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Atasoy M, Bartkova S, Çetecioğlu-Gürol Z, P Mira N, O'Byrne C, Pérez-Rodríguez F, Possas A, Scheler O, Sedláková-Kaduková J, Sinčák M, Steiger M, Ziv C, Lund PA. Methods for studying microbial acid stress responses: from molecules to populations. FEMS Microbiol Rev 2024; 48:fuae015. [PMID: 38760882 PMCID: PMC11418653 DOI: 10.1093/femsre/fuae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 03/27/2024] [Accepted: 05/16/2024] [Indexed: 05/20/2024] Open
Abstract
The study of how micro-organisms detect and respond to different stresses has a long history of producing fundamental biological insights while being simultaneously of significance in many applied microbiological fields including infection, food and drink manufacture, and industrial and environmental biotechnology. This is well-illustrated by the large body of work on acid stress. Numerous different methods have been used to understand the impacts of low pH on growth and survival of micro-organisms, ranging from studies of single cells to large and heterogeneous populations, from the molecular or biophysical to the computational, and from well-understood model organisms to poorly defined and complex microbial consortia. Much is to be gained from an increased general awareness of these methods, and so the present review looks at examples of the different methods that have been used to study acid resistance, acid tolerance, and acid stress responses, and the insights they can lead to, as well as some of the problems involved in using them. We hope this will be of interest both within and well beyond the acid stress research community.
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Affiliation(s)
- Merve Atasoy
- UNLOCK, Wageningen University and Research, PO Box 9101, 6700 HB, the Netherlands
| | - Simona Bartkova
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
| | - Zeynep Çetecioğlu-Gürol
- Department of Industrial Biotechnology, KTH Royal Institute of Technology, Roslagstullsbacken 21 106 91 Stockholm, Stockholm, Sweden
| | - Nuno P Mira
- iBB, Institute for Bioengineering and Biosciences, Department of Bioengineering, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
| | - Conor O'Byrne
- Microbiology, School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland
| | - Fernando Pérez-Rodríguez
- Department of Food Science and Tehcnology, UIC Zoonosis y Enfermedades Emergentes ENZOEM, University of Córdoba, 14014 Córdoba, Spain
| | - Aricia Possas
- Department of Food Science and Tehcnology, UIC Zoonosis y Enfermedades Emergentes ENZOEM, University of Córdoba, 14014 Córdoba, Spain
| | - Ott Scheler
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Ehitajate tee 5, 19086 Tallinn, Estonia
| | - Jana Sedláková-Kaduková
- Institute of Chemistry and Environmental Sciences, University of Ss. Cyril and Methodius, 91701 Trnava, Republic of Slovakia
| | - Mirka Sinčák
- Institute of Chemistry and Environmental Sciences, University of Ss. Cyril and Methodius, 91701 Trnava, Republic of Slovakia
| | - Matthias Steiger
- Institute of Chemical, Environmental and Bioscience Engineering, TU Wien, Getreidemarkt 9, 1060 Vienna, Austria
| | - Carmit Ziv
- Department of Postharvest Science, Agricultural Research Organization, Volcani Center, 7505101 Rishon LeZion, Israel
| | - Peter A Lund
- School of Biosciences and Institute of Microbiology of Infection, University of Birmingham, Birmingham B15 2TT, United Kingdom
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Yin X, Zhang Y, Tu S, Huang Y, Tu K. Model for the Effect of Carbon Dioxide on <i>Listeria Monocytogenes</i> in Fresh-cut Iceberg Lettuce Packaged Under Modified Atmosphere. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2018. [DOI: 10.3136/fstr.24.1021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Xiaoting Yin
- College of Food Science and Technology, Nanjing Agricultural University
| | - Yincheng Zhang
- College of Food Science and Technology, Nanjing Agricultural University
| | - Sicong Tu
- School of Medical Sciences, University of New South Wales
| | - Yangmin Huang
- College of Food Science and Technology, Nanjing Agricultural University
| | - Kang Tu
- College of Food Science and Technology, Nanjing Agricultural University
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Salazar JK, Sahu SN, Hildebrandt IM, Zhang L, Qi Y, Liggans G, Datta AR, Tortorello ML. Growth Kinetics of Listeria monocytogenes in Cut Produce. J Food Prot 2017; 80:1328-1336. [PMID: 28708030 DOI: 10.4315/0362-028x.jfp-16-516] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cut produce continues to constitute a significant portion of the fresh fruit and vegetables sold directly to consumers. As such, the safety of these items during storage, handling, and display remains a concern. Cut tomatoes, cut leafy greens, and cut melons, which have been studied in relation to their ability to support pathogen growth, have been specifically identified as needing temperature control for safety. Data are needed on the growth behavior of foodborne pathogens in other types of cut produce items that are commonly offered for retail purchase and are potentially held without temperature control. This study assessed the survival and growth of Listeria monocytogenes in cut produce items that are commonly offered for retail purchase, specifically broccoli, green and red bell peppers, yellow onions, canned green and black olives, fresh green olives, cantaloupe flesh and rind, avocado pulp, cucumbers, and button mushrooms. The survival of L. monocytogenes strains representing serotypes 1/2a, 1/2b, and 4b was determined on the cut produce items for each strain individually at 5, 10, and 25°C for up to 720 h. The modified Baranyi model was used to determine the growth kinetics (the maximum growth rates and maximum population increases) in the L. monocytogenes populations. The products that supported the most rapid growth of L. monocytogenes, considering the fastest growth and resulting population levels, were cantaloupe flesh and avocado pulp. When stored at 25°C, the maximum growth rates for these products were 0.093 to 0.138 log CFU/g/h and 0.130 to 0.193 log CFU/g/h, respectively, depending on the strain. Green olives and broccoli did not support growth at any temperature. These results can be used to inform discussions surrounding whether specific time and temperature storage conditions should be recommended for additional cut produce items.
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Affiliation(s)
- Joelle K Salazar
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Office of Food Safety, 6502 South Archer Road, Bedford Park, Illinois 60501
| | - Surasri N Sahu
- 3 Illinois Institute of Technology, Institute for Food Safety and Health, 6502 South Archer Road, Bedford Park, Illinois 60501; and
| | - Ian M Hildebrandt
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Office of Food Safety, 6502 South Archer Road, Bedford Park, Illinois 60501
| | - Lijie Zhang
- 2 U.S. Food and Drug Administration, Division of Virulence Assessment, Office of Applied Research and Safety Assessment, 8301 Muirkirk Road, Laurel, Maryland 20708
| | - Yan Qi
- 2 U.S. Food and Drug Administration, Division of Virulence Assessment, Office of Applied Research and Safety Assessment, 8301 Muirkirk Road, Laurel, Maryland 20708
| | - Girvin Liggans
- 4 U.S. Food and Drug Administration, Retail Food Protection Staff, Office of Food Safety, 5001 Campus Drive, College Park, Maryland 20740, USA
| | - Atin R Datta
- 3 Illinois Institute of Technology, Institute for Food Safety and Health, 6502 South Archer Road, Bedford Park, Illinois 60501; and
| | - Mary Lou Tortorello
- 1 U.S. Food and Drug Administration, Division of Food Processing Science and Technology, Office of Food Safety, 6502 South Archer Road, Bedford Park, Illinois 60501
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Neher S, Hazarika AK, Barkalita LM, Borah P, Bora DP, Sharma RK. Isolation and characterization of Shiga toxigenic Escherichia coli of animal and bird origin by multiplex polymerase chain reaction. Vet World 2016; 9:123-7. [PMID: 27051196 PMCID: PMC4819360 DOI: 10.14202/vetworld.2016.123-127] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 12/17/2015] [Accepted: 12/21/2015] [Indexed: 11/16/2022] Open
Abstract
AIM The purpose of this study was to determine the virulence genes and serotype of Shiga toxin producing Escherichia coli (STEC) strains isolated from animals and birds. MATERIALS AND METHODS A total of 226 different samples viz., fecal, intestinal content, rectal swab and heart blood were collected from different clinically affected/healthy animals and birds and were streaked on McConkeys' lactose agar and eosin methylene blue agar for isolation of E. coli, confirmed by staining characteristics and biochemical tests. By polymerase chain reaction (PCR) all the E. coli isolates were screened for certain virulence genes, viz., Shiga toxin 1 (stx1), stx2 and eae and enterohemolytic (Ehly) phenotype was observed in washed sheep blood agar plate. All the isolated E. coli strains were forwarded to the National Salmonella and Escherichia Centre, Central Research Institute, Kasauli (Himachal Pradesh) for serotyping. RESULTS Out of 226 samples 138 yielded E. coli. All the isolates were screened for molecular detection of different virulent genes, viz. stx1, stx2 and eae, based on which 36 (26.08%) were identified as STEC. Among those STEC isolates, 15 (41.67%), 14 (38.89%), 1 (2.78%) exhibited eae, stx2, stx1 alone, respectively, whereas 4 (11.11%) and 2 (5.56%) carried both stx1 and stx2, stx2 and eae, respectively. Among the STEC isolates 22 were belonged to 15 different sero-groups, viz., O2, O20, O22, O25, O43, O60, O69, O90, O91, O95, O106, O118, O130, O162 and O170 and others were untypable. Ehly phenotype was observed in 10 (27.78%) the STEC isolates. CONCLUSION The present study concluded that STEC could be isolated from both clinically affected as well as healthy animals and birds. Regular monitoring of more samples from animal and bird origin is important to identify natural reservoir of STEC to prevent zoonotic infection.
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Affiliation(s)
- S. Neher
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
| | - A. K. Hazarika
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
| | - L. M. Barkalita
- Department of Animal Biotechnology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
| | - P. Borah
- Department of Animal Biotechnology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
| | - D. P. Bora
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
| | - R. K. Sharma
- Department of Veterinary Microbiology, College of Veterinary Science, Assam Agricultural University, Guwahati, Assam, India
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Balamurugan S, Ahmed R, Gao A. Survival of Shiga toxin-producing Escherichia coli in broth as influenced by pH, water activity and temperature. Lett Appl Microbiol 2014; 60:341-6. [PMID: 25458754 DOI: 10.1111/lam.12375] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 11/21/2014] [Accepted: 11/26/2014] [Indexed: 11/28/2022]
Abstract
UNLABELLED This study examined the effects of and interactions between pH, aw and temperature on the survival of the top six non-O157 STECs and Escherichia coli O157:H7. All variables significantly affected the survival of all STEC serotypes. However, aw bore the most significant effect, followed by temperature and then pH. Examination of the effect of the interaction between these variables revealed that the interaction between aw and temperature was the most significant followed by the interaction between pH and temperature and then aw and pH. Decrease in aw resulted in population reduction of all serotypes studied. This reduction in population was significantly increased with the increase in temperature and was further significantly enhanced with decreasing pH. Examination of the differences in the survival among the individual serotypes revealed that the response of each serotype to aw or temperature changes was significantly different, while their response to pH changes was similar. Analysis of the relative survival of individual non-O157 STECs to O157:H7 revealed that the survival of O121 and O45 was not significantly different to O157:H7 while O103, O111, O145 and O26 showed less tolerance to the combined treatments, and their survival was significantly different from O157:H7. SIGNIFICANCE AND IMPACT OF THE STUDY Results of this study estimate the interaction between pH, aw and temperature on the survival of the top six non-O157 STECs relative to Escherichia coli O157:H7 and provide important growth and no-growth condition which will offer risk assessors a means of estimating the likelihood of these pathogens, if present, would grow in response to the interaction between the three variables assessed.
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Affiliation(s)
- S Balamurugan
- Guelph Food Research Centre, Agriculture and Agri-Food Canada, Guelph, ON, Canada
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Specific growth rate determines the sensitivity of Escherichia coli to lactic acid stress: implications for predictive microbiology. BIOMED RESEARCH INTERNATIONAL 2014; 2014:471317. [PMID: 25110680 PMCID: PMC4109666 DOI: 10.1155/2014/471317] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/18/2014] [Indexed: 12/18/2022]
Abstract
This study tested the hypothesis that sensitivity of Escherichia coli to lactic acid at concentrations relevant for fermented sausages (pH 4.6, 150 mM lactic acid, aw = 0.92, temperature = 20 or 27°C) increases with increasing growth rate. For E. coli strain 683 cultured in TSB in chemostat or batch, subsequent inactivation rates when exposed to lactic acid stress increased with increasing growth rate at harvest. A linear relationship between growth rate at harvest and inactivation rate was found to describe both batch and chemostat cultures. The maximum difference in T90, the estimated times for a one-log reduction, was 10 hours between bacteria harvested during the first 3 hours of batch culture, that is, at different growth rates. A 10-hour difference in T90 would correspond to measuring inactivation at 33°C or 45°C instead of 37°C based on relationships between temperature and inactivation. At similar harvest growth rates, inactivation rates were lower for bacteria cultured at 37°C than at 15-20°C. As demonstrated for E. coli 683, culture conditions leading to variable growth rates may contribute to variable lactic acid inactivation rates. Findings emphasize the use and reporting of standardised culture conditions and can have implications for the interpretation of data when developing inactivation models.
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Predicting the concentration of verotoxin-producing Escherichia coli bacteria during processing and storage of fermented raw-meat sausages. Appl Environ Microbiol 2014; 80:2715-27. [PMID: 24561587 DOI: 10.1128/aem.03791-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A model to predict the population density of verotoxigenic Escherichia coli (VTEC) throughout the elaboration and storage of fermented raw-meat sausages (FRMS) was developed. Probabilistic and kinetic measurement data sets collected from publicly available resources were completed with new measurements when required and used to quantify the dependence of VTEC growth and inactivation on the temperature, pH, water activity (aw), and concentration of lactic acid. Predictions were compared with observations in VTEC-contaminated FRMS manufactured in a pilot plant. Slight differences in the reduction of VTEC were predicted according to the fermentation temperature, 24 or 34°C, with greater inactivation at the highest temperature. The greatest reduction was observed during storage at high temperatures. A population decrease greater than 6 decimal logarithmic units was observed after 66 days of storage at 25°C, while a reduction of only ca. 1 logarithmic unit was detected at 12°C. The performance of our model and other modeling approaches was evaluated throughout the processing of dry and semidry FRMS. The greatest inactivation of VTEC was predicted in dry FRMS with long drying periods, while the smallest reduction was predicted in semidry FMRS with short drying periods. The model is implemented in a computing tool, E. coli SafeFerment (EcSF), freely available from http://www.ifr.ac.uk/safety/EcoliSafeFerment. EcSF integrates growth, probability of growth, and thermal and nonthermal inactivation models to predict the VTEC concentration throughout FRMS manufacturing and storage under constant or fluctuating environmental conditions.
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GLASS KATHLEENA, KASPAR CHARLESW, SINDELAR JEFFREYJ, MILKOWSKI ANDREWL, LOTZ BRIANM, KANG JIHUN, FAITH NANCYG, ENACHE ELENA, KATAOKA AI, HENRY CRAIG. Validation of Pepperoni Process for Control of Shiga Toxin–Producing Escherichia coli. J Food Prot 2012; 75:838-46. [DOI: 10.4315/0362-028x.jfp-11-486] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this study was to compare the survival of non-O157 Shiga toxin–producing Escherichia coli (STEC) with E. coli O157:H7 during pepperoni production. Pepperoni batter was inoculated with 7 log CFU/g of a seven-strain STEC mixture, including strains of serotypes O26, O45, O103, O111, O121, O145, and O157. Sausages were fermented to pH ≤4.8, heated at 53.3°C for 1 h, and dried for up to 20 days. STEC strains were enumerated at designated intervals on sorbitol MacConkey (SMAC) and Rainbow (RA) agars; enrichments were completed in modified EC (mEC) broth and nonselective tryptic soy broth (TSB). When plated on SMAC, total E. coli populations decreased 2.6 to 3.5 log after the 1-h heating step at 53.3°C, and a 4.9- to 5-log reduction was observed after 7 days of drying. RA was more sensitive in recovering survivors; log reductions on it were 1.9 to 2.6, 3.8 to 4.2, and 4.6 to 5.3 at the end of cook, and at day 7 and day 14 of drying, respectively. When numbers were less than the limit of detection by direct plating on days 14 and 20 of drying (representing a 5-log kill), no more than one of three samples in each experiment was positive by enrichment with mEC broth; however, STEC strains were recovered in TSB enrichment. Freezing the 7-day dried sausage for 2 to 3 weeks generated an additional 1- to 1.5-log kill. Confirmation by PCR revealed that O103 and O157 had the greatest survival during pepperoni productions, but all serotypes except O111 and O121 were occasionally recovered during drying. This study suggests that non-O157 STEC strains have comparable or less ability than E. coli O157 to survive the processing steps involved in the manufacture of pepperoni. Processes suitable for control of E. coli O157 will similarly inactivate the other STEC strains tested in this study.
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Affiliation(s)
- KATHLEEN A. GLASS
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - CHARLES W. KASPAR
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - JEFFREY J. SINDELAR
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - ANDREW L. MILKOWSKI
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - BRIAN M. LOTZ
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - JIHUN KANG
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - NANCY G. FAITH
- 1University of Wisconsin-Madison, Food Research Institute, 1550 Linden Drive, Madison, Wisconsin 53706
| | - ELENA ENACHE
- 2Grocery Manufacturers Association, 1350 I Street N.W., Suite 300, Washington, D.C. 20005, USA
| | - AI KATAOKA
- 2Grocery Manufacturers Association, 1350 I Street N.W., Suite 300, Washington, D.C. 20005, USA
| | - CRAIG HENRY
- 2Grocery Manufacturers Association, 1350 I Street N.W., Suite 300, Washington, D.C. 20005, USA
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Sant'Ana AS, Franco BDGM, Schaffner DW. Modeling the growth rate and lag time of different strains of Salmonella enterica and Listeria monocytogenes in ready-to-eat lettuce. Food Microbiol 2012; 30:267-73. [PMID: 22265311 DOI: 10.1016/j.fm.2011.11.003] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 10/13/2011] [Accepted: 11/08/2011] [Indexed: 11/26/2022]
Abstract
The growth parameters (growth rate, μ and lag time, λ) of three different strains each of Salmonella enterica and Listeria monocytogenes in minimally processed lettuce (MPL) and their changes as a function of temperature were modeled. MPL were packed under modified atmosphere (5% O₂, 15% CO₂ and 80% N₂), stored at 7-30 °C and samples collected at different time intervals were enumerated for S. enterica and L. monocytogenes. Growth curves and equations describing the relationship between μ and λ as a function of temperature were constructed using the DMFit Excel add-in and through linear regression, respectively. The predicted growth parameters for the pathogens observed in this study were compared to ComBase, Pathogen modeling program (PMP) and data from the literature. High R² values (0.97 and 0.93) were observed for average growth curves of different strains of pathogens grown on MPL. Secondary models of μ and λ for both pathogens followed a linear trend with high R² values (>0.90). Root mean square error (RMSE) showed that the models obtained are accurate and suitable for modeling the growth of S. enterica and L. monocytogenes in MP lettuce. The current study provides growth models for these foodborne pathogens that can be used in microbial risk assessment.
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Affiliation(s)
- Anderson S Sant'Ana
- Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP, Brazil.
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Rode TM, Holck A, Axelsson L, Høy M, Heir E. Shiga toxigenic Escherichia coli show strain dependent reductions under dry-fermented sausage production and post-processing conditions. Int J Food Microbiol 2012; 155:227-33. [DOI: 10.1016/j.ijfoodmicro.2012.02.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Revised: 01/04/2012] [Accepted: 02/17/2012] [Indexed: 10/28/2022]
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