1
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Sundaresan A, Cheong I. Elucidating Bacterial Spore Dynamics through Lanthanide-Enhanced Live Imaging. ACS Sens 2024; 9:789-798. [PMID: 38221734 DOI: 10.1021/acssensors.3c02083] [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: 01/16/2024]
Abstract
Identifying and distinguishing dormant and active bacterial spores are vital for biosecurity, food safety, and space exploration. Yet, there is a lack of simple, quick, and nondestructive methods to achieve this. The common Schaeffer-Fulton method is both sample-destructive and requires significant operator involvement. In this study, we employed lanthanide-beta-diketonate complexes to directly observe both dormant and germinated single spores. Staining is instantaneous and requires minimal sample processing. The complex stains areas outside the core of dormant spores, leaving the core hollow and nonfluorescent. However, upon germination, the complex enters the core, making it brightly fluorescent. This difference was noted in five bacterial species including Bacillus, Clostridium, and Clostridioides. Various lanthanides and beta-diketonates can be mixed to form a range of spore-visualizing complexes. Due to their low toxicity, these complexes allow for live imaging of single germinating spores. We demonstrate low-cost imaging using a USB microscope as well as imaging of spores in milk matrices. This method provides a valuable tool for studying bacterial spores.
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Affiliation(s)
- Ajitha Sundaresan
- Temasek Life Sciences Laboratory, National University of Singapore, 117604 Singapore
- Department of Biological Sciences, National University of Singapore, 117558 Singapore
| | - Ian Cheong
- Temasek Life Sciences Laboratory, National University of Singapore, 117604 Singapore
- Department of Biological Sciences, National University of Singapore, 117558 Singapore
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2
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Harrellson SG, DeLay MS, Chen X, Cavusoglu AH, Dworkin J, Stone HA, Sahin O. Hydration solids. Nature 2023; 619:500-505. [PMID: 37286609 PMCID: PMC10530534 DOI: 10.1038/s41586-023-06144-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 04/27/2023] [Indexed: 06/09/2023]
Abstract
Hygroscopic biological matter in plants, fungi and bacteria make up a large fraction of Earth's biomass1. Although metabolically inert, these water-responsive materials exchange water with the environment and actuate movement2-5 and have inspired technological uses6,7. Despite the variety in chemical composition, hygroscopic biological materials across multiple kingdoms of life exhibit similar mechanical behaviours including changes in size and stiffness with relative humidity8-13. Here we report atomic force microscopy measurements on the hygroscopic spores14,15 of a common soil bacterium and develop a theory that captures the observed equilibrium, non-equilibrium and water-responsive mechanical behaviours, finding that these are controlled by the hydration force16-18. Our theory based on the hydration force explains an extreme slowdown of water transport and successfully predicts a strong nonlinear elasticity and a transition in mechanical properties that differs from glassy and poroelastic behaviours. These results indicate that water not only endows biological matter with fluidity but also can-through the hydration force-control macroscopic properties and give rise to a 'hydration solid' with unusual properties. A large fraction of biological matter could belong to this distinct class of solid matter.
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Affiliation(s)
| | - Michael S DeLay
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Xi Chen
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Advanced Science Research Center (ASRC) at the Graduate Center of the City University of New York, New York, NY, USA
| | - Ahmet-Hamdi Cavusoglu
- Department of Chemical Engineering, Columbia University, New York, NY, USA
- Merck Digital Sciences Studio (MDSS), Newark, NJ, USA
| | - Jonathan Dworkin
- Department of Microbiology and Immunology, Columbia University, New York, NY, USA
| | - Howard A Stone
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, USA
| | - Ozgur Sahin
- Department of Physics, Columbia University, New York, NY, USA.
- Department of Biological Sciences, Columbia University, New York, NY, USA.
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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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4
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Guerrero M. GG. Sporulation, Structure Assembly, and Germination in the Soil Bacterium Bacillus thuringiensis: Survival and Success in the Environment and the Insect Host. MICROBIOLOGY RESEARCH 2023. [DOI: 10.3390/microbiolres14020035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023] Open
Abstract
Bacillus thuringiensis (Bt) is a rod-shaped, Gram-positive soil bacterium that belongs to the phylum Firmicutes and the genus Bacillus. It is a spore-forming bacterium. During sporulation, it produces a wide range of crystalline proteins that are toxic to different orders of insects. Sporulation, structure assembly, and germination are essential stages in the cell cycle of B. thuringiensis. The majority of studies on these issues have focused on the model organism Bacillus subtilis, followed by Bacillus cereus and Bacillus anthracis. The machinery for sporulation and germination extrapolated to B. thuringiensis. However, in the light of recent findings concerning the role of the sporulation proteins (SPoVS), the germination receptors (Gr), and the cortical enzymes in Bt, the theory strengthened that conservation in sporulation, structure assembly, and germination programs drive the survival and success of B. thuringiensis in the environment and the insect host. In the present minireview, the latter pinpointed and reviewed.
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Affiliation(s)
- Gloria G. Guerrero M.
- Unidad Académica de Ciencias Biológicas, Laboratorio de Immunobiología, Universidad Autónoma de Zacatecas, Av. Preparatoria S/N, Col. Agronomicas, Zacatecas 98066, Mexico
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5
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Korza G, DePratti S, Fairchild D, Wicander J, Kanaan J, Shames H, Nichols FC, Cowan A, Brul S, Setlow P. Expression of the 2Duf protein in wild-type Bacillus subtilis spores stabilizes inner membrane proteins and increases spore resistance to wet heat and hydrogen peroxide. J Appl Microbiol 2023; 134:lxad040. [PMID: 36841229 PMCID: PMC10035073 DOI: 10.1093/jambio/lxad040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 02/09/2023] [Accepted: 02/24/2023] [Indexed: 02/27/2023]
Abstract
AIMS This work aimed to characterize spore inner membrane (IM) properties and the mechanism of spore killing by wet heat and H2O2 with spores overexpressing the 2Duf protein, which is naturally encoded from a transposon found only in some Bacillus strains with much higher spore resistance than wild-type spores. METHODS AND RESULTS Killing of Bacillus subtilis spores by wet heat or hydrogen peroxide (H2O2) was slower when 2Duf was present, and Ca-dipicolinic acid release was slower than killing. Viabilities on rich plates of wet heat- or H2O2 -treated spores +/- 2Duf were lower when NaCl was added, but higher with glucose. Addition of glucose but not Casamino acids addition increased treated spores' viability on minimal medium plates. Spores with 2Duf required higher heat activation for germination, and their germination was more wet-heat resistant than that of wild-type spores, processes that involve IM proteins. IM permeability and lipid mobility were lower in spores with 2Duf, although IM phospholipid composition was similar in spores +/- 2Duf. CONCLUSIONS These results and previous work suggests that wet heat and H2O2 kill spores by damaging an IM enzyme or enzymes involved in oxidative phosphorylation.
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Affiliation(s)
- George Korza
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Sarah DePratti
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Daniel Fairchild
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - James Wicander
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Julia Kanaan
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Hannah Shames
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Frank C Nichols
- Division of Periodontology, UConn Health, Farmington, CT 06030-3305, USA
| | - Ann Cowan
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
| | - Stanley Brul
- Molecular Biology & Microbial Food Safety, Swammerdam Institute for Life Science, University of Amsterdam, 1098XH Amsterdam, UK
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, Farmington, CT 06030-3305, USA
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6
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Liu ZL, Chen X. Water-Content-Dependent Morphologies and Mechanical Properties of Bacillus subtilis Spores' Cortex Peptidoglycan. ACS Biomater Sci Eng 2022; 8:5094-5100. [PMID: 36442506 DOI: 10.1021/acsbiomaterials.2c01209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Peptidoglycan (PG), bacterial spores' major structural component in their cortex layers, was recently found to regulate the spore's water content and deform in response to relative humidity (RH) changes. Here, we report that the cortex PG dominates the Bacillus subtilis spores' water-content-dependent morphological and mechanical properties. When exposed to an environment having RH varied between 10% and 90%, the spores and their cortex PG reversibly expand and contract by 30.7% and 43.2% in volume, which indicates that the cortex PG contributes to 67.3% of a spore's volume change. The spores' and cortex PG's significant volumetric changes also lead to changes in their Young's moduli from 5.7 and 9.0 GPa at 10% RH to 0.62 and 1.2 GPa at 90% RH, respectively. Interestingly, these significant changes in the spores' and cortex PG's morphological and mechanical properties are only caused by a minute amount of the cortex PG's water exchange that occupies 28.0% of the cortex PG's volume. The cortex PG's capability in sensing and responding to environmental RH and effectively changing its structures and properties could provide insight into spores' high desiccation resistance and dormancy mechanisms.
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Affiliation(s)
- Zhi-Lun Liu
- Advanced Science Research Center (ASRC), The City University of New York, 85 St. Nicholas Terrace, New York, New York10031, United States.,Department of Chemical Engineering, The City College of New York, 275 Convent Ave., New York, New York10031, United States
| | - Xi Chen
- Advanced Science Research Center (ASRC), The City University of New York, 85 St. Nicholas Terrace, New York, New York10031, United States.,Department of Chemical Engineering, The City College of New York, 275 Convent Ave., New York, New York10031, United States.,Ph.D. Program in Physics, The Graduate Center of the City University of New York, 365 Fifth Ave., New York, New York10016, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Ave., New York, New York10016, United States
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7
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Alcolombri U, Pioli R, Stocker R, Berry D. Single-cell stable isotope probing in microbial ecology. ISME COMMUNICATIONS 2022; 2:55. [PMID: 37938753 PMCID: PMC9723680 DOI: 10.1038/s43705-022-00142-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/10/2022] [Accepted: 06/09/2022] [Indexed: 05/30/2023]
Abstract
Environmental and host-associated microbiomes are typically diverse assemblages of organisms performing myriad activities and engaging in a network of interactions that play out in spatially structured contexts. As the sum of these activities and interactions give rise to overall microbiome function, with important consequences for environmental processes and human health, elucidating specific microbial activities within complex communities is a pressing challenge. Single-cell stable isotope probing (SC-SIP) encompasses multiple techniques that typically utilize Raman microspectroscopy or nanoscale secondary ion mass spectrometry (NanoSIMS) to enable spatially resolved tracking of isotope tracers in cells, cellular components, and metabolites. SC-SIP techniques are uniquely suited for illuminating single-cell activities in microbial communities and for testing hypotheses about cellular functions generated for example from meta-omics datasets. Here, we illustrate the insights enabled by SC-SIP techniques by reviewing selected applications in microbiology and offer a perspective on their potential for future research.
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Affiliation(s)
- Uria Alcolombri
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Roberto Pioli
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Roman Stocker
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland.
| | - David Berry
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria.
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8
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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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9
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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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10
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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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11
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Luo Y, Korza G, DeMarco AM, Kuipers OP, Li YQ, Setlow P. Properties of spores of Bacillus subtilis with or without a transposon that decreases spore germination and increases spore wet heat resistance. J Appl Microbiol 2021; 131:2918-2928. [PMID: 34042237 DOI: 10.1111/jam.15163] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/14/2021] [Accepted: 05/03/2021] [Indexed: 01/01/2023]
Abstract
AIMS This work aimed to determine how genes on transposon Tn1546 slow Bacillus subtilis spore germination and increase wet heat resistance, and to clarify the transposon's 3 gene spoVA operon's role in spore properties, since the seven wild-type SpoVA proteins form a channel transporting Ca2+ -dipicolinic acid (DPA) in spore formation and germination. METHODS AND RESULTS Deletion of the wild-type spoVA operon from a strain with Tn1546 gave spores with slightly reduced wet heat resistance but some large decreases in germination rate. Spore water content and CaDPA analyses found no significant differences in contents of either component in spores with different Tn1546 components or lacking the wild-type spoVA operon. CONCLUSIONS This work indicates that the SpoVA channel encoded by Tn1546 functions like the wild-type SpoVA channel in CaDPA uptake into developing spores, but not as well in germination. The essentially identical CaDPA and water contents of spores with and without Tn1546 indicate that low core water content does not cause elevated wet heat resistance of spores with Tn1546. SIGNIFICANCE AND IMPACT OF THE STUDY Since wet heat resistance of spores of Bacillus species poses problems in the food industry, understanding mechanisms of spores' wet heat resistance is of significant applied interest.
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Affiliation(s)
- Y Luo
- Department of Physics, East Carolina University, Greenville, NC, USA.,Laboratory for Biomedical Photonics & Engineering, Life Sciences Institute, Guangxi Medical University, Nanning, Guangxi, P.R. China
| | - G Korza
- Department of Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - A M DeMarco
- Department of Molecular Genetics, University of Groningen, Groningen, The Netherlands
| | - O P Kuipers
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| | - Y-Q Li
- Department of Physics, East Carolina University, Greenville, NC, USA.,School of Electronic Engineering, Dongguan University of Technology, Dongguan, Guangdong, P.R. China
| | - P Setlow
- Department of Molecular Genetics, University of Groningen, Groningen, The Netherlands
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12
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DeMarco AM, Korza G, Granados MR, Mok WWK, Setlow P. Dodecylamine rapidly kills of spores of multiple Firmicute species: properties of the killed spores and the mechanism of the killing. J Appl Microbiol 2021; 131:2612-2625. [PMID: 33998749 DOI: 10.1111/jam.15137] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/28/2021] [Accepted: 05/09/2021] [Indexed: 01/07/2023]
Abstract
AIMS Previous work showed that Bacillus subtilis dormant spore killing and germination by dodecylamine take place by different mechanisms. This new work aimed to optimize killing of B. subtilis and other Firmicutes spores and to determine the mechanism of the killing. METHODS AND RESULTS Spores of seven Firmicute species were killed rapidly by dodecylamine under optimal conditions and more slowly by decylamine or tetradecylamine. The killed spores were not recovered by additions to recovery media, and some of the killed spores subsequently germinated, all indicating that dodecylamine-killed spores truly are dead. Spores of two species treated with dodecylamine were more sensitive to killing by a subsequent heat treatment, and spore killing of at least one species was faster with chemically decoated spores. The cores of dodecylamine-killed spores were stained by the nucleic acid stain propidium iodide, and dodecylamine-killed wild-type and germination-deficient spores released their stores of phosphate-containing small molecules. CONCLUSIONS This work indicates that dodecylamine is likely a universal sporicide for Firmicute species, and it kills spores by damaging their inner membrane, with attendant loss of this membrane as a permeability barrier. SIGNIFICANCE AND IMPACT OF THE STUDY There is a significant need for agents that can effectively kill spores of a number of Firmicute species, especially in wide area decontamination. Dodecylamine appears to be a universal sporicide with a novel mechanism of action, and this or some comparable molecule could be useful in wide area spore decontamination.
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Affiliation(s)
- A M DeMarco
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| | - G Korza
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA
| | - M R Granados
- 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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13
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Predicting the Structure and Dynamics of Membrane Protein GerAB from Bacillus subtilis. Int J Mol Sci 2021; 22:ijms22073793. [PMID: 33917581 PMCID: PMC8038838 DOI: 10.3390/ijms22073793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/12/2022] Open
Abstract
Bacillus subtilis forms dormant spores upon nutrient depletion. Germinant receptors (GRs) in spore’s inner membrane respond to ligands such as L-alanine, and trigger spore germination. In B. subtilis spores, GerA is the major GR, and has three subunits, GerAA, GerAB, and GerAC. L-Alanine activation of GerA requires all three subunits, but which binds L-alanine is unknown. To date, how GRs trigger germination is unknown, in particular due to lack of detailed structural information about B subunits. Using homology modelling with molecular dynamics (MD) simulations, we present structural predictions for the integral membrane protein GerAB. These predictions indicate that GerAB is an α-helical transmembrane protein containing a water channel. The MD simulations with free L-alanine show that alanine binds transiently to specific sites on GerAB. These results provide a starting point for unraveling the mechanism of L-alanine mediated signaling by GerAB, which may facilitate early events in spore germination.
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14
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Beskrovnaya P, Sexton DL, Golmohammadzadeh M, Hashimi A, Tocheva EI. Structural, Metabolic and Evolutionary Comparison of Bacterial Endospore and Exospore Formation. Front Microbiol 2021; 12:630573. [PMID: 33767680 PMCID: PMC7985256 DOI: 10.3389/fmicb.2021.630573] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/15/2021] [Indexed: 12/20/2022] Open
Abstract
Sporulation is a specialized developmental program employed by a diverse set of bacteria which culminates in the formation of dormant cells displaying increased resilience to stressors. This represents a major survival strategy for bacteria facing harsh environmental conditions, including nutrient limitation, heat, desiccation, and exposure to antimicrobial compounds. Through dispersal to new environments via biotic or abiotic factors, sporulation provides a means for disseminating genetic material and promotes encounters with preferable environments thus promoting environmental selection. Several types of bacterial sporulation have been characterized, each involving numerous morphological changes regulated and performed by non-homologous pathways. Despite their likely independent evolutionary origins, all known modes of sporulation are typically triggered by limited nutrients and require extensive membrane and peptidoglycan remodeling. While distinct modes of sporulation have been observed in diverse species, two major types are at the forefront of understanding the role of sporulation in human health, and microbial population dynamics and survival. Here, we outline endospore and exospore formation by members of the phyla Firmicutes and Actinobacteria, respectively. Using recent advances in molecular and structural biology, we point to the regulatory, genetic, and morphological differences unique to endo- and exospore formation, discuss shared characteristics that contribute to the enhanced environmental survival of spores and, finally, cover the evolutionary aspects of sporulation that contribute to bacterial species diversification.
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Affiliation(s)
| | | | | | | | - Elitza I. Tocheva
- Department of Microbiology and Immunology, Life Sciences Institute, Health Sciences Mall, The University of British Columbia, Vancouver, BC, Canada
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15
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Setlow P, Christie G. Bacterial Spore mRNA - What's Up With That? Front Microbiol 2020; 11:596092. [PMID: 33193276 PMCID: PMC7649253 DOI: 10.3389/fmicb.2020.596092] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 09/28/2020] [Indexed: 01/19/2023] Open
Abstract
Bacteria belonging to the orders Bacillales and Clostridiales form spores in response to nutrient starvation. From a simplified morphological perspective, the spore can be considered as comprising a central protoplast or core, that is, enveloped sequentially by an inner membrane (IM), a peptidoglycan cortex, an outer membrane, and a proteinaceous coat. All of these structures are characterized by unique morphological and/or structural features, which collectively confer metabolic dormancy and properties of environmental resistance to the quiescent spore. These properties are maintained until the spore is stimulated to germinate, outgrow and form a new vegetative cell. Spore germination comprises a series of partially overlapping biochemical and biophysical events - efflux of ions from the core, rehydration and IM reorganization, disassembly of cortex and coat - all of which appear to take place in the absence of de novo ATP and protein synthesis. If the latter points are correct, why then do spores of all species examined to date contain a diverse range of mRNA molecules deposited within the spore core? Are some of these molecules "functional," serving as translationally active units that are required for efficient spore germination and outgrowth, or are they just remnants from sporulation whose sole purpose is to provide a reservoir of ribonucleotides for the newly outgrowing cell? What is the fate of these molecules during spore senescence, and indeed, are conditions within the spore core likely to provide any opportunity for changes in the transcriptional profile of the spore during dormancy? This review encompasses a historical perspective of spore ribonucleotide biology, from the earliest biochemical led analyses - some of which in hindsight have proved to be remarkably prescient - through the transcriptomic era at the turn of this century, to the latest next generation sequencing derived insights. We provide an overview of the key literature to facilitate reasoned responses to the aforementioned questions, and many others, prior to concluding by identifying the major outstanding issues in this crucial area of spore biology.
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Affiliation(s)
- Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States
| | - Graham Christie
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, United Kingdom
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16
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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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17
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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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18
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Senthilnathan N, Gaurav K, Venkata Ramana C, Radhakrishnan TP. Zwitterionic small molecule based fluorophores for efficient and selective imaging of bacterial endospores. J Mater Chem B 2020; 8:4601-4608. [PMID: 32391841 DOI: 10.1039/d0tb00470g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the emerging scenario of increasing antibiotic resistance and pathogen transmission channels, the grave danger posed by bacterial endospores in critical fields like food industry, health and medicine highlights the urgent need to develop efficient probes for their detection; their sturdy and impermeable multilayer coat makes desirable methods like fluorescence imaging extremely difficult. Selective imaging of the endospores in the presence of the bacteria is even more challenging. Furthermore, it is preferable to maintain the dormant state of endospores through the imaging process, if extended monitoring is required; many of the available techniques involve lethal germination or destruction of the endospores. We show that simple zwitterionic diaminodicyanoquinodimethane (DADQ) molecules with selected functionalities are efficient dyes for fluorescence imaging due to their dipolar structure that facilitates the penetration into the endospore system, and the enhanced fluorescence in their rigid/aggregated state. The facile structural tailorability allows DADQs with various appendage moieties to be synthesized; a derivative with ionic substituents (BT2), and another with optimally long alkyl chains and the resultant hydrophobic character (BHADQ) are shown to be excellent fluorescent probes for endospores. Nanomolar amounts of dyes provide effective staining; while BT2 stains bacteria and endospores, most significantly, BHADQ stains endospores selectively. To the best of our knowledge, this is the first example of selective fluorescence imaging of endospores in their dormant state. A range of spectroscopy, microscopy and calorimetry studies provide insight into the molecular level interactions that enable efficient staining and bright images. DADQ fluorophores are photostable and non-cytotoxic, hence useful in practical applications. The versatile structural tailorability of these dye molecules holds great promise for targeted imaging.
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Affiliation(s)
- N Senthilnathan
- School of Chemistry, University of Hyderabad, Hyderabad - 500 046, India.
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19
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Accumulation and Release of Rare Earth Ions by Spores of Bacillus Species and the Location of These Ions in Spores. Appl Environ Microbiol 2019; 85:AEM.00956-19. [PMID: 31253678 DOI: 10.1128/aem.00956-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/20/2019] [Indexed: 12/28/2022] Open
Abstract
Two rare earth ions, Tb3+ and Dy3+, were incorporated into spores of Bacillus species in ≤5 min at neutral pH to 100 to 200 nmol per mg of dry spores, which is equivalent to 2 to 3% of the spore dry weight. The uptake of these ions had, at most, minimal effects on spore wet heat resistance or germination, and the ions were all released upon germination, probably by complex formation with the huge depot of dipicolinic acid (DPA) released when spores germinate. Adsorbed Tb3+/Dy3+ were also released by exogenous DPA within a few minutes and faster than in spore germination. The accumulation of Tb3+/Dy3+ was not reduced in Bacillus subtilis spores by several types of coat defects, significant modification of the spore cortex peptidoglycan structure, specific loss of components of the outer spore crust layer, or the absence of DPA in the spore core. All of these findings are consistent with Tb3+/Dy3+ being accumulated in spores' outer layers, and this was confirmed by transmission electron microscopy. However, the identity of the outer spore components binding the Tb3+/Dy3+ is not clear. These findings provide new information on the adsorption of rare earth ions by Bacillus spores and suggest this adsorption might have applications in capturing rare earth ions from the environment.IMPORTANCE Biosorption of rare earth ions by growing cells of Bacillus species has been well studied and has attracted attention for possible hydrometallurgy applications. However, the interaction of spores from Bacillus species with rare earth ions has not been well studied. We investigated here the adsorption and/or desorption of two rare earth ions, Tb3+ and Dy3+, by Bacillus spores, the location of the adsorbed ions, and the spore properties after ion accumulation. The significant adsorption of rare earth ions on the surfaces of Bacillus spores and the ions' rapid release by a chelator could allow the development of these spores as a biosorbent to recover rare earth ions from the environment.
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21
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Hauck-Tiburski J, Rosenthal A, Iaconnelli C, Perrier-Cornet JM, Gervais P. Inactivation of dried spores of Bacillus subtilis 168 by a treatment combining high temperature and pressure. Int J Food Microbiol 2019; 295:1-7. [DOI: 10.1016/j.ijfoodmicro.2019.01.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 01/21/2019] [Accepted: 01/26/2019] [Indexed: 10/27/2022]
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22
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Rao L, Zhao L, Wang Y, Chen F, Hu X, Setlow P, Liao X. Mechanism of inactivation of Bacillus subtilis spores by high pressure CO 2 at high temperature. Food Microbiol 2019; 82:36-45. [PMID: 31027794 DOI: 10.1016/j.fm.2019.01.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 11/26/2022]
Abstract
Spores of wild-type Bacillus subtilis and some isogenic mutant strains were treated by high pressure CO2 (HPCD) at high temperature (HT) (HPCD + HT) at 20 MPa and 84-86 °C for 0-60 min, and centrifuged on a high density solution to obtain pelleted spores that retained CaDPA and light spores that lost CaDPA. All treated spores were analyzed for viability, and tested for germination, outgrowth, core protein damage, mutagenesis and inner membrane (IM) properties. The results showed that (i) with HPCD + HT treated spores, most pelleted spores and all light spores were dead; ii) a significant amount of dead HPCD + HT-treated spores that retained CaDPA germinated, but outgrowth was blocked; (iii) minimal mutants were generated in survivors of HPCD + HT treatment; (iv) the GFP fluorescence decrease in HPCD + HT-treated spores with high GFP levels was slower than spore inactivation; (v) the IM of HPCD + HT-treated spores that retained CaDPA lost its ability to retain CaDPA at 85 °C, and almost all of these spores' outgrowth in high salt was blocked; and (vi) HPCD + HT-treated spores that retained CaDPA germinated with l-valine or AGFK were almost all stained with propidium iodide. These results indicated that HPCD + HT inactivated B. subtilis spores by damaging spores' IM, thus blocking spore outgrowth after germination.
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Affiliation(s)
- Lei Rao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China; Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China
| | - Liang Zhao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China; Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China
| | - Yongtao Wang
- Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China
| | - Fang Chen
- Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China
| | - Xiaosong Hu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China; Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, 06030-3305, USA
| | - Xiaojun Liao
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China; Beijing Key Laboratory for Food Nonthermal Processing, National Engineering Research Center for Fruit & Vegetable Processing, Beijing, 100083, China; Key Laboratory of Fruit & Vegetable Processing, Ministry of Agriculture, Beijing, 100083, China.
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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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Rao L, Feeherry FE, Ghosh S, Liao X, Lin X, Zhang P, Li Y, Doona CJ, Setlow P. Effects of lowering water activity by various humectants on germination of spores of Bacillus species with different germinants. Food Microbiol 2018; 72:112-127. [DOI: 10.1016/j.fm.2017.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/19/2017] [Accepted: 11/23/2017] [Indexed: 10/18/2022]
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25
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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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26
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Kohler LJ, Quirk AV, Welkos SL, Cote CK. Incorporating germination-induction into decontamination strategies for bacterial spores. J Appl Microbiol 2017; 124:2-14. [PMID: 28980459 DOI: 10.1111/jam.13600] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 09/28/2017] [Accepted: 09/29/2017] [Indexed: 01/05/2023]
Abstract
Bacterial spores resist environmental extremes and protect key spore macromolecules until more supportive conditions arise. Spores germinate upon sensing specific molecules, such as nutrients. Germination is regulated by specialized mechanisms or structural features of the spore that limit contact with germinants and enzymes that regulate germination. Importantly, germination renders spores more susceptible to inactivating processes such as heat, desiccation, and ultraviolet radiation, to which they are normally refractory. Thus, germination can be intentionally induced through a process called germination-induction and subsequent treatment of these germinated spores with common disinfectants or gentle heat will inactivate them. However, while the principle of germination-induction has been shown effective in the laboratory, this strategy has not yet been fully implemented in real-word scenarios. Here, we briefly review the mechanisms of bacterial spore germination and discuss the evolution of germination-induction as a decontamination strategy. Finally, we examine progress towards implementing germination-induction in three contexts: biodefense, hospital settings and food manufacture. SIGNIFICANCE AND IMPACT This article reviews implementation of germination-induction as part of a decontamination strategy for the cleanup of bacterial spores. To our knowledge this is the first time that germination-induction studies have been reviewed in this context. This article will provide a resource which summarizes the mechanisms of germination in Clostridia and Bacillus species, challenges and successes in germination-induction, and potential areas where this strategy may be implemented.
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Affiliation(s)
- L J Kohler
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - A V Quirk
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - S L Welkos
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - C K Cote
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
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27
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Abstract
Dormant Bacillales and Clostridiales spores begin to grow when small molecules (germinants) trigger germination, potentially leading to food spoilage or disease. Germination-specific proteins sense germinants, transport small molecules, and hydrolyze specific bonds in cortex peptidoglycan and specific proteins. Major events in germination include (a) germinant sensing; (b) commitment to germinate; (c) release of spores' depot of dipicolinic acid (DPA); (d) hydrolysis of spores' peptidoglycan cortex; and (e) spore core swelling and water uptake, cell wall peptidoglycan remodeling, and restoration of core protein and inner spore membrane lipid mobility. Germination is similar between Bacillales and Clostridiales, but some species differ in how germinants are sensed and how cortex hydrolysis and DPA release are triggered. Despite detailed knowledge of the proteins and signal transduction pathways involved in germination, precisely what some germination proteins do and how they do it remain unclear.
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Affiliation(s)
- Peter Setlow
- Molecular Biology and Biophysics, UConn Health, Farmington, Connecticut 06030-3305;
| | - Shiwei Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China;
| | - Yong-Qing Li
- Department of Physics, East Carolina University, Greenville, North Carolina 27858-4353;
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Abstract
To survive adverse conditions, some bacterial species are capable of developing into a cell type, the "spore," which exhibits minimal metabolic activity and remains viable in the presence of multiple environmental challenges. For some pathogenic bacteria, this developmental state serves as a means of survival during transmission from one host to another. Spores are the highly infectious form of these bacteria. Upon entrance into a host, specific signals facilitate germination into metabolically active replicating organisms, resulting in disease pathogenesis. In this article, we will review spore structure and function in well-studied pathogens of two genera, Bacillus and Clostridium, focusing on Bacillus anthracis and Clostridium difficile, and explore current data regarding the lifestyles of these bacteria outside the host and transmission from one host to another.
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29
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Van Der Hofstadt M, Fabregas R, Millan-Solsona R, Juarez A, Fumagalli L, Gomila G. Internal Hydration Properties of Single Bacterial Endospores Probed by Electrostatic Force Microscopy. ACS NANO 2016; 10:11327-11336. [PMID: 28024372 DOI: 10.1021/acsnano.6b06578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
We show that the internal hydration properties of single Bacillus cereus endospores in air under different relative humidity (RH) conditions can be determined through the measurement of its electric permittivity by means of quantitative electrostatic force microscopy (EFM). We show that an increase in the RH from 0% to 80% induces a large increase in the equivalent homogeneous relative electric permittivity of the bacterial endospores, from ∼4 up to ∼17, accompanied only by a small increase in the endospore height, of just a few nanometers. These results correlate the increase of the moisture content of the endospore with the corresponding increase of environmental RH. Three-dimensional finite element numerical calculations, which include the internal structure of the endospores, indicate that the moisture is mainly accumulated in the external layers of the endospore, hence preserving the core of the endospore at low hydration levels. This mechanism is different from what we observe for vegetative bacterial cells of the same species, in which the cell wall at high humid atmospheric conditions is not able to preserve the cytoplasmic region at low hydration levels. These results show the potential of quantitative EFM under environmental humidity control to study the hygroscopic properties of small-scale biological (and nonbiological) entities and to determine its internal hydration state. A better understanding of nanohygroscopic properties can be of relevance in the study of essential biological processes and in the design of bionanotechnological applications.
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Affiliation(s)
- Marc Van Der Hofstadt
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Rene Fabregas
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
| | - Ruben Millan-Solsona
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
| | - Antonio Juarez
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament de Microbiologia, Universitat de Barcelona , Av. Diagonal 643, Barcelona 08028, Spain
| | - Laura Fumagalli
- School of Physics and Astronomy, University of Manchester , Oxford Road, Manchester M13 9PL, United Kingdom
| | - Gabriel Gomila
- Institut de Bioenginyeria de Catalunya (IBEC) , c/Baldiri i Reixac 11-15, Barcelona 08028, Spain
- Departament d'Enginyeries: Electrònica, Universitat de Barcelona , C/Martí i Franqués 1, Barcelona 08028, Spain
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