1
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Trunet C, Vischer N, Coroller L, Brul S. Germination and outgrowth of Bacillus mycoides KBAB4 spores are impacted by environmental pH, quantitatively analyzed at single cell level with sporetracker. Food Microbiol 2024; 121:104509. [PMID: 38637073 DOI: 10.1016/j.fm.2024.104509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/06/2024] [Accepted: 02/24/2024] [Indexed: 04/20/2024]
Abstract
Quantifying spore germination and outgrowth heterogeneity is challenging. Single cell level analysis should provide supplementary knowledge regarding the impact of unfavorable conditions on germination and outgrowth dynamics. This work aimed to quantify the impact of pH on spore germination and outgrowth, investigating the behavior of individual spore crops, produced under optimal and suboptimal conditions. Bacillus mycoides (formerly B. weihenstephanensis) KBAB4 spores, produced at pH 7.4 and at pH 5.5 were incubated at different pH values, from pH 5.2 to 7.4. The spores were monitored by microscopy live imaging, in controlled conditions, at 30 °C. The images were analyzed using SporeTracker, to determine the state of single cells. The impact of pH on germination and outgrowth times and rates was estimated and the correlation between these parameters was quantified. The correlation between germination and outgrowth times was significantly higher at low pH. These results suggest that an environmental pressure highlights the heterogeneity of spore germination and outgrowth within a spore population. Results were consistent with previous observations at population level, now confirmed and extended to single cell level. Therefore, single cell level analyses can be used to quantify the heterogeneity of spore populations, which is of interest in order to control the development of spore-forming bacteria, responsible for food safety issues.
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Affiliation(s)
- C Trunet
- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France.
| | - N Vischer
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands
| | - L Coroller
- Univ Brest, INRAE, Laboratoire Universitaire de Biodiversité et Écologie Microbienne, F-29000, Quimper, France
| | - S Brul
- Laboratory for Molecular Biology and Microbial Food Safety, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, the Netherlands
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2
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Oppezzo OJ, Abrevaya XC, Giacobone AFF. An alternative interpretation for tailing in survival curves for bacteria exposed to germicidal radiation. Photochem Photobiol 2024; 100:129-136. [PMID: 37026990 DOI: 10.1111/php.13808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 03/13/2023] [Accepted: 04/02/2023] [Indexed: 04/08/2023]
Abstract
It has been proposed that transient and reversible phenotypic changes could modify the response of bacteria to germicidal radiation, eventually leading to tailing in the survival curves. If this were the case, changes in susceptibility to radiation would reflect variations in gene expression and should only occur in cells in which gene expression is active. To obtain experimental evidence supporting the involvement of phenotypic changes in the origin of tailing, we studied changes in the susceptibility to radiation of cells able to survive high fluences, using split irradiations. Stationary phase cells of Enterobacter cloacae and Deinococcus radiodurans, in which gene expression is active, and spores of Bacillus subtilis, which are dormant cells without active gene expression, were used as microbial models. While cells of E. cloacae and D. radiodurans became susceptible after surviving exposures to high fluences, tolerant spores exhibited unchanged response to radiation. The results can be interpreted assuming that noise in gene expression modifies bacterial susceptibility to radiation, and tailing is the result of intrinsic phenomena of bacterial physiology rather than a technical artifact. For either theoretical or practical purposes, deviations from simple exponential decay kinetics should be considered in estimations of the effects of germicidal radiation at high fluences.
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Affiliation(s)
- Oscar J Oppezzo
- Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
| | - Ximena C Abrevaya
- Instituto de Astronomía y Física del Espacio (UBA-CONICET), Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, UBA, Buenos Aires, Argentina
| | - Ana F F Giacobone
- Comisión Nacional de Energía Atómica, Buenos Aires, Argentina
- Universidad Nacional de Tres de Febrero, Buenos Aires, Argentina
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3
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Xu J, Guo L, Zhao N, Meng X, Zhang J, Wang T, Wei X, Fan M. Response mechanisms to acid stress of acid-resistant bacteria and biotechnological applications in the food industry. Crit Rev Biotechnol 2023; 43:258-274. [PMID: 35114869 DOI: 10.1080/07388551.2021.2025335] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Acid-resistant bacteria are more and more widely used in industrial production due to their unique acid-resistant properties. In order to survive in various acidic environments, acid-resistant bacteria have developed diverse protective mechanisms such as sensing acid stress and signal transduction, maintaining intracellular pH homeostasis by controlling the flow of H+, protecting and repairing biological macromolecules, metabolic modification, and cross-protection. Acid-resistant bacteria have broad biotechnological application prospects in the food field. The production of fermented foods with high acidity and acidophilic enzymes are the main applications of this kind of bacteria in the food industry. Their acid resistance modules can also be used to construct acid-resistant recombinant engineering strains for special purposes. However, they can also cause negative effects on foods, such as spoilage and toxicity. Herein, the aim of this paper is to summarize the research progress of molecular mechanisms against acid stress of acid-resistant bacteria. Moreover, their effects on the food industry were also discussed. It is useful to lay a foundation for broadening our understanding of the physiological metabolism of acid-resistant bacteria and better serving the food industry.
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Affiliation(s)
- Junnan Xu
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Li Guo
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Ning Zhao
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Xuemei Meng
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Jie Zhang
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Tieru Wang
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Xinyuan Wei
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
| | - Mingtao Fan
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, Shaanxi, China
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4
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Three novel leaderless bacteriocins have antimicrobial activity against gram-positive bacteria to serve as promising food biopreservative. Microb Cell Fact 2022; 21:194. [PMID: 36123739 PMCID: PMC9484092 DOI: 10.1186/s12934-022-01912-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 08/17/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Due to the detrimental effects of chemical preservatives, there has been an increasing demand for safer, healthier and natural bio-preservatives. Bacteriocins have attracted increasing interest because of their potential as natural bio-preservatives. RESULTS We screened a large number of Bacillus thuringiensis strains and isolated one strain (B. thuringiensis P86) with antimicrobial activity against several foodborne pathogens. Three novel leaderless bacteriocins, including thucin A1, thucin A2 and thucin A3, were purified and identified from the culture supernatant of B. thuringiensis P86, whose molecular masses were 5552.02, 5578.07 and 5609.06 Da, respectively. Thucin A1 was then selected as a representative to be tested, and it exhibited potent inhibitory activity against all tested gram-positive bacteria. More importantly, thucin A1 showed stronger antimicrobial activity than nisin A against two important foodborne pathogens Bacillus cereus and Listeria monocytogenes. In addition, thucin A1 exhibited strong acid-base adaptability (pH 2-11), high endurance to heat, good stability to trypsin and pepsin, no hemolysis activity and cytotoxicity, and could effectively inhibit or eliminate Bacillus cereus and Listeria monocytogenes in skim milk. CONCLUSIONS Our findings indicate that these novel leaderless bacteriocins are potentially promising food biopreservatives.
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5
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Lamba S, Mundanda Muthappa D, Fanning S, Scannell AGM. Sporulation and Biofilms as Survival Mechanisms of Bacillus Species in Low-Moisture Food Production Environments. Foodborne Pathog Dis 2022; 19:448-462. [PMID: 35819266 DOI: 10.1089/fpd.2022.0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Low-moisture foods (LMF) have clear advantages with respect to limiting the growth of foodborne pathogens. However, the incidences of Bacillus species in LMF reported in recent years raise concerns about food quality and safety, particularly when these foods are used as ingredients in more complex higher moisture products. This literature review describes the interlinked pathways of sporulation and biofilm formation by Bacillus species and their underlying molecular mechanisms that contribute to the bacteriums' persistence in LMF production environments. The long-standing challenges of food safety and quality in the LMF industry are also discussed with a focus on the bakery industry.
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Affiliation(s)
- Sakshi Lamba
- UCD Institute of Food and Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD Centre for Food Safety, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD School of Agriculture and Food Science, and Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Dechamma Mundanda Muthappa
- UCD Centre for Food Safety, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD School of Agriculture and Food Science, and Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Séamus Fanning
- UCD Institute of Food and Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD Centre for Food Safety, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD School of Public Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
| | - Amalia G M Scannell
- UCD Institute of Food and Health, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD Centre for Food Safety, Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland.,UCD School of Agriculture and Food Science, and Physiotherapy and Sports Science, University College Dublin, Dublin, Ireland
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6
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Dong B, Yu C, Lin Y, Zhou G, Sun C, Wang J, Wu T. Antimicrobial property of Pichia pastoris-derived natto peptide against foodborne bacteria and its preservative potential to maintain pork quality during refrigerated storage. Food Sci Nutr 2022; 10:914-925. [PMID: 35282007 PMCID: PMC8907714 DOI: 10.1002/fsn3.2722] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 12/18/2021] [Accepted: 12/22/2021] [Indexed: 12/17/2022] Open
Abstract
Pork spoilage caused by foodborne bacteria contamination always leads to substantial economic loss in the meat industry. The toxicity and drug resistance of chemical preservatives have raised public concerns about their safety and stability. In this study, natto peptide from Pichia pastoris was prepared using DNA recombinant technology. It showed an excellent antibacterial effect against Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MICs) ranging from 6 to 30 μg/ml. Of note, natto peptide exhibited low cytotoxicity and hemolytic activity. The application of natto peptide on pork during refrigerated storage dramatically decreased the growth of Staphylococcus spp., Escherichia spp., and Pseudomonas spp. The bactericidal properties remained in force when natto peptide was used in pork models contaminated with artificial bacteria. Moreover, the application of natto peptide (90 μg/ml) inhibited the increase in pH variation and drip loss, decreased the generation of total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS), and maintained a high sensory quality score during pork storage. These results implied that P. pastoris-derived natto peptide could extend the storage time of pork, and it has the potential to be a promising antiseptic biopreservative to replace chemical preservatives.
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Affiliation(s)
- Bin Dong
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Cailing Yu
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Yanjun Lin
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Guowen Zhou
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Chunlong Sun
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Jun Wang
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
| | - Tao Wu
- Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River DeltaCollege of Biological and Environmental EngineeringBinzhou UniversityBinzhouChina
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7
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Ren B, Wu W, Soladoye OP, Bak KH, Fu Y, Zhang Y. Application of biopreservatives in meat preservation: a review. Int J Food Sci Technol 2021. [DOI: 10.1111/ijfs.15307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Baojing Ren
- College of Food Science Southwest University Chongqing 400715 China
- National Demonstration Center for Experimental Food Science and Technology Education Southwest University Chongqing 400715 China
- Westa College Southwest University Chongqing 400715 China
| | - Wei Wu
- College of Animal Science and Technology Southwest University Chongqing 400715 China
| | - Olugbenga P. Soladoye
- Agriculture and Agri‐Food Canada Government of Canada Lacombe Research and Development Centre 6000 C&E Trail Lacombe AB T4L 1W1 Canada
| | - Kathrine H. Bak
- Institute of Food Safety, Food Technology and Veterinary Public Health University of Veterinary Medicine, Vienna Veterinärplatz 1 Vienna 1210 Austria
| | - Yu Fu
- College of Food Science Southwest University Chongqing 400715 China
- National Demonstration Center for Experimental Food Science and Technology Education Southwest University Chongqing 400715 China
| | - Yuhao Zhang
- College of Food Science Southwest University Chongqing 400715 China
- National Demonstration Center for Experimental Food Science and Technology Education Southwest University Chongqing 400715 China
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8
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Antimicrobial, anti-biofilm properties of three naturally occurring antimicrobial peptides against spoilage bacteria, and their synergistic effect with chemical preservatives in food storage. Food Control 2021. [DOI: 10.1016/j.foodcont.2020.107729] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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9
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Benarroch JM, Asally M. The Microbiologist’s Guide to Membrane Potential Dynamics. Trends Microbiol 2020; 28:304-314. [DOI: 10.1016/j.tim.2019.12.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/25/2019] [Accepted: 12/09/2019] [Indexed: 10/25/2022]
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10
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Begyn K, Kim TD, Heyndrickx M, Michiels C, Aertsen A, Rajkovic A, Devlieghere F. Directed evolution by UV-C treatment of Bacillus cereus spores. Int J Food Microbiol 2019; 317:108424. [PMID: 31790956 DOI: 10.1016/j.ijfoodmicro.2019.108424] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 09/02/2019] [Accepted: 11/03/2019] [Indexed: 12/23/2022]
Abstract
Bacterial endospores are exposed to a broad variety of sublethal and lethal stresses in the food production chain. Generally, these stresses will not completely eliminate the existing spore populations, and thus constitute a selection pressure on the spores. One stress that is frequently used in the food production chains to disinfect (food) contact surfaces is UV-C. At a wavelength of 254 nm, UV-C has germicidal properties. The aim of this research is to investigate the impact of UV-C stress on the evolution of endospore recalcitrance and germination in B. cereus. A directed evolution experiment was set up in which B. cereus was repeatedly subjected to a cycle of sporulation, sporicidal UV-C treatment, germination and outgrowth. We show here that three independent lineages of UV-C cycled B. cereus spores reproducibly acquired a 30-fold or higher increase in UV-C resistance at 164 mJ/cm2. Surprisingly, the UV-C resistant spores of the clones isolated from each of the lineages also became significantly more sensitive to wet heat as a normally non-lethal heat treatment at 70 °C for 15 min resulted in an average 1.8 log cfu/mL reduction. From time-lapse phase contrast microscopy analysis, UV-C resistant mutant spores also showed a distinctive heterogeneity in refractility and a severe germination defect compared to the wild type. However, UV-C resistance of the corresponding vegetative cells was not altered. In conclusion, this work shows that UV-C resistance of endospores is an adaptive trait that can readily be improved, although at an apparent cost for heat resistance and germination efficiency. As such, these results provide novel insights in the evolvability of, and correlation between, some endospore properties.
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Affiliation(s)
- Katrien Begyn
- Research Unit Food Microbiology and Food Preservation (FMFP-UGent), Department of Food Technology, Safety and Health, Part of Food2Know, Faculty Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Tom Dongmin Kim
- Laboratory of Food Microbiology, Department of Microbial and Molecular systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium
| | - Marc Heyndrickx
- ILVO - Flanders Research Institute for Agriculture, Fisheries and Food, Technology and Food Science, Unit - Food Safety, Melle, Belgium; Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Chris Michiels
- Laboratory of Food Microbiology, Department of Microbial and Molecular systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Leuven, Belgium
| | - Abram Aertsen
- Laboratory of Food Microbiology, Department of Microbial and Molecular systems (M(2)S), Faculty of Bioscience Engineering, KU Leuven, Leuven, Belgium.
| | - Andreja Rajkovic
- Research Unit Food Microbiology and Food Preservation (FMFP-UGent), Department of Food Technology, Safety and Health, Part of Food2Know, Faculty Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Frank Devlieghere
- Research Unit Food Microbiology and Food Preservation (FMFP-UGent), Department of Food Technology, Safety and Health, Part of Food2Know, Faculty Bioscience Engineering, Ghent University, Ghent, Belgium.
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11
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Sirec T, Benarroch JM, Buffard P, Garcia-Ojalvo J, Asally M. Electrical Polarization Enables Integrative Quality Control during Bacterial Differentiation into Spores. iScience 2019; 16:378-389. [PMID: 31226599 PMCID: PMC6586994 DOI: 10.1016/j.isci.2019.05.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 12/18/2018] [Accepted: 05/30/2019] [Indexed: 12/03/2022] Open
Abstract
Quality control of offspring is important for the survival of cells. However, the mechanisms by which quality of offspring cells may be checked while running genetic programs of cellular differentiation remain unclear. Here we investigated quality control during sporulating in Bacillus subtilis by combining single-cell time-lapse microscopy, molecular biology, and mathematical modeling. Our results revealed that the quality control via premature germination is coupled with the electrical polarization of outer membranes of developing forespores. The forespores that accumulate fewer cations on their surface are more likely to be aborted. This charge accumulation enables the projection of multi-dimensional information about the external environment and morphological development of the forespore into one-dimensional information of cation accumulation. We thus present a paradigm of cellular regulation by bacterial electrical signaling. Moreover, based on the insight we gain, we propose an electrophysiology-based approach of reducing the yield and quality of Bacillus endospores. Quality control during bacterial sporulation is coupled with cation accumulation Cation accumulation prevents premature germination Cation accumulation integrates information on morphological defects and environments Spores are less fit when sporulated with Thioflavin T
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Affiliation(s)
- Teja Sirec
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
| | - Jonatan M Benarroch
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK; Warwick Medical School, The University of Warwick, Coventry CV4 7AL, UK
| | - Pauline Buffard
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Munehiro Asally
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK; Warwick Integrative Synthetic Biology Centre, The University of Warwick, Coventry CV4 7AL, UK; Bio-electrical Engineering Innovation Hub, The University of Warwick, Coventry CV4 7AL, UK.
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12
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Zhang Y, Mathys A. Superdormant Spores as a Hurdle for Gentle Germination-Inactivation Based Spore Control Strategies. Front Microbiol 2019; 9:3163. [PMID: 30662433 PMCID: PMC6328458 DOI: 10.3389/fmicb.2018.03163] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/06/2018] [Indexed: 02/04/2023] Open
Abstract
Bacterial spore control strategies based on the germination-inactivation principle can lower the thermal load needed to inactivate bacterial spores and thus preserve food quality better. However, the success of this strategy highly depends on the germination of spores, and a subpopulation of spores that fail to germinate or germinate extremely slowly hinders the application of this strategy. This subpopulation of spores is termed 'superdormant (SD) spores.' Depending on the source of the germination stimulus, SD spores are categorized as nutrient-SD spores, Ca2+-dipicolinic acid SD spores, dodecylamine-SD spores, and high pressure SD spores. In recent decades, research has been done to isolate these different groups of SD spores and unravel the cause of their germination deficiency as well as their germination capacities. This review summarizes the challenges caused by SD spores, their isolation and characterization, the underlying mechanisms of their germination deficiency, and the future research directions needed to tackle this topic in further depth.
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Affiliation(s)
| | - Alexander Mathys
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zurich, Zurich, Switzerland
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13
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Kumariya R, Garsa AK, Rajput YS, Sood SK, Akhtar N, Patel S. Bacteriocins: Classification, synthesis, mechanism of action and resistance development in food spoilage causing bacteria. Microb Pathog 2019; 128:171-177. [PMID: 30610901 DOI: 10.1016/j.micpath.2019.01.002] [Citation(s) in RCA: 185] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/02/2019] [Accepted: 01/02/2019] [Indexed: 01/06/2023]
Abstract
Huge demand of safe and natural preservatives has opened new area for intensive research on bacteriocins to unravel the novel range of antimicrobial compounds that could efficiently fight off the food-borne pathogens. Since food safety has become an increasingly important international concern, the application of bacteriocins from lactic acid bacteria that target food spoilage/pathogenic bacteria without major adverse effects has received great attention. Different modes of actions of these bacteriocins have been suggested and identified, like pore-forming, inhibition of cell-wall/nucleic acid/protein synthesis. However, development of resistance in the food spoilage and pathogenic bacteria against these bacteriocins is a rising concern. Emergence and spread of mutant strains resistant to bacteriocins is hampering food safety. It has spurred an interest to understand the bacteriocin resistance phenomenon displayed by the food pathogens, which will be helpful in mitigating the resistance problem. Therefore, present review is focused on the different resistance mechanisms adopted by food pathogens to overcome bacteriocin.
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Affiliation(s)
- Rashmi Kumariya
- Protein Expression and Purification Facility, Advanced Technology Platform Centre, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, 121001, India.
| | - Anita Kumari Garsa
- Division of Dairy Microbiology, National Dairy Research Institute, Karnal, Haryana, 132001, India
| | - Y S Rajput
- Division of Animal Biochemistry, National Dairy Research Institute, Karnal, Haryana, 132001, India
| | - S K Sood
- Division of Animal Biochemistry, National Dairy Research Institute, Karnal, Haryana, 132001, India
| | - Nadeem Akhtar
- Department of Animal Biosciences, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Seema Patel
- Bioinformatics and Medical Informatics Research Center, San Diego State University, San Diego, 92182, USA
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14
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De Vrieze J, Boon N, Verstraete W. Taking the technical microbiome into the next decade. Environ Microbiol 2018; 20:1991-2000. [PMID: 29745026 DOI: 10.1111/1462-2920.14269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/03/2018] [Indexed: 01/03/2023]
Abstract
The 'microbiome' has become a buzzword. Multiple new technologies allow to gather information about microbial communities as they evolve under stable and variable environmental conditions. The challenge of the next decade will be to develop strategies to compose and manage microbiomes. Here, key aspects are considered that will be of crucial importance for future microbial technological developments. First, the need to deal not only with genotypes but also particularly with phenotypes is addressed. Microbial technologies are often highly dependent on specific core organisms to obtain the desired process outcome. Hence, it is essential to combine omics data with phenotypic information to invoke and control specific phenotypes in the microbiome. Second, the development and application of synthetic microbiomes is evaluated. The central importance of the core species is a no-brainer, but the implementation of proper satellite species is an important route to explore. Overall, for the next decade, microbiome research should no longer almost exclusively focus on its capacity to degrade and dissipate but rather on its remarkable capability to capture disordered components and upgrade them into high-value microbial products. These products can become valuable commodities in the cyclic economy, as reflected in the case of 'reversed sanitation', which is introduced here.
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Affiliation(s)
- Jo De Vrieze
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium
| | - Willy Verstraete
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, Gent 9000, Belgium.,Avecom NV, Industrieweg 122P, Wondelgem 9032, Belgium
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15
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Bressuire-Isoard C, Broussolle V, Carlin F. Sporulation environment influences spore properties in Bacillus: evidence and insights on underlying molecular and physiological mechanisms. FEMS Microbiol Rev 2018; 42:614-626. [DOI: 10.1093/femsre/fuy021] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 05/16/2018] [Indexed: 02/07/2023] Open
Affiliation(s)
- Christelle Bressuire-Isoard
- UMR408 SQPOV “Sécurité et Qualité des Produits d'Origine Végétale”, INRA–Avignon Université, Centre de Recherche PACA, CS40509, Site Agroparc, 84914 Avignon Cedex 9, France
| | - Véronique Broussolle
- UMR408 SQPOV “Sécurité et Qualité des Produits d'Origine Végétale”, INRA–Avignon Université, Centre de Recherche PACA, CS40509, Site Agroparc, 84914 Avignon Cedex 9, France
| | - Frédéric Carlin
- UMR408 SQPOV “Sécurité et Qualité des Produits d'Origine Végétale”, INRA–Avignon Université, Centre de Recherche PACA, CS40509, Site Agroparc, 84914 Avignon Cedex 9, France
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16
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Abstract
Despite being resistant to a variety of environmental insults, the bacterial endospore can sense the presence of small molecules and respond by germinating, losing the specialized structures of the dormant spore, and resuming active metabolism, before outgrowing into vegetative cells. Our current level of understanding of the spore germination process in bacilli and clostridia is reviewed, with particular emphasis on the germinant receptors characterized in Bacillus subtilis, Bacillus cereus, and Bacillus anthracis. The recent evidence for a local clustering of receptors in a "germinosome" would begin to explain how signals from different receptors could be integrated. The SpoVA proteins, involved in the uptake of Ca2+-dipicolinic acid into the forespore during sporulation, are also responsible for its release during germination. Lytic enzymes SleB and CwlJ, found in bacilli and some clostridia, hydrolyze the spore cortex: other clostridia use SleC for this purpose. With genome sequencing has come the appreciation that there is considerable diversity in the setting for the germination machinery between bacilli and clostridia.
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17
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Mutlu A, Trauth S, Ziesack M, Nagler K, Bergeest JP, Rohr K, Becker N, Höfer T, Bischofs IB. Phenotypic memory in Bacillus subtilis links dormancy entry and exit by a spore quantity-quality tradeoff. Nat Commun 2018; 9:69. [PMID: 29302032 PMCID: PMC5754360 DOI: 10.1038/s41467-017-02477-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 12/04/2017] [Indexed: 12/15/2022] Open
Abstract
Some bacteria, such as Bacillus subtilis, withstand starvation by forming dormant spores that revive when nutrients become available. Although sporulation and spore revival jointly determine survival in fluctuating environments, the relationship between them has been unclear. Here we show that these two processes are linked by a phenotypic “memory” that arises from a carry-over of molecules from the vegetative cell into the spore. By imaging life histories of individual B. subtilis cells using fluorescent reporters, we demonstrate that sporulation timing controls nutrient-induced spore revival. Alanine dehydrogenase contributes to spore memory and controls alanine-induced outgrowth, thereby coupling a spore’s revival capacity to the gene expression and growth history of its progenitors. A theoretical analysis, and experiments with signaling mutants exhibiting altered sporulation timing, support the hypothesis that such an intrinsically generated memory leads to a tradeoff between spore quantity and spore quality, which could drive the emergence of complex microbial traits. Bacillus subtilis withstands starvation by forming dormant spores that revive when nutrients become available. Here, Mutlu et al. show that sporulation timing controls spore revival through a phenotypic ‘memory’ that arises from the carry-over of a metabolic enzyme from the vegetative cell into the spore.
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Affiliation(s)
- Alper Mutlu
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Center for Molecular Biology (ZMBH), University of Heidelberg, 69120, Heidelberg, Germany.,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | - Stephanie Trauth
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Center for Molecular Biology (ZMBH), University of Heidelberg, 69120, Heidelberg, Germany.,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | - Marika Ziesack
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Center for Molecular Biology (ZMBH), University of Heidelberg, 69120, Heidelberg, Germany
| | - Katja Nagler
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | - Jan-Philip Bergeest
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Institute of Pharmacy and Molecular Biotechnology (IPMB), 69120, Heidelberg, Germany.,Department of Bioinformatics and Functional Genomics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Karl Rohr
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Institute of Pharmacy and Molecular Biotechnology (IPMB), 69120, Heidelberg, Germany.,Department of Bioinformatics and Functional Genomics, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Nils Becker
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Thomas Höfer
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Division of Theoretical Systems Biology, German Cancer Research Center (DKFZ), 69120, Heidelberg, Germany
| | - Ilka B Bischofs
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany. .,Center for Molecular Biology (ZMBH), University of Heidelberg, 69120, Heidelberg, Germany. .,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
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18
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Borch-Pedersen K, Mellegård H, Reineke K, Boysen P, Sevenich R, Lindbäck T, Aspholm M. Effects of High Pressure on Bacillus licheniformis Spore Germination and Inactivation. Appl Environ Microbiol 2017; 83:e00503-17. [PMID: 28476768 PMCID: PMC5494625 DOI: 10.1128/aem.00503-17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 05/01/2017] [Indexed: 11/20/2022] Open
Abstract
Bacillus and Clostridium species form spores, which pose a challenge to the food industry due to their ubiquitous nature and extreme resistance. Pressurization at <300 MPa triggers spore germination by activating germination receptors (GRs), while pressurization at >300 MPa likely triggers germination by opening dipicolinic acid (DPA) channels present in the inner membrane of the spores. In this work, we expose spores of Bacillus licheniformis, a species associated with food spoilage and occasionally with food poisoning, to high pressure (HP) for holding times of up to 2 h. By using mutant spores lacking one or several GRs, we dissect the roles of the GerA, Ynd, and GerK GRs in moderately HP (mHP; 150 MPa)-induced spore germination. We show that Ynd alone is sufficient for efficient mHP-induced spore germination. GerK also triggers germination with mHP, although at a reduced germination rate compared to that of Ynd. GerA stimulates mHP-induced germination but only in the presence of either the intact GerK or Ynd GR. These results suggests that the effectiveness of the individual GRs in mHP-induced germination differs from their effectiveness in nutrient-induced germination, where GerA plays an essential role. In contrast to Bacillus subtilis spores, treatment with very HP (vHP) of 550 MPa at 37°C did not promote effective germination of B. licheniformis spores. However, treatment with vHP in combination with elevated temperatures (60°C) gave a synergistic effect on spore germination and inactivation. Together, these results provide novel insights into how HP affects B. licheniformis spore germination and inactivation and the role of individual GRs in this process.IMPORTANCE Bacterial spores are inherently resistant to food-processing regimes, such as high-temperature short-time pasteurization, and may therefore compromise food durability and safety. The induction of spore germination facilitates subsequent inactivation by gentler processing conditions that maintain the sensory and nutritional qualities of the food. High-pressure (HP) processing is a nonthermal food-processing technology used to eliminate microbes from food. The application of this technology for spore eradication in the food industry requires a better understanding of how HP affects the spores of different bacterial species. The present study provides novel insights into how HP affects Bacillus licheniformis spores, a species associated with food spoilage and occasionally food poisoning. We describe the roles of different germination receptors in HP-induced germination and the effects of two different pressure levels on the germination and inactivation of spores. This study will potentially contribute to the effort to implement HP technology for spore inactivation in the food industry.
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Affiliation(s)
- Kristina Borch-Pedersen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway
| | - Hilde Mellegård
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway
| | - Kai Reineke
- Quality and Safety of Food and Feed, Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Germany
| | - Preben Boysen
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway
| | - Robert Sevenich
- Department of Food Biotechnology and Food Process Engineering, Technische Universität Berlin, Berlin, Germany
| | - Toril Lindbäck
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway
| | - Marina Aspholm
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, the Norwegian University of Life Sciences, Oslo, Norway
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19
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Abstract
Spores of Clostridiales and Bacillales are encased in a complex series of concentric shells that provide protection, facilitate germination, and mediate interactions with the environment. Analysis of diverse spore-forming species by thin-section transmission electron microscopy reveals that the number and morphology of these encasing shells vary greatly. In some species, they appear to be composed of a small number of discrete layers. In other species, they can comprise multiple, morphologically complex layers. In addition, spore surfaces can possess elaborate appendages. For all their variability, there is a consistent architecture to the layers encasing the spore. A hallmark of all Clostridiales and Bacillales spores is the cortex, a layer made of peptidoglycan. In close association with the cortex, all species examined possess, at a minimum, a series of proteinaceous layers, called the coat. In some species, including Bacillus subtilis, only the coat is present. In other species, including Bacillus anthracis, an additional layer, called the exosporium, surrounds the coat. Our goals here are to review the present understanding of the structure, composition, assembly, and functions of the coat, primarily in the model organism B. subtilis, but also in the small but growing number of other spore-forming species where new data are showing that there is much to be learned beyond the relatively well-developed basis of knowledge in B. subtilis. To help summarize this large field and define future directions for research, we will focus on key findings in recent years.
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20
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Ha TMH, Yong D, Lee EMY, Kumar P, Lee YK, Zhou W. Activation and inactivation of Bacillus pumilus spores by kiloelectron volt X-ray irradiation. PLoS One 2017; 12:e0177571. [PMID: 28493969 PMCID: PMC5426783 DOI: 10.1371/journal.pone.0177571] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 04/28/2017] [Indexed: 11/30/2022] Open
Abstract
In this study, we investigated the inactivation efficacy of endospore-forming bacteria, Bacillus pumilus, irradiated by low-energy X-rays of different beam qualities. The different low-energy X-rays studied had cut-off energies of 50, 100 and 150 keV. Bacillus pumilus spores (in biological indicator strips) were irradiated at step doses between 6.5 to 390 Gy. The resulting bacteria populations were then quantified by a pour plate method. Results showed that X-rays of lower energies were more effective in inactivating bacterial spores. In addition, an increment in bacterial population was observed at doses below 13Gy. We attributed this increase to a radiation-induced activation of bacterial spores. Four kinetic models were then evaluated for their prediction of bacterial spore behavior under irradiation. This included: (i) first-order kinetics model; (ii) Shull model; (iii) Sapru model; and (iv) probabilistic model. From R2 and AIC analyses, we noted that the probabilistic model performed the best, followed by the Sapru model. We highlighted that for simplicity in curve fitting the Sapru model should be used instead of the probabilistic model. A 12-log reduction in bacterial population (corresponding to a sterility assurance level of 10−6 as required in the sterilization of medical devices) was computed to be achievable at doses of 1000, 1600 and 2300 Gy for the three different X-ray cut-off energies respectively. These doses are an order in magnitude lesser than that required in gamma irradiation. This highlights the applicability of cheaper and safer table-top X-ray sources for sterilization application.
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Affiliation(s)
- Thi Mai Hoa Ha
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
- * E-mail:
| | - Derrick Yong
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
| | - Elizabeth Mei Yin Lee
- Singapore Institute of Manufacturing Technology, Singapore, Singapore
- School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore
| | - Prathab Kumar
- Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Yuan Kun Lee
- Department of Microbiology, National University of Singapore, Singapore, Singapore
| | - Weibiao Zhou
- Food Science and Technology Programme, c/o Department of Chemistry, National University of Singapore, Singapore, Singapore
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21
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Nguyen Van Long N, Vasseur V, Coroller L, Dantigny P, Le Panse S, Weill A, Mounier J, Rigalma K. Temperature, water activity and pH during conidia production affect the physiological state and germination time of Penicillium species. Int J Food Microbiol 2016; 241:151-160. [PMID: 27780083 DOI: 10.1016/j.ijfoodmicro.2016.10.022] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 09/28/2016] [Accepted: 10/17/2016] [Indexed: 11/25/2022]
Abstract
Conidial germination and mycelial growth are generally studied with conidia produced under optimal conditions to increase conidial yield. Nonetheless, the physiological state of such conidia most likely differs from those involved in spoilage of naturally contaminated food. The present study aimed at investigating the impact of temperature, pH and water activity (aw) during production of conidia on the germination parameters and compatible solutes of conidia of Penicillium roqueforti and Penicillium expansum. Low temperature (5°C) and reduced aw (0.900 aw) during sporulation significantly reduced conidial germination times whereas the pH of the sporulation medium only had a slight effect at the tested values (2.5, 8.0). Conidia of P. roqueforti produced at 5°C germinated up to 45h earlier than those produced at 20°C. Conidia of P. roqueforti and P. expansum produced at 0.900 aw germinated respectively up to 8h and 3h earlier than conidia produced at 0.980 aw. Furthermore, trehalose and mannitol assessments suggested that earlier germination might be related to delayed conidial maturation even though no ultra-structural modifications were observed by transmission electron microscopy. Taken together, these results highlight the importance of considering environmental conditions during sporulation in mycological studies. The physiological state of fungal conidia should be taken into account to design challenge tests or predictive mycology studies. This knowledge may also be of interest to improve the germination capacity of fungal cultures commonly used in fermented foods.
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Affiliation(s)
- Nicolas Nguyen Van Long
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Valérie Vasseur
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Louis Coroller
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, UMT Spore Risk, IUT Quimper, 6 rue de l'Université, 29334 Quimper, France
| | - Philippe Dantigny
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Sophie Le Panse
- Plateforme Merimage, Station Biologique de Roscoff, CNRS-UPMC, Place Georges Teissier, CS90074, 29688 Roscoff, Cedex, France
| | - Amélie Weill
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Jérôme Mounier
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France
| | - Karim Rigalma
- Université de Brest, EA 3882, Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, IBSAM, ESIAB, Technopôle Brest-Iroise, 29280 Plouzané, France.
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22
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Eijlander RT, Holsappel S, de Jong A, Ghosh A, Christie G, Kuipers OP. SpoVT: From Fine-Tuning Regulator in Bacillus subtilis to Essential Sporulation Protein in Bacillus cereus. Front Microbiol 2016; 7:1607. [PMID: 27790204 PMCID: PMC5061766 DOI: 10.3389/fmicb.2016.01607] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/26/2016] [Indexed: 12/14/2022] Open
Abstract
Sporulation is a highly sophisticated developmental process adopted by most Bacilli as a survival strategy to withstand extreme conditions that normally do not support microbial growth. A complicated regulatory cascade, divided into various stages and taking place in two different compartments of the cell, involves a number of primary and secondary regulator proteins that drive gene expression directed toward the formation and maturation of an endospore. Such regulator proteins are highly conserved among various spore formers. Despite this conservation, both regulatory and phenotypic differences are observed between different species of spore forming bacteria. In this study, we demonstrate that deletion of the regulatory sporulation protein SpoVT results in a severe sporulation defect in Bacillus cereus, whereas this is not observed in Bacillus subtilis. Although spores are initially formed, the process is stalled at a later stage in development, followed by lysis of the forespore and the mother cell. A transcriptomic investigation of B. cereus ΔspoVT shows upregulation of genes involved in germination, potentially leading to premature lysis of prespores formed. Additionally, extreme variation in the expression of species-specific genes of unknown function was observed. Introduction of the B. subtilis SpoVT protein could partly restore the sporulation defect in the B. cereus spoVT mutant strain. The difference in phenotype is thus more than likely explained by differences in promoter targets rather than differences in mode of action of the conserved SpoVT regulator protein. This study stresses that evolutionary variances in regulon members of sporulation regulators can have profound effects on the spore developmental process and that mere protein homology is not a foolproof predictor of similar phenotypes.
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Affiliation(s)
- Robyn T Eijlander
- Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands
| | - Siger Holsappel
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands
| | - Anne de Jong
- Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands
| | - Abhinaba Ghosh
- Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge Cambridge, UK
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, Institute of Biotechnology, University of Cambridge Cambridge, UK
| | - Oscar P Kuipers
- Top Institute Food and NutritionWageningen, Netherlands; Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of GroningenGroningen, Netherlands
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23
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Krawczyk AO, Berendsen EM, de Jong A, Boekhorst J, Wells-Bennik MHJ, Kuipers OP, Eijlander RT. A transposon present in specific strains ofBacillus subtilisnegatively affects nutrient- and dodecylamine-induced spore germination. Environ Microbiol 2016; 18:4830-4846. [DOI: 10.1111/1462-2920.13386] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 11/28/2022]
Affiliation(s)
- Antonina O. Krawczyk
- Laboratory of Molecular Genetics; University of Groningen; Nijenborgh 7 9747 AG Groningen the Netherlands
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
| | - Erwin M. Berendsen
- Laboratory of Molecular Genetics; University of Groningen; Nijenborgh 7 9747 AG Groningen the Netherlands
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
- NIZO Food Research B.V; Kernhemseweg 2 6718 ZB Ede the Netherlands
| | - Anne de Jong
- Laboratory of Molecular Genetics; University of Groningen; Nijenborgh 7 9747 AG Groningen the Netherlands
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
| | - Jos Boekhorst
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
- NIZO Food Research B.V; Kernhemseweg 2 6718 ZB Ede the Netherlands
| | - Marjon H. J. Wells-Bennik
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
- NIZO Food Research B.V; Kernhemseweg 2 6718 ZB Ede the Netherlands
| | - Oscar P. Kuipers
- Laboratory of Molecular Genetics; University of Groningen; Nijenborgh 7 9747 AG Groningen the Netherlands
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
| | - Robyn T. Eijlander
- Laboratory of Molecular Genetics; University of Groningen; Nijenborgh 7 9747 AG Groningen the Netherlands
- Top Institute Food and Nutrition (TIFN); Nieuwe Kanaal 9A 6709 PA Wageningen the Netherlands
- NIZO Food Research B.V; Kernhemseweg 2 6718 ZB Ede the Netherlands
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24
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Molva C, Baysal AH. The effect of sporulation medium on Alicyclobacillus acidoterrestris guaiacol production in apple juice. Lebensm Wiss Technol 2016. [DOI: 10.1016/j.lwt.2016.01.072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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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] [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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26
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Abstract
Spores of various Bacillus and Clostridium species are among the most resistant life forms known. Since the spores of some species are causative agents of much food spoilage, food poisoning, and human disease, and the spores of Bacillus anthracis are a major bioweapon, there is much interest in the mechanisms of spore resistance and how these spores can be killed. This article will discuss the factors involved in spore resistance to agents such as wet and dry heat, desiccation, UV and γ-radiation, enzymes that hydrolyze bacterial cell walls, and a variety of toxic chemicals, including genotoxic agents, oxidizing agents, aldehydes, acid, and alkali. These resistance factors include the outer layers of the spore, such as the thick proteinaceous coat that detoxifies reactive chemicals; the relatively impermeable inner spore membrane that restricts access of toxic chemicals to the spore core containing the spore's DNA and most enzymes; the low water content and high level of dipicolinic acid in the spore core that protect core macromolecules from the effects of heat and desiccation; the saturation of spore DNA with a novel group of proteins that protect the DNA against heat, genotoxic chemicals, and radiation; and the repair of radiation damage to DNA when spores germinate and return to life. Despite their extreme resistance, spores can be killed, including by damage to DNA, crucial spore proteins, the spore's inner membrane, and one or more components of the spore germination apparatus.
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27
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Bacillus thermoamylovorans Spores with Very-High-Level Heat Resistance Germinate Poorly in Rich Medium despite the Presence of ger Clusters but Efficiently upon Exposure to Calcium-Dipicolinic Acid. Appl Environ Microbiol 2015; 81:7791-801. [PMID: 26341201 DOI: 10.1128/aem.01993-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/26/2015] [Indexed: 11/20/2022] Open
Abstract
High-level heat resistance of spores of Bacillus thermoamylovorans poses challenges to the food industry, as industrial sterilization processes may not inactivate such spores, resulting in food spoilage upon germination and outgrowth. In this study, the germination and heat resistance properties of spores of four food-spoiling isolates were determined. Flow cytometry counts of spores were much higher than their counts on rich medium (maximum, 5%). Microscopic analysis revealed inefficient nutrient-induced germination of spores of all four isolates despite the presence of most known germination-related genes, including two operons encoding nutrient germinant receptors (GRs), in their genomes. In contrast, exposure to nonnutrient germinant calcium-dipicolinic acid (Ca-DPA) resulted in efficient (50 to 98%) spore germination. All four strains harbored cwlJ and gerQ genes, which are known to be essential for Ca-DPA-induced germination in Bacillus subtilis. When determining spore survival upon heating, low viable counts can be due to spore inactivation and an inability to germinate. To dissect these two phenomena, the recoveries of spores upon heat treatment were determined on plates with and without preexposure to Ca-DPA. The high-level heat resistance of spores as observed in this study (D120°C, 1.9 ± 0.2 and 1.3 ± 0.1 min; z value, 12.2 ± 1.8°C) is in line with survival of sterilization processes in the food industry. The recovery of B. thermoamylovorans spores can be improved via nonnutrient germination, thereby avoiding gross underestimation of their levels in food ingredients.
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Kaieda S, Setlow B, Setlow P, Halle B. Mobility of core water in Bacillus subtilis spores by 2H NMR. Biophys J 2014; 105:2016-23. [PMID: 24209846 DOI: 10.1016/j.bpj.2013.09.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/17/2013] [Accepted: 09/19/2013] [Indexed: 11/19/2022] Open
Abstract
Bacterial spores in a metabolically dormant state can survive long periods without nutrients under extreme environmental conditions. The molecular basis of spore dormancy is not well understood, but the distribution and physical state of water within the spore is thought to play an important role. Two scenarios have been proposed for the spore's core region, containing the DNA and most enzymes. In the gel scenario, the core is a structured macromolecular framework permeated by mobile water. In the glass scenario, the entire core, including the water, is an amorphous solid and the quenched molecular diffusion accounts for the spore's dormancy and thermal stability. Here, we use (2)H magnetic relaxation dispersion to selectively monitor water mobility in the core of Bacillus subtilis spores in the presence and absence of core Mn(2+) ions. We also report and analyze the solid-state (2)H NMR spectrum from these spores. Our NMR data clearly support the gel scenario with highly mobile core water (~25 ps average rotational correlation time). Furthermore, we find that the large depot of manganese in the core is nearly anhydrous, with merely 1.7% on average of the maximum sixfold water coordination.
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Affiliation(s)
- Shuji Kaieda
- Department of Biophysical Chemistry, Lund University, Lund, Sweden
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29
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Two distinct groups within the Bacillus subtilis group display significantly different spore heat resistance properties. Food Microbiol 2014; 45:18-25. [PMID: 25481058 DOI: 10.1016/j.fm.2014.04.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 04/04/2014] [Accepted: 04/21/2014] [Indexed: 11/21/2022]
Abstract
The survival of bacterial spores after heat treatment and the subsequent germination and outgrowth in a food product can lead to spoilage of the food product and economical losses. Prediction of time-temperature conditions that lead to sufficient inactivation requires access to detailed spore thermal inactivation kinetics of relevant model strains. In this study, the thermal inactivation kinetics of spores of fourteen strains belonging to the Bacillus subtilis group were determined in detail, using both batch heating in capillary tubes and continuous flow heating in a micro heater. The inactivation data were fitted using a log linear model. Based on the spore heat resistance data, two distinct groups (p < 0.001) within the B. subtilis group could be identified. One group of strains had spores with an average D120 °C of 0.33 s, while the spores of the other group displayed significantly higher heat resistances, with an average D120 °C of 45.7 s. When comparing spore inactivation data obtained using batch- and continuous flow heating, the z-values were significantly different, hence extrapolation from one system to the other was not justified. This study clearly shows that heat resistances of spores from different strains in the B. subtilis group can vary greatly. Strains can be separated into two groups, to which different spore heat inactivation kinetics apply.
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van Melis CCJ, den Besten HMW, Nierop Groot MN, Abee T. Quantification of the impact of single and multiple mild stresses on outgrowth heterogeneity of Bacillus cereus spores. Int J Food Microbiol 2014; 177:57-62. [PMID: 24607860 DOI: 10.1016/j.ijfoodmicro.2014.02.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/13/2014] [Accepted: 02/17/2014] [Indexed: 11/19/2022]
Abstract
Outgrowth heterogeneity of bacterial spore populations complicates both prediction and efficient control of spore outgrowth. In this study, the impact of mild preservation stresses on outgrowth of Bacillus cereus ATCC 14579 spores was quantified during the first stages of outgrowth. Heterogeneity in outgrowth of heat-treated (90°C for 10 min) and non-heat-treated germinated single spores to the maximum micro-colony stage of 256 cells was assessed by direct imaging on Anopore strips, placed on BHI plates at pH7 and pH5.5, without and with added NaCl or sorbic acid (HSA). At pH7 non-heated and heat-treated germinated spores required 6h to reach the maximum microcolony stage with limited heterogeneity, and these parameters were only slightly affected with both types of spores when incubated at pH7 with added NaCl. Notably, the most pronounced effects were observed during outgrowth of spores at pH5.5 without and with added NaCl or HSA. Non-heat-treated germinated spores showed again efficient outgrowth with limited heterogeneity reaching the maximum microcolony stage after 6h at pH5.5, which increased to 12h and 16 h with added NaCl and HSA, respectively. In contrast, heat-treated spores displayed a strong delay between initial germination and swelling and further outgrowth at pH5.5, resulting in large heterogeneity and low numbers of fastest growers reaching the maximum microcolony stage after 10, 12 and 24h, without and with added NaCl or HSA, respectively. This work shows that Anopore technology provides quantitative information on the impact of combined preservation stresses on outgrowth of single spores, showing that outgrowth of germinated heat-treated spores is significantly affected at pH5.5 with a large fraction of spores arrested in the early outgrowth stage, and with outgrowing cells showing large heterogeneity with only a small fraction committed to relatively fast outgrowth.
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Affiliation(s)
- C C J van Melis
- Top Institute Food and Nutrition, Nieuwe Kanaal 9A, 6709 PA, Wageningen, The Netherlands; Food Microbiology Laboratory, Wageningen University, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - H M W den Besten
- Food Microbiology Laboratory, Wageningen University, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - M N Nierop Groot
- Top Institute Food and Nutrition, Nieuwe Kanaal 9A, 6709 PA, Wageningen, The Netherlands; Food and Biobased Research, Wageningen University & Research Centre, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - T Abee
- Top Institute Food and Nutrition, Nieuwe Kanaal 9A, 6709 PA, Wageningen, The Netherlands; Food Microbiology Laboratory, Wageningen University, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands.
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Eijlander RT, de Jong A, Krawczyk AO, Holsappel S, Kuipers OP. SporeWeb: an interactive journey through the complete sporulation cycle of Bacillus subtilis. Nucleic Acids Res 2013; 42:D685-91. [PMID: 24170806 PMCID: PMC3964945 DOI: 10.1093/nar/gkt1007] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Bacterial spores are a continuous problem for both food-based and health-related industries. Decades of scientific research dedicated towards understanding molecular and gene regulatory aspects of sporulation, spore germination and spore properties have resulted in a wealth of data and information. To facilitate obtaining a complete overview as well as new insights concerning this complex and tightly regulated process, we have developed a database-driven knowledge platform called SporeWeb (http://sporeweb.molgenrug.nl) that focuses on gene regulatory networks during sporulation in the Gram-positive bacterium Bacillus subtilis. Dynamic features allow the user to navigate through all stages of sporulation with review-like descriptions, schematic overviews on transcriptional regulation and detailed information on all regulators and the genes under their control. The Web site supports data acquisition on sporulation genes and their expression, regulon network interactions and direct links to other knowledge platforms or relevant literature. The information found on SporeWeb (including figures and tables) can and will be updated as new information becomes available in the literature. In this way, SporeWeb offers a novel, convenient and timely reference, an information source and a data acquisition tool that will aid in the general understanding of the dynamics of the complete sporulation cycle.
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Affiliation(s)
- Robyn T Eijlander
- Top Institute Food and Nutrition (TIFN), Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands and Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AG Groningen, The Netherlands
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Setlow P. Summer meeting 2013 - when the sleepers wake: the germination of spores of Bacillus
species. J Appl Microbiol 2013; 115:1251-68. [DOI: 10.1111/jam.12343] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/08/2013] [Accepted: 09/09/2013] [Indexed: 11/27/2022]
Affiliation(s)
- P. Setlow
- Department of Molecular, Microbial and Structural Biology; University of Connecticut Health Center; Farmington CT USA
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Live-cell imaging tool optimization to study gene expression levels and dynamics in single cells of Bacillus cereus. Appl Environ Microbiol 2013; 79:5643-51. [PMID: 23851094 DOI: 10.1128/aem.01347-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Single-cell methods are a powerful application in microbial research to study the molecular mechanism underlying phenotypic heterogeneity and cell-to-cell variability. Here, we describe the optimization and application of single-cell time-lapse fluorescence microscopy for the food spoilage bacterium Bacillus cereus specifically. This technique is useful to study cellular development and adaptation, gene expression, protein localization, protein mobility, and cell-to-cell communication over time at the single-cell level. By adjusting existing protocols, we have enabled the visualization of growth and development of single B. cereus cells within a microcolony over time. Additionally, several different fluorescent reporter proteins were tested in order to select the most suitable green fluorescent protein (GFP) and red fluorescent protein (RFP) candidates for visualization of growth stage- and cell compartment-specific gene expression in B. cereus. With a case study concerning cotD expression during sporulation, we demonstrate the applicability of time-lapse fluorescence microscopy. It enables the assessment of gene expression levels, dynamics, and heterogeneity at the single-cell level. We show that cotD is not heterogeneously expressed among cells of a subpopulation. Furthermore, we discourage using plasmid-based reporter fusions for such studies, due to an introduced heterogeneity through copy number differences. This stresses the importance of using single-copy integrated reporter fusions for single-cell studies.
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Pandey R, Ter Beek A, Vischer NOE, Smelt JPPM, Brul S, Manders EMM. Live cell imaging of germination and outgrowth of individual bacillus subtilis spores; the effect of heat stress quantitatively analyzed with SporeTracker. PLoS One 2013; 8:e58972. [PMID: 23536843 PMCID: PMC3607599 DOI: 10.1371/journal.pone.0058972] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/08/2013] [Indexed: 11/25/2022] Open
Abstract
Spore-forming bacteria are a special problem for the food industry as some of them are able to survive preservation processes. Bacillus spp. spores can remain in a dormant, stress resistant state for a long period of time. Vegetative cells are formed by germination of spores followed by a more extended outgrowth phase. Spore germination and outgrowth progression are often very heterogeneous and therefore, predictions of microbial stability of food products are exceedingly difficult. Mechanistic details of the cause of this heterogeneity are necessary. In order to examine spore heterogeneity we made a novel closed air-containing chamber for live imaging. This chamber was used to analyze Bacillus subtilis spore germination, outgrowth, as well as subsequent vegetative growth. Typically, we examined around 90 starting spores/cells for ≥4 hours per experiment. Image analysis with the purposely built program “SporeTracker” allows for automated data processing from germination to outgrowth and vegetative doubling. In order to check the efficiency of the chamber, growth and division of B. subtilis vegetative cells were monitored. The observed generation times of vegetative cells were comparable to those obtained in well-aerated shake flask cultures. The influence of a heat stress of 85°C for 10 min on germination, outgrowth, and subsequent vegetative growth was investigated in detail. Compared to control samples fewer spores germinated (41.1% less) and fewer grew out (48.4% less) after the treatment. The heat treatment had a significant influence on the average time to the start of germination (increased) and the distribution and average of the duration of germination itself (increased). However, the distribution and the mean outgrowth time and the generation time of vegetative cells, emerging from untreated and thermally injured spores, were similar.
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Affiliation(s)
- Rachna Pandey
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Alex Ter Beek
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
| | - Norbert O. E. Vischer
- Van Leeuwenhoek Centre for Advanced Microscopy Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Jan P. P. M. Smelt
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Stanley Brul
- Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Erik M. M. Manders
- Van Leeuwenhoek Centre for Advanced Microscopy Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, University of Ghent, Ghent, Belgium
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Activation of Bacillus spores at moderately elevated temperatures (30–33 °C). Antonie van Leeuwenhoek 2012; 103:693-700. [DOI: 10.1007/s10482-012-9839-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2012] [Accepted: 10/20/2012] [Indexed: 10/27/2022]
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Sella SRBR, Guizelini BP, Gouvea PM, Figueiredo LFM, Ribeiro CAO, Vandenberghe LPS, Minozzo JC, Soccol CR. Relations between phenotypic changes of spores and biofilm production by Bacillus atrophaeus ATCC 9372 growing in solid-state fermentation. Arch Microbiol 2012; 194:815-25. [DOI: 10.1007/s00203-012-0815-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 03/11/2012] [Accepted: 04/06/2012] [Indexed: 11/30/2022]
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Løvdal IS, Hovda MB, Granum PE, Rosnes JT. Promoting Bacillus cereus spore germination for subsequent inactivation by mild heat treatment. J Food Prot 2011; 74:2079-89. [PMID: 22186048 DOI: 10.4315/0362-028x.jfp-11-292] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Sublethal heat treatment may activate dormant spores and thereby potentiate the conversion of spores to vegetative cells. As the germinated spore is known to possess lower heat resistance than its dormant counterpart, it has been postulated that double heat treatment, i.e., spore heat activation followed by germination and then by heat inactivation, can be used to control spores in foods. Production of refrigerated processed foods of extended durability often includes more than one heat treatment of the food components. This work simulates conventional heat treatment procedures and evaluates double heat treatment as a method to improve spore control in model food matrixes of meat broth and cream sauce. Bacillus cereus NVH 1230-88 spores were supplemented in food model matrixes and heat activated at 70°C and then heat inactivated at 80 or 90°C. The samples were held at 29 to 30°C for 1 h between primary and secondary heat treatments, to allow spore germination. Nutrients naturally present in the food matrixes, e.g., amino acids and inosine, could act as germinants that induce germination. The levels of germinants could be too low to produce effective germination within 1 h. Following primary heat treatment, some samples were therefore supplemented with a combination of L-alanine and inosine, a germinant mixture known to be effective for B. cereus spores. In both matrixes, a combination of double heat treatment (heat activation, germination, and inactivation) and addition of germinants gave a reduction in spore counts equivalent to or greater than that obtained with a single heat treatment for 12 min at 90°C. Addition of germinants was essential to induce effective germination in cream sauce during 1 h at 29 to 30°C, and germinants were therefore a crucial supplement to obtain an effect of double heat treatment in this matrix. These data will be valuable when setting up temperature-time-germinant combinations for an optimized spore reduction in mild-heat-treated foods.
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Affiliation(s)
- Irene Stranden Løvdal
- Nofima AS, Department of Process Technology, P.O. Box 8034, N-4068 Stavanger, Norway
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