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Ma X, Chen J, Zwietering MH, Abee T, Den Besten HMW. Stress resistant rpsU variants of Listeria monocytogenes can become underrepresented due to enrichment bias. Int J Food Microbiol 2024; 416:110680. [PMID: 38522149 DOI: 10.1016/j.ijfoodmicro.2024.110680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/21/2024] [Accepted: 03/09/2024] [Indexed: 03/26/2024]
Abstract
Population heterogeneity is an important component of the survival mechanism of Listeria monocytogenes, leading to cells in a population with diverse stress resistance levels. We previously demonstrated that several ribosomal gene rpsU mutations enhanced the stress resistance of L. monocytogenes and lowered the growth rate at 30 °C and lower temperatures. This study investigated whether these switches in phenotypes could result in a bias in strain detection when standard enrichment-based procedures are applied to a variety of strains. Detailed growth kinetics analysis of L. monocytogenes strains were performed, including the LO28 wild type (WT) and rpsU variants V14 and V15, during two commonly used enrichment-based procedures described in the ISO 11290-1:2017 and the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM). WT had a higher growth rate than the variants during the enrichment processes. Co-culture growth kinetics predictions for WT and rpsU variants showed that the detection chances of the rpsU mutants were reduced from ∼52 % to less than ∼13 % and ∼ 3 % during ISO and BAM enrichment, respectively, which were further validated through subsequent qPCR experiments. Higher heat stress resistance of rpsU variants did not lead to faster recovery during enrichment after heat treatment, and different pre-culturing temperatures before heat treatment did not significantly affect the growth kinetics of the WT and rpsU variants. Additionally, post-enrichment isolation procedures involving streaking on selective agar plates did not show preferences for isolating WT or rpsU variants nor affect the detection chance of rpsU variants. The difference in detection chance suggests that the selective enrichment procedures inadequately represent the genotypic diversity present in a sample. Hence, the enrichment bias during the L. monocytogenes isolation procedure may contribute to the observed underrepresentation of the rpsU mutation among L. monocytogenes isolates deposited in publicly available genome databases. The underrepresentation of rpsU mutants in our findings suggests that biases introduced by standard isolation and enrichment procedures could inadvertently skew our understanding of genetic diversity when relying on public databases.
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Affiliation(s)
- Xuchuan Ma
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Jingjie Chen
- State Key Laboratory of Conservation and Utilization of Bio-resources in Yunnan, Center for Life Sciences, School of Life Sciences, Yunnan University, Kunming, China
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Tjakko Abee
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Heidy M W Den Besten
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands.
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2
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Ssemanda JN, den Besten HMW, van Wagenberg CPA, Zwietering MH. Quantitative assessment of food safety interventions for Campylobacter spp. and Salmonella spp. along the chicken meat supply chain in Burkina Faso and Ethiopia. Int J Food Microbiol 2024; 415:110637. [PMID: 38422679 DOI: 10.1016/j.ijfoodmicro.2024.110637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 01/26/2024] [Accepted: 02/20/2024] [Indexed: 03/02/2024]
Abstract
Rural and small-scale chicken farming is a major source of income in most African countries, and chicken meat is an important source of nutrients. However, chicken meat can be contaminated with Campylobacter spp. and Salmonella spp., pathogens with a high reported burden of foodborne illnesses. Therefore, it is essential to control these pathogens in chicken meat. Quantitative microbial risk assessments (QMRA) can aid the development of effective food safety control measures and are currently lacking in chicken meat supply chains in the African context. In this study, we developed stochastic QMRA models for Salmonella spp. and Campylobacter spp. in the chicken meat supply chain in Burkina Faso and Ethiopia employing the modular process risk model in @Risk software. The study scope covered chicken farming, transport, slaughtering, consumer handling, and consumption. Effectiveness of candidate interventions was assessed against baseline models' outputs, which showed that the mean annual Campylobacter spp. risk estimates were 6482 cases of illness per 100,000 persons and 164 disability adjusted life years (DALYs) per 100,000 persons in Burkina Faso, and 12,145 cases and 272 DALYs per 100,000 persons in Ethiopia. For Salmonella spp., mean annual estimates were 2713 cases and 1212 DALYs per 100,000 persons in Burkina Faso, and 4745 cases and 432 DALYs per 100,000 persons in Ethiopia. Combining interventions (improved hand washing plus designated kitchen utensils plus improved cooking) resulted in 75 % risk reduction in Burkina Faso at restaurants and 93 to 94 % in Ethiopia at homes for both Salmonella spp. and Campylobacter spp. For Burkina Faso, adding good hygienic slaughter practices at the market to these combined interventions led to over 91 % microbial risk reduction. Interventions that involved multiple food safety actions in a particular step of the supply chain or combining different interventions from different steps of the supply chain resulted in more risk reduction than individual action interventions. Overall, this study demonstrates how diverse and scanty food supply chain information can be applied in QMRA to provide estimates that can be used to stimulate risk-based food safety action in African countries.
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Affiliation(s)
- James Noah Ssemanda
- Food Microbiology, Wageningen University & Research, 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, 17, 6700 AA Wageningen, the Netherlands
| | - Coen P A van Wagenberg
- Wageningen Economic Research, Wageningen University & Research, 2970, 2502 LS, The Hague, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, 17, 6700 AA Wageningen, the Netherlands.
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3
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De Gol C, Moodycliffe A, den Besten HMW, Zwietering MH, Beyrer M. Pulsed electric field treatment for preservation of Chlorella suspensions and retention of gelling capacity. Food Res Int 2024; 182:114154. [PMID: 38519182 DOI: 10.1016/j.foodres.2024.114154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 02/04/2024] [Accepted: 02/17/2024] [Indexed: 03/24/2024]
Abstract
Pulsed electric field (PEF) processing has emerged as an alternative to thermal pasteurization for the shelf-life extension of heat-sensitive liquids at industrial scale. It offers the advantage of minimal alteration in physicochemical characteristics and functional properties. In this study, a pilot-scale continuous PEF processing (Toutlet < 55 °C) was applied to microalgae Chlorella vulgaris (Cv) suspensions (pH = 6.5), which was proposed as a functional ingredient for plant-based foods. Cv suspensions were inoculated with three distinct food spoilage microorganisms (Pseudomonas guariconensis, Enterobacter soli and Lactococcus lactis), isolated from the Cv biomass. PEF treatments were applied with varying electric field strength Eel of 16 to 28 kV/cm, pulse repetition rate f of 100 to 140 Hz, with a pulse width τ of 20 μs and an inlet product temperature Tin of 30 °C. The aim was to evaluate the PEF-induced microbial reduction and monitor the microbial outgrowth during a 10-day cold storage period (10 °C). Maximum inactivation of 4.1, 3.7 and 3.6 logs was achieved (28 kV/cm and 120 Hz) for the investigated isolates, respectively. Under these conditions, the critical electric field strengths Ecrit, above which inactivation was observed, ranged from 22.6 to 24.6 kV/cm. Moreover, repeated PEF treatment resulted in similar inactivation efficiency, indicating its potential to enhance shelf-life further.
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Affiliation(s)
- Cora De Gol
- University of Applied Sciences and Arts Western Switzerland, School of Engineering, Sion, Switzerland; Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Ailsa Moodycliffe
- University of Applied Sciences and Arts Western Switzerland, School of Engineering, Sion, Switzerland
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, Wageningen, the Netherlands
| | - Michael Beyrer
- University of Applied Sciences and Arts Western Switzerland, School of Engineering, Sion, Switzerland.
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4
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Koomen J, Ma X, Bombelli A, Tempelaars MH, Boeren S, Zwietering MH, den Besten HMW, Abee T. Ribosomal mutations enable a switch between high fitness and high stress resistance in Listeria monocytogenes. Front Microbiol 2024; 15:1355268. [PMID: 38605704 PMCID: PMC11006974 DOI: 10.3389/fmicb.2024.1355268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 03/08/2024] [Indexed: 04/13/2024] Open
Abstract
Multiple stress resistant variants of Listeria monocytogenes with mutations in rpsU encoding ribosomal protein RpsU have previously been isolated after a single exposure to acid stress. These variants, including L. monocytogenes LO28 variant V14 with a complete deletion of the rpsU gene, showed upregulation of the general stress sigma factor Sigma B-mediated stress resistance genes and had a lower maximum specific growth rate than the LO28 WT, signifying a trade-off between stress resistance and fitness. In the current work V14 has been subjected to an experimental evolution regime, selecting for higher fitness in two parallel evolving cultures. This resulted in two evolved variants with WT-like fitness: 14EV1 and 14EV2. Comparative analysis of growth performance, acid and heat stress resistance, in combination with proteomics and RNA-sequencing, indicated that in both lines reversion to WT-like fitness also resulted in WT-like stress sensitivity, due to lack of Sigma B-activated stress defense. Notably, genotyping of 14EV1 and 14EV2 provided evidence for unique point-mutations in the ribosomal rpsB gene causing amino acid substitutions at the same position in RpsB, resulting in RpsB22Arg-His and RpsB22Arg-Ser, respectively. Combined with data obtained with constructed RpsB22Arg-His and RpsB22Arg-Ser mutants in the V14 background, we provide evidence that loss of function of RpsU resulting in the multiple stress resistant and reduced fitness phenotype, can be reversed by single point mutations in rpsB leading to arginine substitutions in RpsB at position 22 into histidine or serine, resulting in a WT-like high fitness and low stress resistance phenotype. This demonstrates the impact of genetic changes in L. monocytogenes' ribosomes on fitness and stress resistance.
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Affiliation(s)
- Jeroen Koomen
- Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Xuchuan Ma
- Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Alberto Bombelli
- Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | | | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University & Research, Wageningen, Netherlands
| | | | | | - Tjakko Abee
- Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
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5
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van der Vossen-Wijmenga WP, den Besten HMW, Zwietering MH. Temperature status of domestic refrigerators and its effect on the risk of listeriosis from ready-to-eat (RTE) cooked meat products. Int J Food Microbiol 2024; 413:110516. [PMID: 38277870 DOI: 10.1016/j.ijfoodmicro.2023.110516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 11/29/2023] [Accepted: 12/04/2023] [Indexed: 01/28/2024]
Abstract
Inadequate domestic refrigeration is frequently cited as a factor that contributes to foodborne poisoning and infection, and consumer behaviour in this regard can vary largely. This study provides insight into the temperature profiles of domestic refrigerators in the Netherlands and the impact on the number of listeriosis cases related to ready-to-eat (RTE) cooked meat products. A survey was conducted among Dutch consumers (n = 1020) to assess their knowledge and behaviour related to refrigerators. Out of these participants, 534 measured their refrigerator's temperature, revealing an average temperature of 5.7 °C (standard deviation (SD) of 2.2 °C) with a maximum of 17 °C. Elderly people (65 years and older) had refrigerators with temperatures that were on average 0.6 °C higher than those of younger people (35 years or younger). The 24-hour temperature profiles of an additional set of actively surveyed refrigerators (n = 50) showed that the temperature measured on the upper shelf was significantly higher (mean 7.7 °C, SD 2.7 °C) than the temperature measured on the bottom shelf (5.7 °C, SD 2.1 °C). Quantitative Microbiological Risk Assessment (QMRA) predicted that the primary factors contributing to the risk of listeriosis were the initial concentration and the time and temperature during household storage. Scenario analysis revealed that storing opened RTE cooked meat products at home for either <7 days or at temperatures <7 °C resulted in a significant reduction of over 80 % in predicted illness cases. Among all illness cases, the elderly represented nearly 90 %. When assessing the impact of the disease in terms of Years of Life Lost (YLL), the contribution of the elderly was 59 %. Targeted communication, particularly directed towards the elderly, on the importance of storing RTE cooked meat products at the recommended temperature on the bottom or middle shelf as well as consuming within two to three days after opening, holds the potential to significantly reduce the number of cases.
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Affiliation(s)
- Wieke P van der Vossen-Wijmenga
- Food Microbiology, Wageningen University & Research, PO Box 17, 6700 AA Wageningen, the Netherlands; The Netherlands Nutrition Centre (Voedingscentrum), PO Box 85700, 2508 CK The Hague, the Netherlands.
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, PO Box 17, 6700 AA Wageningen, the Netherlands.
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, PO Box 17, 6700 AA Wageningen, the Netherlands
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6
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Yeak KYC, Dank A, den Besten HMW, Zwietering MH. A web-based microbiological hazard identification tool for infant foods. Food Res Int 2024; 178:113940. [PMID: 38309868 DOI: 10.1016/j.foodres.2024.113940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/22/2023] [Accepted: 01/02/2024] [Indexed: 02/05/2024]
Abstract
An integrated approach to identify and assess Microbiological Hazards (MHs) and mitigate risks in infant food chains is crucial to ensure safe foods for infants and young children. A systematic procedure was developed to identify MHs in specific infant foods. This includes five major steps: 1) relevant hazard-food pairing, 2) process inactivation efficiency, 3) recontamination possibility after processing, 4) MHs growth opportunity, and 5) MHs-food association level. These steps were integrated into an online tool called the Microbiological Hazards IDentification (MiID) decision support system (DSS), targeting food companies, governmental agencies and academia users, and is accessible at https://foodmicrobiologywur.shinyapps.io/Microbial_hazards_ID/. The MiID DSS was validated in four case studies, focussing on infant formula, fruit puree, cereal-based meals, and fresh fruits, each representing distinct products and processing characteristics. The results obtained through the application of the MiID DSS, compared with identification by food safety experts, consistently identified the top MHs in these food products. This process affirms its effectiveness in systematic hazard identification. The introduction of the MiID DSS helps to structure the first steps in HACCP (hazard analysis) and in risk assessment (hazard identification) to follow a structured and well-documented procedure, balancing the risk of overlooking relevant MHs or including too many irrelevant MHs. It is a valuable addition to risk analysis/assessment in infant food chains and has the potential for future extension. This includes the incorporation of newly acquired data related to infant foods via a semi-publicly hosted platform, or it can be adapted for hazard identification in general food products using a similar framework.
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Affiliation(s)
- Kah Yen Claire Yeak
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Alexander Dank
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, Wageningen, The Netherlands.
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7
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Bannenberg JW, Boeren S, Zwietering MH, Abee T, den Besten HMW. Insight in lag phase of Listeria monocytogenes during enrichment through proteomic and transcriptomic responses. Food Res Int 2024; 175:113609. [PMID: 38128973 DOI: 10.1016/j.foodres.2023.113609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/16/2023] [Accepted: 10/18/2023] [Indexed: 12/23/2023]
Abstract
The dynamics of the enrichment-based detection procedure of the foodborne pathogen Listeria monocytogenes from food still remains poorly understood. This enrichment is crucial in the reliable detection of this pathogen and more insight into the recovery mechanism during this step is important to advance our understanding of lag phase behaviour during enrichment. In this study we combined transcriptomic and proteomic analyses to better understand the physiological processes within the lag phase of L. monocytogenes during enrichment. Upon transfer of BHI-cultured stationary phase L. monocytogenes cells to half-Fraser enrichment broth (HFB), motility-associated genes and proteins were downregulated, while expression of metal uptake transporters, resuscitation-promoting factors that stimulate growth from dormancy, antibiotic efflux pumps and oxidative stress proteins were upregulated. Next to this, when cells with a heat stress history were cultured in enrichment broth, proteins necessary for recovery were upregulated with functions in DNA-damage repair, protein refolding, cell-wall repair, and zinc transport. Proteomic results pointed to possible factors that support shortening the lag duration, including the addition of 10 µM zinc and the addition of spent HFB containing presumed concentrations of resuscitation-promoting factors. However, these interventions did not lead to biologically relevant reduction of lag phase. Also, when cells were enriched in spent HFB, final cell concentrations were similar to enrichments in fresh HFB, indicating that the enrichment broth seems not to lack critical substrates. Concludingly, this study gives insight into the proteomic changes in the lag phase during enrichment and shows that supplementation of HFB is not the best strategy to optimize the current enrichment method.
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Affiliation(s)
- Jasper W Bannenberg
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University and Research, Wageningen, The Netherlands
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Tjakko Abee
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
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Rodriguez-Caturla MY, Garre A, Castillo CJC, Zwietering MH, den Besten HMW, SantˈAna AS. Shelf life estimation of refrigerated vacuum packed beef accounting for uncertainty. Int J Food Microbiol 2023; 405:110345. [PMID: 37549599 DOI: 10.1016/j.ijfoodmicro.2023.110345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/24/2023] [Accepted: 07/27/2023] [Indexed: 08/09/2023]
Abstract
This study estimates the shelf life of vacuum packed beef meat (three muscles: striploin (longissimus thoracis et lumborum, LTL), tenderloin (psoas major, PM) and outside chuck (trapezius thoracis, TT)) at refrigeration temperatures (0 °C-10 °C) based on modelling the growth of two relevant groups of spoilage microorganisms: lactic acid bacteria (LAB) and Enterobacteriaceae. The growth models were developed combining a two-step and a one-step approach. The primary modelling was used to identify the parameters affecting the growth kinetics, guiding the definition of secondary growth models. For LAB, the secondary model included the effect of temperature and initial pH on the specific growth rate. On the other hand, the model for Enterobacteriaceae incorporated the effect of temperature on the specific growth rate and the lag phase; as well as the effect of the initial pH on the specific growth rate, the lag phase and the initial microbial count. We did not observe any significant effect of the type of muscle on the growth kinetics. Once the equations were defined, the models were fitted to the complete dataset using a one-step approach. Model validation was carried out by cross-validation, mitigating the impact of an arbitrary division between training and validation sets. The models were used to estimate the shelf life of the product, based on the maximum admissible microbial concentration (7 log CFU/g for LAB, 5 log CFU/g for Enterobacteriaceae). Although LAB was the dominant microbiota, in several cases, both LAB and Enterobacteriaceae reached the critical concentration practically at the same time. Furthermore, in some scenarios, the end of shelf life would be determined by Enterobacteriaceae, pointing at the potential importance of non-dominant microorganisms for product spoilage. These results can aid in the implementation of effective control measures in the meat processing industry.
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Affiliation(s)
- Magdevis Y Rodriguez-Caturla
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil
| | - Alberto Garre
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - Carmen Josefina Contreras Castillo
- Department of Agroindustry, Food and Nutrition, Luis Queiroz College of Agriculture, University of São Paulo, Piracicaba Campus, SP, Brazil
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - Anderson S SantˈAna
- Department of Food Science and Nutrition, Faculty of Food Engineering, University of Campinas, Campinas, SP, Brazil.
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9
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Garre A, Zwietering MH, den Besten HMW. The importance of what we cannot observe: Experimental limitations as a source of bias for meta-regression models in predictive microbiology. Int J Food Microbiol 2023; 387:110045. [PMID: 36549087 DOI: 10.1016/j.ijfoodmicro.2022.110045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/22/2022] [Accepted: 11/27/2022] [Indexed: 12/12/2022]
Abstract
Meta-regression models have gained in popularity during the last years as a way to create more generic models for Microbial Risk Assessments that also include variability. However, as with most meta-analyses and empirical models, systematic biases in the data can result in inaccurate models. In this article, we define experimental bias as a type of selection bias due to the practical limitations of microbial inactivation experiments. Conditions with extremely high D-values (i.e. slow inactivation) need very long experimental runs to cause significant reductions. On the other hand, when the D-value is extremely low, not enough data points can be gathered before the microbial population is below the detection limit. Consequently, experimental designs favour conditions within a practical experimental range, introducing a selection bias in the D-values. We demonstrate the impact of experimental bias in meta-regression models using numerical simulations. Models fitted to data with experimental bias overestimated the z-value and underestimated variability. We propose a rapid heuristic method to identify experimental bias in datasets, and we propose truncated regression to mitigate its impact in meta-regression models. Both methods were validated using simulated data. Thereafter the procedures were tested by building a meta-regression model for actual data for the inactivation of Bacillus cereus spores. We concluded that the dataset included experimental bias, and that it would cause an overestimation of the microbial resistance at high temperatures (>120 °C) for classical meta-regression models. This effect was mitigated when the model was built using truncated regression. In conclusion, we demonstrate that experimental bias could potentially result in inaccurate models for predictive microbiology. Therefore, checking for experimental bias should be a routine step in meta-regression modelling, and be included in guidelines on data analysis for meta-regression.
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Affiliation(s)
- Alberto Garre
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700, AA, Wageningen, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700, AA, Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700, AA, Wageningen, the Netherlands.
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10
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Garre A, Pielaat A, Zwietering MH, den Besten HM, Smid JH. Critical comparison of statistical methods for quantifying variability and uncertainty of microbial responses from experimental data. Int J Food Microbiol 2022; 383:109935. [DOI: 10.1016/j.ijfoodmicro.2022.109935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 11/17/2022]
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11
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Garre A, Zwietering MH, van Boekel MAJS. The Most Probable Curve method - A robust approach to estimate kinetic models from low plate count data resulting in reduced uncertainty. Int J Food Microbiol 2022; 380:109871. [PMID: 35985079 DOI: 10.1016/j.ijfoodmicro.2022.109871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 08/03/2022] [Accepted: 08/06/2022] [Indexed: 11/19/2022]
Abstract
A novel method is proposed for fitting microbial inactivation models to data on liquid media: the Most Probable Curve (MPC) method. It is a multilevel model that makes a separation between the "true" microbial concentration according to the model, the "actual" concentration in the media considering chance, and the actual counts on the plate. It is based on the assumptions that stress resistance is homogeneous within a microbial population, and that there is no aggregation of microbial cells. Under these assumptions, the number of colonies in/on a plate follows a Poisson distribution with expected value depending on the proposed kinetic model, the number of dilutions and the plated volume. The novel method is compared against (non)linear regression based on a normal likelihood distribution (traditional method), Poisson regression and gamma-Poisson regression using data on the inactivation of Listeria monocytogenes. The conclusion is that the traditional method has limitations when the data includes plates with low (or zero) cell counts, which can be mitigated using more complex (discrete) likelihoods. However, Poisson regression uses an unrealistic likelihood function, making it unsuitable for survivor curves with several log-reductions. Gamma-Poisson regression uses a more realistic likelihood function, even though it is based mostly on empirical hypotheses. We conclude that the MPC method can be used reliably, especially when the data includes plates with low or zero counts. Furthermore, it generates a more realistic description of uncertainty, integrating the contribution of the plating error and reducing the uncertainty of the primary model parameters. Consequently, although it increases modelling complexity, the MPC method can be of great interest in predictive microbiology, especially in studies focused on variability analysis.
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Affiliation(s)
- Alberto Garre
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Martinus A J S van Boekel
- Food Quality & Design, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
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12
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van den Brule T, Punt M, Seekles SJ, Segers FJ, Houbraken J, Hazeleger WC, Ram AF, Wösten HA, Zwietering MH, Dijksterhuis J, den Besten HM. Intraspecific variability in heat resistance of fungal conidia. Food Res Int 2022; 156:111302. [DOI: 10.1016/j.foodres.2022.111302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/21/2022] [Accepted: 04/23/2022] [Indexed: 11/29/2022]
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13
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Garre A, den Besten HM, Fernandez PS, Zwietering MH. Response to letter to the Editor from M. Peleg on: Not just variability and uncertainty; the relevance of chance for the survival of microbial cells to stress. Trends Food Sci Technol 2022. [DOI: 10.1016/j.tifs.2022.01.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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14
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Lanzl MI, van Mastrigt O, Zwietering MH, Abee T, den Besten HMW. Role of substrate availability in the growth of Campylobacter co-cultured with extended spectrum beta-lactamase-producing Escherichia coli in Bolton broth. Int J Food Microbiol 2021; 363:109518. [PMID: 34996645 DOI: 10.1016/j.ijfoodmicro.2021.109518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 12/17/2021] [Accepted: 12/24/2021] [Indexed: 01/03/2023]
Abstract
It is well-established that Extended-spectrum beta-lactamase-producing (ESBL-) Escherichia coli challenge reliable detection of campylobacters during enrichment in Bolton broth (BB) following ISO 10272-1:2017. The overgrowth of Campylobacter by ESBL-E. coli in the enrichment medium BB can lead to false-negative detection outcomes, but the cause for the growth suppression is yet unknown. A plausible reason could be the competition-induced lack of certain growth substrates. Therefore, this study aimed to investigate whether campylobacters and ESBL-E. coli compete for the same medium components and whether this is the cause for the observed growth repression. The availability of possible growth substrates in BB was determined and changes in their extracellular concentration were measured over time during mono-culture enrichment of C. jejuni, C. coli or ESBL-E. coli as well as in co-culture enrichments of campylobacters and ESBL-E. coli. Comparative analysis showed lactate and fumarate utilization by C. jejuni and C. coli exclusively, whereas ESBL-E. coli rapidly consumed asparagine, glutamine/arginine, lysine, threonine, tryptophan, pyruvate, glycerol, cellobiose, and glucose. Both campylobacters and ESBL-E. coli utilized aspartate, serine, formate, a-ketoglutarate and malate. Trends in compound utilization were similar for C. jejuni and C. coli and trends in compound utilization were rather comparable during enrichment of reference and freeze-stressed campylobacters. Since final cell densities of C. jejuni and C. coli in co-cultures were not enhanced by the addition of surplus l-serine and final cell densities were similar in fresh and spent medium, growth suppression seems not to be caused by a lack of substrates or production of inhibitory compounds. We hypothesized that oxygen availability was limiting growth in co-cultures. Higher oxygen availability increased the competitive fitness of C. jejuni 81-176 in co-culture with ESBL-E. coli in duplicate experiments, as cell concentrations in stationary phase were similar to those without competition. This could indicate the critical role of oxygen availability during the growth of Campylobacter and offers potential for further improvement of Campylobacter spp. enrichment efficacy.
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Affiliation(s)
- M I Lanzl
- Food Microbiology, Wageningen University & Research, Netherlands
| | - O van Mastrigt
- Food Microbiology, Wageningen University & Research, Netherlands
| | - M H Zwietering
- Food Microbiology, Wageningen University & Research, Netherlands
| | - T Abee
- Food Microbiology, Wageningen University & Research, Netherlands
| | - H M W den Besten
- Food Microbiology, Wageningen University & Research, Netherlands.
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15
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Brandsma JB, Rustandi N, Brinkman J, Wolkers‐Rooijackers JCM, Zwietering MH, Smid EJ. Pivotal role of cheese salting method for the production of 3‐methylbutanal by
Lactococcus lactis. INT J DAIRY TECHNOL 2021. [DOI: 10.1111/1471-0307.12839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | | | - Marcel H Zwietering
- Wageningen University & Research Food Microbiology P.O. Box 17 6700 AA Wageningen The Netherlands
| | - Eddy J Smid
- Wageningen University & Research Food Microbiology P.O. Box 17 6700 AA Wageningen The Netherlands
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16
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Bannenberg JW, Tempelaars MH, Zwietering MH, Abee T, den Besten HMW. Heterogeneity in single-cell outgrowth of Listeria monocytogenes in half Fraser enrichment broth is affected by strain variability and physiological state. Food Res Int 2021; 150:110783. [PMID: 34865798 DOI: 10.1016/j.foodres.2021.110783] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/29/2021] [Accepted: 10/20/2021] [Indexed: 10/20/2022]
Abstract
The behaviour of pathogens at the single-cell level can be highly variable and can thus affect the detection efficacy of enrichment-based detection methods. The outgrowth of single cells of three Listeria monocytogenes strains was monitored after fluorescence-activated single-cell sorting in non-selective brain heart infusion (BHI) broth and selective half Fraser enrichment broth (HFB) to quantify outgrowth heterogeneity and its effect on the detection probability. Single-cell heterogeneity was higher in HFB compared to non-selective BHI and heterogeneity increased further when cells were heat-stressed. The increase in heterogeneity was also strain-dependent because the fast-recovering strain Scott A showed less outgrowth heterogeneity than the slower-recovering strains EGDe and H7962. Modelling of the outgrowth kinetics during the primary enrichment demonstrated that starting at low cell concentrations could fail detection of L. monocytogenes at least partly due to cell heterogeneity. This highlights that it is important to take single-cell heterogeneity into account when optimizing enrichment formulations and procedures when L. monocytogenes contamination levels are low.
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Affiliation(s)
- Jasper W Bannenberg
- Food Microbiology, Wageningen University & Research, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands
| | - Marcel H Tempelaars
- Food Microbiology, Wageningen University & Research, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands
| | - Tjakko Abee
- Food Microbiology, Wageningen University & Research, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, Bornse Weilanden 9, 6700 AA Wageningen, the Netherlands.
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17
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Garre A, den Besten HM, Fernandez PS, Zwietering MH. Not just variability and uncertainty; the relevance of chance for the survival of microbial cells to stress. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.10.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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18
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Wemmenhove E, Wells-Bennik MHJ, Zwietering MH. A model to predict the fate of Listeria monocytogenes in different cheese types - A major role for undissociated lactic acid in addition to pH, water activity, and temperature. Int J Food Microbiol 2021; 357:109350. [PMID: 34455130 DOI: 10.1016/j.ijfoodmicro.2021.109350] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 07/20/2021] [Accepted: 07/24/2021] [Indexed: 10/20/2022]
Abstract
Undissociated lactic acid has been shown to play a major role in complete growth inhibition of Listeria monocytogenes in Gouda cheese. In addition, low water activity conditions may contribute to growth inhibition. In the current study, it was assessed whether the major factors that inhibit growth of L. monocytogenes in Gouda cheese are the factors that determine growth in other types of ready-to-eat cheese as well. Various types of cheeses were selected, some of which had been associated with listeriosis, while others had not. Based on the composition of the different cheese types, the concentrations of undissociated lactic acid were calculated for each type. The ability to support growth of L. monocytogenes was predicted using the Gamma model, based on literature data on total lactic acid content, moisture content, fat content, pH, Aw, and temperature, and optimal growth rates in milk at 30-37 °C. In addition, the actual specific growth rates of L. monocytogenes in the various cheeses were calculated based on available experimental growth data. In 9 out of the 10 RTE cheeses reviewed, the undissociated lactic acid concentrations and aw determined growth/no growth of L. monocytogenes. No growth was correctly predicted for feta, Cheddar and Gouda, and growth was correctly predicted for ricotta, queso fresco, Camembert, high-moisture mozzarella, cottage and blue cheese. Growth of L. monocytogenes was not observed in practice upon inoculation of Emmental, whereas growth in this cheese type was predicted when including the above mentioned factors in the models. Other factors, presumably acetic and propionic acid, are thought to be important to inhibit growth of the pathogen in Emmental. The results from our study show that for cheeses in which lactic acid is a main acid, our model based on undissociated lactic acid, temperature, pH and aw gives a good prediction of potential outgrowth of L. monocytogenes. Implications for L. monocytogenes legislation are discussed per type of RTE cheese reviewed.
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Affiliation(s)
- E Wemmenhove
- NIZO, Ede, the Netherlands; Food Microbiology, Wageningen University, the Netherlands
| | | | - M H Zwietering
- Food Microbiology, Wageningen University, the Netherlands.
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19
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Bourdichon F, Betts R, Dufour C, Fanning S, Farber J, McClure P, Stavropoulou DA, Wemmenhove E, Zwietering MH, Winkler A. Processing environment monitoring in low moisture food production facilities: Are we looking for the right microorganisms? Int J Food Microbiol 2021; 356:109351. [PMID: 34500287 DOI: 10.1016/j.ijfoodmicro.2021.109351] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 07/16/2021] [Accepted: 07/28/2021] [Indexed: 11/27/2022]
Abstract
Processing environment monitoring is gaining increasing importance in the context of food safety management plans/HACCP programs, since past outbreaks have shown the relevance of the environment as contamination pathway, therefore requiring to ensure the safety of products. However, there are still many open questions and a lack of clarity on how to set up a meaningful program, which would provide early warnings of potential product contamination. Therefore, the current paper aims to summarize and evaluate existing scientific information on outbreaks, relevant pathogens in low moisture foods, and knowledge on indicators, including their contribution to a "clean" environment capable of limiting the spread of pathogens in dry production environments. This paper also outlines the essential elements of a processing environment monitoring program thereby supporting the design and implementation of better programs focusing on the relevant microorganisms. This guidance document is intended to help industry and regulators focus and set up targeted processing environment monitoring programs depending on their purpose, and therefore provide the essential elements needed to improve food safety.
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Affiliation(s)
- François Bourdichon
- Food Safety, Microbiology, Hygiene, 16 Rue Gaston de Caillavet, 75015 Paris, France; Facoltà di Scienze Agrarie, Alimentarie Ambientali, Università Cattolica del Sacro Cuore, Piacenza-Cremona, Italy.
| | - Roy Betts
- Campden BRI, Chipping Campden, Gloucestershire, United Kingdom
| | - Christophe Dufour
- Mérieux NutriSciences, 25 Boulevard de la Paix, 95891 Cergy Pontoise, France
| | - Séamus Fanning
- UCD - Centre for Food Safety, University College Dublin, Belfield, Dublin D04 N2E5, Ireland
| | - Jeffrey Farber
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada
| | - Peter McClure
- Mondelēz International, Bournville Lane, Birmingham B30 2LU, United Kingdom
| | | | | | - Marcel H Zwietering
- Food Microbiology, Wageningen University, PO Box 17, 6700AA, Wageningen, The Netherlands
| | - Anett Winkler
- Cargill Germany GmbH, Cerestar str. 2, D-47809 Krefeld, Germany
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20
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Koomen J, Huijboom L, Ma X, Tempelaars MH, Boeren S, Zwietering MH, den Besten HMW, Abee T. Amino acid substitutions in ribosomal protein RpsU enable switching between high fitness and multiple-stress resistance in Listeria monocytogenes. Int J Food Microbiol 2021; 351:109269. [PMID: 34102570 DOI: 10.1016/j.ijfoodmicro.2021.109269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/21/2021] [Accepted: 05/24/2021] [Indexed: 11/28/2022]
Abstract
Microbial population heterogeneity contributes to differences in stress response between individual cells in a population, and can lead to the selection of genetically stable variants with increased stress resistance. We previously provided evidence that the multiple-stress resistant Listeria monocytogenes LO28 variant 15, carries a point mutation in the rpsU gene, resulting in an arginine-proline substitution in ribosomal protein RpsU (RpsU17Arg-Pro). Here, we investigated the trade-off between general stress sigma factor SigB-mediated stress resistance and fitness in variant 15 using experimental evolution. By selecting for higher fitness in two parallel evolving cultures, we identified two evolved variants: 15EV1 and 15EV2. Whole genome sequencing and SNP analysis showed that both parallel lines mutated in the same codon in rpsU as the original mutation resulting in RpsU17Pro-His (15EV1) and RpsU17Pro-Thr (15EV2). Using a combined phenotyping and proteomics approach, we assessed the resistance of the evolved variants to both heat and acid stress, and found that in both lines reversion to WT-like fitness also resulted in WT-like stress sensitivity. Proteome analysis of L. monocytogenes LO28 WT, variant 15, 15EV1, and 15EV2 revealed high level expression of SigB regulon members only in variant 15, whereas protein profiles of both evolved variants were highly similar to that of the LO28 WT. Experiments with constructed RpsU17Arg-Pro mutants in L. monocytogenes LO28 and EGDe, and RpsU17Arg-His and RpsU17Arg-Thr in LO28, confirmed that single amino acid substitutions in RpsU enable switching between multiple-stress resistant and high fitness states in L. monocytogenes.
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Affiliation(s)
- Jeroen Koomen
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Linda Huijboom
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Xuchuan Ma
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Marcel H Tempelaars
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Sjef Boeren
- Laboratory of Biochemistry, Wageningen University and Research, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Tjakko Abee
- Food Microbiology, Wageningen University and Research, the Netherlands, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
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21
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Zwietering MH, Garre A, Wiedmann M, Buchanan RL. All food processes have a residual risk, some are small, some very small and some are extremely small: zero risk does not exist. Curr Opin Food Sci 2021. [DOI: 10.1016/j.cofs.2020.12.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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Den Besten HM, Abee T, Zwietering MH. Editorial overview: Food safety. Curr Opin Food Sci 2021. [DOI: 10.1016/j.cofs.2021.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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23
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Zwietering MH, Garre A, den Besten HMW. Incorporating strain variability in the design of heat treatments: A stochastic approach and a kinetic approach. Food Res Int 2020; 139:109973. [PMID: 33509519 DOI: 10.1016/j.foodres.2020.109973] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 09/07/2020] [Accepted: 11/28/2020] [Indexed: 12/26/2022]
Abstract
For the design of thermal processes, the decimal reduction times (D-values) of target organisms can be used. However, many factors influence the D-value, like inherent organism's characteristics (strain variability), the effect of the history of the cells, as well as product factors and process factors. Strain variability is a very large contributor to the overall variation of the D-value. Hence, the overall reduction of microbial contaminants by a heat treatment is a combination of the occurrence of a strain with a certain heat resistance and its reduction given the prevailing conditions. This reduction can be determined using two approaches: a kinetic analysis based on integral equations or a stochastic approach based on Monte Carlo analysis. In this article, these two approaches are compared using as case studies the inactivation of two microorganisms: Listeria monocytogenes in a pasteurization process and the sporeformer Geobacillus stearothermophilus in a UHT process. Both approaches resulted in similar conclusions, highlighting that the strains with the highest heat resistance are determinant for the overall inactivation, even if the probability of cells having such extreme heat resistance is very low.
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Affiliation(s)
- Marcel H Zwietering
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - Alberto Garre
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands.
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24
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Bannenberg JW, Abee T, Zwietering MH, den Besten HMW. Variability in lag duration of Listeria monocytogenes strains in half Fraser enrichment broth after stress affects the detection efficacy using the ISO 11290-1 method. Int J Food Microbiol 2020; 337:108914. [PMID: 33166913 DOI: 10.1016/j.ijfoodmicro.2020.108914] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 11/29/2022]
Abstract
A collection of 23 Listeria monocytogenes strains of clinical and food origin was tested for their ability to recover and grow out in half Fraser enrichment broth following the ISO 11290-1:2017 protocol. Recovery of sub-lethally heat-injured cells in half Fraser broth was compared to reference cells with no stress pre-treatment. The enrichments were followed over time by plate counts and the growth parameters were estimated with the 3-phase model which described the data best. The reference cells without stress pre-treatment showed a short lag duration, which ranged from 1.4 to 2.7 h. However, significant variation in the ability to recover after 60 °C heat stress was observed among the tested strains and resulted in a lag duration from 4.7 to 15.8 h. A subset of strains was also exposed to low-temperature acid stress, and the lag duration showed to be also stress dependent. Scenario analyses and Monte Carlo simulations were carried out using the growth parameters obtained in the enrichments. This demonstrated that when starting with one cell, the detection threshold for efficient transfer of at least one cell to the secondary enrichment step, i.e. 2 log10 CFU/ml, was not reached by 11 of 23 strains tested (48%) after exposure to 60 °C heat stress. Increasing the incubation time from 24 to 26 h and the transfer volume from 0.1 to 1.0 ml can increase the average probability to transfer at least one cell to the secondary enrichment step from 79.9% to 99.0%. When optimizing enrichment procedures, it is crucial to take strain variability into account as this can have a significant impact on the detection efficacy.
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Affiliation(s)
- Jasper W Bannenberg
- Wageningen University & Research, Food Microbiology, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Tjakko Abee
- Wageningen University & Research, Food Microbiology, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Marcel H Zwietering
- Wageningen University & Research, Food Microbiology, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Wageningen University & Research, Food Microbiology, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
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25
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Garre A, Zwietering MH, den Besten HMW. Multilevel modelling as a tool to include variability and uncertainty in quantitative microbiology and risk assessment. Thermal inactivation of Listeria monocytogenes as proof of concept. Food Res Int 2020; 137:109374. [PMID: 33233076 DOI: 10.1016/j.foodres.2020.109374] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 05/27/2020] [Accepted: 05/31/2020] [Indexed: 12/13/2022]
Abstract
Variability is inherent in biology and also substantial for microbial populations. In the context of food safety risk assessment, it refers to differences in the response of different bacterial strains (between-strain variability) and different cells (within-strain variability) to the same condition (e.g. inactivation treatment). However, its quantification based on empirical observations and its incorporation in predictive models is a challenge for both experimental design and (statistical) analysis. In this article we propose the use of multilevel models to quantify (different levels of) variability and uncertainty and include them in the predictions. As proof of concept, we analyse the microbial inactivation of Listeria monocytogenes to thermal treatments including different levels of variability (between-strain and within-strain) and uncertainty. The relationship between the microbial count and time was expressed using a (non-linear) Weibullian model. Moreover, we defined stochastic hypotheses to describe the different types of variation at the level of the kinetic parameters, as well as in the observations (microbial counts). The model parameters (kinetic parameters and variances) are estimated using Bayesian statistics. The multilevel approach was compared against an analogous, single-level model. The multilevel methodology shrinks extreme parameter estimates towards the mean according to uncertainty, thus mitigating overfitting. In addition, this approach enables to easily incorporate different levels of variation (between-strain and/or within-strain variability and/or uncertainty) in the predictions. On the other hand, multilevel (Bayesian) models are more complex to define, implement, analyse and communicate than single-level models. Nevertheless, their ability to incorporate different sources of variability in predictions make them very suitable for Quantitative Microbial Risk Assessment.
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Affiliation(s)
- Alberto Garre
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Marcel H Zwietering
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands
| | - Heidy M W den Besten
- Food Microbiology, Wageningen University & Research, P.O. Box 17, 6700 AA Wageningen, the Netherlands.
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26
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Banach JL, van Bokhorst-van de Veen H, van Overbeek LS, van der Zouwen PS, Zwietering MH, van der Fels-Klerx HJ. Effectiveness of a peracetic acid solution on Escherichia coli reduction during fresh-cut lettuce processing at the laboratory and industrial scales. Int J Food Microbiol 2020; 321:108537. [PMID: 32070904 DOI: 10.1016/j.ijfoodmicro.2020.108537] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/14/2019] [Accepted: 01/22/2020] [Indexed: 11/17/2022]
Abstract
Fresh leafy greens like lettuce can be consumed raw and are susceptible to foodborne pathogens if they become contaminated. Recently, the number of reported pathogenic foodborne outbreaks related to leafy greens has increased. Therefore, it is important to try to alleviate the human health burden associated with these outbreaks. Processing of fresh-cut lettuce, including washing, is a step in the supply chain that needs to be well controlled to avoid cross-contamination. Current measures to control the quality of lettuce during washing include the use of chemicals like chlorine; however, questions regarding the safety of chlorine have prompted research for alternative solutions with peracetic acid (PAA). This study evaluates the effectiveness of a PAA (c.a. 75 mg/L) solution on the reduction of a commensal E. coli strain during the washing of fresh-cut lettuce. Experiments were performed at the laboratory scale and validated at the industrial scale. We observed that the use of PAA was not adversely affected by the organic load in the water. The contact time and dose of the PAA showed to be relevant factors, as observed by the approximately 5-log reduction of E. coli in the water. Results showed that once introduced during washing, E. coli remained attached to the lettuce, thus supporting the need to control for pathogenic bacteria earlier in the supply chain (e.g., during primary production) as well as during washing. Moreover, our results showed that the use of PAA during washing did not have an apparent effect on the levels of fluorescent pseudomonads (FP) and total heterotrophic bacteria (THB) in lettuce. Overall, our results at the laboratory and industrial scales confirmed that during the processing of fresh-cut produce, where the accumulation of soil, debris, and other plant exudates can negatively affect washing, the use of a PAA (c.a. 75 mg/L) solution was an effective and safe wash water disinfectant that can potentially be used at the industrial scale.
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Affiliation(s)
- J L Banach
- Wageningen Food Safety Research, P.O. Box 230, 6700 AE Wageningen, the Netherlands.
| | | | - L S van Overbeek
- Wageningen Plant Research, P.O. Box 16, 6700 AA Wageningen, the Netherlands
| | - P S van der Zouwen
- Wageningen Plant Research, P.O. Box 16, 6700 AA Wageningen, the Netherlands
| | - M H Zwietering
- Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, the Netherlands
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27
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Lanzl MI, Zwietering MH, Hazeleger WC, Abee T, den Besten HMW. Variability in lag-duration of Campylobacter spp. during enrichment after cold and oxidative stress and its impact on growth kinetics and reliable detection. Food Res Int 2020; 134:109253. [PMID: 32517946 DOI: 10.1016/j.foodres.2020.109253] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/26/2020] [Accepted: 04/16/2020] [Indexed: 02/06/2023]
Abstract
Campylobacter jejuni and Campylobacter coli continue to be the leading cause of zoonotic gastroenteritis in the European Union, making reliable detection in food important. Low storage temperatures and atmospheric oxygen concentrations during food production can cause sub-lethal damage or transient non-culturability which is why ISO 10272-1:2017 includes an enrichment step to repair cell damage and increase cell concentrations, thereby supporting detection of campylobacters from foods. The aim of this study was to assess the variability in lag-duration of C. jejuni and C. coli during enrichment after different food-relevant stress treatments and evaluate its impact on growth kinetics and reliability of detection outcomes. Therefore, 13 C. jejuni and 10 C. coli strains were subjected to cold stress during refrigerated and frozen storage. Refrigerated storage did not significantly reduce culturability, but frozen storage reduced cell concentrations by 1.6 ± 0.1 log10cfu/ml for both species. Subsequently, cells were enriched following ISO 10272-1:2017-A and cell concentrations were determined over time and lag-duration and growth rate were determined by fitting the Baranyi-model. Without prior stress treatment, mean lag-duration for C. jejuni and C. coli was 2.5 ± 0.2 h and 2.2 ± 0.3 h, respectively. Refrigerated storage increased lag-duration for C. jejuni to 4.6 ± 0.4 h and for C. coli to 5.0 ± 0.4 h and frozen storage increased lag-duration to 5.0 ± 0.3 h and 6.1 ± 0.4 h for C. jejuni and C. coli, respectively. Comparison of strain- and biological variability showed that differences in recovery after cold stress can be attributed mainly to strain variability since strain variability after refrigeration and freeze stress increased respectively 3-fold and 4-fold while biological variability remained constant. A subset of strains was also subjected to oxidative stress that reduced cell concentrations by 0.7 ± 0.2 log10 cfu/ml and comparison of recovery patterns after oxidative and freeze stress indicated that recovery behaviour was also dependent on the stress applied. A scenario analysis was conducted to evaluate the impact of heterogeneity in outgrowth kinetics of single cells on the reliability of detection outcomes following ISO protocol 10272-1:2017. This revealed that a 'worst-case'-scenario for successful detection by a combination of the longest lag-duration of 7.6 h and lowest growth rate of 0.47 h-1 still resulted in positive detection outcomes since the detection limit was reached within 32.5 h. This suggests that other factors such as competitive microbiota can act as a causative factor in false-negative outcomes of tested food samples.
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Affiliation(s)
- M I Lanzl
- Food Microbiology, Wageningen University, Bornse Weilanden 9, 6708WG Wageningen, the Netherlands
| | - M H Zwietering
- Food Microbiology, Wageningen University, Bornse Weilanden 9, 6708WG Wageningen, the Netherlands
| | - W C Hazeleger
- Food Microbiology, Wageningen University, Bornse Weilanden 9, 6708WG Wageningen, the Netherlands
| | - T Abee
- Food Microbiology, Wageningen University, Bornse Weilanden 9, 6708WG Wageningen, the Netherlands
| | - H M W den Besten
- Food Microbiology, Wageningen University, Bornse Weilanden 9, 6708WG Wageningen, the Netherlands.
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van Rijswijck IM, van Mastrigt O, Pijffers G, Wolkers – Rooijackers JC, Abee T, Zwietering MH, Smid EJ. Dynamic modelling of brewers’ yeast and Cyberlindnera fabianii co-culture behaviour for steering fermentation performance. Food Microbiol 2019; 83:113-121. [DOI: 10.1016/j.fm.2019.04.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/15/2019] [Accepted: 04/21/2019] [Indexed: 11/15/2022]
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29
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Franz CM, den Besten HM, Böhnlein C, Gareis M, Zwietering MH, Fusco V. Reprint of: Microbial food safety in the 21st century: Emerging challenges and foodborne pathogenic bacteria. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.01.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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30
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Cocolin L, Membré JM, Zwietering MH. Editorial: Integration of omics into MRA. Int J Food Microbiol 2018; 287:1-2. [DOI: 10.1016/j.ijfoodmicro.2017.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 10/18/2017] [Accepted: 11/12/2017] [Indexed: 10/18/2022]
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31
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Haddad N, Johnson N, Kathariou S, Métris A, Phister T, Pielaat A, Tassou C, Wells-Bennik MH, Zwietering MH. Next generation microbiological risk assessment—Potential of omics data for hazard characterisation. Int J Food Microbiol 2018; 287:28-39. [DOI: 10.1016/j.ijfoodmicro.2018.04.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Revised: 03/31/2018] [Accepted: 04/10/2018] [Indexed: 12/18/2022]
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32
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Franz CM, den Besten HM, Böhnlein C, Gareis M, Zwietering MH, Fusco V. Microbial food safety in the 21st century: Emerging challenges and foodborne pathogenic bacteria. Trends Food Sci Technol 2018. [DOI: 10.1016/j.tifs.2018.09.019] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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33
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Koomen J, den Besten HM, Metselaar KI, Tempelaars MH, Wijnands LM, Zwietering MH, Abee T. Gene profiling-based phenotyping for identification of cellular parameters that contribute to fitness, stress-tolerance and virulence of Listeria monocytogenes variants. Int J Food Microbiol 2018; 283:14-21. [DOI: 10.1016/j.ijfoodmicro.2018.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 05/31/2018] [Accepted: 06/06/2018] [Indexed: 10/14/2022]
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34
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den Besten HM, Wells-Bennik MH, Zwietering MH. Natural Diversity in Heat Resistance of Bacteria and Bacterial Spores: Impact on Food Safety and Quality. Annu Rev Food Sci Technol 2018; 9:383-410. [DOI: 10.1146/annurev-food-030117-012808] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Heidy M.W. den Besten
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marjon H.J. Wells-Bennik
- NIZO Food Research B.V., 6718 ZB, Ede, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marcel H. Zwietering
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
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35
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Ssemanda JN, Joosten H, Bagabe MC, Zwietering MH, Reij MW. Reduction of microbial counts during kitchen scale washing and sanitization of salad vegetables. Food Control 2018. [DOI: 10.1016/j.foodcont.2017.10.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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36
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Ssemanda JN, Reij M, Bagabe MC, Muvunyi CM, Joosten H, Zwietering MH. Indicator microorganisms in fresh vegetables from “farm to fork” in Rwanda. Food Control 2017. [DOI: 10.1016/j.foodcont.2016.12.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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37
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den Besten HM, Aryani DC, Metselaar KI, Zwietering MH. Microbial variability in growth and heat resistance of a pathogen and a spoiler: All variabilities are equal but some are more equal than others. Int J Food Microbiol 2017; 240:24-31. [DOI: 10.1016/j.ijfoodmicro.2016.04.025] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 04/14/2016] [Accepted: 04/22/2016] [Indexed: 11/25/2022]
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38
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Zwietering MH, den Besten HMW. Microbial testing in food safety: effect of specificity and sensitivity on sampling plans—how does the OC curve move. Curr Opin Food Sci 2016. [DOI: 10.1016/j.cofs.2016.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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39
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Metselaar KI, Abee T, Zwietering MH, den Besten HMW. Modeling and Validation of the Ecological Behavior of Wild-Type Listeria monocytogenes and Stress-Resistant Variants. Appl Environ Microbiol 2016; 82:5389-401. [PMID: 27342563 PMCID: PMC4988195 DOI: 10.1128/aem.00442-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 06/21/2016] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Listeria monocytogenes exhibits a heterogeneous response upon stress exposure which can be partially attributed to the presence of stable stress-resistant variants. This study aimed to evaluate the impact of the presence of stress-resistant variants of Listeria monocytogenes and their corresponding trade-offs on population composition under different environmental conditions. A set of stress robustness and growth parameters of the wild type (WT) and an rpsU deletion variant was obtained and used to model their growth behavior under combined mild stress conditions and to model their kinetics under single- and mixed-strain conditions in a simulated food chain. Growth predictions for the WT and the rpsU deletion variant matched the experimental data generally well, although some deviations from the predictions were observed. The data highlighted the influence of the environmental conditions on the ratio between the WT and variant. Prediction of performance in the simulated food chain proved to be challenging. The trend of faster growth and lower stress robustness for the WT than for the rpsU variant in the different steps of the chain was confirmed, but especially for the inactivation steps and the time needed to resume growth after an inactivation step, the experimental data deviated from the model predictions. This report provides insights into the conditions which can select for stress-resistant variants in industrial settings and discusses their potential persistence in food processing environments. IMPORTANCE Listeria monocytogenes exhibits a heterogeneous stress response which can partially be attributed to the presence of genetic variants. These stress-resistant variants survive better under severe conditions but have, on the other hand, a reduced growth rate. To date, the ecological behavior and potential impact of the presence of stress-resistant variants is not fully understood. In this study, we quantitatively assessed growth and inactivation behavior of wild-type L. monocytogenes and its stress-resistant variants. Predictions were validated under different conditions, as well as along a model food chain. This work illustrates the effects of environmental factors on population dynamics of L. monocytogenes and is a first step in evaluating the impact of population diversity on food safety.
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Affiliation(s)
- Karin I Metselaar
- Top Institute Food and Nutrition, Wageningen, the Netherlands Laboratory of Food Microbiology, Wageningen University, Wageningen, the Netherlands
| | - Tjakko Abee
- Top Institute Food and Nutrition, Wageningen, the Netherlands Laboratory of Food Microbiology, Wageningen University, Wageningen, the Netherlands
| | - Marcel H Zwietering
- Top Institute Food and Nutrition, Wageningen, the Netherlands Laboratory of Food Microbiology, Wageningen University, Wageningen, the Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University, Wageningen, the Netherlands
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40
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Aryani DC, den Besten HMW, Zwietering MH. Quantifying Variability in Growth and Thermal Inactivation Kinetics of Lactobacillus plantarum. Appl Environ Microbiol 2016; 82:4896-908. [PMID: 27260362 PMCID: PMC4968553 DOI: 10.1128/aem.00277-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 05/20/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The presence and growth of spoilage organisms in food might affect the shelf life. In this study, the effects of experimental, reproduction, and strain variabilities were quantified with respect to growth and thermal inactivation using 20 Lactobacillus plantarum strains. Also, the effect of growth history on thermal resistance was quantified. The strain variability in μmax was similar (P > 0.05) to reproduction variability as a function of pH, aw, and temperature, while being around half of the reproduction variability (P < 0.05) as a function of undissociated lactic acid concentration [HLa]. The cardinal growth parameters were estimated for the L. plantarum strains, and the pHmin was between 3.2 and 3.5, the aw,min was between 0.936 and 0.953, the [HLamax], at pH 4.5, was between 29 and 38 mM, and the Tmin was between 3.4 and 8.3°C. The average D values ranged from 0.80 min to 19 min at 55°C, 0.22 to 3.9 min at 58°C, 3.1 to 45 s at 60°C, and 1.8 to 19 s at 63°C. In contrast to growth, the strain variability in thermal resistance was on average six times higher than the reproduction variability and more than ten times higher than the experimental variability. The strain variability was also 1.8 times higher (P < 0.05) than the effect of growth history. The combined effects of strain variability and growth history on D value explained all of the variability as found in the literature, although with bias. Based on an illustrative milk-processing chain, strain variability caused ∼2-log10 differences in growth between the most and least robust strains and >10-log10 differences after thermal treatment. IMPORTANCE Accurate control and realistic prediction of shelf life is complicated by the natural diversity among microbial strains, and limited information on microbiological variability is available for spoilage microorganisms. Therefore, the objectives of the present study were to quantify strain variability, reproduction (biological) variability, and experimental variability with respect to the growth and thermal inactivation kinetics of Lactobacillus plantarum and to quantify the variability in thermal resistance attributed to growth history. The quantitative knowledge obtained on experimental, reproduction, and strain variabilities can be used to improve experimental designs and to adequately select strains for challenge growth and inactivation tests. Moreover, the integration of strain variability in prediction of microbial growth and inactivation kinetics will result in more realistic predictions of L. plantarum dynamics along the food production chain.
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Affiliation(s)
- D C Aryani
- Top Institute Food and Nutrition, Wageningen, The Netherlands Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
| | - H M W den Besten
- Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
| | - M H Zwietering
- Top Institute Food and Nutrition, Wageningen, The Netherlands Laboratory of Food Microbiology, Wageningen University, Wageningen, The Netherlands
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41
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Monaghan JM, Augustin JC, Bassett J, Betts R, Pourkomailian B, Zwietering MH. Risk Assessment or Assessment of Risk? Developing an Evidence-Based Approach for Primary Producers of Leafy Vegetables To Assess and Manage Microbial Risks. J Food Prot 2016; 80:725-733. [PMID: 28350184 DOI: 10.4315/0362-028x.jfp-16-237] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 11/03/2016] [Indexed: 11/11/2022]
Abstract
Over the last 10 years, some high-profile foodborne illness outbreaks have been linked to the consumption of leafy greens. Growers are required to complete microbiological risk assessments (RAs) for the production of leafy crops supplied either to retail or for further processing. These RAs are based primarily on qualitative judgements of hazard and risks at various stages in the production process but lack many of the steps defined for quantitative microbiological RAs by the Codex Alimentarius Commission. This article is based on the discussions of an industry expert group and proposes a grower RA approach based on a structured qualitative assessment, which requires all decisions to be based on evidence and a framework for describing the decision process that can be challenged and defended within the supply chain. In addition, this article highlights the need for evidence to be more easily available and accessible to primary producers and identifies the need to develop hygiene criteria to aid validation of proposed interventions.
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Affiliation(s)
- J M Monaghan
- Fresh Produce Research Centre, Crop and Environment Sciences, Harper Adams University, TF10 8NB, Newport, UK
| | - J C Augustin
- Ecole Nationale Vétérinaire d'Alfort, 7 Avenue du Général de Gaulle, 95704, Maisons Alfort, France
| | - J Bassett
- John Bassett Consulting Ltd., Bedford, MK40 3DJ, Bedfordshire, UK
| | - R Betts
- Campden BRI, Chipping Campden, GL55 6LD, Gloucestershire, UK
| | - B Pourkomailian
- McDonald's Europe, Food Safety & Supplier Workplace Accountability, N2 8AW, London, UK; and
| | - M H Zwietering
- Food Microbiology Laboratory, Wageningen University, Postbus 17, 6700AA, Wageningen, The Netherlands
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42
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Wells-Bennik MH, Eijlander RT, den Besten HM, Berendsen EM, Warda AK, Krawczyk AO, Nierop Groot MN, Xiao Y, Zwietering MH, Kuipers OP, Abee T. Bacterial Spores in Food: Survival, Emergence, and Outgrowth. Annu Rev Food Sci Technol 2016; 7:457-82. [DOI: 10.1146/annurev-food-041715-033144] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Marjon H.J. Wells-Bennik
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
| | - Robyn T. Eijlander
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
| | - Heidy M.W. den Besten
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Erwin M. Berendsen
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- NIZO Food Research, 6718 ZB Ede, The Netherlands;
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Alicja K. Warda
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, 6700 AA Wageningen, The Netherlands
| | - Antonina O. Krawczyk
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Masja N. Nierop Groot
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Wageningen UR Food & Biobased Research, 6700 AA Wageningen, The Netherlands
| | - Yinghua Xiao
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Marcel H. Zwietering
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
| | - Oscar P. Kuipers
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Molecular Genetics Department, University of Groningen, 9700 AB Groningen, The Netherlands
| | - Tjakko Abee
- TI Food and Nutrition, 6700 AN Wageningen, The Netherlands
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
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43
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Biesta-Peters EG, Dissel S, Reij MW, Zwietering MH, in't Veld PH. Characterization and Exposure Assessment of Emetic Bacillus cereus and Cereulide Production in Food Products on the Dutch Market. J Food Prot 2016; 79:230-8. [PMID: 26818983 DOI: 10.4315/0362-028x.jfp-15-217] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The emetic toxin cereulide, which can be produced by Bacillus cereus, can be the cause of food poisoning upon ingestion by the consumer. The toxin causes vomiting and is mainly produced in farinaceous food products. This article includes the prevalence of B. cereus and of cereulide in food products in The Netherlands, a characterization of B. cereus isolates obtained, cereulide production conditions, and a comparison of consumer exposure estimates with those of a previous exposure assessment. Food samples (n = 1,489) were tested for the presence of B. cereus; 5.4% of the samples contained detectable levels (>10(2) CFU/g), and 0.7% contained levels above 10(5) CFU/g. Samples (n = 3,008) also were tested for the presence of cereulide. Two samples (0.067%) contained detectable levels of cereulide at 3.2 and 5.4 μg/kg of food product. Of the 481 tested isolates, 81 produced cereulide and/or contained the ces gene. None of the starch-positive and hbl-containing isolates possessed the ces gene, whereas all strains contained the nhe genes. Culture of emetic B. cereus under nonoptimal conditions revealed a delay in onset of cereulide production compared with culture under optimal conditions, and cereulide was produced in all cases when B. cereus cells had been in the stationary phase for some time. The prevalence of cereulide-contaminated food approached the prevalence of contaminated products estimated in an exposure assessment. The main food safety focus associated with this pathogen should be to prevent germination and growth of any B. cereus present in food products and thus prevent cereulide production in foods.
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Affiliation(s)
- Elisabeth G Biesta-Peters
- Laboratory for Food and Feed Safety, Consumer and Safety Division, Netherlands Food and Consumer Product Safety Authority, Akkermaalsbos 2, 6708 WB Wageningen, The Netherlands.
| | - Serge Dissel
- Laboratory for Food and Feed Safety, Consumer and Safety Division, Netherlands Food and Consumer Product Safety Authority, Akkermaalsbos 2, 6708 WB Wageningen, The Netherlands
| | - Martine W Reij
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Paul H in't Veld
- Department of Enforcement Development, Consumer and Safety Division, Netherlands Food and Consumer Product Safety Authority, Catharijnesingel 59, 3511 GG Utrecht, The Netherlands
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44
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Dabadé DS, Wolkers-Rooijackers JCM, Azokpota P, Hounhouigan DJ, Zwietering MH, Nout MJR, den Besten HMW. Bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and the surrounding brackish waters and sediment. Int J Food Microbiol 2015; 218:96-104. [PMID: 26656527 DOI: 10.1016/j.ijfoodmicro.2015.11.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 11/19/2015] [Accepted: 11/22/2015] [Indexed: 11/24/2022]
Abstract
This study aimed at determining bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and their surrounding brackish waters and sediment. Freshly caught shrimp, water and sediment samples were collected in Lakes Nokoue and Aheme in Benin (West Africa) during two periods with different water salinity and temperature. We used complementary culture-dependent and culture-independent methods for microbiota analysis. During both sampling periods, total mesophilic aerobic counts in shrimp samples ranged between 4.4 and 5.9 log CFU/g and were significantly higher than in water or sediment samples. In contrast, bacterial diversity was higher in sediment or water than in shrimps. The dominant phyla were Firmicutes and Proteobacteria in shrimps, Firmicutes, Proteobacteria, and Actinobacteria in water, and Proteobacteria and Chloroflexi in sediment. At species level, distinct bacterial communities were associated with sediment, water and shrimps sampled at the same site the same day. The study suggests that the bacterial community of tropical brackish water shrimps cannot be predicted from the microbiota of their aquatic environment. Thus, monitoring of microbiological quality of aquatic environments might not reflect shrimp microbiological quality.
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Affiliation(s)
- D Sylvain Dabadé
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | | | - Paulin Azokpota
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin
| | - D Joseph Hounhouigan
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - M J Rob Nout
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
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45
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Mpofu A, Linnemann AR, Nout MJR, Zwietering MH, Smid EJ, den Besten HMW. Inactivation of bacterial pathogens in yoba mutandabota, a dairy product fermented with the probiotic Lactobacillus rhamnosus yoba. Int J Food Microbiol 2015; 217:42-8. [PMID: 26490648 DOI: 10.1016/j.ijfoodmicro.2015.09.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 09/11/2015] [Accepted: 09/26/2015] [Indexed: 12/28/2022]
Abstract
Mutandabota is a dairy product consumed as a major source of proteins and micronutrients in Southern Africa. In this study the microbial safety of traditional and a variant of mutandabota fermented with the probiotic Lactobacillus rhamnosus yoba (yoba mutandabota) was investigated by challenging the products with five important food pathogens: Listeria monocytogenes, Salmonella spp., Campylobacter jejuni, Escherichia coli O157:H7 and Bacillus cereus. Pasteurized full-fat cow's milk was used for producing traditional and yoba mutandabota, and was inoculated with a cocktail of strains of the pathogens at an inoculum level of 5.5 log cfu/mL. Survival of the pathogens was monitored over a potential consumption time of 24h for traditional mutandabota, and over 24h of fermentation followed by 24h of potential consumption time for yoba mutandabota. In traditional mutandabota (pH3.4 ± 0.1) no viable cells of B. cereus and C. jejuni were detected 3h after inoculation, while L. monocytogenes, E. coli O157:H7 and Salmonella spp. significantly declined (P<0.05), but could still be detected (<3.5 log inactivation) at the end of the potential consumption time. This indicated that consumption of traditional mutandabota exposes consumers to the risk of food-borne microbial infections. In yoba mutandabota, L. rhamnosus yoba grew from 5.5 ± 0.1 log cfu/mL to 9.1 ± 0.4 log cfu/mL in the presence of pathogens. The pH of yoba mutandabota dropped from 4.2 ± 0.1 to 3.3 ± 0.1 after 24h of fermentation, mainly due to organic acids produced during fermentation. Only Salmonella spp. was able to grow in yoba mutandabota during the first 9h of fermentation, but then decreased in viable plate count. None of the tested pathogens were detected (>3.5 log inactivation) after 3h into potential consumption time of yoba mutandabota. Inactivation of pathogens in mutandabota is of public health significance because food-borne pathogens endanger public health upon consumption of contaminated food, especially in Southern Africa where there are many vulnerable consumers of mutandabota such as children, elderly and immuno-compromised people with HIV/AIDS. The findings of this study demonstrate that mutandabota fermented with L. rhamnosus yoba has antimicrobial properties against the tested pathogens and it is safer compared to the traditional mutandabota.
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Affiliation(s)
- Augustine Mpofu
- Department of Food Science and Technology, Chinhoyi University of Technology, P. Bag 7724 Chinhoyi, Zimbabwe; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands; Food Quality and Design, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands
| | - Anita R Linnemann
- Food Quality and Design, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands
| | - Martinus J R Nout
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands
| | - Eddy J Smid
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700AA Wageningen, The Netherlands.
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Settachaimongkon S, van Valenberg HJ, Winata V, Wang X, Nout MR, van Hooijdonk TC, Zwietering MH, Smid EJ. Effect of sublethal preculturing on the survival of probiotics and metabolite formation in set-yoghurt. Food Microbiol 2015; 49:104-15. [DOI: 10.1016/j.fm.2015.01.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 01/23/2015] [Accepted: 01/31/2015] [Indexed: 01/05/2023]
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Dabadé DS, Azokpota P, Nout MJR, Hounhouigan DJ, Zwietering MH, den Besten HMW. Prediction of spoilage of tropical shrimp (Penaeus notialis) under dynamic temperature regimes. Int J Food Microbiol 2015; 210:121-30. [PMID: 26119189 DOI: 10.1016/j.ijfoodmicro.2015.06.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 06/03/2015] [Accepted: 06/10/2015] [Indexed: 11/19/2022]
Abstract
The spoilage activity of Pseudomonas psychrophila and Carnobacterium maltaromaticum, two tropical shrimp (Penaeus notialis) spoilage organisms, was assessed in cooked shrimps stored at 0 to 28 °C. Microbiological, chemical and sensory analyses were performed during storage. P. psychrophila had a higher growth rate and showed a higher spoilage activity at temperatures from 0 to 15 °C, while at 28 °C, C. maltaromaticum had a higher growth rate. The spoilage activity of P. psychrophila was found to be higher in cooked shrimp than in fresh shrimp. Observed shelf-life data of shrimps stored at constant temperatures were used to validate a previously developed model that predicts tropical shrimp shelf-life at constant storage temperatures. Models predicting the growth of the spoilage organisms as a function of temperature were constructed. The validation of these models under dynamic storage temperatures simulating temperature fluctuation in the shrimp supply chain showed that they can be used to predict the shelf-life of cooked and fresh tropical shrimps.
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Affiliation(s)
- D Sylvain Dabadé
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Paulin Azokpota
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin
| | - M J Robert Nout
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - D Joseph Hounhouigan
- Laboratoire de Biochimie Microbienne et de Biotechnologie Alimentaire, University of Abomey-Calavi, 01 B.P. 526 Cotonou, Benin
| | - Marcel H Zwietering
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
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48
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Spus M, Li M, Alexeeva S, Wolkers-Rooijackers JCM, Zwietering MH, Abee T, Smid EJ. Strain diversity and phage resistance in complex dairy starter cultures. J Dairy Sci 2015; 98:5173-82. [PMID: 26026763 DOI: 10.3168/jds.2015-9535] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/11/2015] [Indexed: 11/19/2022]
Abstract
The compositional stability of the complex Gouda cheese starter culture Ur is thought to be influenced by diversity in phage resistance of highly related strains that co-exist together with bacteriophages. To analyze the role of bacteriophages in maintaining culture diversity at the level of genetic lineages, simple blends of Lactococcus lactis strains were made and subsequently propagated for 152 generations in the absence and presence of selected bacteriophages. We first screened 102 single-colony isolates (strains) from the complex cheese starter for resistance to bacteriophages isolated from this starter. The collection of isolates represents all lactococcal genetic lineages present in the culture. Large differences were found in bacteriophage resistance among strains belonging to the same genetic lineage and among strains from different lineages. The blends of strains were designed such that 3 genetic lineages were represented by strains with different levels of phage resistance. The relative abundance of the lineages in blends with phages was not stable throughout propagation, leading to continuous changes in composition up to 152 generations. The individual resistance of strains to phage predation was confirmed as one of the factors influencing starter culture diversity. Furthermore, loss of proteolytic activity of initially proteolytic strains was found. Reconstituted blends with only 4 strains with a variable degree of phage resistance showed complex behavior during prolonged propagation.
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Affiliation(s)
- M Spus
- TI Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - M Li
- TI Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - S Alexeeva
- TI Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - J C M Wolkers-Rooijackers
- TI Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - M H Zwietering
- Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - T Abee
- Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands
| | - E J Smid
- TI Food and Nutrition, PO Box 557, 6700 AN Wageningen, the Netherlands; Laboratory of Food Microbiology, Wageningen University, PO Box 17, 6700 AA Wageningen, the Netherlands.
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49
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Metselaar KI, den Besten HMW, Boekhorst J, van Hijum SAFT, Zwietering MH, Abee T. Diversity of acid stress resistant variants of Listeria monocytogenes and the potential role of ribosomal protein S21 encoded by rpsU. Front Microbiol 2015; 6:422. [PMID: 26005439 PMCID: PMC4424878 DOI: 10.3389/fmicb.2015.00422] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 04/21/2015] [Indexed: 12/02/2022] Open
Abstract
The dynamic response of microorganisms to environmental conditions depends on the behavior of individual cells within the population. Adverse environments can select for stable stress resistant subpopulations. In this study, we aimed to get more insight in the diversity within Listeria monocytogenes LO28 populations, and the genetic basis for the increased resistance of stable resistant fractions isolated after acid exposure. Phenotypic cluster analysis of 23 variants resulted in three clusters and four individual variants and revealed multiple-stress resistance, with both unique and overlapping features related to stress resistance, growth, motility, biofilm formation, and virulence indicators. A higher glutamate decarboxylase activity correlated with increased acid resistance. Whole genome sequencing revealed mutations in rpsU, encoding ribosomal protein S21 in the largest phenotypic cluster, while mutations in ctsR, which were previously shown to be responsible for increased resistance of heat and high hydrostatic pressure resistant variants, were not found in the acid resistant variants. This underlined that large population diversity exists within one L. monocytogenes strain and that different adverse conditions drive selection for different variants. The finding that acid stress selects for rpsU variants provides potential insights in the mechanisms underlying population diversity of L. monocytogenes.
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Affiliation(s)
- Karin I Metselaar
- Top Institute Food and Nutrition Wageningen, Netherlands ; Laboratory of Food Microbiology, Wageningen University Wageningen, Netherlands
| | | | - Jos Boekhorst
- Top Institute Food and Nutrition Wageningen, Netherlands ; NIZO Food Research Ede, Netherlands
| | - Sacha A F T van Hijum
- Top Institute Food and Nutrition Wageningen, Netherlands ; NIZO Food Research Ede, Netherlands ; Bacterial Genomics Group, CMBI Centre for Molecular and Biomolecular Informatics, Radboud University Medical Center Nijmegen, Netherlands
| | - Marcel H Zwietering
- Top Institute Food and Nutrition Wageningen, Netherlands ; Laboratory of Food Microbiology, Wageningen University Wageningen, Netherlands
| | - Tjakko Abee
- Top Institute Food and Nutrition Wageningen, Netherlands ; Laboratory of Food Microbiology, Wageningen University Wageningen, Netherlands
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50
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Metselaar KI, Saá Ibusquiza P, Ortiz Camargo AR, Krieg M, Zwietering MH, den Besten HMW, Abee T. Performance of stress resistant variants of Listeria monocytogenes in mixed species biofilms with Lactobacillus plantarum. Int J Food Microbiol 2015; 213:24-30. [PMID: 25935090 DOI: 10.1016/j.ijfoodmicro.2015.04.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 11/25/2022]
Abstract
Population diversity and the ability to adapt to changing environments allow Listeria monocytogenes to grow and survive under a wide range of environmental conditions. In this study, we aimed to evaluate the performance of a set of acid resistant L. monocytogenes variants in mixed-species biofilms with Lactobacillus plantarum as well as their benzalkonium chloride (BAC) resistance in these biofilms. L. monocytogenes LO28 wild type and acid resistant variants were capable of forming mixed biofilms with L. plantarum at 20°C and 30°C in BHI supplemented with manganese and glucose. Homolactic fermentation of glucose by L. plantarum created an acidic environment with pH values below the growth boundary of L. monocytogenes. Some of the variants were able to withstand the low pH in the mixed biofilms for a longer time than the WT and there were clear differences in survival between the variants which could not be correlated to (lactic) acid resistance alone. Adaptation to mild pH of liquid cultures during growth to stationary phase increased the acid resistance of some variants to a greater extent than of others, indicating differences in adaptive behaviour between the variants. Two variants that showed a high level of acid adaptation when grown in liquid cultures, showed also better performance in mixed species biofilms. There were no clear differences in BAC resistance between the wild type and variants in mixed biofilms. It can be concluded that acid resistant variants of L. monocytogenes show diversity in their adaptation to acidic conditions and their capacity to survive in mixed cultures and biofilms with L. plantarum.
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Affiliation(s)
- Karin I Metselaar
- Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Paula Saá Ibusquiza
- Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Angela R Ortiz Camargo
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Myriam Krieg
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Marcel H Zwietering
- Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Heidy M W den Besten
- Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands
| | - Tjakko Abee
- Top Institute Food and Nutrition, P.O. Box 557, 6700 AN Wageningen, The Netherlands; Laboratory of Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
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