1
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Greer HM, Overton K, Ferguson MA, Spain EM, Darling LEO, Núñez ME, Volle CB. Extracellular Polymeric Substance Protects Some Cells in an Escherichia coli Biofilm from the Biomechanical Consequences of Treatment with Magainin 2. Microorganisms 2021; 9:microorganisms9050976. [PMID: 33946431 PMCID: PMC8147140 DOI: 10.3390/microorganisms9050976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/26/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022] Open
Abstract
Bacterial biofilms have long been recognized as a source of persistent infections and industrial contamination with their intransigence generally attributed to their protective layer of extracellular polymeric substances (EPS). EPS, consisting of secreted nucleic acids, proteins, and polysaccharides, make it difficult to fully eliminate biofilms by conventional chemical or physical means. Since most bacteria are capable of forming biofilms, understanding how biofilms respond to new antibiotic compounds and components of the immune system has important ramifications. Antimicrobial peptides (AMPs) are both potential novel antibiotic compounds and part of the immune response in many different organisms. Here, we use atomic force microscopy to investigate the biomechanical changes that occur in individual cells when a biofilm is exposed to the AMP magainin 2 (MAG2), which acts by permeabilizing bacterial membranes. While MAG2 is able to prevent biofilm initiation, cells in an established biofilm can withstand exposure to high concentrations of MAG2. Treated cells in the biofilm are classified into two distinct populations after treatment: one population of cells is indistinguishable from untreated cells, maintaining cellular turgor pressure and a smooth outer surface, and the second population of cells are softer than untreated cells and have a rough outer surface after treatment. Notably, the latter population is similar to planktonic cells treated with MAG2. The EPS likely reduces the local MAG2 concentration around the stiffer cells since once the EPS was enzymatically removed, all cells became softer and had rough outer surfaces. Thus, while MAG2 appears to have the same mechanism of action in biofilm cells as in planktonic ones, MAG2 cannot eradicate a biofilm unless coupled with the removal of the EPS.
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Affiliation(s)
- Helen M. Greer
- Department of Biology, Cottey College, Nevada, MO 64772, USA; (H.M.G.); (K.O.)
| | - Kanesha Overton
- Department of Biology, Cottey College, Nevada, MO 64772, USA; (H.M.G.); (K.O.)
| | - Megan A. Ferguson
- Department of Chemistry, State University of New York, New Paltz, NY 12561, USA;
| | - Eileen M. Spain
- Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA;
| | - Louise E. O. Darling
- Department of Biological Sciences and Program in Biochemistry, Wellesley College, Wellesley, MA 02481, USA;
| | - Megan E. Núñez
- Department of Chemistry and Program in Biochemistry, Wellesley College, Wellesley, MA 02481, USA;
| | - Catherine B. Volle
- Departments of Biology and Chemistry, Cornell College, Mount Vernon, IA 52314, USA
- Correspondence: ; Tel.: +1-(319)-895-4413
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2
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Kasas S, Malovichko A, Villalba MI, Vela ME, Yantorno O, Willaert RG. Nanomotion Detection-Based Rapid Antibiotic Susceptibility Testing. Antibiotics (Basel) 2021; 10:287. [PMID: 33801939 PMCID: PMC7999052 DOI: 10.3390/antibiotics10030287] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 02/26/2021] [Accepted: 03/07/2021] [Indexed: 01/04/2023] Open
Abstract
Rapid antibiotic susceptibility testing (AST) could play a major role in fighting multidrug-resistant bacteria. Recently, it was discovered that all living organisms oscillate in the range of nanometers and that these oscillations, referred to as nanomotion, stop as soon the organism dies. This finding led to the development of rapid AST techniques based on the monitoring of these oscillations upon exposure to antibiotics. In this review, we explain the working principle of this novel technique, compare the method with current ASTs, explore its application and give some advice about its implementation. As an illustrative example, we present the application of the technique to the slowly growing and pathogenic Bordetella pertussis bacteria.
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Affiliation(s)
- Sandor Kasas
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (A.M.); (M.I.V.)
- Unité Facultaire d’Anatomie et de Morphologie (UFAM), CUMRL, University of Lausanne, 1005 Lausanne, Switzerland
- International Joint Research Group VUB-EPFL NanoBiotechnology and NanoMedicine (NANO), Vrije Universiteit Brussel, 1050 Brussels, Belgium;
| | - Anton Malovichko
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (A.M.); (M.I.V.)
- International Joint Research Group VUB-EPFL NanoBiotechnology and NanoMedicine (NANO), Vrije Universiteit Brussel, 1050 Brussels, Belgium;
| | - Maria Ines Villalba
- Laboratory of Biological Electron Microscopy, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; (A.M.); (M.I.V.)
- International Joint Research Group VUB-EPFL NanoBiotechnology and NanoMedicine (NANO), Vrije Universiteit Brussel, 1050 Brussels, Belgium;
| | - María Elena Vela
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, and CONICET, Diagonal 113 y 64, 1900 La Plata, Argentina;
| | - Osvaldo Yantorno
- Centro de Investigación y Desarrollo en Fermentaciones Industriales (CINDEFI-CONICET-CCT La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata, Argentina;
| | - Ronnie G. Willaert
- International Joint Research Group VUB-EPFL NanoBiotechnology and NanoMedicine (NANO), Vrije Universiteit Brussel, 1050 Brussels, Belgium;
- Research Group Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium
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3
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Pavissich JP, Li M, Nerenberg R. Spatial distribution of mechanical properties in Pseudomonas aeruginosa biofilms, and their potential impacts on biofilm deformation. Biotechnol Bioeng 2021; 118:1564-1575. [PMID: 33415727 DOI: 10.1002/bit.27671] [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: 10/05/2020] [Revised: 01/01/2021] [Accepted: 01/04/2021] [Indexed: 11/08/2022]
Abstract
The mechanical properties of biofilms can be used to predict biofilm deformation under external forces, for example, under fluid flow. We used magnetic tweezers to spatially map the compliance of Pseudomonas aeruginosa biofilms at the microscale, then applied modeling to assess its effects on biofilm deformation. Biofilms were grown in capillary flow cells with Reynolds numbers (Re) ranging from 0.28 to 13.9, bulk dissolved oxygen (DO) concentrations from 1 mg/L to 8 mg/L, and bulk calcium ion (Ca2+ ) concentrations of 0 and 100 mg CaCl2 /L. Higher Re numbers resulted in more uniform biofilm morphologies. The biofilm was stiffer at the center of the flow cell than near the walls. Lower bulk DO led to more stratified biofilms. Higher Ca2+ concentrations led to increased stiffness and more uniform mechanical properties. Using the experimental mechanical properties, fluid-structure interaction models predicted up to 64% greater deformation for heterogeneous biofilms, compared with a homogeneous biofilms with the same average properties. However, the deviation depended on the biofilm morphology and flow regime. Our results show significant spatial mechanical variability exists at the microscale, and that this variability can potentially affect biofilm deformation. The average biofilm mechanical properties, provided in many studies, should be used with caution when predicting biofilm deformation.
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Affiliation(s)
- Juan P Pavissich
- Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile.,Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile.,Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Mengfei Li
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Robert Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
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4
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Wang Z, Liu H, Wang F, Yang Y, Wang X, Chen B, Stampfli MR, Zhou H, Shu W, Brightling CE, Liang Z, Chen R. A Refined View of Airway Microbiome in Chronic Obstructive Pulmonary Disease at Species and Strain-Levels. Front Microbiol 2020; 11:1758. [PMID: 32849386 PMCID: PMC7406711 DOI: 10.3389/fmicb.2020.01758] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/06/2020] [Indexed: 12/12/2022] Open
Abstract
Little is known about the underlying airway microbiome diversity in chronic obstructive pulmonary disease (COPD) at in-depth taxonomic levels. Here we present the first insights on the COPD airway microbiome at species and strain-levels. The full-length 16S rRNA gene was characterized from sputum in 98 COPD patients and 27 age-matched healthy controls, using the Pacific Biosciences sequencing platform. Individual species within the same genus exhibited reciprocal relationships with COPD and disease severity. Species dominant in health can be taken over by another species within the same genus but with potentially increasing pathogenicity in severe COPD patients. Ralstonia mannitolilytica, an opportunistic pathogen, was significantly increased in frequent exacerbators (fold-change = 4.94, FDR P = 0.005). There were distinct patterns of interaction between bacterial species and host inflammatory mediators according to neutrophilic or eosinophilic inflammations, two major airway inflammatory phenotypes in COPD. Haemophilus influenzae, Moraxella catarrhalis, Pseudomonas aeruginosa, and Neisseria meningitidis were associated with enhanced Th1, Th17 and pro-inflammatory mediators, while a group of seven species including Tropheryma whipplei were specifically associated with Th2 mediators related to eosinophilia. We developed an automated pipeline to assign strain-level taxonomy leveraging bacterial intra-genomic 16S allele frequency. Using this pipeline we further resolved three non-typeable H. influenzae strains PittEE, PittGG and 86-028NP with reasonable precision and uncovered strain-level variation related to airway inflammation. In particular, 86-028NP and PittGG strains exhibited inverse associations with Th2 chemokines CCL17 and CCL13, suggesting their abundances may inversely predict eosinophilic inflammation. A systematic comparison of 16S hypervariable regions indicated V1V3 instead of the commonly used V4 region was the best surrogate for airway microbiome. The full-length 16S data augmented the power of functional inference, which slightly better recapitulated the actual metagenomes. This led to the unique identification of butyrate-producing and nitrate reduction pathways as depleted in COPD. Our analysis uncovered finer-scale airway microbial diversity that was previously underappreciated, thus enabled a refined view of the airway microbiome in COPD.
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Affiliation(s)
- Zhang Wang
- Institute of Ecological Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Haiyue Liu
- State Key Laboratory of Organ Failure Research, Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Fengyan Wang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yuqiong Yang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xiaojuan Wang
- Institute of Ecological Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Boxuan Chen
- Institute of Ecological Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Martin R. Stampfli
- Department of Medicine, Firestone Institute for Respiratory Health at St. Joseph’s Healthcare, McMaster University, Hamilton, ON, Canada
| | - Hongwei Zhou
- State Key Laboratory of Organ Failure Research, Microbiome Medicine Center, Division of Laboratory Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China
| | - Wensheng Shu
- Institute of Ecological Science, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Christopher E. Brightling
- Institute for Lung Health, NIHR Leicester Biomedical Research Centre, Department of Respiratory Sciences, University of Leicester, Leicester, United Kingdom
| | - Zhenyu Liang
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Rongchang Chen
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- Pulmonary and Critical Care Department, Shenzhen Institute of Respiratory Diseases, Shenzhen People’s Hospital, Shenzhen, China
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5
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Bae S, Lyons C, Onstad N. A culture-dependent and metagenomic approach of household drinking water from the source to point of use in a developing country. WATER RESEARCH X 2019; 2:100026. [PMID: 31194061 PMCID: PMC6549904 DOI: 10.1016/j.wroa.2019.100026] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 12/11/2018] [Accepted: 12/31/2018] [Indexed: 05/21/2023]
Abstract
Rural households in developing countries rely on communal water supplies and household water frequently becomes contaminated following its collection, transportation and during its storage. Using culture-dependent and -independent techniques, we examined the changes in microbial water quality between communal tap water and household water storage in a rural area of Cameroon, Africa. The culturable fecal indicator bacteria (FIB) were used to assess the potential health risks associated with different household water storage conditions (e.g., type of container and open vs. closed container) and interventions (e.g., water storage days, cleaned on the last day of use, and hygiene practices). Only the amount of days the water was stored significantly differed (p-value < 0.05), which showed that potential health risks increased when water was stored for more than 3 days. The higher abundance of molecular FIB in biofilm than household water suggested that omnipresent biofilm in household water could potential health risk. The high-throughput sequencing revealed that the most abundant phylum was Proteobacteria, followed by Actinobacteria and Bacteroidetes in both the water and the biofilm samples. Bacterial genera seen in biofilm bacteria, such as Pseudomonas, Acinetobacter and Comamonas. Acinetobacter, Chryseobacterium, Stenotrophomonas and Corynebacterium, were relatively more abundant in the biofilm than in the water. Potential bacterial pathogens including Acinetobacter baumannii, Citrobacter freundii, Stenotrophomonas maltophilia and Haemophilus influenza, were detected in household water and biofilm. The microbial quality might be affected by water-storage time and households repeatedly using the same water storage containers without proper sanitization, triggering microbial regrowth and biofilm formation on water containers. Higher bacterial diversity and potentially pathogenic bacteria found in the biofilm samples of a household water supply are unhealthy for the house's inhabitants. It is important to develop interventions aimed at preventing the formation of these dangerous biofilms in a communal water supply.
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Affiliation(s)
- Sungwoo Bae
- Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore, 117576, Singapore
- Corresponding author.
| | - Colleen Lyons
- Department of Civil, Architectural and Environmental Engineering, The University of Texas, Austin, 301E. Dean Keeton St, Austin, TX, 78712, USA
| | - Nora Onstad
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, 1304 W. Pennsylvania Ave, Urbana, IL, 61801, USA
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6
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Dsouza R, Won J, Monroy GL, Hill MC, Porter RG, Novak MA, Boppart SA. In vivo detection of nanometer-scale structural changes of the human tympanic membrane in otitis media. Sci Rep 2018; 8:8777. [PMID: 29884809 PMCID: PMC5993811 DOI: 10.1038/s41598-018-26514-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 05/11/2018] [Indexed: 01/25/2023] Open
Abstract
Otitis media (OM) is a common ear infection and a leading cause of conductive hearing loss in the pediatric population. Current technologies such as otoscopy, pneumatic otoscopy, tympanometry, and acoustic reflectometry are used to diagnose OM, which can reasonably diagnose the infection with a sensitivity and specificity of 50-90% and 60-90%, respectively. However, these techniques provide limited information about the physical architecture of the tympanic membrane (TM), or what may lie behind it. Here, we report the detection of nanometer-scale structural changes of the TM using nano-sensitive optical coherence tomography (nsOCT). In total, an image dataset from 65 pediatric subjects from three different groups (normal, acute OM, and chronic OM) and with longitudinal image-based analysis of ear infections were included in this study. The nsOCT data were correlated with physician diagnosis and with OCT thickness measurements and were found to be in good agreement with these results. We report that nsOCT detects in vivo structural deformations of the TM earlier than OCT alone, and enhances the detection sensitivity of OCT measurements. This unique technique for early detection of nano-scale structural modifications in the TM has the potential to aid in our understanding of microbiological effects, and possibly for early diagnosis and more effective treatment of OM.
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Affiliation(s)
- Roshan Dsouza
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Jungeun Won
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Guillermo L Monroy
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Malcolm C Hill
- Department of Pediatrics, Carle Foundation Hospital, Urbana, Illinois, USA
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Ryan G Porter
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Otolaryngology, Carle Foundation Hospital, Urbana, Illinois, USA
| | - Michael A Novak
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Department of Otolaryngology, Carle Foundation Hospital, Urbana, Illinois, USA
| | - Stephen A Boppart
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Carle-Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
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7
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AFM contribution to unveil pro- and eukaryotic cell mechanical properties. Semin Cell Dev Biol 2018; 73:177-187. [DOI: 10.1016/j.semcdb.2017.08.032] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 07/28/2017] [Accepted: 08/14/2017] [Indexed: 02/06/2023]
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8
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Ahearn CP, Gallo MC, Murphy TF. Insights on persistent airway infection by non-typeable Haemophilus influenzae in chronic obstructive pulmonary disease. Pathog Dis 2017; 75:3753446. [PMID: 28449098 PMCID: PMC5437125 DOI: 10.1093/femspd/ftx042] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 04/28/2017] [Indexed: 12/21/2022] Open
Abstract
Non-typeable Haemophilus influenzae (NTHi) is the most common bacterial cause of infection of the lower airways in adults with chronic obstructive pulmonary disease (COPD). Infection of the COPD airways causes acute exacerbations, resulting in substantial morbidity and mortality. NTHi has evolved multiple mechanisms to establish infection in the hostile environment of the COPD airways, allowing the pathogen to persist in the airways for months to years. Persistent infection of the COPD airways contributes to chronic airway inflammation that increases symptoms and accelerates the progressive loss of pulmonary function, which is a hallmark of the disease. Persistence mechanisms of NTHi include the expression of multiple redundant adhesins that mediate binding to host cellular and extracellular matrix components. NTHi evades host immune recognition and clearance by invading host epithelial cells, forming biofilms, altering gene expression and displaying surface antigenic variation. NTHi also binds host serum factors that confer serum resistance. Here we discuss the burden of COPD and the role of NTHi infections in the course of the disease. We provide an overview of NTHi mechanisms of persistence that allow the pathogen to establish a niche in the hostile COPD airways.
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Affiliation(s)
- Christian P. Ahearn
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Mary C. Gallo
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Timothy F. Murphy
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Clinical and Translational Research Center, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
- Division of Infectious Disease, Department of Medicine, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
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9
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Fahs A, Quilès F, Jamal D, Humbert F, Francius G. In Situ Analysis of Bacterial Extracellular Polymeric Substances from a Pseudomonas fluorescens Biofilm by Combined Vibrational and Single Molecule Force Spectroscopies. J Phys Chem B 2014; 118:6702-13. [DOI: 10.1021/jp5030872] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ahmad Fahs
- Université de Lorraine, Laboratoire de Chimie Physique
et Microbiologie pour l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour
l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
| | - Fabienne Quilès
- Université de Lorraine, Laboratoire de Chimie Physique
et Microbiologie pour l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour
l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
| | - Dima Jamal
- Université de Lorraine, Laboratoire de Chimie Physique
et Microbiologie pour l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour
l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
| | - François Humbert
- Université de Lorraine, Laboratoire de Chimie Physique
et Microbiologie pour l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour
l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
| | - Grégory Francius
- Université de Lorraine, Laboratoire de Chimie Physique
et Microbiologie pour l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
- CNRS, Laboratoire de Chimie Physique et Microbiologie pour
l’Environnement, UMR 7564, Villers-lès-Nancy, F-54600, France
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10
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Sharma S, Lavender S, Woo J, Guo L, Shi W, Kilpatrick-Liverman L, Gimzewski JK. Nanoscale characterization of effect of L-arginine on Streptococcus mutans biofilm adhesion by atomic force microscopy. MICROBIOLOGY-SGM 2014; 160:1466-1473. [PMID: 24763427 DOI: 10.1099/mic.0.075267-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A major aetiological factor of dental caries is the pathology of the dental plaque biofilms. The amino acid L-arginine (Arg) is found naturally in saliva as a free molecule or as a part of salivary peptides and proteins. Plaque bacteria metabolize Arg to produce alkali and neutralize glycolytic acids, promoting a less cariogenous oral microbiome. Here, we explored an alternative and complementary mechanism of action of Arg using atomic force microscopy. The nanomechanical properties of Streptococcus mutans biofilm extracellular matrix were characterized under physiological buffer conditions. We report the effect of Arg on the adhesive behaviour and structural properties of extracellular polysaccharides in S. mutans biofilms. High-resolution imaging of biofilm surfaces can reveal additional structural information on bacterial cells embedded within the surrounding extracellular matrix. A dense extracellular matrix was observed in biofilms without Arg compared to those grown in the presence of Arg. S. mutans biofilms grown in the presence of Arg could influence the production and/or composition of extracellular membrane glucans and thereby affect their adhesion properties. Our results suggest that the presence of Arg in the oral cavity could influence the adhesion properties of S. mutans to the tooth surface.
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Affiliation(s)
- Shivani Sharma
- California NanoSystems Institute, University of California, Los Angeles, CA, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | | | - JungReem Woo
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
| | - Lihong Guo
- Department of Dentistry, University of California, Los Angeles, CA, USA
| | - Wenyuan Shi
- Department of Dentistry, University of California, Los Angeles, CA, USA
| | | | - James K Gimzewski
- International Center for Materials Nanoarchitectonics Satellite (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan.,Jonsson Comprehensive Cancer Center, University of California, Los Angeles, CA, USA.,California NanoSystems Institute, University of California, Los Angeles, CA, USA.,Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, USA
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11
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Qin L, Kida Y, Ishiwada N, Ohkusu K, Kaji C, Sakai Y, Watanabe K, Furumoto A, Ichinose A, Watanabe H. The relationship between biofilm formations and capsule in Haemophilus influenzae. J Infect Chemother 2014; 20:151-6. [DOI: 10.1016/j.jiac.2013.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/27/2013] [Accepted: 06/17/2013] [Indexed: 11/30/2022]
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12
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Longo G, Kasas S. Effects of antibacterial agents and drugs monitored by atomic force microscopy. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2014; 6:230-44. [PMID: 24616433 DOI: 10.1002/wnan.1258] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/06/2014] [Accepted: 01/13/2014] [Indexed: 11/07/2022]
Abstract
Originally invented for topographic imaging, atomic force microscopy (AFM) has evolved into a multifunctional biological toolkit, enabling to measure structural and functional details of cells and molecules. Its versatility and the large scope of information it can yield make it an invaluable tool in any biologically oriented laboratory, where researchers need to perform characterizations of living samples as well as single molecules in quasi-physiological conditions and with nanoscale resolution. In the last 20 years, AFM has revolutionized the characterization of microbial cells by allowing a better understanding of their cell wall and of the mechanism of action of drugs and by becoming itself a powerful diagnostic tool to study bacteria. Indeed, AFM is much more than a high-resolution microscopy technique. It can reconstruct force maps that can be used to explore the nanomechanical properties of microorganisms and probe at the same time the morphological and mechanical modifications induced by external stimuli. Furthermore it can be used to map chemical species or specific receptors with nanometric resolution directly on the membranes of living organisms. In summary, AFM offers new capabilities and a more in-depth insight in the structure and mechanics of biological specimens with an unrivaled spatial and force resolution. Its application to the study of bacteria is extremely significant since it has already delivered important information on the metabolism of these small microorganisms and, through new and exciting technical developments, will shed more light on the real-time interaction of antimicrobial agents and bacteria.
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Affiliation(s)
- Giovanni Longo
- Ecole Polytechnique Fédérale de Lausanne, LPMV, Lausanne, Switzerland; Istituto Superiore di Sanità, Rome, Italy
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13
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Cayé-Thomasen P, Hermansson A, Bakaletz L, Hellstrøm S, Kanzaki S, Kerschner J, Lim D, Lin J, Mason K, Spratley J. Panel 3: Recent advances in anatomy, pathology, and cell biology in relation to otitis media pathogenesis. Otolaryngol Head Neck Surg 2013; 148:E37-51. [PMID: 23536531 DOI: 10.1177/0194599813476257] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 01/08/2012] [Indexed: 12/11/2022]
Abstract
BACKGROUND AND OBJECTIVES The pathogenesis of otitis media (OM) involves a number of factors related to the anatomy, pathology, and cell biology of the middle ear, the mastoid, the Eustachian tube, and the nasopharynx. Although some issues of pathogenesis are fairly well established, others are only marginally indicated by current knowledge, and yet others remain undisclosed. The objective of this article is to provide a state-of-the-art review on recent scientific achievements in the pathogenesis of OM, as related to anatomy, pathology, and cell biology. DATA SOURCES PubMed, Ovid Medline, and Cochrane Library. REVIEW METHODS Articles published on the pathogenesis of OM and the anatomy, pathology, and cell biology of the middle ear, the mastoid, the Eustachian tube, and the nasopharynx between January 2007 and June 2011 were identified. Among almost 1900 abstracts, the authors selected 130 articles for full article review and inclusion in this report. RESULTS New knowledge on a number of issues emerged, including cell-specific expression and function of fluid transportation and innate immune system molecules, mucous cell metaplasia, mucin expression, bacterial adherence, and epithelial internalization, as well as the occurrence, composition, dynamics, and potential role of bacterial biofilm. In addition, the potential role of gastroesophageal reflux disease and cigarette smoke exposure has been explored further. CONCLUSIONS AND IMPLICATIONS FOR PRACTICE Over the past 4 years, considerable scientific progress has been made on the pathogenesis of OM, as related to issues of anatomy, pathology, and cell biology. Based on these new achievements and a sustained lack of essential knowledge, suggestions for future research are outlined.
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Affiliation(s)
- Per Cayé-Thomasen
- Department of Oto-rhino-laryngology, Head and Neck Surgery, University Hospital of Copenhagen, Copenhagen, Denmark.
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14
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Otero J, Baños R, González L, Torrents E, Juárez A, Puig-Vidal M. Quartz tuning fork studies on the surface properties of Pseudomonas aeruginosa during early stages of biofilm formation. Colloids Surf B Biointerfaces 2013; 102:117-23. [DOI: 10.1016/j.colsurfb.2012.08.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 07/19/2012] [Accepted: 08/07/2012] [Indexed: 11/29/2022]
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Abstract
Pili or fimbriae are recognized as essential virulence determinants assembled on the bacterial surface. Gram-positive bacteria produce covalently linked pilus structures that are distinct from gram-negative counterparts. In this chapter, we describe three commonly used techniques to extract, detect, and visualize pili from gram-positive bacteria: (1) Western blot analysis, (2) Immuno-Electron Microscopy, and (3) Atomic Force Microscopy.
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Böl M, Ehret AE, Bolea Albero A, Hellriegel J, Krull R. Recent advances in mechanical characterisation of biofilm and their significance for material modelling. Crit Rev Biotechnol 2012; 33:145-71. [DOI: 10.3109/07388551.2012.679250] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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17
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Rheinlaender J, Gräbner A, Ott L, Burkovski A, Schäffer TE. Contour and persistence length of Corynebacterium diphtheriae pili by atomic force microscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 41:561-70. [DOI: 10.1007/s00249-012-0818-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 04/05/2012] [Accepted: 04/21/2012] [Indexed: 10/28/2022]
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18
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Shalá AA, Restrepo S, González Barrios AF. A network model for biofilm development in Escherichia coli K-12. Theor Biol Med Model 2011; 8:34. [PMID: 21939518 PMCID: PMC3224578 DOI: 10.1186/1742-4682-8-34] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 09/22/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In nature, bacteria often exist as biofilms. Biofilms are communities of microorganisms attached to a surface. It is clear that biofilm-grown cells harbor properties remarkably distinct from planktonic cells. Biofilms frequently complicate treatments of infections by protecting bacteria from the immune system, decreasing antibiotic efficacy and dispersing planktonic cells to distant body sites. In this work, we employed enhanced Boolean algebra to model biofilm formation. RESULTS The network obtained describes biofilm formation successfully, assuming - in accordance with the literature - that when the negative regulators (RscCD and EnvZ/OmpR) are off, the positive regulator (FlhDC) is on. The network was modeled under three different conditions through time with satisfactory outcomes. Each cluster was constructed using the K-means/medians Clustering Support algorithm on the basis of published Affymetrix microarray gene expression data from biofilm-forming bacteria and the planktonic state over four time points for Escherichia coli K-12. CONCLUSIONS The different phenotypes obtained demonstrate that the network model of biofilm formation can simulate the formation or repression of biofilm efficiently in E. coli K-12.
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Affiliation(s)
- Andrew A Shalá
- Departamento de Ingeniería Química, Universidad de los Andes, Bogotá, Colombia
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19
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Chao Y, Zhang T. Optimization of fixation methods for observation of bacterial cell morphology and surface ultrastructures by atomic force microscopy. Appl Microbiol Biotechnol 2011; 92:381-92. [PMID: 21881891 PMCID: PMC3181414 DOI: 10.1007/s00253-011-3551-5] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 08/06/2011] [Accepted: 08/13/2011] [Indexed: 11/14/2022]
Abstract
Fixation ability of five common fixation solutions, including 2.5% glutaraldehyde, 10% formalin, 4% paraformaldehyde, methanol/acetone (1:1), and ethanol/acetic acid (3:1) were evaluated by using atomic force microscopy in the present study. Three model bacteria, i.e., Escherichia coli, Pseudomonas putida, and Bacillus subtilis were applied to observe the above fixation methods for the morphology preservation of bacterial cells and surface ultrastructures. All the fixation methods could effectively preserve cell morphology. However, for preserving bacterial surface ultrastructures, the methods applying aldehyde fixations performed much better than those using alcohols, since the alcohols could detach the surface filaments (i.e., flagella and pili) significantly. Based on the quantitative and qualitative assessments, the 2.5% glutaraldehyde was proposed as a promising fixation solution both for observing morphology of both bacterial cell and surface ultrastructures, while the methonal/acetone mixture was the worst fixation solution which may obtain unreliable results.
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Affiliation(s)
- Yuanqing Chao
- Environmental Biotechnology Laboratory, The University of Hong Kong, Pokfulam Road, Hong Kong, SAR, China
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20
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Ramachandran S, Teran Arce F, Lal R. Potential role of atomic force microscopy in systems biology. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2011; 3:702-16. [PMID: 21766465 DOI: 10.1002/wsbm.154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Systems biology is a quantitative approach for understanding a biological system at its global level through systematic perturbation and integrated analysis of all its components. Simultaneous acquisition of information data sets pertaining to the system components (e.g., genome, proteome) is essential to implement this approach. There are limitations to such an approach in measuring gene expression levels and accounting for all proteins in the system. The success of genomic studies is critically dependent on polymerase chain reaction (PCR) for its amplification, but PCR is very uneven in amplifying the samples, ineffective in scarce samples and unreliable in low copy number transcripts. On the other hand, lack of amplifying techniques for proteins critically limits their identification to only a small fraction of high concentration proteins. Atomic force microscopy (AFM), AFM cantilever sensors, and AFM force spectroscopy in particular, could address these issues directly. In this article, we reviewed and assessed their potential role in systems biology.
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Trappetti C, Ogunniyi AD, Oggioni MR, Paton JC. Extracellular matrix formation enhances the ability of Streptococcus pneumoniae to cause invasive disease. PLoS One 2011; 6:e19844. [PMID: 21611130 PMCID: PMC3097209 DOI: 10.1371/journal.pone.0019844] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 04/04/2011] [Indexed: 11/22/2022] Open
Abstract
During infection, pneumococci exist mainly in sessile biofilms rather than in planktonic form, except during sepsis. However, relatively little is known about how biofilms contribute to pneumococcal pathogenesis. Here, we carried out a biofilm assay on opaque and transparent variants of a clinical serotype 19F strain WCH159. After 4 days incubation, scanning electron microscopy revealed that opaque biofilm bacteria produced an extracellular matrix, whereas the transparent variant did not. The opaque biofilm-derived bacteria translocated from the nasopharynx to the lungs and brain of mice, and showed 100-fold greater in vitro adherence to A549 cells than transparent bacteria. Microarray analysis of planktonic and sessile bacteria from transparent and opaque variants showed differential gene expression in two operons: the lic operon, which is involved in choline uptake, and in the two-component system, ciaRH. Mutants of these genes did not form an extracellular matrix, could not translocate from the nasopharynx to the lungs or the brain, and adhered poorly to A549 cells. We conclude that only the opaque phenotype is able to form extracellular matrix, and that the lic operon and ciaRH contribute to this process. We propose that during infection, extracellular matrix formation enhances the ability of pneumococci to cause invasive disease.
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Affiliation(s)
- Claudia Trappetti
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia
| | - Abiodun D. Ogunniyi
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia
- * E-mail:
| | - Marco R. Oggioni
- Laboratorio di Microbiologia Molecolare e Biotecnologia, Dipartimento di Biologia Molecolare, Università di Siena, Siena, Italy
| | - James C. Paton
- Research Centre for Infectious Diseases, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, South Australia, Australia
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Lower SK, Yongsunthon R, Casillas-Ituarte NN, Taylor ES, DiBartola AC, Lower BH, Beveridge TJ, Buck AW, Fowler VG. A tactile response in Staphylococcus aureus. Biophys J 2011; 99:2803-11. [PMID: 21044577 DOI: 10.1016/j.bpj.2010.08.063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Revised: 07/16/2010] [Accepted: 08/30/2010] [Indexed: 01/22/2023] Open
Abstract
It is well established that bacteria are able to respond to temporal gradients (e.g., by chemotaxis). However, it is widely held that prokaryotes are too small to sense spatial gradients. This contradicts the common observation that the vast majority of bacteria live on the surface of a solid substrate (e.g., as a biofilm). Herein we report direct experimental evidence that the nonmotile bacterium Staphylococcus aureus possesses a tactile response, or primitive sense of touch, that allows it to respond to spatial gradients. Attached cells recognize their substrate interface and localize adhesins toward that region. Braille-like avidity maps reflect a cell's biochemical sensory response and reveal ultrastructural regions defined by the actual binding activity of specific proteins.
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Allison DP, Mortensen NP, Sullivan CJ, Doktycz MJ. Atomic force microscopy of biological samples. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2011; 2:618-34. [PMID: 20672388 DOI: 10.1002/wnan.104] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The ability to evaluate structural-functional relationships in real time has allowed scanning probe microscopy (SPM) to assume a prominent role in post genomic biological research. In this mini-review, we highlight the development of imaging and ancillary techniques that have allowed SPM to permeate many key areas of contemporary research. We begin by examining the invention of the scanning tunneling microscope (STM) by Binnig and Rohrer in 1982 and discuss how it served to team biologists with physicists to integrate high-resolution microscopy into biological science. We point to the problems of imaging nonconductive biological samples with the STM and relate how this led to the evolution of the atomic force microscope (AFM) developed by Binnig, Quate, and Gerber, in 1986. Commercialization in the late 1980s established SPM as a powerful research tool in the biological research community. Contact mode AFM imaging was soon complemented by the development of non-contact imaging modes. These non-contact modes eventually became the primary focus for further new applications including the development of fast scanning methods. The extreme sensitivity of the AFM cantilever was recognized and has been developed into applications for measuring forces required for indenting biological surfaces and breaking bonds between biomolecules. Further functional augmentation to the cantilever tip allowed development of new and emerging techniques including scanning ion-conductance microscopy (SICM), scanning electrochemical microscope (SECM), Kelvin force microscopy (KFM) and scanning near field ultrasonic holography (SNFUH).
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Affiliation(s)
- David P Allison
- Biosciences Division, Oak Ridge National Laboratory, TN 37831-6445, USA
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Wright CJ, Shah MK, Powell LC, Armstrong I. Application of AFM from microbial cell to biofilm. SCANNING 2010; 32:134-49. [PMID: 20648545 DOI: 10.1002/sca.20193] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Atomic Force Microscopy (AFM) has proven itself over recent years as an essential tool for the analysis of microbial systems. This article will review how AFM has been used to study microbial systems to provide unique insight into their behavior and relationship with their environment. Immobilization of live cells has enabled AFM imaging and force measurement to provide understanding of the structure and function of numerous microbial cells. At the macromolecular level AFM investigation into the properties of surface macromolecules and the energies associated with their mechanical conformation and functionality has helped unravel the complex interactions of microbial cells. At the level of the whole cell AFM has provided an integrated analysis of how the microbial cell exploits its environment through its selective, adaptable interface, the cell surface. In addition to these areas of study the AFM investigation of microbial biofilms has been vital for industrial and medical process analysis. There exists a tremendous potential for the future application of AFM to microbial systems and this has been strengthened by the trend to use AFM in combination with other characterization methods, such as confocal microscopy and Raman spectroscopy, to elucidate dynamic cellular processes.
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Affiliation(s)
- Chris J Wright
- Multidisciplinary Nanotechnology Centre, School of Engineering, Swansea University, Swansea, United Kingdom.
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25
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Park BJ, Abu-Lail NI. Variations in the Nanomechanical Properties of Virulent and Avirulent Listeria monocytogenes. SOFT MATTER 2010; 6:3898-3909. [PMID: 20871743 PMCID: PMC2944262 DOI: 10.1039/b927260g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Atomic force microscopy (AFM) was used to quantify both the nanomechanical properties of pathogenic (ATCC 51776 & EGDe) and non-pathogenic (ATCC 15313 & HCC25) Listeria monocytogenes strains and the conformational properties of their surface biopolymers. The nanomechanical properties of the various L. monocytogenes strains were quantified in terms of Young's moduli of cells. To estimate Young's moduli, the classic Hertz model of contact mechanics and a modified version of it that takes into account substrate effects were used to fit the AFM nanoindentation-force measurements collected while pushing onto the bacterial surface biopolymer brush. When compared, the classic Hertz model always predicted higher Young's moduli values of bacterial cell elasticity compared to the modified Hertz model. On average, the modified Hertz model showed that virulent strains are approximately twice as rigid (88.1 ± 14.5 KPa) as the avirulent strains (47.3 ± 7.6 kPa). To quantify the conformational properties of L. monocytogenes' strains surface biopolymers, two models were used. First, the entropic-based, statistical mechanical, random walk formulation, the wormlike chain (WLC) model was used to estimate the elastic properties of the bacterial surface molecules. The WLC model results indicated that the virulent strains are characterized by a more flexible surface biopolymers as indicated by shorter persistence lengths (L(p) = 0.21 ± 0.08 nm) compared to the avirulent strains (L(p) = 0.24 ± 0.14 nm). Second, a steric model developed to describe the repulsive forces measured between the AFM tip and bacterial surface biopolymers indicated that the virulent strains are characterized by crowded and longer biopolymer brushes compared to those of the avirulent strains. Finally, scaling relationships developed for grafted polyelectrolyte brushes indicated L. monocytogenes strains' biopolymer brushes are charged. Collectively, our data indicate that the conformational properties of the bacterial surface biopolymers and their surface densities play an important role in controlling the overall bacterial cell elasticity.
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Affiliation(s)
| | - Nehal I. Abu-Lail
- Corresponding Author: Nehal I. Abu-Lail, Ph.D., Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164-2710, United States, , 509-335-4961
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Differential lipopolysaccharide core capping leads to quantitative and correlated modifications of mechanical and structural properties in Pseudomonas aeruginosa biofilms. J Bacteriol 2009; 191:6618-31. [PMID: 19717596 DOI: 10.1128/jb.00698-09] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial biofilms are responsible for the majority of all microbial infections and have profound impact on industrial and geochemical processes. While many studies documented phenotypic differentiation and gene regulation of biofilms, the importance of their structural and mechanical properties is poorly understood. Here we investigate how changes in lipopolysaccharide (LPS) core capping in Pseudomonas aeruginosa affect biofilm structure through modification of adhesive, cohesive, and viscoelastic properties at an early stage of biofilm development. Microbead force spectroscopy and atomic force microscopy were used to characterize P. aeruginosa biofilm interactions with either glass substrata or bacterial lawns. Using isogenic migA, wapR, and rmlC mutants with defined LPS characteristics, we observed significant changes in cell mechanical properties among these strains compared to wild-type strain PAO1. Specifically, truncation of core oligosaccharides enhanced both adhesive and cohesive forces by up to 10-fold, whereas changes in instantaneous elasticity were correlated with the presence of O antigen. Using confocal laser scanning microscopy to quantify biofilm structural changes with respect to differences in LPS core capping, we observed that textural parameters varied with adhesion or the inverse of cohesion, while areal and volumetric parameters were linked to adhesion, cohesion, or the balance between them. In conclusion, this report demonstrated for the first time that changes in LPS expression resulted in quantifiable cellular mechanical changes that were correlated with structural changes in bacterial biofilms. Thus, the interplay between architectural and functional properties may be an important contributor to bacterial community survival.
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