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Freire V, Condón S, Gayán E. Impact of sporulation temperature on germination of Bacillus subtilis spores under optimal and adverse environmental conditions. Food Res Int 2024; 182:114064. [PMID: 38519157 DOI: 10.1016/j.foodres.2024.114064] [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: 10/20/2023] [Revised: 01/13/2024] [Accepted: 01/25/2024] [Indexed: 03/24/2024]
Abstract
Bacillus subtilis spores are important food spoilage agents and are occasionally involved in food poisoning. In foods that are not processed with intense heat, such bacterial spores are controlled by a combination of different hurdles, such as refrigeration, acidification, and low water activity (aw), which inhibit or delay germination and/or growth. Sporulation temperature has long been regarded as a relevant factor for the assessment of germination in chemically defined media, but little is known about its impact on food preservation environments. In this study, we compared germination dynamics of B. subtilis spores produced at optimal temperature (37 °C) with others incubated at suboptimal (20 °C) and supraoptimal (43 °C) temperatures in a variety of nutrients (rich-growth medium, L-alanine, L-valine, and AGFK) under optimal conditions as well as under food-related stresses (low aw, pH, and temperature). Spores produced at 20 °C had a lower germination rate and efficiency than those incubated at 37 °C in all the nutrients, while those sporulated at 43 °C displayed a higher germination rate and/or efficiency in response to rich-growth medium and mostly to L-alanine and AGFK under optimal environmental conditions. However, differences in germination induced by changes in sporulation temperature decreased when spores were activated by heat, mainly due to the greater benefit of heat for spores produced at 20 °C and 37 °C than at 43 °C, especially in AGFK. Non-heat-activated spores produced at 43 °C still displayed superior germination fitness under certain stresses that had considerably impaired the germination of the other two populations, such as reduced temperature and aw. Moreover, they presented lower temperature and pH boundaries for the inhibition of germination in rich-growth medium, while requiring a higher NaCl concentration threshold compared to spores obtained at optimal and suboptimal temperature. Sporulation temperature is therefore a relevant source of variability in spore germination that should be taken into account for the accurate prediction of spore behaviour under variable food preservation conditions with the aim of improving food safety and stability.
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Affiliation(s)
- Víctor Freire
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain
| | - Santiago Condón
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain
| | - Elisa Gayán
- Department of Animal Production and Food Science, AgriFood Institute of Aragon (IA2), University of Zaragoza-CITA, Faculty of Veterinary, Miguel Servet 177, 50013 Zaragoza, Spain.
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2
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Geraldes C, Tavares L, Gil S, Oliveira M. Biocides in the Hospital Environment: Application and Tolerance Development. Microb Drug Resist 2023; 29:456-476. [PMID: 37643289 DOI: 10.1089/mdr.2023.0074] [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] [Indexed: 08/31/2023] Open
Abstract
Hospital-acquired infections are a rising problem with consequences for patients, hospitals, and health care workers. Biocides can be employed to prevent these infections, contributing to eliminate or reduce microorganisms' concentrations at the hospital environment. These antimicrobials belong to several groups, each with distinct characteristics that need to be taken into account in their selection for specific applications. Moreover, their activity is influenced by many factors, such as compound concentration and the presence of organic matter. This article aims to review some of the chemical biocides available for hospital infection control, as well as the main factors that influence their efficacy and promote susceptibility decreases, with the purpose to contribute for reducing misusage and consequently for preventing the development of resistance to these antimicrobials.
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Affiliation(s)
- Catarina Geraldes
- Department of Animal Health, Centre for Interdisciplinary Research in Animal Health (CIISA), Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
- Associate Laboratory for Animal and Veterinary Science (AL4AnimalS), Lisbon, Portugal
| | - Luís Tavares
- Department of Animal Health, Centre for Interdisciplinary Research in Animal Health (CIISA), Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
- Associate Laboratory for Animal and Veterinary Science (AL4AnimalS), Lisbon, Portugal
| | - Solange Gil
- Department of Animal Health, Centre for Interdisciplinary Research in Animal Health (CIISA), Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
- Associate Laboratory for Animal and Veterinary Science (AL4AnimalS), Lisbon, Portugal
- Department of Animal Health, Biological Isolation and Containment Unit (BICU), Veterinary Hospital, Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
| | - Manuela Oliveira
- Department of Animal Health, Centre for Interdisciplinary Research in Animal Health (CIISA), Faculty of Veterinary Medicine, University of Lisbon, Lisbon, Portugal
- Associate Laboratory for Animal and Veterinary Science (AL4AnimalS), Lisbon, Portugal
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3
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Setlow P, Christie G. New Thoughts on an Old Topic: Secrets of Bacterial Spore Resistance Slowly Being Revealed. Microbiol Mol Biol Rev 2023; 87:e0008022. [PMID: 36927044 PMCID: PMC10304885 DOI: 10.1128/mmbr.00080-22] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
The quest for bacterial survival is exemplified by spores formed by some Firmicutes members. They turn up everywhere one looks, and their ubiquity reflects adaptations to the stresses bacteria face. Spores are impactful in public health, food safety, and biowarfare. Heat resistance is the hallmark of spores and is countered principally by a mineralized gel-like protoplast, termed the spore core, with reduced water which minimizes macromolecular movement/denaturation/aggregation. Dry heat, however, introduces mutations into spore DNA. Spores have countermeasures to extreme conditions that are multifactorial, but the fact that spore DNA is in a crystalline-like nucleoid in the spore core, likely due to DNA saturation with small acid-soluble spore proteins (SASPs), suggests that reduced macromolecular motion is also critical in spore dry heat resistance. SASPs are also central in the radiation resistance characteristic of spores, where the contributions of four spore features-SASP; Ca2+, with pyridine-2,6-dicarboxylic acid (CaDPA); photoproduct lyase; and low water content-minimize DNA damage. Notably, the spore environment steers UV photochemistry toward a product that germinated spores can repair without significant mutagenesis. This resistance extends to chemicals and macromolecules that could damage spores. Macromolecules are excluded by the spore coat which impedes the passage of moieties of ≥10 kDa. Additionally, damaging chemicals may be degraded or neutralized by coat enzymes/proteins. However, the principal protective mechanism here is the inner membrane, a compressed structure lacking lipid fluidity and presenting a barrier to the diffusion of chemicals into the spore core; SASP saturation of DNA also protects against genotoxic chemicals. Spores are also resistant to other stresses, including high pressure and abrasion. Regardless, overarching mechanisms associated with resistance seem to revolve around reduced molecular motion, a fine balance between rigidity and flexibility, and perhaps efficient repair.
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Affiliation(s)
- Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
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Deng S. The origin of genetic and metabolic systems: Evolutionary structuralinsights. Heliyon 2023; 9:e14466. [PMID: 36967965 PMCID: PMC10036676 DOI: 10.1016/j.heliyon.2023.e14466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Revised: 02/27/2023] [Accepted: 03/06/2023] [Indexed: 03/16/2023] Open
Abstract
DNA is derived from reverse transcription and its origin is related to reverse transcriptase, DNA polymerase and integrase. The gene structure originated from the evolution of the first RNA polymerase. Thus, an explanation of the origin of the genetic system must also explain the evolution of these enzymes. This paper proposes a polymer structure model, termed the stable complex evolution model, which explains the evolution of enzymes and functional molecules. Enzymes evolved their functions by forming locally tightly packed complexes with specific substrates. A metabolic reaction can therefore be considered to be the result of adaptive evolution in this way when a certain essential molecule is lacking in a cell. The evolution of the primitive genetic and metabolic systems was thus coordinated and synchronized. According to the stable complex model, almost all functional molecules establish binding affinity and specific recognition through complementary interactions, and functional molecules therefore have the nature of being auto-reactive. This is thermodynamically favorable and leads to functional duplication and self-organization. Therefore, it can be speculated that biological systems have a certain tendency to maintain functional stability or are influenced by an inherent selective power. The evolution of dormant bacteria may support this hypothesis, and inherent selectivity can be unified with natural selection at the molecular level.
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Mechanisms and Applications of Bacterial Sporulation and Germination in the Intestine. Int J Mol Sci 2022; 23:ijms23063405. [PMID: 35328823 PMCID: PMC8953710 DOI: 10.3390/ijms23063405] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 02/04/2023] Open
Abstract
Recent studies have suggested a major role for endospore forming bacteria within the gut microbiota, not only as pathogens but also as commensal and beneficial members contributing to gut homeostasis. In this review the sporulation processes, spore properties, and germination processes will be explained within the scope of the human gut. Within the gut, spore-forming bacteria are known to interact with the host’s immune system, both in vegetative cell and spore form. Together with the resistant nature of the spore, these characteristics offer potential for spores’ use as delivery vehicles for therapeutics. In the last part of the review, the therapeutic potential of spores as probiotics, vaccine vehicles, and drug delivery systems will be discussed.
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Stier P, Maul S, Kulozik U. Effect of sporulation conditions following solid-state cultivation on the resistance of Geobacillus stearothermophilus spores for use as bioindicators testing inactivation by H2O2. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.112078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kanaan J, Murray J, Higgins R, Nana M, DeMarco AM, Korza G, Setlow P. Resistance properties and the role of the inner membrane and coat of Bacillus subtilis spores with extreme wet heat resistance. J Appl Microbiol 2021; 132:2157-2166. [PMID: 34724311 DOI: 10.1111/jam.15345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/01/2021] [Accepted: 10/28/2021] [Indexed: 11/27/2022]
Abstract
AIMS A protein termed 2Duf greatly increases wet heat resistance of Bacillus subtilis spores. The current work examines the effects of 2Duf on spore resistance to other sporicides, including chemicals that act on or must cross spores' inner membrane (IM), where 2Duf is likely present. The overall aim was to gain a deeper understanding of how 2Duf affects spore resistance, and of spore resistance itself. METHODS AND RESULTS 2Duf's presence increased spore resistance to chemicals that damage or must cross the IM to kill spores. Spore coat removal decreased 2Duf-spore resistance to chemicals and wet heat, and 2Duf-spores made at higher temperatures were more resistant to wet heat and chemicals. 2Duf-less spores lacking coats and Ca-dipicolinic acid were also extremely sensitive to wet heat and chemicals that transit the IM to kill spores. CONCLUSIONS The new work plus previous results lead to a number of important conclusions as follows. (1) 2Duf may influence spore resistance by decreasing the permeability of and lipid mobility in spores' IM. (2) Since wet heat-killed spores that germinate do not accumulate ATP, wet heat may inactivate some spore IM protein essential in ATP production which is stabilized in a more rigid IM. (3) Both Ca-dipicolinic acid and the spore coat play an important role in the permeability of the spore IM, and thus in many spore resistance properties. SIGNIFICANCE AND IMPACT OF THE STUDY The work in this manuscript gives a new insight into mechanisms of spore resistance to chemicals and wet heat, to the understanding of spore wet heat killing, and the role of Ca-dipicolinic acid and the coat in spore resistance.
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Affiliation(s)
- Julia Kanaan
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Jillian Murray
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Ryan Higgins
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Mishil Nana
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Angela M DeMarco
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - George Korza
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut, USA
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Clostridioides difficile SpoVAD and SpoVAE Interact and Are Required for Dipicolinic Acid Uptake into Spores. J Bacteriol 2021; 203:e0039421. [PMID: 34424035 DOI: 10.1128/jb.00394-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Clostridioides difficile spores, like the spores from most endospore-forming organisms, are a metabolically dormant stage of development with a complex structure that conveys considerable resistance to environmental conditions, e.g., wet heat. This resistance is due to the large amount of dipicolinic acid (DPA) that is taken up by the spore core, preventing rotational motion of the core proteins. DPA is synthesized by the mother cell, and its packaging into the spore core is mediated by the products of the spoVA operon, which has a variable number of genes, depending on the organism. C. difficile encodes 3 spoVA orthologues, spoVAC, spoVAD, and spoVAE. Prior work has shown that C. difficile SpoVAC is a mechanosensing protein responsible for DPA release from the spore core upon the initiation of germination. However, the roles of SpoVAD and SpoVAE remain unclear in C. difficile. In this study, we analyzed the roles of SpoVAD and SpoVAE and found that they are essential for DPA uptake into the spore, similar to SpoVAC. Using split luciferase protein interaction assays, we found that these proteins interact, and we propose a model where SpoVAC/SpoVAD/SpoVAE proteins interact at or near the inner spore membrane, and each member of the complex is essential for DPA uptake into the spore core. IMPORTANCE C. difficile spore heat resistance provides an avenue for it to survive the disinfection protocols in hospital and community settings. The spore heat resistance is mainly the consequence of the high DPA content within the spore core. By elucidating the mechanism by which DPA is taken up by the spore core, this study may provide insight into how to disrupt the spore heat resistance with the aim of making the current disinfection protocols more efficient at preventing the spread of C. difficile in the environment.
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Stier P, Kulozik U. Submerged Bioreactor Production of Geobacillus stearothermophilus ATCC 7953 Spores for Use as Bioindicators to Validate Hydrogen Peroxide Inactivation Processes. Methods Protoc 2021; 4:mps4030063. [PMID: 34564309 PMCID: PMC8482076 DOI: 10.3390/mps4030063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 11/30/2022] Open
Abstract
In the food and pharmaceutical industries, evaluating the sterilization performance preceding aseptic production processes is of central importance. In the case of hydrogen peroxide sterilization of solid surfaces, bioindicators (BI) consisting of spores of Bacillus atrophaeus or Geobacillus stearothermophilus are used to validate the effectiveness and efficiency of the inactivation procedure. Commercial production of G. stearothermophilus is commonly performed on agar plates, where cultivation and sporulation conditions are not well-defined. Therefore, the produced BI can vary in their resistance, which in turn creates unacceptable uncertainties in the evaluation of aseptic processes. Submerged production in the bioreactor would allow more control over sporulation conditions, while reducing production time, resistance variability, and avoidance of false-positive or false-negative test results. In addition, submerged production of G. stearothermophilus so far was a challenge to achieve sufficiently high spore concentrations for BI production. This study reports on the development of a method for submerged production of G. stearothermophilus spores (pH 7.0, 57 °C, 30% pO2) that can achieve 1.6 × 107 spores/mL with a resistance against 35% H2O2 at 25 °C of D25°C,35% H2O2 = 73 s. This resistance ranks within the range of commercially available BI, making the results directly transferable to industrial applications.
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What's new and notable in bacterial spore killing! World J Microbiol Biotechnol 2021; 37:144. [PMID: 34351499 PMCID: PMC8342367 DOI: 10.1007/s11274-021-03108-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/05/2021] [Indexed: 02/08/2023]
Abstract
Spores of many species of the orders Bacillales and Clostridiales can be vectors for food spoilage, human diseases and intoxications, and biological warfare. Many agents are used for spore killing, including moist heat in an autoclave, dry heat at elevated temperatures, UV radiation at 254 and more recently 222 and 400 nm, ionizing radiation of various types, high hydrostatic pressures and a host of chemical decontaminants. An alternative strategy is to trigger spore germination, as germinated spores are much easier to kill than the highly resistant dormant spores—the so called “germinate to eradicate” strategy. Factors important to consider in choosing methods for spore killing include the: (1) cost; (2) killing efficacy and kinetics; (3) ability to decontaminate large areas in buildings or outside; and (4) compatibility of killing regimens with the: (i) presence of people; (ii) food quality; (iii) presence of significant amounts of organic matter; and (iv) minimal damage to equipment in the decontamination zone. This review will summarize research on spore killing and point out some common flaws which can make results from spore killing research questionable.
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Delbrück AI, Zhang Y, Heydenreich R, Mathys A. Bacillus spore germination at moderate high pressure: A review on underlying mechanisms, influencing factors, and its comparison with nutrient germination. Compr Rev Food Sci Food Saf 2021; 20:4159-4181. [PMID: 34147040 DOI: 10.1111/1541-4337.12789] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/14/2021] [Accepted: 05/18/2021] [Indexed: 02/05/2023]
Abstract
Spore-forming bacteria are resistant to stress conditions owing to their ability to form highly resistant dormant spores. These spores can survive adverse environmental conditions in nature, as well as decontamination processes in the food and related industries. Bacterial spores may return to their vegetative state through a process called germination. As spore germination is critical for the loss of resistance, outgrowth, and development of pathogenicity and spoilage potential, the germination pathway has piqued the interest of the scientific community. The inhibition and induction of germination have critical applications in the food industry. Targeted germination can aid in decreasing the resistance of spores and allow the application of milder inactivation procedures. This germination-inactivation strategy allows better maintenance of important food quality attributes. Different stimuli are reported to trigger germination. Among those, isostatic high pressure (HP) has gained increasing attention due to its potential applications in industrial processes. However, pressure-mediated spore germination is extremely heterogeneous as some spores germinate rapidly, while others exhibit slow germination or do not undergo germination at all. The successful and safe implementation of the germination-inactivation strategy, however, depends on the germination of all spores. Therefore, there is a need to elucidate the mechanisms of HP-mediated germination. This work aimed to critically review the current state of knowledge on Bacillus spore germination at a moderate HP of 50-300 MPa. In this review, the germination mechanism, heterogeneity, and influencing factors have been outlined along with knowledge gaps.
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Affiliation(s)
- Alessia I Delbrück
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zürich, Zurich, Switzerland
| | - Yifan Zhang
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zürich, Zurich, Switzerland
| | - Rosa Heydenreich
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zürich, Zurich, Switzerland
| | - Alexander Mathys
- Sustainable Food Processing Laboratory, Institute of Food, Nutrition and Health, Department of Health Science and Technology, ETH Zürich, Zurich, Switzerland
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Toyoncin, a Novel Leaderless Bacteriocin That Is Produced by Bacillus toyonensis XIN-YC13 and Specifically Targets B. cereus and Listeria monocytogenes. Appl Environ Microbiol 2021; 87:e0018521. [PMID: 33811023 PMCID: PMC8174769 DOI: 10.1128/aem.00185-21] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bacteriocins have attracted increasing interest because of their potential as natural preservatives. Recent studies showed that the Bacillus cereus group is a prominent producer of bacteriocins. Using a laboratory-based screening strategy, we identified a strain in the B. cereus group, Bacillus toyonensis XIN-YC13, with antimicrobial activity against B. cereus. A novel, 70-amino-acid-long leaderless bacteriocin, toyoncin, was purified from the culture supernatant of strain XIN-YC13, and its molecular mass was found to be 7,817.1012 Da. Toyoncin shares no similarity with any other known bacteriocins, and its N-terminal amino acid is formylmethionine rather than methionine. Toyoncin shows good pH and heat stability and exhibits specific antimicrobial activity against two important foodborne pathogens, B. cereus and Listeria monocytogenes. Additionally, toyoncin exerts bactericidal activity and induces cell membrane damage. Toyoncin can also inhibit the outgrowth of B. cereus spores. Preservation assays showed that toyoncin effectively suppressed or eradicated B. cereus and L. monocytogenes in pasteurized skim milk. These results suggest that toyoncin can be used as a new biopreservative against B. cereus and L. monocytogenes in the food industry. IMPORTANCE We identified a novel leaderless bacteriocin, toyoncin, produced by B. toyonensis XIN-YC13. Toyoncin shows good pH and heat stability, and it has specific antimicrobial activity against B. cereus and L. monocytogenes (two important foodborne pathogens), likely by destroying their cell membrane integrity. Toyoncin inhibited the outgrowth of B. cereus spores and effectively inhibited or eliminated B. cereus and L. monocytogenes in a milk model system. These results indicate the potential of toyoncin as a food preservative.
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13
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Stier P, Kulozik U. Effect of Sporulation Conditions Following Submerged Cultivation on the Resistance of Bacillus atrophaeus Spores against Inactivation by H 2O 2. Molecules 2020; 25:molecules25132985. [PMID: 32629775 PMCID: PMC7412142 DOI: 10.3390/molecules25132985] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/16/2020] [Accepted: 06/29/2020] [Indexed: 12/02/2022] Open
Abstract
The resistance formation of spores in general and of Bacillus atrophaeus in particular has long been the focus of science in the bio-defense, pharmaceutical and food industries. In the food industry, it is used as a biological indicator (BI) for the evaluation of the inactivation effects of hydrogen peroxide in processing and end packaging lines’ sterilization. Defined BI resistances are critical to avoid false positive and negative tests, which are salient problems due to the variable resistance of currently available commercial BIs. Although spores for use as BIs have been produced for years, little is known about the influence of sporulation conditions on the resistance as a potential source of random variability. This study therefore examines the dependence of spore resistance on the temperature, pH and partial oxygen saturation during submerged production in a bioreactor. For this purpose, spores were produced under different sporulation conditions and their resistance, defined by the D-value, was determined using a count reduction test in tempered 35% liquid hydrogen peroxide. The statistical analysis of the test results shows a quadratic dependence of the resistance on the pH, with the highest D-values at neutral pH. The sporulation temperature has a linear influence on the resistance. The higher the temperature, the higher the D-value. However, these factors interact with each other, which means that the temperature only influences the resistance when the pH is within a certain range. The oxygen partial pressure during sporulation has no significant influence. Based on the data obtained, a model could be developed enabling the resistance of BIs to be calculated, predicted and standardized depending on the sporulation conditions. BI manufacturers could thus produce BIs with defined resistances for the validation of sterilization effects in aseptic packaging/filling lines for the reliable manufacture of shelf-stable and safe food products.
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Mokashi S, Kanaan J, Craft D, Byrd B, Zenick B, Laue M, Korza G, Mok W, Setlow P. Killing of bacterial spores by dodecylamine and its effects on spore inner membrane properties. J Appl Microbiol 2020; 129:1511-1522. [DOI: 10.1111/jam.14732] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/30/2020] [Accepted: 05/26/2020] [Indexed: 11/29/2022]
Affiliation(s)
- S. Mokashi
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - J. Kanaan
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - D.L. Craft
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - B. Byrd
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - B. Zenick
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - M. Laue
- Advanced Light and Electron Microscopy (ZBS 4) Robert Koch Institute Berlin Germany
| | - G. Korza
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - W.W.K. Mok
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
| | - P. Setlow
- Department of Molecular Biology and Biophysics UConn Health Farmington CT USA
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15
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The molecular dynamics of bacterial spore and the role of calcium dipicolinate in core properties at the sub-nanosecond time-scale. Sci Rep 2020; 10:8265. [PMID: 32427943 PMCID: PMC7237433 DOI: 10.1038/s41598-020-65093-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 04/21/2020] [Indexed: 11/18/2022] Open
Abstract
Bacterial spores are among the most resistant forms of life on Earth. Their exceptional resistance properties rely on various strategies, among them the core singular structure, organization and hydration. By using elastic incoherent neutron scattering, we probed the dynamics of Bacillus subtilis spores to determine whether core macromolecular motions at the sub-nanosecond timescale could also contribute to their resistance to physical stresses. In addition, in order to better specify the role of the various spore components, we used different mutants lacking essential structure such as the coat (PS4150 mutant), or the calcium dipicolinic acid complex (CaDPA) located in the core (FB122 mutant). PS4150 allows to better probe the core’s dynamics, as proteins of the coat represent an important part of spore proteins, and FB122 gives information about the role of the large CaDPA depot for the mobility of core’s components. We show that core’s macromolecular mobility is not particularly constrained at the sub-nanosecond timescale in spite of its low water content as some dynamical characteristics as force constants are very close to those of vegetative bacteria such as Escherichia coli or to those of fully hydrated proteins. Although the force constants of the coatless mutant are similar to the wild-type’s ones, it has lower mean square displacements (MSDs) at high Q showing that core macromolecules are somewhat more constrained than the rest of spore components. However, no behavior reflecting the glassy state regularly evoked in the literature could be drawn from our data. As hydration and macromolecules’ mobility are highly correlated, the previous assumption, that core low water content might explain spores’ exceptional resistance properties seems unlikely. Thus, we confirm recent theories, suggesting that core water is mostly as free as bulk water and proteins/macromolecules are fully hydrated. The germination of spores leads to a much less stable system with a force constant of 0.1 N/m and MSDs ~2.5 times higher at low Q than in the dormant state. DPA has also an influence on core mobility with a slightly lower force constant for the DPA-less mutant than for the wild-type, and MSDs that are ~ 1.8 times higher on average than for the wild-type at low Q. At high Q, germinated and DPA-less spores were very similar to the wild-type ones, showing that DPA and core compact structure might influence large amplitude motions rather than local dynamics of macromolecules.
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16
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Reineke K, Mathys A. Endospore Inactivation by Emerging Technologies: A Review of Target Structures and Inactivation Mechanisms. Annu Rev Food Sci Technol 2020; 11:255-274. [DOI: 10.1146/annurev-food-032519-051632] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent developments in preservation technologies allow for the delivery of food with nutritional value and superior taste. Of special interest are low-acid, shelf-stable foods in which the complete control or inactivation of bacterial endospores is the crucial step to ensure consumer safety. Relevant preservation methods can be classified into physicochemical or physical hurdles, and the latter can be subclassified into thermal and nonthermal processes. The underlying inactivation mechanisms for each of these physicochemical or physical processes impact different morphological or molecular structures essential for spore germination and integrity in the dormant state. This review provides an overview of distinct endospore defense mechanisms that affect emerging physical hurdles as well as which technologies address these mechanisms. The physical spore-inactivation technologies considered include thermal, dynamic, and isostatic high pressure and electromagnetic technologies, such as pulsed electric fields, UV light, cold atmospheric pressure plasma, and high- or low-energy electron beam.
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Affiliation(s)
| | - Alexander Mathys
- Sustainable Food Processing Laboratory, Department of Health Science and Technology, ETH Zurich, CH-8092 Zurich, Switzerland
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17
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Fan L, Ismail BB, Hou F, Muhammad AI, Zou M, Ding T, Liu D. Thermosonication damages the inner membrane of Bacillus subtilis spores and impels their inactivation. Food Res Int 2019; 125:108514. [DOI: 10.1016/j.foodres.2019.108514] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 05/25/2019] [Accepted: 06/21/2019] [Indexed: 02/02/2023]
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18
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Gradini R, Chen F, Tan R, Newlin L. A summary on cutting edge advancements in sterilization and cleaning technologies in medical, food, and drug industries, and its applicability to spacecraft hardware. LIFE SCIENCES IN SPACE RESEARCH 2019; 23:31-49. [PMID: 31791604 DOI: 10.1016/j.lssr.2019.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 05/03/2019] [Accepted: 05/14/2019] [Indexed: 05/08/2023]
Abstract
Issued primarily by COSPAR (the Committee On SPAce Research), international Planetary Protection Policies mandate that all spacecraft hardware in contact with extraterrestrial environments "of chemical evolution and/or origin of life interest and for which scientific opinion provides a significant chance of contamination which could compromise future investigations" (Kminek and Rummel, 2015) undergo biological burden control processes. These policies seek to limit the (forward) biological contamination of the target body by terrestrial microorganisms on the spacecraft, so that future missions to the target body will provide accurate and reliable scientific results. Also, these policies seek to prevent the (backward) biological contamination of the Earth by a sample returned from the target body. Bioburden reduction is an integral part of current space missions and its importance will magnify as bioburden requirements become more stringent in the future. Since life-detection and sample-return procedures require sterile handling in situ (to protect scientific results), subsystems and instruments which will be in contact with extraterrestrial matter must be sterilized to prevent a false positive. Since the first Viking mission, heat microbial reduction (HMR) has served as a well-understood common practice for reducing bioburden. More recently, NASA and ESA have approved a standard protocol for vapor hydrogen peroxide (VHP) microbial reduction to address some of the drawbacks of HMR by lowering operating costs and decreasing schedule impacts, as detailed in the certification processes conducted by NASA's Jet Propulsion Laboratory and Steris. Steris has also conducted many testing campaigns on behalf of JPL over the past 20 years. The main results of their campaigns are hence reported. However, even VHP has certain limitations that do not make it an all-encompassing microbial reduction/sterilization modality for spacecraft hardware. Therefore, this review also investigates the state-of-the-art sterilization and cleaning techniques used in other fields, such as in the medical, food, and drug industries, for application to flight hardware. Major techniques covered include cold atmospheric plasma, electron beam irradiation, and gamma irradiation. Some techniques have proven to be good candidates for adaptation for future NASA spacecraft missions. Techniques such as gamma irradiation (γ rad), can broaden the scope of NASA-approved protocols and expand the currently limited toolkit. Cleaning, the removal of bioburden, is also an important aspect of bioburden reduction; despite the best microbial reduction/sterilization technologies, dead microbes can interfere with and potentially invalidate the results of biosignature models of relevant celestial bodies. Therefore, cleaning techniques, such as carbon dioxide snow, can significantly contribute to the bioburden reduction process. With the development of standardized protocols for these additional microbial reduction/sterilization and cleaning modalities - in combination with the well-known techniques with NASA and ESA approved protocols - we anticipate that future space missions may be able to achieve a higher biological standard.
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Affiliation(s)
- Raffaele Gradini
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
| | - Fei Chen
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
| | - Richmund Tan
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States
| | - Laura Newlin
- Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109, United States.
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19
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Kumar M, Flint SH, Palmer J, Plieger PG, Waterland M. The effect of phosphate on the heat resistance of spores of dairy isolates of Geobacillus stearothermophilus. Int J Food Microbiol 2019; 309:108334. [PMID: 31520893 DOI: 10.1016/j.ijfoodmicro.2019.108334] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 08/15/2019] [Accepted: 09/01/2019] [Indexed: 10/26/2022]
Abstract
In this study, we show that phosphate decreases the spore heat resistance by accelerating the rate of loss of cations from spores. Heat resistance of spores of Geobacillus stearothermophilus A1, D1, P3 and ATCC 12980 were determined in distilled water containing varying concentrations (0.1, 1 and 2% w/v) of di‑sodium phosphate. The average decimal reduction times (D value) for strains A1, D1, P3 and ATCC 12980 in distilled water were 5.8, 6.8, 5.7 and 9 min at 110 °C respectively. On the addition of 0.1, 1 and 2% w/v of di‑sodium phosphate, the average D110 values of all the strains in distilled water were lowered by 50, 61 and 70% respectively. Addition of 0.05% w/v of Na-EDTA to distilled water resulted in lowering of the average D110 value of all the strains by 55%. Heat resistance of spores of A1, D1, P3 and ATCC 12980 was found to be associated with the Dipicolinic Acid (DPA) content whose concentrations were 0.25, 0.30, 0.27 and 1.6 pg per spore respectively. Analysis by atomic absorption spectroscopy revealed that the phosphate present in the heating medium causes excess release of calcium from spores with 2% w/v phosphate being highly effective, thus confirming the chelating effect of phosphate. This study provides insight into the heat resistance and the increased heat sensitivity of spores of G. stearothermophilus A1, D1 and P3 in the presence of phosphate, which can be used in the design of Cleaning in Place (CIP) systems involving phosphate based cleaning agents to combat biofilms and spores in the dairy industry.
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Affiliation(s)
- M Kumar
- Massey Institute of Food Science and Technology, Massey University, Palmerston North 4442, New Zealand
| | - S H Flint
- Massey Institute of Food Science and Technology, Massey University, Palmerston North 4442, New Zealand.
| | - J Palmer
- Massey Institute of Food Science and Technology, Massey University, Palmerston North 4442, New Zealand
| | - P G Plieger
- School of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - M Waterland
- School of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
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20
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Wahia H, Zhou C, Sarpong F, Mustapha AT, Liu S, Yu X, Li C. Simultaneous optimization of
Alicyclobacillus acidoterrestris
reduction, pectin methylesterase inactivation, and bioactive compounds enhancement affected by thermosonication in orange juice. J FOOD PROCESS PRES 2019. [DOI: 10.1111/jfpp.14180] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hafida Wahia
- School of Food and Biological Engineering Jiangsu University Zhenjiang People's Republic of China
| | - Cunshan Zhou
- School of Food and Biological Engineering Jiangsu University Zhenjiang People's Republic of China
- School of Biological and Food Engineering Chuzhou University Chuzhou People's Republic of China
- Co‐Innovation Center of Jiangsu Marine Bio‐industry Technology Huaihai Institute of Technology Lianyungang People's Republic of China
| | - Frederick Sarpong
- School of Food and Biological Engineering Jiangsu University Zhenjiang People's Republic of China
| | | | - Shulan Liu
- School of Biological and Food Engineering Chuzhou University Chuzhou People's Republic of China
| | - Xiaojie Yu
- School of Food and Biological Engineering Jiangsu University Zhenjiang People's Republic of China
| | - Chen Li
- Co‐Innovation Center of Jiangsu Marine Bio‐industry Technology Huaihai Institute of Technology Lianyungang People's Republic of China
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21
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McEvoy B, Rowan NJ. Terminal sterilization of medical devices using vaporized hydrogen peroxide: a review of current methods and emerging opportunities. J Appl Microbiol 2019; 127:1403-1420. [PMID: 31410952 DOI: 10.1111/jam.14412] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 07/03/2019] [Accepted: 07/25/2019] [Indexed: 01/08/2023]
Abstract
Medical devices are an important and growing aspect of healthcare provision and are increasing in complexity to meet established and emerging patient needs. Terminal sterilization plays a vital role in the provision of safe medical devices. While terminal sterilization technologies for medical devices include multiple radiation options, ethylene oxide remains the predominant nonthermal gaseous option, sterilizing c. 50% of all manufactured devices. Vaporized hydrogen peroxide (abbreviated VH2O2 by the International Organization for Standardization) is currently deployed for clinical sterilization applications, where its performance characteristics appear aligned to requirements, constituting a viable alternative low-temperature process for terminal processing of medical devices. However, VH2O2 has operational limitations that create technical challenges for industrial-scale adoption. This timely review provides a succinct overview of VH2O2 in gaseous sterilization and addresses its applicability for terminal sterilization of medical devices. It also describes underappreciated factors such as the occurrence of nonlinear microbial inactivation kinetic plots that may dictate a need to develop a new standard approach to validate VH2O2 for terminal sterilization of medical devices.
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Affiliation(s)
- B McEvoy
- STERIS Applied Sterilization Technologies, IDA Business and Technology Park, Tullamore, Ireland
| | - N J Rowan
- Bioscience Research Institute, Athlone Institute of Technology, Athlone, Ireland
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22
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Setlow P. Observations on research with spores of Bacillales and Clostridiales species. J Appl Microbiol 2019; 126:348-358. [PMID: 30106202 PMCID: PMC6329651 DOI: 10.1111/jam.14067] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 08/03/2018] [Accepted: 08/07/2018] [Indexed: 01/06/2023]
Abstract
The purpose of this article is to highlight some areas of research with spores of bacteria of Firmicute species in which the methodology too commonly used is not optimal and generates misleading results. As a consequence, conclusions drawn from data obtained are often flawed or not appropriate. Topics covered in the article include the following: (i) the importance of using well-purified bacterial spores in studies on spore resistance, composition, killing, disinfection and germination; (ii) methods for obtaining good purification of spores of various species; (iii) appropriate experimental approaches to determine mechanisms of spore resistance and spore killing by a variety of agents, as well as known mechanisms of spore resistance and killing; (iv) common errors made in drawing conclusions about spore killing by various agents, including failure to neutralize chemical agents before plating for viable spore enumeration, and equating correlations between changes in spore properties accompanying spore killing with causation. It is hoped that a consideration of these topics will improve the quality of spore research going forward.
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Affiliation(s)
- Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT 06030-3305 USA
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23
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Dong W, Setlow P. Fluoride movement into and out of Bacillus spores and growing cells and effects of fluoride accumulation on spore properties. J Appl Microbiol 2018; 126:503-515. [PMID: 30430725 DOI: 10.1111/jam.14155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 11/04/2018] [Accepted: 11/05/2018] [Indexed: 12/25/2022]
Abstract
AIMS To investigate effects of fluoride ion (F- ) on, and kinetics of its movement into and out of, spores and growing cells of Bacillus species. METHODS AND RESULTS Effects of F- on Bacillus cell growth, spore germination and outgrowth and heat resistance were investigated, as well as F- movement into and out of spores using 19 F-NMR. F- inhibited Bacillus subtilis spore germination and outgrowth, and YhdU, now named FluC, was crucial to prevent F- accumulation in growing cells and to minimize F- inhibition of spore germination. Dormant wild-type, yhdU and coat defective B. subtilis spores, and Bacillus cereus spores incubated in 40 mmol l-1 NaF for 48 h accumulated 2-2·6 mol l-1 F- and its movement into Bacillus spores was highest at low pH. Bacillus subtilis spores lacking Ca-dipicolinic acid accumulated higher F- levels than wild-type spores. CONCLUSIONS These results are consistent with F- incorporation into the dormant spore core, and as HF and/or NaF, but not CaF2 . YhdU played no significant role in F- uptake or efflux in dormant spores, but assisted in F- export early in spore germination. SIGNIFICANCE AND IMPACT OF STUDY This knowledge provides new insight into effects of F- on Bacillus cells and spores and how this anion moves into, and out of spores.
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Affiliation(s)
- W Dong
- School of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou, China.,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| | - P Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
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24
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Omardien S, Drijfhout JW, Zaat SA, Brul S. Cationic Amphipathic Antimicrobial Peptides Perturb the Inner Membrane of Germinated Spores Thus Inhibiting Their Outgrowth. Front Microbiol 2018; 9:2277. [PMID: 30319583 PMCID: PMC6168669 DOI: 10.3389/fmicb.2018.02277] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/06/2018] [Indexed: 11/13/2022] Open
Abstract
The mode of action of four cationic amphipathic antimicrobial peptides (AMPs) was evaluated against the non-pathogenic, Gram-positive, spore-forming bacterium, Bacillus subtilis. The AMPs were TC19, TC84, BP2, and the lantibiotic Nisin A. TC19 and TC84 were derived from the human thrombocidin-1. Bactericidal peptide 2 (BP2) was derived from the human bactericidal permeability increasing protein (BPI). We employed structured illumination microscopy (SIM), fluorescence microscopy, Alexa 488-labeled TC84, B. subtilis mutants producing proteins fused to the green fluorescent protein (GFP) and single-cell live imaging to determine the effects of the peptides against spores. TC19, TC84, BP2, and Nisin A showed to be bactericidal against germinated spores by perturbing the inner membrane, thus preventing outgrowth to vegetative cells. Single cell live imaging showed that the AMPs do not affect the germination process, but the burst time and subsequent generation time of vegetative cells. Alexa 488-labeled TC84 suggested that the TC84 might be binding to the dormant spore-coat. Therefore, dormant spores were also pre-coated with the AMPs and cultured on AMP-free culture medium during single-cell live imaging. Pre-coating of the spores with TC19, TC84, and BP2 had no effect on the germination process, and variably affected the burst time and generation time. However, the percentage of spores that burst and grew out into vegetative cells was drastically lower when pre-coated with Nisin A, suggesting a novel application potential of this lantibiotic peptide against spores. Our findings contribute to the understanding of AMPs and show the potential of AMPs as eventual therapeutic agents against spore-forming bacteria.
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Affiliation(s)
- Soraya Omardien
- Swammerdam Institute for Life Sciences, Department of Molecular Biology and Microbial Food Safety, University of Amsterdam, Amsterdam, Netherlands
| | | | - Sebastian A Zaat
- Department of Medical Microbiology, Centre for Infection and Immunity Amsterdam (CINIMA), Academic Medical Centre, University of Amsterdam, Amsterdam, Netherlands
| | - Stanley Brul
- Swammerdam Institute for Life Sciences, Department of Molecular Biology and Microbial Food Safety, University of Amsterdam, Amsterdam, Netherlands
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25
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Life from the ashes: survival of dry bacterial spores after very high temperature exposure. Extremophiles 2018; 22:751-759. [PMID: 29869718 DOI: 10.1007/s00792-018-1035-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 05/31/2018] [Indexed: 01/09/2023]
Abstract
We found that spores of Bacillus amyloliquefaciens rank amongst the most resistant to high temperatures with a maximum dry heat tolerance determined at 420 °C. We found that this extreme heat resistance was also maintained after several generations suggesting that the DNA was able to replicate after exposure to these temperatures. Nonetheless, amplifying the bacterial DNA using BOXA1R and (GTG)5 primers was unsuccessful immediately after extreme heating, but was successful after incubation of the heated then cooled spores. Moreover, enzymes such as amylases and proteases were active directly after heating and spore regeneration, indicating that DNA coding for these enzymes were not degraded at these temperatures. Our results suggest that extensive DNA damage may occur in spores of B. amyloliquefaciens directly after an extreme heat shock. However, the successful germination of spores after inoculation and incubation indicates that these spores could have a very effective DNA repair mechanism, most likely protein-based, able to function after exposure to temperatures up to 420 °C. Therefore, we propose that B. amyloliquefaciens is one of the most heat resistant life forms known to science and can be used as a model organism for studying heat resistance and DNA repair. Furthermore, the extremely high temperature resistivity of these spores has exceptional consequences for general methodology, such as the use of dry heat sterilization and, therefore, virtually all studies in the broad area of high temperature biology.
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26
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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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27
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Lopes RP, Mota MJ, Gomes AM, Delgadillo I, Saraiva JA. Application of High Pressure with Homogenization, Temperature, Carbon Dioxide, and Cold Plasma for the Inactivation of Bacterial Spores: A Review. Compr Rev Food Sci Food Saf 2018; 17:532-555. [PMID: 33350128 DOI: 10.1111/1541-4337.12311] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 08/29/2017] [Accepted: 09/01/2017] [Indexed: 12/18/2022]
Abstract
Formation of highly resistant spores is a concern for the safety of low-acid foods as they are a perfect vehicle for food spoilage and/or human infection. For spore inactivation, the strategy usually applied in the food industry is the intensification of traditional preservation methods to sterilization levels, which is often accompanied by decreases of nutritional and sensory properties. In order to overcome these unwanted side effects in food products, novel and emerging sterilization technologies are being developed, such as pressure-assisted thermal sterilization, high-pressure carbon dioxide, high-pressure homogenization, and cold plasma. In this review, the application of these emergent technologies is discussed, in order to understand the effects on bacterial spores and their inactivation and thus ensure food safety of low-acid foods. In general, the application of these novel technologies for inactivating spores is showing promising results. However, it is important to note that each technique has specific features that can be more suitable for a particular type of product. Thus, the most appropriate sterilization method for each product (and target microorganisms) should be assessed and carefully selected.
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Affiliation(s)
- Rita P Lopes
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Maria J Mota
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Ana M Gomes
- Escola Superior de Biotecnologia, Univ. Católica Portuguesa, 4200-072 Porto, Portugal
| | - Ivonne Delgadillo
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
| | - Jorge A Saraiva
- QOPNA, Chemistry Dept., Univ. of Aveiro, Campus Univ. de Santiago, 3810-193 Aveiro, Portugal
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28
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Bak EN, Larsen MG, Moeller R, Nissen SB, Jensen LR, Nørnberg P, Jensen SJK, Finster K. Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria-A Challenge for Life on Mars. Front Microbiol 2017; 8:1709. [PMID: 28955310 PMCID: PMC5601068 DOI: 10.3389/fmicb.2017.01709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 08/23/2017] [Indexed: 11/17/2022] Open
Abstract
The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.
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Affiliation(s)
- Ebbe N Bak
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | | | - Ralf Moeller
- Space Microbiology Research Group, Institute of Aerospace Medicine, German Aerospace Center (DLR)Cologne, Germany
| | - Silas B Nissen
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | - Lasse R Jensen
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | - Per Nørnberg
- Department of Bioscience, Aarhus UniversityAarhus, Denmark
| | | | - Kai Finster
- Department of Bioscience, Aarhus UniversityAarhus, Denmark.,Stellar Astrophysics Center, Department of Physics and Astronomy, Aarhus UniversityAarhus, Denmark
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29
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Sadykov MR, Ahn JS, Widhelm TJ, Eckrich VM, Endres JL, Driks A, Rutkowski GE, Wingerd KL, Bayles KW. Poly(3-hydroxybutyrate) fuels the tricarboxylic acid cycle andde novolipid biosynthesis duringBacillus anthracissporulation. Mol Microbiol 2017; 104:793-803. [DOI: 10.1111/mmi.13665] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Marat R. Sadykov
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Jong-Sam Ahn
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Todd J. Widhelm
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Valerie M. Eckrich
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Jennifer L. Endres
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
| | - Adam Driks
- Department of Microbiology and Immunology; Loyola University Chicago, Stritch School of Medicine; Maywood IL 60153 USA
| | | | | | - Kenneth W. Bayles
- Department of Pathology and Microbiology; University of Nebraska Medical Center; Omaha NE 68198 USA
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Sporicidal activity of ceragenin CSA-13 against Bacillus subtilis. Sci Rep 2017; 7:44452. [PMID: 28294162 PMCID: PMC5353641 DOI: 10.1038/srep44452] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 02/07/2017] [Indexed: 02/07/2023] Open
Abstract
Spore-forming bacteria are a class of microorganisms that possess the ability to survive in extreme environmental conditions. Morphological features of spores assure their resistance to stress factors such as high temperature, radiation, disinfectants, and drying. Consequently, spore elimination in industrial and medical environments is very challenging. Ceragenins are a new class of cationic lipids characterized by a broad spectrum of bactericidal activity resulting from amphipathic nature and membrane-permeabilizing properties. To assess the impact of ceragenin CSA-13 on spores formed by Bacillus subtilis (ATCC 6051), we performed the series of experiments confirming that amphipathic and membrane-permeabilizing properties of CSA-13 are sufficient to disrupt the structure of B. subtilis spores resulting in decreased viability. Raman spectroscopy analysis provided evidence that upon CSA-13 treatment the number of CaDPA-positive spores was clearly diminished. As a consequence, a loss of impermeability of the inner membranes of spores, accompanied by a decrease in spore resistance and killing take place. In addition to their broad antimicrobial spectrum, ceragenins possess great potential for development as new sporicidal agents.
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Sevenich R, Rauh C, Knorr D. A scientific and interdisciplinary approach for high pressure processing as a future toolbox for safe and high quality products: A review. INNOV FOOD SCI EMERG 2016. [DOI: 10.1016/j.ifset.2016.09.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Egan K, Field D, Rea MC, Ross RP, Hill C, Cotter PD. Bacteriocins: Novel Solutions to Age Old Spore-Related Problems? Front Microbiol 2016; 7:461. [PMID: 27092121 PMCID: PMC4824776 DOI: 10.3389/fmicb.2016.00461] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/21/2016] [Indexed: 02/01/2023] Open
Abstract
Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria, which have the ability to kill or inhibit other bacteria. Many bacteriocins are produced by food grade lactic acid bacteria (LAB). Indeed, the prototypic bacteriocin, nisin, is produced by Lactococcus lactis, and is licensed in over 50 countries. With consumers becoming more concerned about the levels of chemical preservatives present in food, bacteriocins offer an alternative, more natural approach, while ensuring both food safety and product shelf life. Bacteriocins also show additive/synergistic effects when used in combination with other treatments, such as heating, high pressure, organic compounds, and as part of food packaging. These features are particularly attractive from the perspective of controlling sporeforming bacteria. Bacterial spores are common contaminants of food products, and their outgrowth may cause food spoilage or food-borne illness. They are of particular concern to the food industry due to their thermal and chemical resistance in their dormant state. However, when spores germinate they lose the majority of their resistance traits, making them susceptible to a variety of food processing treatments. Bacteriocins represent one potential treatment as they may inhibit spores in the post-germination/outgrowth phase of the spore cycle. Spore eradication and control in food is critical, as they are able to spoil and in certain cases compromise the safety of food by producing dangerous toxins. Thus, understanding the mechanisms by which bacteriocins exert their sporostatic/sporicidal activity against bacterial spores will ultimately facilitate their optimal use in food. This review will focus on the use of bacteriocins alone, or in combination with other innovative processing methods to control spores in food, the current knowledge and gaps therein with regard to bacteriocin-spore interactions and discuss future research approaches to enable spores to be more effectively targeted by bacteriocins in food settings.
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Affiliation(s)
- Kevin Egan
- School of Microbiology, University College Cork Cork, Ireland
| | - Des Field
- School of Microbiology, University College Cork Cork, Ireland
| | - Mary C Rea
- Teagasc Food Research Centre, MooreparkFermoy, Ireland; APC Microbiome InstituteUniversity College Cork, Ireland
| | - R Paul Ross
- APC Microbiome InstituteUniversity College Cork, Ireland; College of Science, Engineering and Food Science, University College CorkCork, Ireland
| | - Colin Hill
- School of Microbiology, University College CorkCork, Ireland; APC Microbiome InstituteUniversity College Cork, Ireland
| | - Paul D Cotter
- Teagasc Food Research Centre, MooreparkFermoy, Ireland; APC Microbiome InstituteUniversity College Cork, Ireland
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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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Water and Small-Molecule Permeation of Dormant Bacillus subtilis Spores. J Bacteriol 2015; 198:168-77. [PMID: 26483518 DOI: 10.1128/jb.00435-15] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/05/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED We use a suspended microchannel resonator to characterize the water and small-molecule permeability of Bacillus subtilis spores based on spores' buoyant mass in different solutions. Consistent with previous results, we found that the spore coat is not a significant barrier to small molecules, and the extent to which small molecules may enter the spore is size dependent. We have developed a method to directly observe the exchange kinetics of intraspore water with deuterium oxide, and we applied this method to wild-type spores and a panel of congenic mutants with deficiencies in the assembly or structure of the coat. Compared to wild-type spores, which exchange in approximately 1 s, several coat mutant spores were found to have relatively high water permeability with exchange times below the ∼200-ms temporal resolution of our assay. In addition, we found that the water permeability of the spore correlates with the ability of spores to germinate with dodecylamine and with the ability of TbCl3 to inhibit germination with l-valine. These results suggest that the structure of the coat may be necessary for maintaining low water permeability. IMPORTANCE Spores of Bacillus species cause food spoilage and disease and are extremely resistant to standard decontamination methods. This hardiness is partly due to spores' extremely low permeability to chemicals, including water. We present a method to directly monitor the uptake of molecules into B. subtilis spores by weighing spores in fluid. The results demonstrate the exchange of core water with subsecond resolution and show a correlation between water permeability and the rate at which small molecules can initiate or inhibit germination in coat-damaged spores. The ability to directly measure the uptake of molecules in the context of spores with known structural or genetic deficiencies is expected to provide insight into the determinants of spores' extreme resistance.
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Meaney CA, Cartman ST, McClure PJ, Minton NP. The role of small acid-soluble proteins (SASPs) in protection of spores of Clostridium botulinum against nitrous acid. Int J Food Microbiol 2015; 216:25-30. [PMID: 26386202 DOI: 10.1016/j.ijfoodmicro.2015.08.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 07/16/2015] [Accepted: 08/30/2015] [Indexed: 11/28/2022]
Abstract
Mutant strains of Clostridium botulinum ATCC 3502 were generated using the ClosTron in four genes (CBO1789, CBO1790, CBO3048, CBO3145) identified as encoding α/β-type SASP homologues. The spores of mutant strains in which CBO1789 or CBO1790 was inactivated demonstrated a significant increase in sensitivity to the damaging agent nitrous acid (P<0.01), a phenotype that was partially restored to wild-type in complementation studies. In contrast to nitrous acid, the spores of the CBO1789 and CBO1790 mutants showed no change in their resistance to formaldehyde and hydrogen peroxide (P>0.05), two other chemicals commonly used as components of disinfection regimes. These data indicate that the SASPs CBO1789 or CBO1790 play a significant role in resistance to nitrous acid, but not in resistance to formaldehyde or hydrogen peroxide.
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Affiliation(s)
- Carolyn A Meaney
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | - Stephen T Cartman
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK
| | | | - Nigel P Minton
- School of Life Sciences, Centre for Biomolecular Sciences, University of Nottingham, Nottingham NG7 2RD, UK.
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Doona CJ, Feeherry FE, Kustin K, Olinger GG, Setlow P, Malkin AJ, Leighton T. Fighting Ebola with novel spore decontamination technologies for the military. Front Microbiol 2015; 6:663. [PMID: 26322021 PMCID: PMC4533522 DOI: 10.3389/fmicb.2015.00663] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 06/17/2015] [Indexed: 11/13/2022] Open
Abstract
Recently, global public health organizations such as Doctors without Borders (MSF), the World Health Organization (WHO), Public Health Canada, National Institutes of Health (NIH), and the U.S. government developed and deployed Field Decontamination Kits (FDKs), a novel, lightweight, compact, reusable decontamination technology to sterilize Ebola-contaminated medical devices at remote clinical sites lacking infra-structure in crisis-stricken regions of West Africa (medical waste materials are placed in bags and burned). The basis for effectuating sterilization with FDKs is chlorine dioxide (ClO2) produced from a patented invention developed by researchers at the US Army Natick Soldier RD&E Center (NSRDEC) and commercialized as a dry mixed-chemical for bacterial spore decontamination. In fact, the NSRDEC research scientists developed an ensemble of ClO2 technologies designed for different applications in decontaminating fresh produce; food contact and handling surfaces; personal protective equipment; textiles used in clothing, uniforms, tents, and shelters; graywater recycling; airplanes; surgical instruments; and hard surfaces in latrines, laundries, and deployable medical facilities. These examples demonstrate the far-reaching impact, adaptability, and versatility of these innovative technologies. We present herein the unique attributes of NSRDEC's novel decontamination technologies and a Case Study of the development of FDKs that were deployed in West Africa by international public health organizations to sterilize Ebola-contaminated medical equipment. FDKs use bacterial spores as indicators of sterility. We review the properties and structures of spores and the mechanisms of bacterial spore inactivation by ClO2. We also review mechanisms of bacterial spore inactivation by novel, emerging, and established non-thermal technologies for food preservation, such as high pressure processing, irradiation, cold plasma, and chemical sanitizers, using an array of Bacillus subtilis mutants to probe mechanisms of spore germination and inactivation. We employ techniques of high-resolution atomic force microscopy and phase contrast microscopy to examine the effects of γ-irradiation on bacterial spores of Bacillus anthracis, Bacillus thuringiensis, and Bacillus atrophaeus spp. and of ClO2 on B. subtilis spores, and present in detail assays using spore bio-indicators to ensure sterility when decontaminating with ClO2.
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Affiliation(s)
- Christopher J Doona
- U.S. Army Natick - Soldier RD&E Center, Warfighter Directorate, Natick, MA USA
| | - Florence E Feeherry
- U.S. Army Natick - Soldier RD&E Center, Warfighter Directorate, Natick, MA USA
| | - Kenneth Kustin
- Department of Chemistry, Emeritus, Brandeis University, Waltham, MA USA
| | - Gene G Olinger
- National Institute of Allergy and Infectious Diseases, Integrated Research Facility - Division of Clinical Research, Fort Detrick, MD USA
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT USA
| | - Alexander J Malkin
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA USA
| | - Terrance Leighton
- Children's Hospital - Oakland Research Institute, University of California San Francisco - Benioff, Oakland, CA USA
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Dittmann C, Han HM, Grabenbauer M, Laue M. Dormant Bacillus spores protect their DNA in crystalline nucleoids against environmental stress. J Struct Biol 2015; 191:156-64. [DOI: 10.1016/j.jsb.2015.06.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 06/10/2015] [Accepted: 06/18/2015] [Indexed: 12/23/2022]
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Checinska A, Paszczynski A, Burbank M. Bacillusand Other Spore-Forming Genera: Variations in Responses and Mechanisms for Survival. Annu Rev Food Sci Technol 2015; 6:351-69. [DOI: 10.1146/annurev-food-030713-092332] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Aleksandra Checinska
- School of Food Science, University of Idaho, Moscow, Idaho 83844-1052 and Washington State University, Pullman, Washington 99164-6376; ,
- Present address: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109;
| | - Andrzej Paszczynski
- School of Food Science, University of Idaho, Moscow, Idaho 83844-1052 and Washington State University, Pullman, Washington 99164-6376; ,
| | - Malcolm Burbank
- School of Food Science, University of Idaho, Moscow, Idaho 83844-1052 and Washington State University, Pullman, Washington 99164-6376; ,
- Present address: BioCement Technologies Inc., Seattle, Washington 98101
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Rao L, Bi X, Zhao F, Wu J, Hu X, Liao X. Effect of High-pressure CO2Processing on Bacterial Spores. Crit Rev Food Sci Nutr 2015; 56:1808-25. [DOI: 10.1080/10408398.2013.787385] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Geobacillus stearothermophilus ATCC 7953 spore chemical germination mechanisms in model systems. Food Control 2015. [DOI: 10.1016/j.foodcont.2014.08.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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41
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The effects of heat activation on Bacillus spore germination, with nutrients or under high pressure, with or without various germination proteins. Appl Environ Microbiol 2015; 81:2927-38. [PMID: 25681191 DOI: 10.1128/aem.00193-15] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nutrient germination of spores of Bacillus species occurs through germinant receptors (GRs) in spores' inner membrane (IM) in a process stimulated by sublethal heat activation. Bacillus subtilis spores maximum germination rates via different GRs required different 75 °C heat activation times: 15 min for l-valine germination via the GerA GR and 4 h for germination with the L-asparagine-glucose-fructose-K(+) mixture via the GerB and GerK GRs, with GerK requiring the most heat activation. In some cases, optimal heat activation decreased nutrient concentrations for half-maximal germination rates. Germination of spores via various GRs by high pressure (HP) of 150 MPa exhibited heat activation requirements similar to those of nutrient germination, and the loss of the GerD protein, required for optimal GR function, did not eliminate heat activation requirements for maximal germination rates. These results are consistent with heat activation acting primarily on GRs. However, (i) heat activation had no effects on GR or GerD protein conformation, as probed by biotinylation by an external reagent; (ii) spores prepared at low and high temperatures that affect spores' IM properties exhibited large differences in heat activation requirements for nutrient germination; and (iii) spore germination by 550 MPa of HP was also affected by heat activation, but the effects were relatively GR independent. The last results are consistent with heat activation affecting spores' IM and only indirectly affecting GRs. The 150- and 550-MPa HP germinations of Bacillus amyloliquefaciens spores, a potential surrogate for Clostridium botulinum spores in HP treatments of foods, were also stimulated by heat activation.
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Abstract
Since the first application of high hydrostatic pressure (HHP) for food preservation more than 100 years ago, a wealth of knowledge has been gained on molecular mechanisms underlying the HHP-mediated destruction of microorganisms. However, one observation made back then is still valid, i.e. that HHP alone is not sufficient for the complete inactivation of bacterial endospores. To achieve "commercial sterility" of low-acid foods, i.e. inactivation of spores capable of growing in a specific product under typical storage conditions, a combination of HHP with other hurdles is required (most effectively with heat (HPT)). Although HPT processes are not yet industrially applied, continuous technical progress and increasing consumer demand for minimally processed, additive-free food with long shelf life, makes HPT sterilization a promising alternative to thermal processing.In recent years, considerable progress has been made in understanding the response of spores of the model organism B. subtilis to HPT treatments and detailed insights into some basic mechanisms in Clostridium species shed new light on differences in the HPT-mediated inactivation of Bacillus and Clostridium spores. In this chapter, current knowledge on sporulation and germination processes, which presents the basis for understanding development and loss of the extreme resistance properties of spores, is summarized highlighting commonalities and differences between Bacillus and Clostridium species. In this context, the effect of HPT treatments on spores, inactivation mechanism and kinetics, the role of population heterogeneity, and influence factors on the results of inactivation studies are discussed.
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Affiliation(s)
- Christian A Lenz
- Lehrstuhl für Technische Mikrobiologie, Technische Universität München, 85354, Freising, Germany
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43
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Abbas AA, Planchon S, Jobin M, Schmitt P. Absence of oxygen affects the capacity to sporulate and the spore properties of Bacillus cereus. Food Microbiol 2014; 42:122-31. [DOI: 10.1016/j.fm.2014.03.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 01/28/2014] [Accepted: 03/06/2014] [Indexed: 11/16/2022]
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44
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In situ investigation of Geobacillus stearothermophilus spore germination and inactivation mechanisms under moderate high pressure. Food Microbiol 2014; 41:8-18. [DOI: 10.1016/j.fm.2014.01.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/21/2013] [Accepted: 01/10/2014] [Indexed: 01/18/2023]
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45
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Sella SRBR, Vandenberghe LPS, Soccol CR. Life cycle and spore resistance of spore-forming Bacillus atrophaeus. Microbiol Res 2014; 169:931-9. [PMID: 24880805 DOI: 10.1016/j.micres.2014.05.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Revised: 04/29/2014] [Accepted: 05/04/2014] [Indexed: 12/28/2022]
Abstract
Bacillus endospores have a wide variety of important medical and industrial applications. This is an overview of the fundamental aspects of the life cycle, spore structure and factors that influence the spore resistance of spore-forming Bacillus. Bacillus atrophaeus was used as reference microorganism for this review because their spores are widely used to study spore resistance and morphology. Understanding the mechanisms involved in the cell cycle and spore survival is important for developing strategies for spore killing; producing highly resistant spores for biodefense, food and pharmaceutical applications; and developing new bioactive molecules and methods for spore surface display.
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Affiliation(s)
- Sandra R B R Sella
- Production and Research Centre of Immunobiological Products, Secretaria de Saúde do Estado do Paraná, Piraquara, PR, Brazil; Bioprocess Engineering and Biotechnology Department, Federal University of Paraná, Curitiba, PR, Brazil.
| | - Luciana P S Vandenberghe
- Bioprocess Engineering and Biotechnology Department, Federal University of Paraná, Curitiba, PR, Brazil
| | - Carlos Ricardo Soccol
- Bioprocess Engineering and Biotechnology Department, Federal University of Paraná, Curitiba, PR, Brazil
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46
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Reineke K, Mathys A, Heinz V, Knorr D. Mechanisms of endospore inactivation under high pressure. Trends Microbiol 2013; 21:296-304. [DOI: 10.1016/j.tim.2013.03.001] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/01/2013] [Accepted: 03/05/2013] [Indexed: 01/27/2023]
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Markland SM, Farkas DF, Kniel KE, Hoover DG. Pathogenic psychrotolerant sporeformers: an emerging challenge for low-temperature storage of minimally processed foods. Foodborne Pathog Dis 2013; 10:413-9. [PMID: 23536982 DOI: 10.1089/fpd.2012.1355] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Sporeforming bacteria are a significant problem in the food industry as they are ubiquitous in nature and capable of resisting inactivation by heat and chemical treatments designed to inactivate them. Beyond spoilage issues, psychrotolerant sporeformers are becoming increasingly recognized as a potential hazard given the ever-expanding demand for refrigerated processed foods with extended shelf-life. In these products, the sporeforming pathogens of concern are Bacillus cereus, Bacillus weihenstephanensis, and Clostridium botulinum type E. This review article examines the foods, conditions, and organisms responsible for the food safety issue caused by the germination and outgrowth of psychrotolerant sporeforming pathogens in minimally processed refrigerated foods.
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Affiliation(s)
- Sarah M Markland
- Department of Animal and Food Sciences, University of Delaware, Newark, Delaware 19716, USA
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48
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Olivier S, Bull M, Chapman B. Bacillus spp. spores produced at lower temperatures are more resistant to high pressure thermal processes but mineralization does not predict relative resistance. INNOV FOOD SCI EMERG 2012. [DOI: 10.1016/j.ifset.2012.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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49
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Leggett MJ, McDonnell G, Denyer SP, Setlow P, Maillard JY. Bacterial spore structures and their protective role in biocide resistance. J Appl Microbiol 2012; 113:485-98. [PMID: 22574673 DOI: 10.1111/j.1365-2672.2012.05336.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The structure and chemical composition of bacterial spores differ considerably from those of vegetative cells. These differences largely account for the unique resistance properties of the spore to environmental stresses, including disinfectants and sterilants, resulting in the emergence of spore-forming bacteria such as Clostridium difficile as major hospital pathogens. Although there has been considerable work investigating the mechanisms of action of many sporicidal biocides against Bacillus subtilis spores, there is far less information available for other species and particularly for various Clostridia. This paucity of information represents a major gap in our knowledge given the importance of Clostridia as human pathogens. This review considers the main spore structures, highlighting their relevance to spore resistance properties and detailing their chemical composition, with a particular emphasis on the differences between various spore formers. Such information will be vital for the rational design and development of novel sporicidal chemistries with enhanced activity in the future.
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Affiliation(s)
- M J Leggett
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Cardiff, UK
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50
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Huo Z, Zhang N, Raza W, Huang X, Yong X, Liu Y, Wang D, Li S, Shen Q, Zhang R. Comparison of the spores of Paenibacillus polymyxa prepared at different temperatures. Biotechnol Lett 2012; 34:925-33. [DOI: 10.1007/s10529-012-0853-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Accepted: 01/05/2012] [Indexed: 10/14/2022]
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