Abstract
Daqu is a spontaneous solid-state cereal fermentation used as saccharification and starter culture in Chinese vinegar and liquor production. The evolution of microbiota in this spontaneous fermentation is controlled by the temperature profile, which reaches temperatures from 50 to 65°C for several days. Despite these high temperatures, mesophilic Enterobacteriaceae (including Cronobacter) and bacilli are present throughout Daqu fermentation. This study aimed to determine whether Daqu spontaneous solid-state fermentation selects for heat-resistant variants of these organisms. Heat resistance in Enterobacteriaceae is mediated by the locus of heat resistance (LHR). One LHR-positive strain of Kosakonia cowanii was identified in Daqu, and it exhibited higher heat resistance than the LHR-negative K. cowanii isolated from malted oats. Heat resistance in Bacillus endospores is mediated by the spoVA 2mob operon. Out of 10 Daqu isolates of the species Bacillus licheniformis, Brevibacillus parabrevis, Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus velezensis, 5 did not contain spoVA 2mob, 3 contained one copy, and 2 contained two copies. The presence and copy number of the spoVA 2mob operon increased the resistance of spores to treatment with 110°C. To confirm the selection of LHR- and spoVA 2mob-positive strains during Daqu fermentation, the copy numbers of these genetic elements in Daqu samples were quantified by quantitative PCR (qPCR). The abundance of LHR and the spoVA 2mob operon in community DNA relative to that of total bacterial 16S rRNA genes increased 3-fold and 5-fold, respectively, during processing. In conclusion, culture-dependent and culture-independent analyses suggest that Daqu fermentation selects for heat-resistant Enterobacteriaceae and bacilli.IMPORTANCE Daqu fermentations select for mobile genetic elements conferring heat resistance in Enterobacteriaceae and bacilli. The locus of heat resistance (LHR), a genomic island conferring heat resistance in Enterobacteriaceae, and the spoVA 2mob operon, conferring heat resistance on bacterial endospores, were enriched 3- to 5-fold during Daqu fermentation and maturation. It is therefore remarkable that the LHR and the spoVA 2mob operon are accumulated in the same food fermentation. The presence of heat-resistant Kosakonia spp. and Bacillus spp. in Daqu is not of concern for food safety; however, both genomic islands are mobile and transferable to pathogenic bacteria or toxin-producing bacteria by horizontal gene transfer. The identification of the LHR and the spoVA 2mob operon as indicators of fitness of Enterobacteriaceae and bacilli in Daqu fermentation provides insights into environmental sources of heat-resistant organisms that may contaminate the food supply.
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Huang CY, Sheen S, Sommers C, Sheen LY. Modeling the Survival of Escherichia coli O157:H7 Under Hydrostatic Pressure, Process Temperature, Time and Allyl Isothiocyanate Stresses in Ground Chicken Meat. Front Microbiol 2018; 9:1871. [PMID: 30154776 PMCID: PMC6102346 DOI: 10.3389/fmicb.2018.01871] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 07/25/2018] [Indexed: 12/30/2022] Open
Abstract
Shiga toxin-producing Escherichia coli O157:H7 (STEC) is a common contaminant in meat and poultry. We investigated the use of non-thermal high pressure processing (HPP), with or without allyl isothiocyanate (AITC) essential oil, to kill STEC in ground chicken meat. Temperature was found an important factor affecting the inactivation of STEC in addition to pressure and process time. A full factorial experiment design (4 factors × 2 levels) was used to facilitate and evaluate the effect of pressure (250–350 MPa), operation temperature (−15–4°C), AITC concentration (0.05–0.15%, w/w), and pressure-holding time (10–20 min) on the inactivation of STEC. A linear model (a polynomial equation) was developed to predict/describe those four parameters’ impact on E. coli O157:H7 survival (R2 = 0.90), as well as a dimensionless non-linear model. Both types of models were validated with data obtained from separate experimental points. The dimensionless model also demonstrated that it may predict the lethality (defined as the log CFU/g reduction of STEC before and after treatment) reasonably well with some factors set slightly outside the design ranges (e.g., a wider application than the linear model). The results provide important information regarding STEC survival as affected by HPP (e.g., pressure, time and temperature) and AITC. With the addition of AITC, the hydrostatic pressure may be lowered to the 250–350 MPa level. Regulatory agencies and food industry may use those models for STEC risk assessment in ground chicken meat. A storage test (at 4 and 10°C, 10 days) after HPP+AITC treatment indicated that AITC may continue depressing or killing the pressure-damaged cells.
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Affiliation(s)
- Chi-Yun Huang
- Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan.,Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor, PA, United States
| | - Shiowshuh Sheen
- Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor, PA, United States
| | - Christopher Sommers
- Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor, PA, United States
| | - Lee-Yan Sheen
- Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan
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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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Population-Wide Survey of Salmonella enterica Response to High-Pressure Processing Reveals a Diversity of Responses and Tolerance Mechanisms. Appl Environ Microbiol 2018; 84:AEM.01673-17. [PMID: 29101197 DOI: 10.1128/aem.01673-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 10/27/2017] [Indexed: 01/24/2023] Open
Abstract
High-pressure processing is a nonthermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species. Herein, the responses of 99 diverse Salmonella enterica strains to high pressure are reported. Members of this population belonged to 24 serovars and were isolated from various Canadian sources over a period of 26 years. When cells were exposed to 600 MPa for 3 min, the average reduction in cell numbers for this population was 5.6 log10 CFU/ml, with a range of 0.9 log10 CFU/ml to 6 log10 CFU/ml. Eleven strains, from 5 serovars, with variable levels of pressure resistance were selected for further study. The membrane characteristics (propidium iodide uptake during and after pressure treatment, sensitivity to membrane-active agents, and membrane fatty acid composition) and responses to stressors (heat, nutrient deprivation, desiccation, and acid) for this panel suggested potential roles for the cell membrane and the RpoS regulon in mediating pressure resistance in S. enterica The data indicate heterogeneous and multifactorial responses to high pressure that cannot be predicted for individual S. enterica strains.IMPORTANCE The responses of foodborne pathogens to increasingly popular minimal food decontamination methods are not understood and therefore are difficult to predict. This report shows that the responses of Salmonella enterica strains to high-pressure processing are diverse. The magnitude of inactivation does not depend on how closely related the strains are or where they were isolated. Moreover, strains that are resistant to high pressure do not behave similarly to other stresses, suggesting that more than one mechanism might be responsible for resistance to high pressure and the mechanisms used may vary from one strain to another.
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Induction of Shiga Toxin-Encoding Prophage by Abiotic Environmental Stress in Food. Appl Environ Microbiol 2017; 83:AEM.01378-17. [PMID: 28778890 DOI: 10.1128/aem.01378-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/24/2017] [Indexed: 11/20/2022] Open
Abstract
The prophage-encoded Shiga toxin is a major virulence factor in Stx-producing Escherichia coli (STEC). Toxin production and phage production are linked and occur after induction of the RecA-dependent SOS response. However, food-related stress and Stx-prophage induction have not been studied at the single-cell level. This study investigated the effects of abiotic environmental stress on stx expression by single-cell quantification of gene expression in STEC O104:H4 Δstx2::gfp::ampr In addition, the effect of stress on production of phage particles was determined. The lethality of stressors, including heat, HCl, lactic acid, hydrogen peroxide, and high hydrostatic pressure, was selected to reduce cell counts by 1 to 2 log CFU/ml. The integrity of the bacterial membrane after exposure to stress was measured by propidium iodide (PI). The fluorescent signals of green fluorescent protein (GFP) and PI were quantified by flow cytometry. The mechanism of prophage induction by stress was evaluated by relative gene expression of recA and cell morphology. Acid (pH < 3.5) and H2O2 (2.5 mM) induced the expression of stx2 in about 18% and 3% of the population, respectively. The mechanism of prophage induction by acid differs from that of induction by H2O2 H2O2 induction but not acid induction corresponded to production of infectious phage particles, upregulation of recA, and cell filamentation. Pressure (200 MPa) or heat did not induce the Stx2-encoding prophage (Stx2-prophage). Overall, the quantification method developed in this study allowed investigation of prophage induction and physiological properties at the single-cell level. H2O2 and acids mediate different pathways to induce Stx2-prophage.IMPORTANCE Induction of the Stx-prophage in STEC results in production of phage particles and Stx and thus relates to virulence as well as the transduction of virulence genes. This study developed a method for a detection of the induction of Stx-prophages at the single-cell level; membrane permeability and an indication of SOS response to environmental stress were additionally assessed. H2O2 and mitomycin C induced expression of the prophage and activated a SOS response. In contrast, HCl and lactic acid induced the Stx-prophage but not the SOS response. The lifestyle of STEC exposes the organism to intestinal and extraintestinal environments that impose oxidative and acid stress. A more thorough understanding of the influence of food processing-related stressors on Stx-prophage expression thus facilitates control of STEC in food systems by minimizing prophage induction during food production and storage.
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Trevisani M, Valero A, Mancusi R. Effectiveness of the Thermal Treatments Used for Curd Stretching in the Inactivation of Shiga Toxin-Producing O157 and O26 Escherichia coli. BIOMED RESEARCH INTERNATIONAL 2017; 2017:1609836. [PMID: 28904945 PMCID: PMC5585639 DOI: 10.1155/2017/1609836] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/24/2017] [Accepted: 07/24/2017] [Indexed: 11/23/2022]
Abstract
The kneading treatment of the fresh curd in hot water is a critical control point in the manufacturing of mozzarella. Factors such as the ratio between hot water and curd mass, the rheological properties, and the mixing and kneading activity affect the processing time and the internal temperature of the curd. The aim of this study was to investigate the effect of thermal treatments on the fate of Shiga toxin-producing Escherichia coli (STEC). Nine curd samples (weight 160-270 g) were artificially contaminated with O157 or O26 STEC and stretched in hot water (90-95°C) for 5-10 min. Depending on the heating process and spinning, different nonisothermal profiles were recorded. Observed reductions of O157 and O26 STEC varied between 1.01 and more than 5.38 logMPN (Most Probable Number)/g at the end of the temperature treatments. Further, nonisothermal log-linear tail models were developed to compare observed reductions for O157 and O26 VTEC under variable temperature conditions. Results obtained showed that the comparison of predictions provided by the dynamic model with observations described well the linear inactivation pattern since nonsignificant differences were denoted at all profiles tested. The dynamic model developed can be useful to evaluate the effectiveness of the thermal treatments used in the manufacturing of mozzarella in the inactivation of STEC.
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Affiliation(s)
- M. Trevisani
- Department of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell'Emilia, Italy
| | - A. Valero
- Department of Food Science and Technology, University of Cordoba, International Campus of Excellence in the AgriFood Sector (ceiA3), Campus de Rabanales, Edificio Darwin, 14014 Córdoba, Spain
| | - R. Mancusi
- Department of Veterinary Medical Sciences, University of Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell'Emilia, Italy
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Gayán E, Cambré A, Michiels CW, Aertsen A. RpoS-independent evolution reveals the importance of attenuated cAMP/CRP regulation in high hydrostatic pressure resistance acquisition in E. coli. Sci Rep 2017; 7:8600. [PMID: 28819154 PMCID: PMC5561100 DOI: 10.1038/s41598-017-08958-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 07/20/2017] [Indexed: 11/09/2022] Open
Abstract
High hydrostatic pressure (HHP) processing is an attractive non-thermal alternative to food pasteurization. Nevertheless, the large inter- and intra-species variations in HHP resistance among foodborne pathogens and the ease by which they can acquire extreme resistance are an issue of increasing concern. Since RpoS activity has been considered as a central determinant in the HHP resistance of E. coli and its pathovars, this study probed for the potential of an E. coli MG1655 ΔrpoS mutant to acquire HHP resistance by directed evolution. Despite the higher initial HHP sensitivity of the ΔrpoS mutant compared to the wild-type strain, evolved lineages of the former readily managed to restore or even succeed wild-type levels of resistance. A number of these ΔrpoS derivatives were affected in cAMP/CRP regulation, and this could be causally related to their HHP resistance. Subsequent inspection revealed that some of previously isolated HHP-resistant mutants derived from the wild-type strain also incurred a causal decrease in cAMP/CRP regulation. cAMP/CRP attenuated HHP-resistant mutants also exhibited higher resistance to fosfomycin, a preferred treatment for STEC infections. As such, this study reveals attenuation of cAMP/CRP regulation as a relevant and RpoS-independent evolutionary route towards HHP resistance in E. coli that coincides with fosfomycin resistance.
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Affiliation(s)
- Elisa Gayán
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Alexander Cambré
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Chris W Michiels
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium
| | - Abram Aertsen
- KU Leuven, Laboratory of Food Microbiology, Department of Microbial and Molecular Systems (M2S), Faculty of Bioscience Engineering, Leuven, Belgium.
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Kimura K, Morimatsu K, Inaoka T, Yamamoto K. Injury and recovery of Escherichia coli ATCC25922 cells treated by high hydrostatic pressure at 400–600 MPa. J Biosci Bioeng 2017; 123:698-706. [DOI: 10.1016/j.jbiosc.2017.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/13/2017] [Indexed: 11/26/2022]
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41
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Visvalingam J, Liu Y, Yang X. Impact of dry chilling on the genetic diversity of Escherichia coli on beef carcasses and on the survival of E. coli and E. coli O157. Int J Food Microbiol 2017; 244:62-66. [DOI: 10.1016/j.ijfoodmicro.2016.12.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/29/2016] [Accepted: 12/26/2016] [Indexed: 11/25/2022]
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42
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Mercer RG, Walker BD, Yang X, McMullen LM, Gänzle MG. The locus of heat resistance (LHR) mediates heat resistance in Salmonella enterica, Escherichia coli and Enterobacter cloacae. Food Microbiol 2016; 64:96-103. [PMID: 28213040 DOI: 10.1016/j.fm.2016.12.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 10/21/2016] [Accepted: 12/26/2016] [Indexed: 10/20/2022]
Abstract
Enterobacteriaceae comprise food spoilage organisms as well as food-borne pathogens including Escherichia coli. Heat resistance in E. coli was attributed to a genomic island called the locus of heat resistance (LHR). This genomic island is also present in several other genera of Enterobacteriaceae, but its function in the enteric pathogens Salmonella enterica and Enterobacter cloacae is unknown. This study aimed to determine the frequency of the LHR in food isolates of E. coli, and its influence on heat resistance in S. enterica and Enterobacter spp. Cell counts of LHR-positive strains of E. coli, S. enterica and E. cloacae were reduced by less than 1, 1, and 4 log (cfu/mL), respectively, after exposure to 60 °C for 5 min, while cell counts of LHR-negative strains of the same species were reduced by more than 7 log (cfu/mL). Introducing an exogenous copy of the LHR into heat-sensitive enteropathogenic E. coli and S. enterica increased heat resistance to a level that was comparable to LHR-positive wild type strains. Cell counts of LHR-positive S. enterica were reduced by less than 1 log(cfu/mL) after heating to 60 °C for 5 min. Survival of LHR-positive strains was improved by increasing the NaCl concentration from 0 to 4%. Cell counts of LHR-positive strains of E. coli and S. enterica were reduced by less than 2 log (cfu/g) in ground beef patties cooked to an internal core temperature of 71 °C. This study indicates that LHR-positive Enterobacteriaceae pose a risk to food safety.
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Affiliation(s)
- Ryan G Mercer
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Brian D Walker
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Xianqin Yang
- Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C&E Trail, Lacombe, Alberta, Canada
| | - Lynn M McMullen
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada
| | - Michael G Gänzle
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, Canada.
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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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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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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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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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Mercer RG, Zheng J, Garcia-Hernandez R, Ruan L, Gänzle MG, McMullen LM. Genetic determinants of heat resistance in Escherichia coli. Front Microbiol 2015; 6:932. [PMID: 26441869 PMCID: PMC4563881 DOI: 10.3389/fmicb.2015.00932] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 08/24/2015] [Indexed: 12/20/2022] Open
Abstract
Escherichia coli AW1.7 is a heat resistant food isolate and the occurrence of pathogenic strains with comparable heat resistance may pose a risk to food safety. To identify the genetic determinants of heat resistance, 29 strains of E. coli that differed in their of heat resistance were analyzed by comparative genomics. Strains were classified as highly heat resistant strains, exhibiting a D60-value of more than 6 min; moderately heat resistant strains, exhibiting a D60-value of more than 1 min; or as heat sensitive. A ~14 kb genomic island containing 16 predicted open reading frames encoding putative heat shock proteins and proteases was identified only in highly heat resistant strains. The genomic island was termed the locus of heat resistance (LHR). This putative operon is flanked by mobile elements and possesses >99% sequence identity to genomic islands contributing to heat resistance in Cronobacter sakazakii and Klebsiella pneumoniae. An additional 41 LHR sequences with >87% sequence identity were identified in 11 different species of β- and γ-proteobacteria. Cloning of the full length LHR conferred high heat resistance to the heat sensitive E. coli AW1.7ΔpHR1 and DH5α. The presence of the LHR correlates perfectly to heat resistance in several species of Enterobacteriaceae and occurs at a frequency of 2% of all E. coli genomes, including pathogenic strains. This study suggests the LHR has been laterally exchanged among the β- and γ-proteobacteria and is a reliable indicator of high heat resistance in E. coli.
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Affiliation(s)
- Ryan G Mercer
- Department of Agricultural, Food and Nutritional Science, University of Alberta Edmonton, AB, Canada
| | - Jinshui Zheng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | | | - Lifang Ruan
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University Wuhan, China
| | - Michael G Gänzle
- Department of Agricultural, Food and Nutritional Science, University of Alberta Edmonton, AB, Canada
| | - Lynn M McMullen
- Department of Agricultural, Food and Nutritional Science, University of Alberta Edmonton, AB, Canada
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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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49
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Garcia-Hernandez R, McMullen L, Gänzle MG. Development and validation of a surrogate strain cocktail to evaluate bactericidal effects of pressure on verotoxigenic Escherichia coli. Int J Food Microbiol 2015; 205:16-22. [PMID: 25866907 DOI: 10.1016/j.ijfoodmicro.2015.03.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/19/2015] [Accepted: 03/24/2015] [Indexed: 12/21/2022]
Abstract
Many strains of verotoxigenic Escherichia coli (VTEC) are highly resistant to pressure. To facilitate future studies to improve the elimination of VTEC by pressure processing of food, this study developed and validated a cocktail of non-pathogenic strains of E. coli with equal or higher resistance to pressure when compared to pressure resistant strains of VTEC. Strains of E. coli obtained from a beef processing plant were screened for their resistance to heat and pressure. Treatments were carried out in LB broth. Cell counts of 3 out of 16 strains were reduced by 5-6 log (cfu/mL) after 30 min at 60 °C, and cell counts of 10 out of 16 strains were reduced by 5-6 log (cfu/mL) after 30 min at 40 °C and 400 MPa. All highly heat resistant strains were also pressure resistant but not all pressure resistant strains were also heat resistant. Pressure resistant and -sensitive strains of E. coli were treated in presence of 0 or 2% NaCl and at 3, 20, or 40 °C. The effect of these parameters on the lethality of pressure treatments was comparable for all strains. The addition of 2% NaCl did not increase pressure resistance. The bactericidal effect of treatments at 3 and 20 °C and 600 MPa was comparable but inactivation of E. coli was faster at 40 °C and 600 MPa. The resistance to treatment with 600 MPa at 20 °C of a cocktail of 5 non-pathogenic strains of E. coli was compared to a 5 strain cocktail of pressure resistant VTEC. Treatments were performed in ground beef containing 15% fat. Survival and sublethal injury of the two cocktails was comparable; cell counts of beef inoculated with either cocktail were reduced by about 4 log (cfu/mL) after 30 min of treatment. In conclusion, this study validated a cocktail of non-pathogenic strains of E. coli for use as surrogate organisms in studies on the elimination of E. coli by pressure.
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Affiliation(s)
| | - Lynn McMullen
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada
| | - Michael G Gänzle
- University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Canada.
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