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Mertaoja A, Mascher G, Nowakowska MB, Korkeala H, Henriques AO, Lindstrom M. Cellular and population strategies underpinning neurotoxin production and sporulation in Clostridium botulinum type E cultures. mBio 2023; 14:e0186623. [PMID: 37971252 PMCID: PMC10746260 DOI: 10.1128/mbio.01866-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 10/06/2023] [Indexed: 11/19/2023] Open
Abstract
IMPORTANCE Toxin production and sporulation are key determinants of pathogenesis in Clostridia. Toxins cause the clinical manifestation of clostridial diseases, including diarrhea and colitis, tissue damage, and systemic effects on the nervous system. Spores ensure long-term survival and persistence in the environment, act as infectious agents, and initiate the host tissue colonization leading to infection. Understanding the interplay between toxin production and sporulation and their coordination in bacterial cells and cultures provides novel intervention points for controlling the public health and food safety risks caused by clostridial diseases. We demonstrate environmentally driven cellular heterogeneity in botulinum neurotoxin and spore production in Clostridium botulinum type E populations and discuss the biological rationale of toxin and spore production in the pathogenicity and ecology of C. botulinum. The results invite to reassess the epidemiology of botulism and may have important implications in the risk assessment and risk management strategies in food processing and human and animal health.
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Affiliation(s)
- Anna Mertaoja
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Gerald Mascher
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Maria B. Nowakowska
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Hannu Korkeala
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
| | - Adriano O. Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Lisbon, Portugal
| | - Miia Lindstrom
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland
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2
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Gao P, Wu C, Zhang J, Wang S, Huang Y, Dong Y, Liu T, Ye C, Xu X, Xin W. Evaluation and Optimization of Microdrop Digital PCR for Detection of Serotype A and B Clostridium botulinum. Front Microbiol 2022; 13:860992. [PMID: 35615503 PMCID: PMC9125207 DOI: 10.3389/fmicb.2022.860992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 02/11/2022] [Indexed: 12/02/2022] Open
Abstract
Clostridium botulinum is the causative pathogen of botulism. Laboratory detection of C. botulinum is essential for clinical therapy treatment of botulism due to the difficulty in diagnosis, especially in infant botulism. The extreme toxicity of botulinum neurotoxin (BoNT) requires a sensitive detection method. Due to the detection limit of real-time quantitative PCR (q-PCR), a more sensitive detection method, micro-drop digital PCR (ddPCR) was applied in C. botulinum main serotypes A and B. The following performance criteria were evaluated by ddPCR: analytical sensitivity; repeatability; and diagnostic specificity. The limit of detection (LOD) was 0.84 and 0.88 copies/μl for BoNT A and B genes, respectively, by ddPCR with high specificity, compared to 5.04×102 and 6.91×102 copies/μl by q-PCR. It was increased 10 times compared with q-PCR in spiked stool samples. This improvement in sensitivity was especially important in clinical samples as more positive samples were detected by digital PCR compared with q-PCR. Meanwhile, enrichment time for low bacteria content samples was shortened by four hours both in serotypes A and B C. botulinum by ddPCR compared with q-PCR, which are important for laboratory diagnosis and epidemiology work.
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Affiliation(s)
- Pengya Gao
- State Key Laboratory for Infectious Disease Prevention and Control and National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Changde Wu
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Jin Zhang
- Criminal Investigation School, People's Public Security University of China, Beijing, China
| | - Shuping Wang
- College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, China
| | - Ying Huang
- State Key Laboratory for Infectious Disease Prevention and Control and National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Yinping Dong
- NHC Key Laboratory of Food Safety Risk Assessment, China National Center for Food Safety Risk Assessment, Beijing, China
| | - Tingting Liu
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
| | - Changyun Ye
- State Key Laboratory for Infectious Disease Prevention and Control and National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Xuefang Xu
- State Key Laboratory for Infectious Disease Prevention and Control and National Institute for Communicable Diseases Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
- *Correspondence: Xuefang Xu
| | - Wenwen Xin
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- Wenwen Xin
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3
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Koukou I, Dahl Devitt T, Dalgaard P. Extensive growth and growth boundary model for non-proteolytic Clostridium botulinum - Evaluation and validation with MAP and smoked foods. Food Microbiol 2021; 102:103931. [PMID: 34809957 DOI: 10.1016/j.fm.2021.103931] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/27/2021] [Accepted: 10/29/2021] [Indexed: 11/29/2022]
Abstract
The growth inhibiting effect of lactic acid bacteria (LAB) on non-proteolytic Clostridium botulinum was studied. LAB had no significant effect on growth of C. botulinum and their effect was not included in the model to be evaluated. An available cardinal parameter growth and growth boundary model for non-proteolytic C. botulinum (Koukou et al., 2021; https://doi.org/10.1016/j.ijfoodmicro.2021.109162) was evaluated using a total of 822 time-to-toxin (TTT) formation data extracted from the scientific literature for seafood, poultry, vegetables and meat products. These data included smoked products and food stored in air, vacuum or modified atmosphere packaging (MAP) with added CO2. The available extensive model predicted TTT formation without bias (Bf-TTT value = 0.99) and with a reasonable accuracy (Af-TTT value = 1.76). The model was successfully validated for seafood and poultry products. This study substantially increased the range of applicability of the available growth and growth boundary model for non-proteolytic C. botulinum. The performed evaluation showed this model can be used to predict environmental conditions to prevent growth in seafood and poultry products including smoked fish and MAP foods. It is expected that this validated model will contribute to product development and innovation including new sodium reduced foods.
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Affiliation(s)
- Ioulia Koukou
- National Food Institute (DTU Food), Technical University of Denmark, Kemitorvet Building 202, DK-2800 Kgs. Lyngby, Denmark.
| | - Tina Dahl Devitt
- National Food Institute (DTU Food), Technical University of Denmark, Kemitorvet Building 202, DK-2800 Kgs. Lyngby, Denmark
| | - Paw Dalgaard
- National Food Institute (DTU Food), Technical University of Denmark, Kemitorvet Building 202, DK-2800 Kgs. Lyngby, Denmark
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4
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Cardinal parameter growth and growth boundary model for non-proteolytic Clostridium botulinum - Effect of eight environmental factors. Int J Food Microbiol 2021; 346:109162. [PMID: 33827003 DOI: 10.1016/j.ijfoodmicro.2021.109162] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 01/05/2021] [Accepted: 03/06/2021] [Indexed: 11/20/2022]
Abstract
A new cardinal parameter growth and growth boundary model for non-proteolytic C. botulinum was developed and validated for fresh and lightly preserved seafood and poultry products. 523 growth rates in broth were used to determine cardinal parameter values and terms for temperature, pH, NaCl/water activity, acetic, benzoic, citric, lactic and sorbic acids. The new growth and growth boundary model included the inhibiting interactive effect between these factors and it was calibrated using growth curves from 10 challenge tests with unprocessed seafood. For model evaluation, 40 challenge tests with well characterized fresh and lightly preserved seafood were performed. Comparison of these observed growth curves and growth rates (μmax-values) predicted by the new model resulted in a bias factor (Bf) of 1.12 and an accuracy factor (Af) of 1.40. Furthermore, the new model was evaluated with 94 growth rates and 432 time to toxin formation data extracted from the scientific literature for seafood, poultry, meat, pasta and prepared meals. These data included responses for 36 different toxigenic strains of non-proteolytic C. botulinum. The obtained Bf-/Af-values were 0.97/2.04 for μmax-values and 0.96/1.80 for time to toxin formation. The model correctly predicted 93.8% of the growth responses with 5.6% being fail-safe and <1% fail-dangerous. A cocktail of four non-toxin producing Clostridium spp. isolates was used to develop the new model and these isolates had more than 99.8% 16S rRNA gene similarity to non-proteolytic C. botulinum (Group II). The high number of environmental factors included in the new model makes it a flexible tool to facilitate development or reformulation of seafood and poultry products that do not support the growth of non-proteolytic C. botulinum. Further, evaluation of the new model with well characterized products is desirable particularly for meat, vegetables, pasta and prepared meals as well as for dairy products that was not included in the present study.
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5
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Silva DR, Haddad GB, de Moura AP, de Souza PM, Ramos AL, Hopkins DL, Ramos EM. Safe cured meat using gamma radiation: Effects on spores of Clostridium sporogenes and technological and sensorial characteristics of low nitrite cooked ham. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2020.110392] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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6
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Mathot AG, Postollec F, Leguerinel I. Bacterial spores in spices and dried herbs: The risks for processed food. Compr Rev Food Sci Food Saf 2020; 20:840-862. [DOI: 10.1111/1541-4337.12690] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/15/2020] [Accepted: 11/20/2020] [Indexed: 11/26/2022]
Affiliation(s)
- Anne Gabrielle Mathot
- Université de Brest, Laboratoire Universitaire de Biodiversité et d'Ecologie Microbienne Quimper France
| | | | - Ivan Leguerinel
- Université de Brest, Laboratoire Universitaire de Biodiversité et d'Ecologie Microbienne Quimper France
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7
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van Boekel MAJS, ter Steeg PF, Dahoe AE. Co-optimization of safety, quality and legislation: opening Pandora’s box? Curr Opin Food Sci 2020. [DOI: 10.1016/j.cofs.2020.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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8
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Peck MW, Webb MD, Goodburn KE. Assessment of the risk of botulism from chilled, vacuum/modified atmosphere packed fresh beef, lamb and pork held at 3 °C-8 °C. Food Microbiol 2020; 91:103544. [PMID: 32539958 DOI: 10.1016/j.fm.2020.103544] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 04/12/2020] [Accepted: 05/03/2020] [Indexed: 02/06/2023]
Abstract
The safety of current UK industry practice (including shelf-life) for chilled, vacuum/modified atmosphere-packed fresh red meat (beef, lamb and pork) held at 3°C-8°C has been evaluated with respect to non-proteolytic Clostridium botulinum. UK industry typically applies a retail pack shelf-life at 3°C-8°C to 13 days for fresh red meat, with a maximum of 23 days for beef, 27 days for lamb, and 18 days for pork. An exposure assessment established that current commercial practice for fresh red meat provided strong protection with more than 1010 person servings marketed in the UK without association with foodborne botulism. A challenge test demonstrated that spores of non-proteolytic C. botulinum inoculated on chilled vacuum-packed fresh red meat did not lead to detectable neurotoxin at day 50 for beef, day 35 for lamb, or day 25 for pork (i.e. <40 pg type B toxin and type E toxin g-1 of meat). The products were visually spoiled many days before these end points. The exposure assessment and challenge test demonstrated the safety of current UK industry practices for the shelf-life of fresh, vacuum-packed beef, lamb and pork held at 3°C-8°C with respect to C. botulinum, and that botulinum neurotoxin was not detected within their organoleptic shelf-life.
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Affiliation(s)
- Michael W Peck
- QIB Extra, Quadram Institute, Norwich Research Park, Norwich, NR4 7UQ, UK.
| | - Martin D Webb
- QIB Extra, Quadram Institute, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Karin E Goodburn
- Chilled Food Associates, C/o 3 Weekley Wood Close, Kettering, NN14 1UQ, UK
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9
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Brunt J, van Vliet AHM, Stringer SC, Carter AT, Lindström M, Peck MW. Pan-Genomic Analysis of Clostridium botulinum Group II (Non-Proteolytic C. botulinum) Associated with Foodborne Botulism and Isolated from the Environment. Toxins (Basel) 2020; 12:E306. [PMID: 32397147 PMCID: PMC7291236 DOI: 10.3390/toxins12050306] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 12/21/2022] Open
Abstract
The neurotoxin formed by Clostridium botulinum Group II is a major cause of foodborne botulism, a deadly intoxication. This study aims to understand the genetic diversity and spread of C. botulinum Group II strains and their neurotoxin genes. A comparative genomic study has been conducted with 208 highly diverse C. botulinum Group II strains (180 newly sequenced strains isolated from 16 countries over 80 years, 28 sequences from Genbank). Strains possessed a single type B, E, or F neurotoxin gene or were closely related strains with no neurotoxin gene. Botulinum neurotoxin subtype variants (including novel variants) with a unique amino acid sequence were identified. Core genome single-nucleotide polymorphism (SNP) analysis identified two major lineages-one with type E strains, and the second dominated by subtype B4 strains with subtype F6 strains. This study revealed novel details of population structure/diversity and established relationships between whole-genome lineage, botulinum neurotoxin subtype variant, association with foodborne botulism, epidemiology, and geographical source. Additionally, the genome sequences represent a valuable resource for the research community (e.g., understanding evolution of C. botulinum and its neurotoxin genes, dissecting key aspects of C. botulinum Group II biology). This may contribute to improved risk assessments and the prevention of foodborne botulism.
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Affiliation(s)
- Jason Brunt
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, UK
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Arnoud H. M. van Vliet
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK;
| | - Sandra C. Stringer
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Andrew T. Carter
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
| | - Miia Lindström
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, 00014 Helsinki, Finland;
| | - Michael W. Peck
- Gut Health and Food Safety, Quadram Institute, Norwich Research Park, Norwich NR4 7UQ, UK; (S.C.S.); (A.T.C.)
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10
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High prevalence of Clostridium botulinum in vegetarian sausages. Food Microbiol 2020; 91:103512. [PMID: 32539985 DOI: 10.1016/j.fm.2020.103512] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/04/2020] [Accepted: 04/12/2020] [Indexed: 11/22/2022]
Abstract
Clostridium botulinum is a significant food safety concern due to its ability to produce highly potent neurotoxin and resistant endospores. Vegetarian sausages have become a popular source of plant protein and alternative for meat products. While vegetarian sausages have not been linked to botulism, numerous outbreaks due to preserved vegetables suggest a frequent occurrence of C. botulinum spores in the raw material. The product formulation of vegetarian sausages involves limited NaCl and preservatives, and shelf-lives may be several months. The safety of vegetarian sausages thus relies mainly on heat treatment and chilled storage. The main food safety concern is C. botulinum Group II that can grow and produce toxin at refrigeration temperatures. Here we show a high overall prevalence (32%) of C. botulinum in 74 samples of vegetarian sausages from seven producers. Both Groups I and II strains and genes for neurotoxin types A, B, E and F were detected in the products. The highest cell counts (1200 spores/kg) were observed for C. botulinum Group II in products with remaining shelf-lives of 6 months at the time of purchase. We conclude that vacuum-packaged vegetarian sausage products frequently contain C. botulinum spores and may possess a high risk of C. botulinum growth and toxin production. Chilled storage below 3°C and thorough reheating before consumption are warranted.
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Webb MD, Barker GC, Goodburn KE, Peck MW. Risk presented to minimally processed chilled foods by psychrotrophic Bacillus cereus. Trends Food Sci Technol 2019; 93:94-105. [PMID: 31764911 PMCID: PMC6853023 DOI: 10.1016/j.tifs.2019.08.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 08/19/2019] [Accepted: 08/29/2019] [Indexed: 11/13/2022]
Abstract
BACKGROUND Spores of psychrotrophic Bacillus cereus may survive the mild heat treatments given to minimally processed chilled foods. Subsequent germination and cell multiplication during refrigerated storage may lead to bacterial concentrations that are hazardous to health. SCOPE AND APPROACH This review is concerned with the characterisation of factors that prevent psychrotrophic B. cereus reaching hazardous concentrations in minimally processed chilled foods and associated foodborne illness. A risk assessment framework is used to quantify the risk associated with B. cereus and minimally processed chilled foods. KEY FINDINGS AND CONCLUSIONS Bacillus cereus is responsible for two types of food poisoning, diarrhoeal (an infection) and emetic (an intoxication); however, no reported outbreaks of food poisoning have been associated with B. cereus and correctly stored commercially-produced minimally processed chilled foods. In the UK alone, more than 1010 packs of these foods have been sold in recent years without reported illness, thus the risk presented is very low. Further quantification of the risk is merited, and this requires additional data. The lack of association between diarrhoeal food poisoning and correctly stored commercially-produced minimally processed chilled foods indicates that an infectious dose has not been reached. This may reflect low pathogenicity of psychrotrophic strains. The lack of reported association of psychrotrophic B. cereus with emetic illness and correctly stored commercially-produced minimally processed chilled foods indicates that a toxic dose of the emetic toxin has not been formed. Laboratory studies show that strains form very small quantities of emetic toxin at chilled temperatures.
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Affiliation(s)
- Martin D. Webb
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Gary C. Barker
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
| | - Kaarin E. Goodburn
- Chilled Food Associates, c/o 3 Weekley Wood Close, Kettering, NN14 1UQ, UK
| | - Michael W. Peck
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, UK
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12
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Ihekwaba AEC, Mura I, Walshaw J, Peck MW, Barker GC. An Integrative Approach to Computational Modelling of the Gene Regulatory Network Controlling Clostridium botulinum Type A1 Toxin Production. PLoS Comput Biol 2016; 12:e1005205. [PMID: 27855161 PMCID: PMC5113860 DOI: 10.1371/journal.pcbi.1005205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 10/16/2016] [Indexed: 11/19/2022] Open
Abstract
Clostridium botulinum produces botulinum neurotoxins (BoNTs), highly potent substances responsible for botulism. Currently, mathematical models of C. botulinum growth and toxigenesis are largely aimed at risk assessment and do not include explicit genetic information beyond group level but integrate many component processes, such as signalling, membrane permeability and metabolic activity. In this paper we present a scheme for modelling neurotoxin production in C. botulinum Group I type A1, based on the integration of diverse information coming from experimental results available in the literature. Experiments show that production of BoNTs depends on the growth-phase and is under the control of positive and negative regulatory elements at the intracellular level. Toxins are released as large protein complexes and are associated with non-toxic components. Here, we systematically review and integrate those regulatory elements previously described in the literature for C. botulinum Group I type A1 into a population dynamics model, to build the very first computational model of toxin production at the molecular level. We conduct a validation of our model against several items of published experimental data for different wild type and mutant strains of C. botulinum Group I type A1. The result of this process underscores the potential of mathematical modelling at the cellular level, as a means of creating opportunities in developing new strategies that could be used to prevent botulism; and potentially contribute to improved methods for the production of toxin that is used for therapeutics. Clostridium botulinum produces botulinum neurotoxins (BoNTs), highly potent substances responsible for botulism. Currently, mathematical models of C. botulinum growth and toxigenesis are largely aimed at risk assessment and do not include explicit genetic information. In this paper we present modelling based on the integration of diverse information from experimental results available in the literature. Experiments show that production of BoNTs depends on the growth-phase and is under the control of positive and negative regulatory elements at the intracellular level. Here, we integrate these regulatory elements into a combined model of population dynamics and gene regulation to build the first computational model of toxin production at the molecular level. We conduct a validation of our model against several items of published experimental data for different wild type and mutant strains of C. botulinum Group I type A1. The result of this process underscores the potential of mathematical modelling at the cellular level, as a means of creating opportunities that could be used to prevent botulism, and potentially contribute to improved methods for the production of toxin used for therapeutics.
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Affiliation(s)
- Adaoha E. C. Ihekwaba
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
- * E-mail: (AECI); (IM)
| | - Ivan Mura
- Department of Industrial Engineering, Universidad de los Andes, Bogotá, Colombia
- * E-mail: (AECI); (IM)
| | - John Walshaw
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
- School of Computing Sciences, University of East Anglia, Norwich, United Kingdom
| | - Michael W. Peck
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
| | - Gary C. Barker
- Gut Health and Food Safety, Institute of Food Research, Norwich Research Park, Colney, Norwich, United Kingdom
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13
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Brunt J, van Vliet AHM, van den Bos F, Carter AT, Peck MW. Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III, and IV. Front Microbiol 2016; 7:1702. [PMID: 27840626 PMCID: PMC5083711 DOI: 10.3389/fmicb.2016.01702] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Accepted: 10/12/2016] [Indexed: 01/17/2023] Open
Abstract
Clostridium botulinum is a highly dangerous pathogen that forms very resistant endospores that are ubiquitous in the environment, and which, under favorable conditions germinate to produce vegetative cells that multiply and form the exceptionally potent botulinum neurotoxin. To improve the control of botulinum neurotoxin-forming clostridia, it is important to understand the mechanisms involved in spore germination. Here we present models for spore germination in C. botulinum based on comparative genomics analyses, with C. botulinum Groups I and III sharing similar pathways, which differ from those proposed for C. botulinum Groups II and IV. All spores germinate in response to amino acids interacting with a germinant receptor, with four types of germinant receptor identified [encoded by various combinations of gerA, gerB, and gerC genes (gerX)]. There are three gene clusters with an ABC-like configuration; ABC [gerX1], ABABCB [gerX2] and ACxBBB [gerX4], and a single CA-B [gerX3] gene cluster. Subtypes have been identified for most germinant receptor types, and the individual GerX subunits of each cluster show similar grouping in phylogenetic trees. C. botulinum Group I contained the largest variety of gerX subtypes, with three gerX1, three gerX2, and one gerX3 subtypes, while C. botulinum Group III contained two gerX1 types and one gerX4. C. botulinum Groups II and IV contained a single germinant receptor, gerX3 and gerX1, respectively. It is likely that all four C. botulinum Groups include a SpoVA channel involved in dipicolinic acid release. The cortex-lytic enzymes present in C. botulinum Groups I and III appear to be CwlJ and SleB, while in C. botulinum Groups II and IV, SleC appears to be important.
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Affiliation(s)
- Jason Brunt
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
| | - Arnoud H. M. van Vliet
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
- School of Veterinary Medicine, Faculty of Health and Medical Sciences, University of SurreyGuildford, UK
| | | | - Andrew T. Carter
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
| | - Michael W. Peck
- Gut Health and Food Safety, Institute of Food ResearchNorwich, UK
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14
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Wachnicka E, Stringer SC, Barker GC, Peck MW. Systematic Assessment of Nonproteolytic Clostridium botulinum Spores for Heat Resistance. Appl Environ Microbiol 2016; 82:6019-29. [PMID: 27474721 PMCID: PMC5038052 DOI: 10.1128/aem.01737-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 07/26/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Heat treatment is an important controlling factor that, in combination with other hurdles (e.g., pH, aw), is used to reduce numbers and prevent the growth of and associated neurotoxin formation by nonproteolytic C. botulinum in chilled foods. It is generally agreed that a heating process that reduces the spore concentration by a factor of 10(6) is an acceptable barrier in relation to this hazard. The purposes of the present study were to review the available data relating to heat resistance properties of nonproteolytic C. botulinum spores and to obtain an appropriate representation of parameter values suitable for use in quantitative microbial risk assessment. In total, 753 D values and 436 z values were extracted from the literature and reveal significant differences in spore heat resistance properties, particularly those corresponding to recovery in the presence or absence of lysozyme. A total of 503 D and 338 z values collected for heating temperatures at or below 83°C were used to obtain a probability distribution representing variability in spore heat resistance for strains recovered in media that did not contain lysozyme. IMPORTANCE In total, 753 D values and 436 z values extracted from literature sources reveal significant differences in spore heat resistance properties. On the basis of collected data, two z values have been identified, z = 7°C and z = 9°C, for spores recovered without and with lysozyme, respectively. The findings support the use of heat treatment at 90°C for 10 min to reduce the spore concentration by a factor of 10(6), providing that lysozyme is not present during recovery. This study indicates that greater heat treatment is required for food products containing lysozyme, and this might require consideration of alternative recommendation/guidance. In addition, the data set has been used to test hypotheses regarding the dependence of spore heat resistance on the toxin type and strain, on the heating technique used, and on the method of D value determination used.
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Affiliation(s)
- Ewelina Wachnicka
- Institute of Food Research, Norwich Research Park, Colney, United Kingdom
| | - Sandra C Stringer
- Institute of Food Research, Norwich Research Park, Colney, United Kingdom
| | - Gary C Barker
- Institute of Food Research, Norwich Research Park, Colney, United Kingdom
| | - Michael W Peck
- Institute of Food Research, Norwich Research Park, Colney, United Kingdom
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Abstract
C. botulinum Groups I and II form botulinum neurotoxin and cause foodborne botulism. Increased knowledge of C. botulinum Group I and II genomes and neurotoxin diversity. Impact on food safety via improved surveillance and tracing/tracking during outbreaks. New insights into C. botulinum biology, food chain transmission, evolution.
The deadly botulinum neurotoxin formed by Clostridium botulinum is the causative agent of foodborne botulism. The increasing availability of C. botulinum genome sequences is starting to allow the genomic diversity of C. botulinum Groups I and II and their neurotoxins to be characterised. This information will impact on microbiological food safety through improved surveillance and tracing/tracking during outbreaks, and a better characterisation of C. botulinum Groups I and II, including the risk presented, and new insights into their biology, food chain transmission, and evolution.
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