1
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Xing Y, Szabo J, Magnuson M, Harper WF. Clustering, morphology, and treatment resistance of Bacillus globigii spores recovered from a pilot-scale activated sludge system. CHEMOSPHERE 2020; 260:127591. [PMID: 32758773 PMCID: PMC7816126 DOI: 10.1016/j.chemosphere.2020.127591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 05/27/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
This study examines the organization and morphology of Bacillus globigii (BG) spores, a common surrogate for Bacillus anthracis, which were seeded and then recovered at various times from several points within a conventional, pilot-scale activated sludge system. Recovered BG spores were enumerated, microscopically examined, and tested for resistance to chemical (i.e. 5% H2O2 for 8 min), thermal (80 °C for 30 min), and ultraviolet light (8 W, 254 nm UV for 1 min) inactivation. Spores exposed to activated sludge germinated, sporulated, and exhibited unique multilayer clustering patterns and statistically significant changes (p < 0.005) in dimensional morphology. Spores collected in the later experimental stages (i.e., during weeks 6 and 7) were significantly more resistant (p ≤ 0.05) to inactivation than those collected on the first day of testing. These results have direct consequences for sludge treatment requirements at wastewater treatment plants that receive spore-containing waste streams.
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Affiliation(s)
- Yun Xing
- Air Force Institute of Technology, Department of Systems Engineering and Management, Wright-Patterson AFB, OH, USA
| | - Jeff Szabo
- US Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Homeland Security and Materials Management Division, Cincinnati, OH, USA
| | - Matthew Magnuson
- US Environmental Protection Agency, Center for Environmental Solutions and Emergency Response, Homeland Security and Materials Management Division, Cincinnati, OH, USA
| | - Willie F Harper
- Air Force Institute of Technology, Department of Systems Engineering and Management, Wright-Patterson AFB, OH, USA.
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2
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The Detection of Long-Chain Bio-Markers Using Atomic Force Microscopy. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9071280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The detection of long-chain biomolecules on mineral surfaces is presented using an atomic force microscope (AFM). This is achieved by using the AFM’s ability to manipulate molecules and measure forces at the pico-newton scale. We show that a highly characteristic force-distance signal is produced when the AFM tip is used to detach long-chain molecules from a surface. This AFM force spectroscopy method is demonstrated on bio-films, spores, fossils and mineral surfaces. The method works with AFM imaging and correlated tip enhanced infrared spectroscopy. The use of AFM force spectroscopy to detect this class of long chain bio-markers has applications in paleontology, life detection and planetary science.
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3
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Electrical discharges in water induce spores' DNA damage. PLoS One 2018; 13:e0201448. [PMID: 30102709 PMCID: PMC6089432 DOI: 10.1371/journal.pone.0201448] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 07/15/2018] [Indexed: 11/19/2022] Open
Abstract
Bacterial spores are one of the most resilient life forms on earth and are involved in many human diseases, such as infectious diarrhea, fatal paralytic illnesses and respiratory infections. Here, we investigated the mechanisms involved in the death of Bacillus pumilus spores after exposure to electric arcs in water. Cutting-edge microscopies at the nanoscale did not reveal any structural disorganization of spores exposed to electric arcs. This result suggested the absence of physical destruction by a propagating shock wave or an exposure to an electric field. However, Pulsed-Field Gel Electrophoresis (PFGE) revealed genomic DNA damage induced by UV radiation and Reactive Oxygen Species (ROS). UV induced single-strand DNA breaks and thymine dimers while ROS were mainly involved in base excision. Our findings revealed a correlation between DNA damage and the treatment of spores with electrical discharges.
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4
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Van Impe J, Smet C, Tiwari B, Greiner R, Ojha S, Stulić V, Vukušić T, Režek Jambrak A. State of the art of nonthermal and thermal processing for inactivation of micro-organisms. J Appl Microbiol 2018; 125:16-35. [DOI: 10.1111/jam.13751] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 02/16/2018] [Accepted: 02/27/2018] [Indexed: 02/03/2023]
Affiliation(s)
- J. Van Impe
- Department of Chemical Engineering; KU Leuven; Leuven Belgium
| | - C. Smet
- Department of Chemical Engineering; KU Leuven; Leuven Belgium
| | - B. Tiwari
- Department of Food Biosciences; Teagasc - Irish Agriculture and Food Development Authority; Carlow Ireland
| | - R. Greiner
- Department of Food Technology and Bioprocess Engineering; Max Rubner-Institut; Karlsruhe Germany
| | - S. Ojha
- Department of Food Biosciences; Teagasc - Irish Agriculture and Food Development Authority; Carlow Ireland
| | - V. Stulić
- Faculty of Food Technology and Biotechnology; University of Zagreb; Zagreb Croatia
| | - T. Vukušić
- Faculty of Food Technology and Biotechnology; University of Zagreb; Zagreb Croatia
| | - A. Režek Jambrak
- Faculty of Food Technology and Biotechnology; University of Zagreb; Zagreb Croatia
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5
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Cell wall as a target for bacteria inactivation by pulsed electric fields. Sci Rep 2016; 6:19778. [PMID: 26830154 PMCID: PMC4735277 DOI: 10.1038/srep19778] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 12/07/2015] [Indexed: 12/23/2022] Open
Abstract
The integrity and morphology of bacteria is sustained by the cell wall, the target of the main microbial inactivation processes. One promising approach to inactivation is based on the use of pulsed electric fields (PEF). The current dogma is that irreversible cell membrane electro-permeabilisation causes the death of the bacteria. However, the actual effect on the cell-wall architecture has been poorly explored. Here we combine atomic force microscopy and electron microscopy to study the cell-wall organization of living Bacillus pumilus bacteria at the nanoscale. For vegetative bacteria, exposure to PEF led to structural disorganization correlated with morphological and mechanical alterations of the cell wall. For spores, PEF exposure led to the partial destruction of coat protein nanostructures, associated with internal alterations of cortex and core. Our findings reveal for the first time that the cell wall and coat architecture are directly involved in the electro-eradication of bacteria.
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6
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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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7
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Wu IL, Narayan K, Castaing JP, Tian F, Subramaniam S, Ramamurthi KS. A versatile nano display platform from bacterial spore coat proteins. Nat Commun 2015; 6:6777. [PMID: 25854653 PMCID: PMC4396682 DOI: 10.1038/ncomms7777] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/26/2015] [Indexed: 12/20/2022] Open
Abstract
Dormant bacterial spores are encased in a thick protein shell, the ‘coat', which contains ∼70 different proteins. The coat protects the spore from environmental insults, and is among the most durable static structures in biology. Owing to extensive cross-linking among coat proteins, this structure has been recalcitrant to detailed biochemical analysis, so molecular details of how it assembles are largely unknown. Here, we reconstitute the basement layer of the coat atop spherical membranes supported by silica beads to create artificial spore-like particles. We report that these synthetic spore husk-encased lipid bilayers (SSHELs) assemble and polymerize into a static structure, mimicking in vivo basement layer assembly during sporulation in Bacillus subtilis. In addition, we demonstrate that SSHELs may be easily covalently modified with small molecules and proteins. We propose that SSHELs may be versatile display platforms for drugs and vaccines in clinical settings, or for enzymes that neutralize pollutants for environmental remediation. The densely crosslinked protein coats of bacterial spores are among the most durable static structures in biology. Wu et al. reconstitute the basement layer of a bacterial spore coat on membrane-coated beads, and generate covalently-modified spore-like particles with therapeutic potential.
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Affiliation(s)
- I-Lin Wu
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kedar Narayan
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jean-Philippe Castaing
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Fang Tian
- Department of Biochemistry and Molecular Biology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania 17033, USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kumaran S Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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8
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Plomp M, Carroll AM, Setlow P, Malkin AJ. Architecture and assembly of the Bacillus subtilis spore coat. PLoS One 2014; 9:e108560. [PMID: 25259857 PMCID: PMC4178626 DOI: 10.1371/journal.pone.0108560] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/28/2014] [Indexed: 11/30/2022] Open
Abstract
Bacillus spores are encased in a multilayer, proteinaceous self-assembled coat structure that assists in protecting the bacterial genome from stresses and consists of at least 70 proteins. The elucidation of Bacillus spore coat assembly, architecture, and function is critical to determining mechanisms of spore pathogenesis, environmental resistance, immune response, and physicochemical properties. Recently, genetic, biochemical and microscopy methods have provided new insight into spore coat architecture, assembly, structure and function. However, detailed spore coat architecture and assembly, comprehensive understanding of the proteomic composition of coat layers, and specific roles of coat proteins in coat assembly and their precise localization within the coat remain in question. In this study, atomic force microscopy was used to probe the coat structure of Bacillus subtilis wild type and cotA, cotB, safA, cotH, cotO, cotE, gerE, and cotE gerE spores. This approach provided high-resolution visualization of the various spore coat structures, new insight into the function of specific coat proteins, and enabled the development of a detailed model of spore coat architecture. This model is consistent with a recently reported four-layer coat assembly and further adds several coat layers not reported previously. The coat is organized starting from the outside into an outermost amorphous (crust) layer, a rodlet layer, a honeycomb layer, a fibrous layer, a layer of “nanodot” particles, a multilayer assembly, and finally the undercoat/basement layer. We propose that the assembly of the previously unreported fibrous layer, which we link to the darkly stained outer coat seen by electron microscopy, and the nanodot layer are cotH- and cotE- dependent and cotE-specific respectively. We further propose that the inner coat multilayer structure is crystalline with its apparent two-dimensional (2D) nuclei being the first example of a non-mineral 2D nucleation crystallization pattern in a biological organism.
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Affiliation(s)
- Marco Plomp
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
| | - Alicia Monroe Carroll
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Peter Setlow
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, Connecticut, United States of America
- * E-mail: (PS); (AJM)
| | - Alexander J. Malkin
- Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States of America
- * E-mail: (PS); (AJM)
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9
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White CP, Popovici J, Lytle DA, Rice EW. Endospore surface properties of commonly used Bacillus anthracis surrogates vary in aqueous solution. Antonie van Leeuwenhoek 2014; 106:243-51. [PMID: 24817579 DOI: 10.1007/s10482-014-0187-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 04/23/2014] [Indexed: 10/25/2022]
Abstract
The hydrophobic character and electrophoretic mobility (EPM) of microorganisms are vital aspects of understanding their interactions with the environment. These properties are fundamental in fate-and-transport, physiological, and virulence studies, and thus integral in surrogate selection. Hydrophobic and electrostatic forces are significant contributors to particle and microorganism mobility in the environment. Herein, the surface properties of commonly used Bacillus anthracis surrogate endospores were tested under comparable conditions with respect to culture, endospore purification, buffer type and strength. Additionally, data is presented of endospores suspended in dechlorinated tap water to evaluate the surrogates in regard to a breach of water infrastructure security. The surface properties of B. anthracis were found to be the most hydrophobic and least electronegative among the six Bacillus species tested across buffer strength. The effect of EPM on hydrophobicity varies in a species-specific manner. This study demonstrates that surrogate surface properties differ and care must be taken when choosing the most suitable surrogate. Moreover, it is shown that Bacillus thuringensis best represents Bacillus anthracis-Sterne with respect to both EPM and hydrophobicity across all test buffers.
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Affiliation(s)
- Colin P White
- Pegasus Technical Services Inc., Cincinnati, OH, 45219, USA,
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10
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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: 54] [Impact Index Per Article: 5.4] [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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11
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Xing Y, Li A, Felker DL, Burggraf LW. Nanoscale structural and mechanical analysis of Bacillus anthracis spores inactivated with rapid dry heating. Appl Environ Microbiol 2014; 80:1739-49. [PMID: 24375142 PMCID: PMC3957622 DOI: 10.1128/aem.03483-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 12/21/2013] [Indexed: 11/20/2022] Open
Abstract
Effective killing of Bacillus anthracis spores is of paramount importance to antibioterrorism, food safety, environmental protection, and the medical device industry. Thus, a deeper understanding of the mechanisms of spore resistance and inactivation is highly desired for developing new strategies or improving the known methods for spore destruction. Previous studies have shown that spore inactivation mechanisms differ considerably depending upon the killing agents, such as heat (wet heat, dry heat), UV, ionizing radiation, and chemicals. It is believed that wet heat kills spores by inactivating critical enzymes, while dry heat kills spores by damaging their DNA. Many studies have focused on the biochemical aspects of spore inactivation by dry heat; few have investigated structural damages and changes in spore mechanical properties. In this study, we have inactivated Bacillus anthracis spores with rapid dry heating and performed nanoscale topographical and mechanical analysis of inactivated spores using atomic force microscopy (AFM). Our results revealed significant changes in spore morphology and nanomechanical properties after heat inactivation. In addition, we also found that these changes were different under different heating conditions that produced similar inactivation probabilities (high temperature for short exposure time versus low temperature for long exposure time). We attributed the differences to the differential thermal and mechanical stresses in the spore. The buildup of internal thermal and mechanical stresses may become prominent only in ultrafast, high-temperature heat inactivation when the experimental timescale is too short for heat-generated vapor to efficiently escape from the spore. Our results thus provide direct, visual evidences of the importance of thermal stresses and heat and mass transfer to spore inactivation by very rapid dry heating.
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Affiliation(s)
- Yun Xing
- Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio, USA
- Oak Ridge Institute for Science and Education (ORISE), Oak Ridge, Tennessee, USA
| | - Alex Li
- Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio, USA
| | - Daniel L. Felker
- Department of Systems Engineering & Management, Air Force Institute of Technology, WPAFB, Dayton, Ohio, USA
| | - Larry W. Burggraf
- Department of Engineering Physics, Air Force Institute of Technology, Wright-Patterson Air Force Base (WPAFB), Dayton, Ohio, USA
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12
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Bacillus thuringiensis as a surrogate for Bacillus anthracis in aerosol research. World J Microbiol Biotechnol 2013; 30:1453-61. [PMID: 24338558 DOI: 10.1007/s11274-013-1576-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 12/03/2013] [Indexed: 10/25/2022]
Abstract
Characterization of candidate surrogate spores prior to experimental use is critical to confirm that the surrogate characteristics are as closely similar as possible to those of the pathogenic agent of interest. This review compares the physical properties inherent to spores of Bacillus anthracis (Ba) and Bacillus thuringiensis (Bt) that impact their movement in air and interaction with surfaces, including size, shape, density, surface morphology, structure and hydrophobicity. Also evaluated is the impact of irradiation on the physical properties of both Bacillus species. Many physical features of Bt and Ba have been found to be similar and, while Bt is considered typically non-pathogenic, it is in the B. cereus group, as is Ba. When cultured and sporulated under similar conditions, both microorganisms share a similar cylindrical pellet shape, an aerodynamic diameter of approximately 1 μm (in the respirable size range), have an exosporium with a hairy nap, and have higher relative hydrophobicities than other Bacillus species. While spore size, morphology, and other physical properties can vary among strains of the same species, the variations can be due to growth/sporulation conditions and may, therefore, be controlled. Growth and sporulation conditions are likely among the most important factors that influence the representativeness of one species, or preparation, to another. All Bt spores may, therefore, not be representative of all Ba spores. Irradiated spores do not appear to be a good surrogate to predict the behavior of non-irradiated spores due to structural damage caused by the irradiation. While the use of Bt as a surrogate for Ba in aerosol testing appears to be well supported, this review does not attempt to narrow selection between Bt strains. Comparative studies should be performed to test the hypothesis that viable Ba and Bt spores will behave similarly when suspended in the air (as an aerosol) and to compare the known microscale characteristics versus the macroscale response.
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13
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Pillet F, Chopinet L, Formosa C, Dague E. Atomic Force Microscopy and pharmacology: from microbiology to cancerology. Biochim Biophys Acta Gen Subj 2013; 1840:1028-50. [PMID: 24291690 DOI: 10.1016/j.bbagen.2013.11.019] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Revised: 11/18/2013] [Accepted: 11/20/2013] [Indexed: 02/06/2023]
Abstract
BACKGROUND Atomic Force Microscopy (AFM) has been extensively used to study biological samples. Researchers take advantage of its ability to image living samples to increase our fundamental knowledge (biophysical properties/biochemical behavior) on living cell surface properties, at the nano-scale. SCOPE OF REVIEW AFM, in the imaging modes, can probe cells morphological modifications induced by drugs. In the force spectroscopy mode, it is possible to follow the nanomechanical properties of a cell and to probe the mechanical modifications induced by drugs. AFM can be used to map single molecule distribution at the cell surface. We will focus on a collection of results aiming at evaluating the nano-scale effects of drugs, by AFM. Studies on yeast, bacteria and mammal cells will illustrate our discussion. Especially, we will show how AFM can help in getting a better understanding of drug mechanism of action. MAJOR CONCLUSIONS This review demonstrates that AFM is a versatile tool, useful in pharmacology. In microbiology, it has been used to study the drugs fighting Candida albicans or Pseudomonas aeruginosa. The major conclusions are a better understanding of the microbes' cell wall and of the drugs mechanism of action. In cancerology, AFM has been used to explore the effects of cytotoxic drugs or as an innovative diagnostic technology. AFM has provided original results on cultured cells, cells extracted from patient and directly on patient biopsies. GENERAL SIGNIFICANCE This review enhances the interest of AFM technologies for pharmacology. The applications reviewed range from microbiology to cancerology.
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Affiliation(s)
- Flavien Pillet
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France
| | - Louise Chopinet
- CNRS, IPBS-UMR 5089, BP64182, 205 route de Narbonne, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France
| | - Cécile Formosa
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France; CNRS, UMR 7565, SRSMC, Vandoeuvre-lès-Nancy, France; Université de Lorraine, UMR 7565, Faculté de Pharmacie, Nancy, France
| | - Etienne Dague
- CNRS, LAAS, 7 avenue du colonel Roche, F-31077 Toulouse Cedex 4, France; Université de Toulouse, UPS, INSA, INP, ISAE, UT1, UTM, LAAS, ITAV, F-31077 Toulouse Cedex 4, France; CNRS; ITAV-USR 3505; F31106 Toulouse, France.
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14
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Abstract
Bacterial endospores are some of the most resilient forms of life known to us, with their persistent survival capability resulting from a complex and effective structural organization. The outer membrane of endospores is surrounded by the densely packed endospore coat and exosporium, containing amyloid or amyloid-like proteins. In fact, it is the impenetrable composition of the endospore coat and the exosporium that makes staining methodologies for endospore detection complex and challenging. Therefore, a plausible strategy for facile and expedient staining would be to target components of the protective surface layers of the endospores. Instead of targeting endogenous markers encapsulated in the spores, here we demonstrated staining of these dormant life entities that targets the amyloid domains, i.e., the very surface components that make the coats of these species impenetrable. Using an amyloid staining dye, thioflavin T (ThT), we examined this strategy. A short incubation of bacillus endospore suspensions with ThT, under ambient conditions, resulted in (i) an enhancement of the fluorescence of ThT and (ii) the accumulation of ThT in the endospores, affording fluorescence images with excellent contrast ratios. Fluorescence images revealed that ThT tends to accumulate in the surface regions of the endospores. The observed fluorescence enhancement and dye accumulation, coupled with the sensitivity of emission techniques, provide an effective and rapid means of staining endospores without the inconvenience of pre- or posttreatment of samples.
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15
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Sun W, Romagnoli JA, Palazoglu A, Stroeve P. Characterization of Surface Coats of Bacterial Spores with Atomic Force Microscopy and Wavelets. Ind Eng Chem Res 2011. [DOI: 10.1021/ie101153y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Wei Sun
- College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jose A. Romagnoli
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803-7303, United States
| | - Ahmet Palazoglu
- Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616, United States
| | - Pieter Stroeve
- Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616, United States
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16
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Sun J, Zborowski M, Chalmers JJ. Quantification of both the presence, and oxidation state, of Mn in Bacillus atrophaeus spores and its imparting of magnetic susceptibility to the spores. Biotechnol Bioeng 2011; 108:1119-29. [PMID: 21449026 DOI: 10.1002/bit.23034] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 11/26/2010] [Accepted: 12/02/2010] [Indexed: 11/11/2022]
Abstract
Bacillus atrophaeus spores were previously reported to have significant magnetic susceptibility in a magnetic field due to the presence of Mn. However, relatively little is known about the total amount and distribution of the oxidation state of Mn associated with this specific strain's spores. Using the instrument, cell tracking velocimetry (CTV) both magnetically induced velocity and settling velocity was quantitatively measured. Visual observations, and calculated diameter using previously reported densities, indicate that the spores are present in the form of clusters of approximately 3-6 µm. Treatment of these clusters with EDTA or pH of 2.0 or below resulted in not only the disruption of the spore clusters, but also a significant decrease in magnetic susceptibility, in some cases by almost two orders of magnitude. Since the magnetic susceptibility of Mn varies significantly between the three typically reported valance states of Mn, Mn(II), Mn(III), and Mn(IV); X-Ray Photoelectron Spectroscopy, XPS, was used to determined the valance states of Mn in the spores. This XPS analysis, which penetrates up to 10 nm into the spore, returned the following fractions: 0.41, 0.38, and 0.21 for the valance states: Mn(II), Mn(III), and Mn(IV), respectively. The total mass of Mn associated with each spore cluster was determined by ICP-MS. A second, completely independent estimate of Mn mass associated with each spore cluster was made, by mathematically solving for the amount of Mn per spore cluster using the experimentally measured magnetophoretic mobility and the magnetic susceptibility of each of the three valence states from the XPS analysis. IPC-MS returned a value of 3.28 × 10(-11) g of Mn per spore cluster while the calculated estimation from mobility and XPS analysis retuned a value of 1.16 × 10(-11) g, which given the complexity of the two techniques, is a reasonable agreement. Finally, a discussion of potential applications of the magnetic properties of these spores is presented.
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Affiliation(s)
- Jianxin Sun
- William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, Ohio 43210, USA
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17
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Greenberg DL, Busch JD, Keim P, Wagner DM. Identifying experimental surrogates for Bacillus anthracis spores: a review. INVESTIGATIVE GENETICS 2010; 1:4. [PMID: 21092338 PMCID: PMC2988482 DOI: 10.1186/2041-2223-1-4] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 09/01/2010] [Indexed: 01/05/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax, is a proven biological weapon. In order to study this threat, a number of experimental surrogates have been used over the past 70 years. However, not all surrogates are appropriate for B. anthracis, especially when investigating transport, fate and survival. Although B. atrophaeus has been widely used as a B. anthracis surrogate, the two species do not always behave identically in transport and survival models. Therefore, we devised a scheme to identify a more appropriate surrogate for B. anthracis. Our selection criteria included risk of use (pathogenicity), phylogenetic relationship, morphology and comparative survivability when challenged with biocides. Although our knowledge of certain parameters remains incomplete, especially with regards to comparisons of spore longevity under natural conditions, we found that B. thuringiensis provided the best overall fit as a non-pathogenic surrogate for B. anthracis. Thus, we suggest focusing on this surrogate in future experiments of spore fate and transport modelling.
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Affiliation(s)
- David L Greenberg
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | - Joseph D Busch
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
| | | | - David M Wagner
- Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011-4073, USA
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18
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Pinzón-Arango PA, Nagarajan R, Camesano TA. Effects of L-alanine and inosine germinants on the elasticity of Bacillus anthracis spores. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:6535-6541. [PMID: 20095533 DOI: 10.1021/la904071y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The surface of dormant Bacillus anthracis spores consists of a multilayer of protein coats and a thick peptidoglycan layer that allow the cells to resist chemical and environmental insults. During germination, the spore coat is degraded, making the spore susceptible to chemical inactivation by antisporal agents as well as to mechanical inactivation by high-pressure or mechanical abrasion processes. While chemical changes during germination, especially the release of the germination marker, dipicolinic acid (DPA), have been extensively studied, there is as yet no investigation of the corresponding changes in the mechanical properties of the spore. In this work, we use atomic force microscopy (AFM) to characterize the mechanical properties of the surface of Bacillus anthracis spores during germination. The Hertz model of continuum mechanics of contact was used to evaluate the Young's moduli of the spores before and after germination by applying the model to load-indentation curves. The highest modulus was observed for dormant spores, with average elasticity values of 197 +/- 81 MPa. The elasticity decreased significantly after incubation of the spores with the germinants L-alanine or inosine (47.5 +/- 41.7 and 35.4 +/- 15.8 MPa, respectively). Exposure of B. anthracis spores to a mixture of both germinants resulted in a synergistic effect with even lower elasticity, with a Young's modulus of 23.5 +/- 14.8 MPa. The elasticity of the vegetative B. anthracis cells was nearly 15 times lower than that of the dormant spores (12.4 +/- 6.3 MPa vs 197.0 +/- 80.5 MPa, respectively). Indeed from a mechanical strength point of view, the germinated spores were closer to the vegetative cells than to the dormant spores. Further, the decrease in the elasticity of the cells was accompanied by increasing AFM tip indentation depths on the cell surfaces. Indentation depths of up to 246.2 nm were observed for vegetative B. anthracis compared to 20.5 nm for the dormant spores. These results provide quantitative information on how the mechanical properties of the cell wall change during germination, which may explain how spores become susceptible to inactivation processes based on mechanical forces during germination and outgrowth. The study of spore elasticity may be a valuable tool in the design of improved antisporal treatments.
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Affiliation(s)
- Paola A Pinzón-Arango
- Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
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19
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Pinzón-Arango PA, Liu Y, Camesano TA. Role of cranberry on bacterial adhesion forces and implications for Escherichia coli-uroepithelial cell attachment. J Med Food 2009; 12:259-70. [PMID: 19257836 DOI: 10.1089/jmf.2008.0196] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Previous clinical research has suggested that the consumption of cranberry products prevents the adhesion of Escherichia coli to uroepithelial cells by causing changes in bacterial fimbriae. Atomic force microscopy was used to probe the adhesion forces between E. coli (nonfimbriated strain HB101 and the P-fimbriated variant HB101pDC1) and a model surface (silicon nitride), to determine the effect of growth in cranberry products on bacterial adhesion. Bacteria were grown in tryptic soy broth supplemented with either light cranberry juice cocktail (L-CJC) or cranberry proanthocyanidins (PACs). Growth of E. coli HB101pDC1 and HB101 in L-CJC or PACs resulted in a decrease in adhesion forces with increasing number of cultures. In a macroscale bacteria-uroepithelial cell adhesion assay a decrease in bacterial attachment was observed for E. coli HB101pDC1 grown in L-CJC or PACs. This effect was reversible because bacteria that were regrown in cranberry-free medium regained their ability to attach to uroepithelial cells, and their adhesion forces reverted to the values observed in the control condition. Exposure to increasing concentrations of L-CJC resulted in a decrease of bacterial attachment to uroepithelial cells for the P-fimbriated strain after L-CJC treatment (27% by weight) and after PACs treatment (345.8 microg/mL). Cranberry products affect the surface properties, such as fimbriae and lipopolysaccharides, and adhesion of fimbriated and nonfimbriated E. coli. The concentration of cranberry products and the number of cultures the bacteria were exposed to cranberry determines how much the adhesion forces and attachment are altered.
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Affiliation(s)
- Paola A Pinzón-Arango
- Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609, USA
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20
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Abstract
We chemically immobilized live, motile Escherichia coli on micrometer-scale, photocatalytically patterned silicon surfaces via amine- and carboxylic acid-based chemistries. Immobilization facilitated (i) controlled positioning; (ii) high resolution cell wall imaging via atomic force microscopy (AFM); and (iii) chemical analysis with time-of-flight-secondary ion mass spectrometry (ToF-SIMS). Spinning motion of tethered bacteria, captured with fast-acquisition video, proved microbe viability. We expect our protocols to open new experimental doors for basic and applied studies of microorganisms, from host-pathogen relationships, to microbial forensics and drug discovery, to biosensors and biofuel cell optimization.
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21
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Pinzón-Arango PA, Scholl G, Nagarajan R, Mello CM, Camesano TA. Atomic force microscopy study of germination and killing ofBacillusatrophaeusspores. J Mol Recognit 2009; 22:373-9. [DOI: 10.1002/jmr.945] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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22
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Nanoscale structural and mechanical properties of nontypeable Haemophilus influenzae biofilms. J Bacteriol 2009; 191:2512-20. [PMID: 19218382 DOI: 10.1128/jb.01596-08] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHI) bacteria are commensals in the human nasopharynx, as well as pathogens associated with a spectrum of acute and chronic infections. Two important factors that influence NTHI pathogenicity are their ability to adhere to human tissue and their ability to form biofilms. Extracellular polymeric substances (EPS) and bacterial appendages such as pili critically influence cell adhesion and intercellular cohesion during biofilm formation. Structural components in the outer cell membrane, such as lipopolysaccharides, also play a fundamental role in infection of the host organism. In spite of their importance, these pathogenic factors are not yet well characterized at the nanoscale. Here, atomic force microscopy (AFM) was used in aqueous environments to visualize structural details, including probable Hif-type pili, of live NTHI bacteria at the early stages of biofilm formation. Using single-molecule AFM-based spectroscopy, the molecular elasticities of lipooligosaccharides present on NTHI cell surfaces were analyzed and compared between two strains (PittEE and PittGG) with very different pathogenicity profiles. Furthermore, the stiffness of single cells of both strains was measured and subsequently their turgor pressure was estimated.
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23
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Plomp M, Malkin AJ. Mapping of proteomic composition on the surfaces of bacillus spores by atomic force microscopy-based immunolabeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:403-409. [PMID: 19063625 DOI: 10.1021/la803129r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Atomic force microscopy (AFM) provides a unique capability to image high-resolution architecture and structural dynamics of pathogens (e.g., viruses, bacteria, and bacterial spores) at near-molecular resolution in native conditions. Further development of atomic force microscopy to enable the correlation of pathogen protein surface structures with specific gene products is essential to understand the mechanisms of the pathogen life cycle. We applied an AFM-based immunolabeling technique for the proteomic mapping of macromolecular structures through the visualization of the binding of antibodies, conjugated with nanogold particles, to specific epitopes on Bacillus spore surfaces. This information is generated while simultaneously acquiring the surface morphology of the pathogen. The immunospecificity of this labeling method was established through the utilization of specific polyclonal and monoclonal antibodies that target spore coat and exosporium epitopes of Bacillus atrophaeus and Bacillus anthracis spores.
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Affiliation(s)
- Marco Plomp
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, L-233, Livermore, California 94551, USA
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24
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Protozoal digestion of coat-defective Bacillus subtilis spores produces "rinds" composed of insoluble coat protein. Appl Environ Microbiol 2008; 74:5875-81. [PMID: 18689521 DOI: 10.1128/aem.01228-08] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Bacillus subtilis spore coat is a multilayer, proteinaceous structure that consists of more than 50 proteins. Located on the surface of the spore, the coat provides resistance to potentially toxic molecules as well as to predation by the protozoan Tetrahymena thermophila. When coat-defective spores are fed to Tetrahymena, the spores are readily digested. However, a residue termed a "rind" that looks like coat material remains. As observed with a phase-contrast microscope, the rinds are spherical or hemispherical structures that appear to be devoid of internal contents. Atomic force microscopy and chemical analyses showed that (i) the rinds are composed of insoluble protein largely derived from both outer and inner spore coat layers, (ii) the amorphous layer of the outer coat is largely responsible for providing spore resistance to protozoal digestion, and (iii) the rinds and intact spores do not contain significant levels of silicon.
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25
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Abstract
Endospores formed by Bacillus, Clostridia, and related genera are encased in a protein shell called the coat. In many species, including B. subtilis, the coat is the outermost spore structure, and in other species, such as the pathogenic organisms B. anthracis and B. cereus, the spore is encased in an additional layer called the exosporium. Both the coat and the exosporium have roles in protection of the spore and in its environmental interactions. Assembly of both structures is a function of the mother cell, one of two cellular compartments of the developing sporangium. Studies in B. subtilis have revealed that the timing of coat protein production, the guiding role of a small group of morphogenetic proteins, and several types of posttranslational modifications are essential for the fidelity of the assembly process. Assembly of the exosporium requires a set of novel proteins as well as homologues of proteins found in the outermost layers of the coat and of some of the coat morphogenetic factors, suggesting that the exosporium is a more specialized structure of a multifunctional coat. These and other insights into the molecular details of spore surface morphogenesis provide avenues for exploitation of the spore surface layers in applications for biotechnology and medicine.
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Affiliation(s)
- Adriano O Henriques
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, 2781-901 Oeiras Codex, Portugal.
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26
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Wang L, Perpich J, Driks A, Kroos L. Maintaining the transcription factor SpoIIID level late during sporulation causes spore defects in Bacillus subtilis. J Bacteriol 2007; 189:7302-9. [PMID: 17693499 PMCID: PMC2168458 DOI: 10.1128/jb.00839-07] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During sporulation of Bacillus subtilis, four regulatory proteins act in the order sigma(E), SpoIIID, sigma(K), and GerE to temporally control gene expression in the mother cell. sigma(E) and sigma(K) work sequentially with core RNA polymerase to transcribe different sets of genes. SpoIIID and GerE are small, sequence-specific DNA-binding proteins that activate or repress transcription of many genes. Previous studies showed that transcriptionally active sigma(K) RNA polymerase inhibits early mother cell gene expression, reducing accumulation of SpoIIID late in sporulation. Here, the effects of perturbing the mother cell gene regulatory network by maintaining the SpoIIID level late during sporulation are reported. Persistent expression was obtained by fusing spoIIID to the sigma(K)-controlled gerE promoter on a multicopy plasmid. Fewer heat- and lysozyme-resistant spores were produced by the strain with persistent spoIIID expression, but the number of spores resistant to organic solvents was unchanged, as was their germination ability. Transmission electron microscopy showed structural defects in the spore coat. Reporter fusions to sigma(K)-dependent promoters showed lower expression of gerE and cotC and higher expression of cotD. Altered expression of cot genes, which encode spore coat proteins, may account for the spore structural defects. These results suggest that one role of negative feedback by sigma(K) RNA polymerase on early mother cell gene expression is to lower the level of SpoIIID late during sporulation in order to allow normal expression of genes in the sigma(K) regulon.
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MESH Headings
- Anti-Bacterial Agents/pharmacology
- Artificial Gene Fusion
- Bacillus subtilis/genetics
- Bacillus subtilis/physiology
- Bacterial Proteins/biosynthesis
- Bacterial Proteins/genetics
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/genetics
- Gene Expression Regulation, Bacterial/genetics
- Gene Expression Regulation, Bacterial/physiology
- Genes, Reporter
- Hot Temperature
- Microscopy, Electron, Transmission
- Muramidase/metabolism
- Organic Chemicals/pharmacology
- Promoter Regions, Genetic
- Spores, Bacterial/drug effects
- Spores, Bacterial/genetics
- Spores, Bacterial/isolation & purification
- Spores, Bacterial/physiology
- Transcription Factors/biosynthesis
- Transcription Factors/genetics
- Transcription Factors/physiology
- beta-Galactosidase/analysis
- beta-Galactosidase/genetics
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Affiliation(s)
- Lijuan Wang
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
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27
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Plomp M, McCaffery JM, Cheong I, Huang X, Bettegowda C, Kinzler KW, Zhou S, Vogelstein B, Malkin AJ. Spore coat architecture of Clostridium novyi NT spores. J Bacteriol 2007; 189:6457-68. [PMID: 17586633 PMCID: PMC1951917 DOI: 10.1128/jb.00757-07] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spores of the anaerobic bacterium Clostridium novyi NT are able to germinate in and destroy hypoxic regions of tumors in experimental animals. Future progress in this area will benefit from a better understanding of the germination and outgrowth processes that are essential for the tumorilytic properties of these spores. Toward this end, we have used both transmission electron microscopy and atomic force microscopy to determine the structure of both dormant and germinating spores. We found that the spores are surrounded by an amorphous layer intertwined with honeycomb parasporal layers. Moreover, the spore coat layers had apparently self-assembled, and this assembly was likely to be governed by crystal growth principles. During germination and outgrowth, the honeycomb layers, as well as the underlying spore coat and undercoat layers, sequentially dissolved until the vegetative cell was released. In addition to their implications for understanding the biology of C. novyi NT, these studies document the presence of proteinaceous growth spirals in a biological organism.
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Affiliation(s)
- Marco Plomp
- Department of Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, CA 94551, USA
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28
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Plomp M, Leighton TJ, Wheeler KE, Hill HD, Malkin AJ. In vitro high-resolution structural dynamics of single germinating bacterial spores. Proc Natl Acad Sci U S A 2007; 104:9644-9. [PMID: 17535925 PMCID: PMC1877984 DOI: 10.1073/pnas.0610626104] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Although significant progress has been achieved in understanding the genetic and biochemical bases of the spore germination process, the structural basis for breaking the dormant spore state remains poorly understood. We have used atomic force microscopy (AFM) to probe the high-resolution structural dynamics of single Bacillus atrophaeus spores germinating under native conditions. Here, we show that AFM can reveal previously unrecognized germination-induced alterations in spore coat architecture and topology as well as the disassembly of outer spore coat rodlet structures. These results and previous studies in other microorganisms suggest that the spore coat rodlets are structurally similar to amyloid fibrils. AFM analysis of the nascent surface of the emerging germ cell revealed a porous network of peptidoglycan fibers. The results are consistent with a honeycomb model structure for synthetic peptidoglycan oligomers determined by NMR. AFM is a promising experimental tool for investigating the morphogenesis of spore germination and cell wall peptidoglycan structure.
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Affiliation(s)
- Marco Plomp
- *Department of Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, L-234, Livermore, CA 94551
| | | | | | - Haley D. Hill
- Department of Chemistry and International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208
| | - Alexander J. Malkin
- *Department of Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, L-234, Livermore, CA 94551
- To whom correspondence should be addressed at:
Department of Chemistry, Materials, and Life Sciences, L-234, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551. E-mail:
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29
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Suo Z, Yang X, Avci R, Kellerman L, Pascual DW, Fries M, Steele A. HEPES-stabilized encapsulation of Salmonella typhimurium. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:1365-74. [PMID: 17241060 DOI: 10.1021/la0621721] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Most bacteria, planktonic and sessile, are encapsulated inside loosely bound extracellular polymeric substance (EPS) in their physiological environment. Imaging a bacterium with its capsule requires lengthy sample preparation to enhance the capsular contrast. In this study, Salmonella typhimurium was investigated using atomic force microscopy for a practical means of imaging an encapsulated bacterium in air. The investigation further aimed to determine the relation between the buffers used for preparing the bacterium and the preservation of the capsular material surrounding it. It was observed that rinsing bacteria with HEPES buffer could stabilize and promote capsule formation, while rinsing with PBS, Tris, or glycine removes most of the capsular EPS. For bacteria rinsed with HEPES and air-dried, the height images showed only the contour of the capsular material, while the phase and amplitude images presented the detailed structures of the bacterial surface, including the flagella encapsulated inside the capsular EPS. The encapsulation was attributed to the cross-linking of the acidic exopolysaccharides mediated by the piperazine moiety of HEPES through electrostatic attraction. This explanation is supported by encapsulated bacteria observed for samples rinsed with N,N'-bis(2-hydroxyethyl)-piperazine solution and by the presence of entrapped HEPES within the dry capsular EPS suggested by micro-Raman spectroscopy.
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Affiliation(s)
- Zhiyong Suo
- Imaging and Chemical Analysis Laboratory, Department of Physics, Montana State University, Bozeman, MT 59717, USA
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