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Kaneko S, Hirotaka S, Tsujii M, Maruyama H, Uozumi N, Arai F. Instantaneous extracellular solution exchange for concurrent evaluation of membrane permeability of single cells. LAB ON A CHIP 2024; 24:281-291. [PMID: 38086698 DOI: 10.1039/d3lc00633f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
The osmotic stress imposed on microorganisms by hypotonic conditions is perceived to regulate water and solute flux via cell membranes, which are crucial for survival. Some cells that fail to perceive osmotic stress die because this results in the rupture of the cell membrane. The flux through the membrane is characterized by the membrane permeability, which is measured using a stopped-flow apparatus in response to a millisecond-order osmolarity change. However, the obtained data are an ensemble average of each cell response. Additionally, the measurement of permeability, considering cellular viability, contributes to a more accurate evaluation of osmoadaptation. Here, we present a novel on-chip instantaneous extracellular solution exchange method using an air-liquid interface. The presented method provides a concurrent evaluation at the single-cell level in response to a millisecond-order osmotic shock, considering cellular viability by solution exchange. This method utilizes a liquid bridge with a locally formed droplet on the surface of a micropillar fabricated inside a microchannel. We evaluated a solution exchange time of 3.6 ms and applied this method to Synechocystis PCC 6803 under two different osmolarity conditions. The live/dead ratio of 1 M to 0.5 M osmotic down shock condition was 78.8/21.2% while that of 1 M to 0.25 M osmotic down shock condition was 40.0/60.0%. We evaluated the water permeability of two groups: cells that were still live before and after osmotic shock (hereafter named cell type 1), and cells that were live before but were dead 10 minutes after osmotic shock (hereafter named cell type 2). The results indicated that the water permeability of cell type 2 was higher than that of cell type 1. The results obtained using the presented methods confirmed that the effect of osmotic stress can be accurately evaluated using single-cell analysis.
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Affiliation(s)
- Shingo Kaneko
- Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Sugiura Hirotaka
- Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
| | - Masaru Tsujii
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-07, Aobayama, Aoba-ku, Sendai 980-8579, Japan
| | - Hisataka Maruyama
- Department of Micro-Nano Mechanical Science and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, 6-6-07, Aobayama, Aoba-ku, Sendai 980-8579, Japan
| | - Fumihito Arai
- Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
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2
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Penman R, Kariuki R, Shaw ZL, Dekiwadia C, Christofferson AJ, Bryant G, Vongsvivut J, Bryant SJ, Elbourne A. Gold nanoparticle adsorption alters the cell stiffness and cell wall bio-chemical landscape of Candida albicans fungal cells. J Colloid Interface Sci 2024; 654:390-404. [PMID: 37852025 DOI: 10.1016/j.jcis.2023.10.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 09/08/2023] [Accepted: 10/04/2023] [Indexed: 10/20/2023]
Abstract
HYPOTHESIS Nanomaterials have been extensively investigated for a wide range of biomedical applications, including as antimicrobial agents, drug delivery vehicles, and diagnostic devices. The commonality between these biomedical applications is the necessity for the nanoparticle to interact with or pass through the cellular wall and membrane. Cell-nanomaterial interactions/uptake can occur in various ways, including adhering to the cell wall, forming aggregates on the surface, becoming absorbed within the cell wall itself, or transversing into the cell cytoplasm. These interactions are common to mammalian cells, bacteria, and yeast cells. This variety of interactions can cause changes to the integrity of the cell wall and the cell overall, but the precise mechanisms underpinning such interactions remain poorly understood. Here, we investigate the interaction between commonly investigated gold nanoparticles (AuNPs) and the cell wall/membrane of a model fungal cell to explore the general effects of interaction and uptake. EXPERIMENTS The interactions between 100 nm citrate-capped AuNPs and the cell wall of Candida albicans fungal cells were studied using a range of advanced microscopy techniques, including atomic force microscopy, confocal laser scanning microscopy, scanning electron microscopy, transmission electron microscopy, and synchrotron-FTIR micro-spectroscopy. FINDINGS In most cases, particles adhered on the cell surface, although instances of particles being up-taken into the cell cytoplasm and localised within the cell wall and membrane were also observed. There was a measurable increase in the stiffness of the fungal cell after AuNPs were introduced. Analysis of the synchrotron-FTIR data showed significant changes in spectral features associated with phospholipids and proteins after exposure to AuNPs.
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Affiliation(s)
- Rowan Penman
- School of Science, STEM College, RMIT University, Melbourne, VIC 3001, Australia
| | - Rashad Kariuki
- School of Science, STEM College, RMIT University, Melbourne, VIC 3001, Australia
| | - Z L Shaw
- School of Engineering, STEM College, RMIT University, Melbourne, VIC 3001, Australia
| | - Chaitali Dekiwadia
- RMIT Microscopy and Microanalysis Facility (RMMF), RMIT University, Melbourne, Victoria 3001, Australia
| | | | - Gary Bryant
- School of Science, STEM College, RMIT University, Melbourne, VIC 3001, Australia
| | - Jitraporn Vongsvivut
- Infrared Microspectroscopy (IRM) Beamline, ANSTO - Australian Synchrotron, Clayton, VIC 3168, Australia
| | - Saffron J Bryant
- School of Science, STEM College, RMIT University, Melbourne, VIC 3001, Australia.
| | - Aaron Elbourne
- School of Science, STEM College, RMIT University, Melbourne, VIC 3001, Australia.
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3
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Rabinowitz J, Hartel AJW, Dayton H, Fabbri JD, Jo J, Dietrich LEP, Shepard KL. Charge Mapping of Pseudomonas aeruginosa Using a Hopping Mode Scanning Ion Conductance Microscopy Technique. Anal Chem 2023; 95:5285-5292. [PMID: 36920847 PMCID: PMC10359948 DOI: 10.1021/acs.analchem.2c05303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Scanning ion conductance microscopy (SICM) is a topographic imaging technique capable of probing biological samples in electrolyte conditions. SICM enhancements have enabled surface charge detection based on voltage-dependent signals. Here, we show how the hopping mode SICM method (HP-SICM) can be used for rapid and minimally invasive surface charge mapping. We validate our method usingPseudomonas aeruginosaPA14 (PA) cells and observe a surface charge density of σPA = -2.0 ± 0.45 mC/m2 that is homogeneous within the ∼80 nm lateral scan resolution. This biological surface charge is detected from at least 1.7 μm above the membrane (395× the Debye length), and the long-range charge detection is attributed to electroosmotic amplification. We show that imaging with a nanobubble-plugged probe reduces perturbation of the underlying sample. We extend the technique to PA biofilms and observe a charge density exceeding -20 mC/m2. We use a solid-state calibration to quantify surface charge density and show that HP-SICM cannot be quantitatively described by a steady-state finite element model. This work contributes to the body of scanning probe methods that can uniquely contribute to microbiology and cellular biology.
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Affiliation(s)
- Jake Rabinowitz
- Department of Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Andreas J W Hartel
- Department of Electrical Engineering, Columbia University, New York, New York 10027, United States.,Department of Biology, Columbia University, New York, New York 10027, United States
| | - Hannah Dayton
- Department of Biology, Columbia University, New York, New York 10027, United States
| | - Jason D Fabbri
- Department of Electrical Engineering, Columbia University, New York, New York 10027, United States
| | - Jeanyoung Jo
- Department of Biology, Columbia University, New York, New York 10027, United States
| | - Lars E P Dietrich
- Department of Biology, Columbia University, New York, New York 10027, United States
| | - Kenneth L Shepard
- Department of Electrical Engineering, Columbia University, New York, New York 10027, United States
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4
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Savin N, Erofeev A, Kolmogorov V, Salikhov S, Efremov Y, Timashev P, Grammatikova N, Levshin I, Edwards C, Korchev Y, Gorelkin P. Scanning ion-conductance microscopy technique for studying the topography and mechanical properties of Candida parapsilosis yeast microorganisms. Biomater Sci 2023; 11:611-617. [PMID: 36477151 DOI: 10.1039/d2bm00964a] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Super-resolution microscopy is widely used in the development of novel antimicrobial testing in vitro. In the presented work, a scanning protocol was developed by the method of scanning ion-conducting microscopy (SICM), which makes it possible to study microorganisms without rigid fixation and in saline, obtaining an index map of nanosized structures. The effect of azole and echinocandins drugs on the morphology and mechanical properties of Candida parapsilosis yeast was studied. The findings are consistent with previously proposed drug mechanisms and reports that have examined antifungal agents using AFM, SEM, and TEM. We have shown that the SICM method is capable of scanning and detecting the nanomechanical properties of yeast non-invasively.
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Affiliation(s)
| | - Alexander Erofeev
- NUST MISiS, Moscow, Russian Federation. .,Lomonosov Moscow State University, Moscow, Russian Federation
| | - Vasilii Kolmogorov
- NUST MISiS, Moscow, Russian Federation. .,Lomonosov Moscow State University, Moscow, Russian Federation
| | | | - Yuri Efremov
- Institute for Regenerative Medicine I. M. Sechenov, Moscow, Russian Federation
| | - Peter Timashev
- Institute for Regenerative Medicine I. M. Sechenov, Moscow, Russian Federation.,World-class Research Center "Digital Biodesign and Personalized Healthcare", Moscow, Russian Federation.,Chemistry department Lomonosov Moscow State University, Moscow, Russian Federation
| | | | - Igor Levshin
- G. F. Gauze Research Institute for New Antibiotics, Moscow, Russian Federation
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Water Stress-Driven Changes in Bacterial Cell Surface Properties. Appl Environ Microbiol 2022; 88:e0073222. [PMID: 36226960 PMCID: PMC9642014 DOI: 10.1128/aem.00732-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Increased drought intensity and frequency exposes soil bacteria to prolonged water stress. While numerous studies reported on behavioral and physiological mechanisms of bacterial adaptation to water stress, changes in bacterial cell surface properties during adaptation are not well researched. We studied adaptive changes in cell surface hydrophobicity (CSH) after exposure to osmotic (NaCl) and matric stress (polyethylene glycol 8000 [PEG 8000]) for six typical soil bacteria (Bacillus subtilis, Arthrobacter chlorophenolicus, Pseudomonas fluorescens, Novosphingobium aromaticivorans, Rhodococcus erythropolis, and Mycobacterium pallens) covering a wide range of cell surface properties. Additional physicochemical parameters (surface chemical composition, surface charge, cell size and stiffness) of B. subtilis and P. fluorescens were analyzed to understand their possible contribution to CSH development. Changes in CSH caused by osmotic and matric stress depend on strain and stress type. CSH of B. subtilis and P. fluorescens increased with stress intensity, R. erythropolis and M. pallens exhibited a generally high but constant contact angle, while the response of A. chlorophenolicus and N. aromaticivorans depended on growth conditions and stress type. Osmotically driven changes in CSH of B. subtilis and P. fluorescens are accompanied by increasing surface N/C ratio, suggesting an increase in protein concentration within the cell wall. Cell envelope proteins thus presumably control bacterial CSH in two ways: (i) by increases in the relative density of surface proteins due to efflux of cytoplasmic water and subsequent cell shrinkage, and (ii) by destabilization of cell wall proteins, resulting in conformational changes which render the surface more hydrophobic. IMPORTANCE Changes in precipitation frequency, intensity, and temporal distribution are projected to result in increased frequency and intensity of droughts and heavy rainfall events. Prolonged droughts can promote the development of soil water repellency (SWR); this impacts the infiltration and distribution of water in the soil profile, exposing soil microorganisms to water stress. Exposure to water stress has recently been reported to result in increased cell surface hydrophobicity. However, the mechanism of this development is poorly understood. This study investigates the changes in the physicochemical properties of bacterial cell surfaces under water stress as a possible mechanism of increased surface hydrophobicity. Our results improve understanding of the microbial response to water stress in terms of surface properties, the variations in stress response depending on cell wall composition, and its contribution to the development of SWR.
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6
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Han R, Vollmer W, Perry JD, Stoodley P, Chen J. Simultaneous determination of the mechanical properties and turgor of a single bacterial cell using atomic force microscopy. NANOSCALE 2022; 14:12060-12068. [PMID: 35946610 DOI: 10.1039/d2nr02577a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Bacterial mechanical properties (cell wall stiffness and turgor) are important factors for bacterial survival in harsh environments. For an individual bacterial cell, it is challenging to determine the cell wall stiffness and turgor simultaneously. In this study, we adopted a combined finite element modelling and mathematical modelling approach to simultaneously determine bacterial cell wall stiffness and turgor of an individual bacterial cell based on atomic force microscopy (AFM) nanoindentation. The mechanical properties and turgor of Staphylococcus epidermidis, determined by our method are consistent with other independent studies. For a given aqueous environment, bacterial cell wall stiffness increased linearly with an increase in turgor. Higher osmolarity leads to a decrease in both cell wall stiffness and turgor. We also demonstrated that the change of turgor is associated with a change in viscosity of the bacterial cell.
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Affiliation(s)
- Rui Han
- School of Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK.
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Richardson Road, Newcastle upon Tyne, NE2 4AX, UK
| | - John D Perry
- Microbiology Department, The Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, NE7 7DN, UK
| | - Paul Stoodley
- Department of Microbial Infection and Immunity and the Department of Orthopaedics, The Ohio State University, Columbus, OH, 43210, USA
- National Centre for Advanced Tribology at Southampton (nCATS), National Biofilm Innovation Centre (NBIC), Mechanical Engineering, University of Southampton, Southampton, S017 1BJ, UK
| | - Jinju Chen
- School of Engineering, Newcastle University, Newcastle Upon Tyne, NE1 7RU, UK.
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Rosłoń IE, Japaridze A, Steeneken PG, Dekker C, Alijani F. Probing nanomotion of single bacteria with graphene drums. NATURE NANOTECHNOLOGY 2022; 17:637-642. [PMID: 35437320 DOI: 10.1038/s41565-022-01111-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 03/02/2022] [Indexed: 06/14/2023]
Abstract
Motion is a key characteristic of every form of life1. Even at the microscale, it has been reported that colonies of bacteria can generate nanomotion on mechanical cantilevers2, but the origin of these nanoscale vibrations has remained unresolved3,4. Here, we present a new technique using drums made of ultrathin bilayer graphene, where the nanomotion of single bacteria can be measured in its aqueous growth environment. A single Escherichia coli cell is found to generate random oscillations with amplitudes of up to 60 nm, exerting forces of up to 6 nN to its environment. Using mutant strains that differ by single gene deletions that affect motility, we are able to pinpoint the bacterial flagella as the main source of nanomotion. By real-time tracing of changes in nanomotion on administering antibiotics, we demonstrate that graphene drums can perform antibiotic susceptibility testing with single-cell sensitivity. These findings deepen our understanding of processes underlying cellular dynamics, and pave the way towards high-throughput and parallelized rapid screening of the effectiveness of antibiotics in bacterial infections with graphene devices.
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Affiliation(s)
- Irek E Rosłoń
- Delft University of Technology, Delft, the Netherlands
| | | | | | - Cees Dekker
- Delft University of Technology, Delft, the Netherlands
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Palankar R, Sachs L, Wesche J, Greinacher A. Cytoskeleton Dependent Mobility Dynamics of FcγRIIA Facilitates Platelet Haptotaxis and Capture of Opsonized Bacteria. Cells 2022; 11:cells11101615. [PMID: 35626650 PMCID: PMC9139458 DOI: 10.3390/cells11101615] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 05/05/2022] [Accepted: 05/10/2022] [Indexed: 12/04/2022] Open
Abstract
Platelet adhesion and spreading at the sites of vascular injury is vital to hemostasis. As an integral part of the innate immune system, platelets interact with opsonized bacterial pathogens through FcγRIIA and contribute to host defense. As mechanoscavangers, platelets actively migrate and capture bacteria via cytoskeleton-rich, dynamic structures, such as filopodia and lamellipodia. However, the role of human platelet FcγRIIA in cytoskeleton-dependent interaction with opsonized bacteria is not well understood. To decipher this, we used a reductionist approach with well-defined micropatterns functionalized with immunoglobulins mimicking immune complexes at planar interfaces and bacteriamimetic microbeads. By specifically blocking of FcγRIIA and selective disruption of the platelet cytoskeleton, we show that both functional FcγRIIA and cytoskeleton are necessary for human platelet adhesion and haptotaxis. The direct link between FcγRIIA and the cytoskeleton is further explored by single-particle tracking. We then demonstrate the relevance of cytoskeleton-dependent differential mobilities of FcγRIIA on bacteria opsonized with the chemokine platelet factor 4 (PF4) and patient-derived anti-PF4/polyanion IgG. Our data suggest that efficient capture of opsonized bacteria during host-defense is governed by mobility dynamics of FcγRIIA on filopodia and lamellipodia, and the cytoskeleton plays an essential role in platelet morphodynamics at biological interfaces that display immune complexes.
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Simpson JD, Ray A, Koehler M, Mohammed D, Alsteens D. Atomic force microscopy applied to interrogate nanoscale cellular chemistry and supramolecular bond dynamics for biomedical applications. Chem Commun (Camb) 2022; 58:5072-5087. [PMID: 35315846 DOI: 10.1039/d1cc07200e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding biological interactions at a molecular level grants valuable information relevant to improving medical treatments and outcomes. Among the suite of technologies available, Atomic Force Microscopy (AFM) is unique in its ability to quantitatively probe forces and receptor-ligand interactions in real-time. The ability to assess the formation of supramolecular bonds and intermediates in real-time on surfaces and living cells generates important information relevant to understanding biological phenomena. Combining AFM with fluorescence-based techniques allows for an unprecedented level of insight not only concerning the formation and rupture of bonds, but understanding medically relevant interactions at a molecular level. As the ability of AFM to probe cells and more complex models improves, being able to assess binding kinetics, chemical topographies, and garner spectroscopic information will likely become key to developing further improvements in fields such as cancer, nanomaterials, and virology. The rapid response to the COVID-19 crisis, producing information regarding not just receptor affinities, but also strain-dependent efficacy of neutralizing nanobodies, demonstrates just how viable and integral to the pre-clinical development of information AFM techniques are in this era of medicine.
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Affiliation(s)
- Joshua D Simpson
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Ankita Ray
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Melanie Koehler
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - Danahe Mohammed
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium.
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10
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Nanoscopic characterization of hepatocytes treated with normoxic and hypoxic tumor-derived exosomes. Micron 2022; 158:103283. [DOI: 10.1016/j.micron.2022.103283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/06/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022]
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Shahina Z, Bhat SV, Ndlovu E, Sultana T, Körnig A, Dague É, Dahms TES. Cellulomics of Live Yeast by Advanced and Correlative Microscopy. Fungal Biol 2022. [DOI: 10.1007/978-3-030-83749-5_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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TANABE S, ITAGAKI S, SUEKUNI S, SHIIGI H. Development of an Electrochemical Evaluation for the Respiration of Escherichia coli. BUNSEKI KAGAKU 2021. [DOI: 10.2116/bunsekikagaku.70.715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- So TANABE
- Department of Applied Chemistry, Osaka Prefecture University
| | | | - Satoshi SUEKUNI
- Department of Applied Chemistry, Osaka Prefecture University
| | - Hiroshi SHIIGI
- Department of Applied Chemistry, Osaka Prefecture University
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13
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Dunker K, de la Torre Canny SG, Nordgård CT, Dague E, Formosa-Dague C, Bakke I, Sletmoen M. Elucidating bacterial adhesion to mucosal surface by an original AFM approach. BMC Microbiol 2021; 21:244. [PMID: 34488629 PMCID: PMC8422614 DOI: 10.1186/s12866-021-02303-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 08/27/2021] [Indexed: 11/10/2022] Open
Abstract
Background Fish skin represents an ancient vertebrate mucosal surface, sharing characteristics with other mucosal surfaces including those of the intestine. The skin mucosa is continuously exposed to microbes in the surrounding water and is therefore important in the first line defense against environmental pathogens by preventing bacteria from accessing the underlying surfaces. Understanding the microbe-host interactions at the fish skin mucosa is highly relevant in order to understand and control infection, commensalism, colonization, persistence, infection, and disease. Here we investigate the interactions between the pathogenic bacteria Aeromonas salmonicida (A. salmonicida) and Yersinia ruckeri (Y. ruckeri), respectively, and the skin mucosal surface of Atlantic salmon fry using AFM force spectroscopy. Results The results obtained revealed that when retracting probes functionalized with bacteria from surfaces coated with immobilized mucins, isolated from salmon mucosal surfaces, rupture events reflecting the disruption of adhesive interactions were observed, with rupture strengths centered around 200 pN. However, when retracting probes functionalized with bacteria from the intact mucosal surface of salmon fish fry no adhesive interactions could be detected. Furthermore, rheological measurements revealed a near fluid-like behavior for the fish fry skin mucus. Taken together, the experimental data indicate that the adhesion between the mucin molecules within the mucous layer may be significantly weaker than the interaction between the bacteria and the mucin molecules. The bacteria, immobilized on the AFM probe, do bind to individual mucins in the mucosal layer, but are released from the near fluid mucus with little resistance upon retraction of the AFM probe, to which they are immobilized. Conclusion The data provided in the current paper reveal that A. salmonicida and Y. ruckeri do bind to the immobilized mucins. However, when retracting the bacteria from intact mucosal surfaces, no adhesive interactions are detected. These observations suggest a mechanism underlying the protective function of the mucosal surface based on the clearing of potential threats by adhering them to loosely attached mucus that is subsequently released from the fish skin.
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Affiliation(s)
- Karen Dunker
- Department of Biotechnology, NTNU Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Sol Gomez de la Torre Canny
- Department of Biotechnology, NTNU Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Catherine Taylor Nordgård
- Department of Biotechnology, NTNU Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Etienne Dague
- LAAS-CNRS, Université de Toulouse, CNRS, 31400, Toulouse, France
| | | | - Ingrid Bakke
- Department of Biotechnology, NTNU Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Marit Sletmoen
- Department of Biotechnology, NTNU Norwegian University of Science and Technology, NO-7491, Trondheim, Norway.
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14
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Pattem J, Davrandi M, Aguayo S, Slak B, Maev R, Allan E, Spratt D, Bozec L. Dependency of hydration and growth conditions on the mechanical properties of oral biofilms. Sci Rep 2021; 11:16234. [PMID: 34376751 PMCID: PMC8355335 DOI: 10.1038/s41598-021-95701-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 07/21/2021] [Indexed: 11/21/2022] Open
Abstract
Within the oral cavity, dental biofilms experience dynamic environments, in part due to changes in dietary content, frequency of intake and health conditions. This can impact bacterial diversity and morpho-mechanical properties. While phenotypic properties of oral biofilms are closely related to their composition, these can readily change according to dynamic variations in the growth environment and nutrient availability. Understanding the interlink between phenotypic properties, variable growth conditions, and community characterization is an essential requirement to develop structure–property relationships in oral-biofilms. In this study, the impact of two distinct growth media types with increasing richness on the properties of oral biofilms was assessed through a new combination of in-vitro time-lapse biophysical methods with microbiological assays. Oral biofilms grown in the enriched media composition presented a decrease in their pH, an increase in soluble EPS production, and a severe reduction in bacterial diversity. Additionally, enriched media conditions presented an increase in biofilm volumetric changes (upon hydration) as well as a reduction in elastic modulus upon indentation. With hydration time considered a major factor contributing to changes in biofilm mechanical properties, we have shown that it is less associated than media richness. Future investigations can now use this time-lapse approach, with a clearer focus on the extracellular matrix of oral biofilms dictating their morpho-mechanical properties.
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Affiliation(s)
- J Pattem
- Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK. .,National Centre for Molecular Hydrodynamics, and Soft Matter Biomaterials and Bio-Interfaces, University of Nottingham, The Limes Building, Sutton Bonington Campus, Sutton Bonington, Leicestershire, LE12 5RD, UK.
| | - M Davrandi
- Division of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK
| | - S Aguayo
- School of Dentistry, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - B Slak
- Department of Electrical and Computer Engineering, University of Windsor, Windsor, Canada
| | - R Maev
- Department of Electrical and Computer Engineering, University of Windsor, Windsor, Canada
| | - E Allan
- Division of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK
| | - D Spratt
- Division of Microbial Diseases, UCL Eastman Dental Institute, University College London, London, UK
| | - L Bozec
- Division of Biomaterials and Tissue Engineering, UCL Eastman Dental Institute, University College London, London, UK.,Faculty of Dentistry, University of Toronto, Toronto, Canada
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15
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Bacterial extracellular protein interacts with silver ions to produce protein-encapsulated bactericidal AgNPs. Process Biochem 2021. [DOI: 10.1016/j.procbio.2021.04.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Abraham S, Kaufman Y, Perreault F, Young R, Bar-Zeev E. Bursting out: linking changes in nanotopography and biomechanical properties of biofilm-forming Escherichia coli to the T4 lytic cycle. NPJ Biofilms Microbiomes 2021; 7:26. [PMID: 33731698 PMCID: PMC7969764 DOI: 10.1038/s41522-021-00195-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 01/20/2021] [Indexed: 11/09/2022] Open
Abstract
The bacteriophage infection cycle has been extensively studied, yet little is known about the nanostructure and mechanical changes that lead to bacterial lysis. Here, atomic force microscopy was used to study in real time and in situ the impact of the canonical phage T4 on the nanotopography and biomechanics of irreversibly attached, biofilm-forming E. coli cells. The results show that in contrast to the lytic cycle in planktonic cells, which ends explosively, anchored cells that are in the process of forming a biofilm undergo a more gradual lysis, developing distinct nanoscale lesions (~300 nm in diameter) within the cell envelope. Furthermore, it is shown that the envelope rigidity and cell elasticity decrease (>50% and >40%, respectively) following T4 infection, a process likely linked to changes in the nanostructure of infected cells. These insights show that the well-established lytic pathway of planktonic cells may be significantly different from that of biofilm-forming cells. Elucidating the lysis paradigm of these cells may advance biofilm removal and phage therapeutics.
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Affiliation(s)
- Shiju Abraham
- Zuckerberg Institute for Water Research, The Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sde Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Yair Kaufman
- Zuckerberg Institute for Water Research, The Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sde Boqer Campus, Midreshet Ben-Gurion, Israel.
| | - François Perreault
- School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
| | - Ry Young
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- Texas A&M AgriLife, College Station, TX, USA
| | - Edo Bar-Zeev
- Zuckerberg Institute for Water Research, The Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sde Boqer Campus, Midreshet Ben-Gurion, Israel.
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17
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Kimkes TEP, Heinemann M. How bacteria recognise and respond to surface contact. FEMS Microbiol Rev 2020; 44:106-122. [PMID: 31769807 PMCID: PMC7053574 DOI: 10.1093/femsre/fuz029] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/23/2019] [Indexed: 12/27/2022] Open
Abstract
Bacterial biofilms can cause medical problems and issues in technical systems. While a large body of knowledge exists on the phenotypes of planktonic and of sessile cells in mature biofilms, our understanding of what happens when bacteria change from the planktonic to the sessile state is still very incomplete. Fundamental questions are unanswered: for instance, how do bacteria sense that they are in contact with a surface, and what are the very initial cellular responses to surface contact. Here, we review the current knowledge on the signals that bacteria could perceive once they attach to a surface, the signal transduction systems that could be involved in sensing the surface contact and the cellular responses that are triggered as a consequence to surface contact ultimately leading to biofilm formation. Finally, as the main obstacle in investigating the initial responses to surface contact has been the difficulty to experimentally study the dynamic response of single cells upon surface attachment, we also review recent experimental approaches that could be employed to study bacterial surface sensing, which ultimately could lead to an improved understanding of how biofilm formation could be prevented.
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Affiliation(s)
- Tom E P Kimkes
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
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18
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Del Valle A, Torra J, Bondia P, Tone CM, Pedraz P, Vadillo-Rodriguez V, Flors C. Mechanically Induced Bacterial Death Imaged in Real Time: A Simultaneous Nanoindentation and Fluorescence Microscopy Study. ACS APPLIED MATERIALS & INTERFACES 2020; 12:31235-31241. [PMID: 32476402 DOI: 10.1021/acsami.0c08184] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Mechano-bactericidal nanomaterials rely on their mechanical or physical interactions with bacteria and are promising antimicrobial strategies that overcome bacterial resistance. However, the real effect of mechanical versus chemical action on their activity is under debate. In this paper, we quantify the forces necessary to produce critical damage to the bacterial cell wall by performing simultaneous nanoindentation and fluorescence imaging of single bacterial cells. Our experimental setup allows puncturing the cell wall of an immobilized bacterium with the tip of an atomic force microscope (AFM) and following in real time the increase in the fluorescence signal from a cell membrane integrity marker. We correlate the forces exerted by the AFM tip with the fluorescence dynamics for tens of cells, and we find that forces above 20 nN are necessary to exert critical damage. Moreover, a similar experiment is performed in which bacterial viability is assessed through physiological activity, in order to gain a more complete view of the effect of mechanical forces on bacteria. Our results contribute to the quantitative understanding of the interaction between bacteria and nanomaterials.
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Affiliation(s)
- Adrián Del Valle
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
| | - Joaquim Torra
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
| | - Patricia Bondia
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
| | - Caterina M Tone
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
| | - Patricia Pedraz
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
| | | | - Cristina Flors
- Madrid Institute for Advanced Studies in Nanoscience (IMDEA Nanociencia), C/Faraday 9, Madrid 28049, Spain
- Nanobiotechnology Unit Associated to the National Center for Biotechnology (CNB-CSIC-IMDEA), Madrid 28049, Spain
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19
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Hofherr L, Müller-Renno C, Ziegler C. FluidFM as a tool to study adhesion forces of bacteria - Optimization of parameters and comparison to conventional bacterial probe Scanning Force Spectroscopy. PLoS One 2020; 15:e0227395. [PMID: 32628681 PMCID: PMC7337302 DOI: 10.1371/journal.pone.0227395] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2019] [Accepted: 05/28/2020] [Indexed: 12/03/2022] Open
Abstract
The FluidFM enables the immobilization of single cells on a hollow cantilever using relative underpressure. In this study, we systematically optimize versatile measurement parameters (setpoint, z-speed, z-length, pause time, and relative underpressure) to improve the quality of force-distance curves recorded with a FluidFM. Using single bacterial cells (here the gram negative seawater bacterium Paracoccus seriniphilus and the gram positive bacterium Lactococcus lactis), we show that Single Cell Force Spectroscopy experiments with the FluidFM lead to comparable results to a conventional Single Cell Force Spectroscopy approach using polydopamine for chemical fixation of a bacterial cell on a tipless cantilever. Even for the bacterium Lactococcus lactis, which is difficult to immobilze chemically (like seen in an earlier study), immobilization and the measurement of force-distance curves are possible by using the FluidFM technology.
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Affiliation(s)
- Linda Hofherr
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
| | - Christine Müller-Renno
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
- * E-mail:
| | - Christiane Ziegler
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Kaiserslautern, Germany
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20
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Tokonami S, Kurita S, Yoshikawa R, Sakurai K, Suehiro T, Yamamoto Y, Tamura M, Karthaus O, Iida T. Light-induced assembly of living bacteria with honeycomb substrate. SCIENCE ADVANCES 2020; 6:eaaz5757. [PMID: 32158951 PMCID: PMC7048417 DOI: 10.1126/sciadv.aaz5757] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 12/05/2019] [Indexed: 05/14/2023]
Abstract
Some bacteria are recognized to produce useful substances and electric currents, offering a promising solution to environmental and energy problems. However, applications of high-performance microbial devices require a method to accumulate living bacteria into a higher-density condition in larger substrates. Here, we propose a method for the high-density assembly of bacteria (106 to 107 cells/cm2) with a high survival rate of 80 to 90% using laser-induced convection onto a self-organized honeycomb-like photothermal film. Furthermore, the electricity-producing bacteria can be optically assembled, and the electrical current can be increased by one to two orders of magnitude simply by increasing the number of laser irradiations. This concept can facilitate the development of high-density microbial energy conversion devices and provide new platforms for unconventional environmental technology.
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Affiliation(s)
- Shiho Tokonami
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
| | - Shinya Kurita
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
| | - Ryo Yoshikawa
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
| | - Kenji Sakurai
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
| | - Taichi Suehiro
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8570, Japan
| | - Yasuyuki Yamamoto
- Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai 599-8570, Japan
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8570, Japan
| | - Mamoru Tamura
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8570, Japan
| | - Olaf Karthaus
- Department of Applied Chemistry and Bioscience, Chitose Institute of Science and Technology, Chitose, Hokkaido 066-8655, Japan
| | - Takuya Iida
- Research Institute for Light-induced Acceleration System, Osaka Prefecture University, Sakai 599-8570, Japan
- Department of Physical Science, Graduate School of Science, Osaka Prefecture University, Sakai, Osaka 599-8570, Japan
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21
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Marshall H, Aguayo S, Kilian M, Petersen F, Bozec L, Brown J. In Vivo Relationship between the Nano-Biomechanical Properties of Streptococcal Polysaccharide Capsules and Virulence Phenotype. ACS NANO 2020; 14:1070-1083. [PMID: 31854972 DOI: 10.1021/acsnano.9b08631] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In common with many bacterial pathogens, Streptococcus pneumoniae has a polysaccharide capsule which facilitates immune evasion and determines virulence. Recent data have shown that the closely related Streptococcus mitis also expresses polysaccharide capsules including those with an identical chemical structure to S. pneumoniae capsular serotypes. We utilized atomic force microscopy (AFM) techniques to investigate the biophysical properties of S. mitis and S. pneumoniae strains expressing the same capsular serotypes that might relate to differences in virulence potential. When comparing S. mitis and S. pneumoniae strains with identical capsule serotypes, S. mitis strains were susceptible to neutrophil killing, and electron microscopy and AFM demonstrated significant morphological differences. Force-volume mapping using AFM showed distinct force-curve profiles for the center and edge areas of encapsulated streptococcal strains. This "edge effect" was not observed in unencapsulated bacteria and therefore was a direct representation of the mechanical properties of the bacterial capsule. When two strains of S. mitis and S. pneumoniae expressed an identical capsular serotype, they presented similar biomechanical characteristics. This infers a potential relationship between capsule biochemistry and nanomechanics, independent of bacterial strain. Overall, this study demonstrates that it is possible to investigate reproducibly the mechanistic, structural, and mechanical properties of both the capsule and the body of individual living bacterial cells and relate the data to virulence phenotypes. We have demonstrated that using nanomechanics to investigate individual bacterial cells we can now begin to identify the surface properties bacterial pathogens require to avoid host-mediated immunity.
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Affiliation(s)
- Helina Marshall
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School , Rayne Institute , London WC1E 6JF , United Kingdom
- School of Biological Sciences , Queen's University Belfast , Belfast BT7 1NN , United Kingdom
| | - Sebastian Aguayo
- Biomaterials and Tissue Engineering, Eastman Dental Institute , University College London , London WC1E 6BT , United Kingdom
- School of Dentistry, Faculty of Medicine , Pontificia Universidad Catolica de Chile , Santiago , Chile
| | - Mogens Kilian
- Department of Biomedicine, Faculty of Health , Aarhus University , Aarhus 8000 , Denmark
| | - Fernanda Petersen
- Faculty of Dentistry, Institute of Oral Biology , University of Oslo , Oslo 0315 , Norway
| | - Laurent Bozec
- Biomaterials and Tissue Engineering, Eastman Dental Institute , University College London , London WC1E 6BT , United Kingdom
- Faculty of Dentistry , University of Toronto , Toronto , Ontario M5G 1G6 , Canada
| | - Jeremy Brown
- Centre for Inflammation and Tissue Repair, Department of Medicine, Royal Free and University College Medical School , Rayne Institute , London WC1E 6JF , United Kingdom
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22
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Probing the surface ultrastructure of Brevibacillus laterosporus using atomic force microscopy. Micron 2020; 131:102827. [PMID: 31951938 DOI: 10.1016/j.micron.2020.102827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 01/12/2020] [Accepted: 01/12/2020] [Indexed: 11/21/2022]
Abstract
One of the main obstacles to studying the surface ultrastructure of microbial cells by atomic force microscopy (AFM) is determining how to immobilize live cells on the AFM substrates. Each method has its own advantages and disadvantages. The aim of this study was to characterize a new simple and inexpensive method using two types of polyethersulfone (PES) membrane filters that differ in pore size (micropore and nanopore) to immobilize live and dead Brevibacillus laterosporus for AFM imaging. B. laterosporus was easily trapped by the microporous PES membrane, facilitating the successful AFM scanning of the bacterial surface ultrastructure. In addition, B. laterosporus strongly attached to the nanoporous membranes and withstood the pulling forces exerted by the AFM tip during scanning. These methods of immobilization did not affect the cell viability. The nanostructure and roughness of the bacterial surface were also observed for live, fixed, and air-dried cells. Live and dead bacteria displayed similar morphologies at low resolution, while at high resolution, live bacteria displayed a more convoluted surface ("brain-like structure").
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23
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Wang YK, Krasnopeeva E, Lin SY, Bai F, Pilizota T, Lo CJ. Comparison of Escherichia coli surface attachment methods for single-cell microscopy. Sci Rep 2019; 9:19418. [PMID: 31857669 PMCID: PMC6923479 DOI: 10.1038/s41598-019-55798-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/05/2019] [Indexed: 12/22/2022] Open
Abstract
For in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate that E. coli grow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studying E. coli physiology.
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Affiliation(s)
- Yao-Kuan Wang
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Ekaterina Krasnopeeva
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK
| | - Ssu-Yuan Lin
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Fan Bai
- Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, 100871, China
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK.
| | - Chien-Jung Lo
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China.
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24
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Benn G, Pyne ALB, Ryadnov MG, Hoogenboom BW. Imaging live bacteria at the nanoscale: comparison of immobilisation strategies. Analyst 2019; 144:6944-6952. [PMID: 31620716 PMCID: PMC7138128 DOI: 10.1039/c9an01185d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/10/2019] [Indexed: 12/17/2022]
Abstract
Atomic force microscopy (AFM) provides an effective, label-free technique enabling the imaging of live bacteria under physiological conditions with nanometre precision. However, AFM is a surface scanning technique, and the accuracy of its performance requires the effective and reliable immobilisation of bacterial cells onto substrates. Here, we compare the effectiveness of various chemical approaches to facilitate the immobilisation of Escherichia coli onto glass cover slips in terms of bacterial adsorption, viability and compatibility with correlative imaging by fluorescence microscopy. We assess surface functionalisation using gelatin, poly-l-lysine, Cell-Tak™, and Vectabond®. We describe how bacterial immobilisation, viability and suitability for AFM experiments depend on bacterial strain, buffer conditions and surface functionalisation. We demonstrate the use of such immobilisation by AFM images that resolve the porin lattice on the bacterial surface; local degradation of the bacterial cell envelope by an antimicrobial peptide (Cecropin B); and the formation of membrane attack complexes on the bacterial membrane.
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Affiliation(s)
- Georgina Benn
- London Centre for Nanotechnology
, University College London
,
London WC1H 0AH
, UK
.
- Institute of Structural and Molecular Biology
, University College London
,
London WC1E 6BT
, UK
- National Physical Laboratory
,
Hampton Road
, Teddington TW11 0LW
, UK
| | - Alice L. B. Pyne
- London Centre for Nanotechnology
, University College London
,
London WC1H 0AH
, UK
.
- Department of Materials Science and Engineering
, University of Sheffield
,
S1 3JD
, UK
| | - Maxim G. Ryadnov
- National Physical Laboratory
,
Hampton Road
, Teddington TW11 0LW
, UK
- Department of Physics
, King's College London
,
Strand Lane
, London WC2R 2LS
, UK
| | - Bart W. Hoogenboom
- London Centre for Nanotechnology
, University College London
,
London WC1H 0AH
, UK
.
- Institute of Structural and Molecular Biology
, University College London
,
London WC1E 6BT
, UK
- Department of Physics & Astronomy
, University College London
,
London WC1E 6BT
, UK
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25
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Satapute P, Paidi MK, Kurjogi M, Jogaiah S. Physiological adaptation and spectral annotation of Arsenic and Cadmium heavy metal-resistant and susceptible strain Pseudomonas taiwanensis. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 251:555-563. [PMID: 31108288 DOI: 10.1016/j.envpol.2019.05.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/03/2019] [Accepted: 05/12/2019] [Indexed: 06/09/2023]
Abstract
In the present study, the 16S-rRNA sequencing of heavy metal-resistant and susceptible bacterial strains isolated from the industrial and agriculture soil showed resemblance with Pseudomonas taiwanensis. Based on the growth rate, two bacterial strains SJPS_KUD54 and KUD-MBBT4 exhibited 10 ppm tolerance to Arsenic and Cadmium. These two heavy metals caused, a significant increase in stress enzymes like superoxide dismutase, catalase and glutathione S-transferase activities in SJPS_KUD54 when compared to KUD-MBBT4. Following heavy metal treatment, the atomic-force-microscopy observations showed no change in the cell-wall of SJPS_KUD54, whereas the cell-wall of KUD-MBBT4 got ruptured. Moreover, the protein-profile of SJPS_KUD54 treated with heavy metals exhibited varied patterns in comparison with untreated control. In addition, the accumulation of hydroxyl, thiol and amides were found in the SJPS_KUD54 relative to its control. Furthermore, the resistant SJPS_KUD54 strain showed a remarkable bioaccumulation properties to both Arsenic and Cadmium. Thus, it is inferred that the growth rate, stress enzymes and functional-groups play a significant role in the physiological-adaption of SJPS_KUD54 during stress conditions, which is positively involved in the prevention or repair mechanism for reducing the risks caused by heavy metal stress.
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Affiliation(s)
- Praveen Satapute
- Laboratory of Plant Healthcare and Diagnostics, P.G. Department of Biotechnology and Microbiology, Karnatak University, Dharwad, Karnataka 580003, India
| | - Murali Krishna Paidi
- Laboratory of Plant Healthcare and Diagnostics, P.G. Department of Biotechnology and Microbiology, Karnatak University, Dharwad, Karnataka 580003, India
| | - Mahantesh Kurjogi
- Laboratory of Plant Healthcare and Diagnostics, P.G. Department of Biotechnology and Microbiology, Karnatak University, Dharwad, Karnataka 580003, India
| | - Sudisha Jogaiah
- Laboratory of Plant Healthcare and Diagnostics, P.G. Department of Biotechnology and Microbiology, Karnatak University, Dharwad, Karnataka 580003, India.
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26
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Ashraf N, Ahmad F, Jing Jie C, Tuo Di Z, Feng-Zhu Z, Yin DC. Optimization of Enterobacter cloacae mediated synthesis of extracellular silver nanoparticles by response surface methodology and their characterization. PARTICULATE SCIENCE AND TECHNOLOGY 2019. [DOI: 10.1080/02726351.2019.1636915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Noreen Ashraf
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Fiaz Ahmad
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Chen Jing Jie
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Zhang Tuo Di
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Zhao Feng-Zhu
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
| | - Da-Chuan Yin
- Key Laboratory for Space Bioscience & Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, P.R. China
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27
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Rončević T, Vukičević D, Krce L, Benincasa M, Aviani I, Maravić A, Tossi A. Selection and redesign for high selectivity of membrane-active antimicrobial peptides from a dedicated sequence/function database. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:827-834. [DOI: 10.1016/j.bbamem.2019.01.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 01/25/2019] [Accepted: 01/29/2019] [Indexed: 12/19/2022]
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28
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A modular atomic force microscopy approach reveals a large range of hydrophobic adhesion forces among bacterial members of the leaf microbiota. ISME JOURNAL 2019; 13:1878-1882. [PMID: 30894689 PMCID: PMC6591122 DOI: 10.1038/s41396-019-0404-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 03/08/2019] [Accepted: 03/10/2019] [Indexed: 12/27/2022]
Abstract
Bacterial adhesion is the initial step in surface colonization and community formation. At the single-cell level, atomic force microscopy (AFM) techniques have enabled the quantification of adhesive forces between bacteria and substrata. However, conventional techniques depend on the irreversible immobilization of cells onto cantilevers, thus hampering throughput. Here, we developed a modular AFM method to reversibly immobilize functionalized beads as surface mimic and to probe adhesion of individual bacteria. We performed single-cell force spectroscopies with phylogenetically diverse leaf isolates of various size and morphology. Adhesion measurement of 28 bacterial strains revealed large differences in hydrophobic interactions of about three orders of magnitude. The highest adhesion forces of up to 50 nN were recorded for members of the Gammaproteobacteria. The hydrophobicity of the different isolates correlated positively with the retention of bacteria observed in planta and might provide a basis for successful leaf colonization and potentially disease outbreaks of pathogens.
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29
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Alam F, Kumar S, Varadarajan KM. Quantification of Adhesion Force of Bacteria on the Surface of Biomaterials: Techniques and Assays. ACS Biomater Sci Eng 2019; 5:2093-2110. [DOI: 10.1021/acsbiomaterials.9b00213] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fahad Alam
- Biomaterials Processing and Characterization Laboratory, Materials Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
- Department of Mechanical and Materials Engineering, Khalifa University of Science and Technology, Masdar Institute, Masdar City, Abu Dhabi United Arab Emirates
| | - Shanmugam Kumar
- Department of Mechanical and Materials Engineering, Khalifa University of Science and Technology, Masdar Institute, Masdar City, Abu Dhabi United Arab Emirates
| | - Kartik M. Varadarajan
- Department of Orthopaedic Surgery, Harvard Medical School, A-111, 25 Shattuck Street, Boston, Massachusetts 02115, United States
- Department of Orthopaedic Surgery, Harris Orthopaedics Laboratory, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114, United States
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Boudjemaa R, Steenkeste K, Canette A, Briandet R, Fontaine-Aupart MP, Marlière C. Direct observation of the cell-wall remodeling in adhering Staphylococcus aureus 27217: An AFM study supported by SEM and TEM. Cell Surf 2019; 5:100018. [PMID: 32743135 PMCID: PMC7389151 DOI: 10.1016/j.tcsw.2019.100018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 12/19/2018] [Accepted: 01/24/2019] [Indexed: 01/28/2023] Open
Abstract
We took benefit from Atomic Force Microscopy (AFM) in the force spectroscopy mode to describe the time evolution – over 24 h – of the surface nanotopography and mechanical properties of the strain Staphylococcus aureus 27217 from bacterial adhesion to the first stage of biofilm genesis. In addition, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) experiments allowed identifying two types of self-adhering subpopulations (the so-called “bald” and “hairy” cells) and revealed changes in their relative populations with the bacterial culture age and the protocol of preparation. We indeed observed a dramatic evanescing of the “hairy” subpopulation for samples that underwent centrifugation and resuspension processes. When examined by AFM, the “hairy” cell surface resembled to a herringbone structure characterized by upper structural units with lateral dimensions of ∼70 nm and a high Young modulus value (∼2.3 MPa), a mean depth of the trough between them of ∼15 nm and a resulting roughness of ∼5 nm. By contrast, the “bald” cells appeared much softer (∼0.35 MPa) with a roughness one order of magnitude lower. We observed too the gradual detachment of the herringbone patterns from the “hairy” bacterial envelope of cell harvested from a 16 h old culture and their progressive accumulation between the bacteria in the form of globular clusters. The secretion of a soft extracellular polymeric substance was also identified that, in addition to the globular clusters, may contribute to the initiation of the biofilm spatial organization.
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Affiliation(s)
- Rym Boudjemaa
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - Karine Steenkeste
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - Alexis Canette
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.,Institut de Biologie Paris-Seine (FR 3631), Unité Mixte de Service (UMS 30) d'Imagerie et de Cytométrie (LUMIC), Sorbonne Université, CNRS, Paris, France
| | - Romain Briandet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Marie-Pierre Fontaine-Aupart
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
| | - Christian Marlière
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris-Saclay, Orsay, France
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Membrane-active antimicrobial peptide identified in Rana arvalis by targeted DNA sequencing. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:651-659. [DOI: 10.1016/j.bbamem.2018.12.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 11/21/2022]
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Bazina L, Maravić A, Krce L, Soldo B, Odžak R, Popović VB, Aviani I, Primožič I, Šprung M. Discovery of novel quaternary ammonium compounds based on quinuclidine-3-ol as new potential antimicrobial candidates. Eur J Med Chem 2019; 163:626-635. [DOI: 10.1016/j.ejmech.2018.12.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Revised: 12/06/2018] [Accepted: 12/11/2018] [Indexed: 01/18/2023]
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Abstract
Antimicrobial peptides (AMPs) are one of the most promising alternatives to conventional antibiotics. Atomic force microscopy (AFM), as imaging and force spectroscopy tool, has been applied to study their mechanism of action and development. Here, we describe different methods to be applied in the study of AMP effects on bacteria, either by imaging or by force spectroscopy studies, essential to underlie their action and to identify possibly outcomes of the same.
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Affiliation(s)
- Marco M Domingues
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
| | - Mário R Felício
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Sónia Gonçalves
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.
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Laskowski D, Strzelecki J, Pawlak K, Dahm H, Balter A. Effect of ampicillin on adhesive properties of bacteria examined by atomic force microscopy. Micron 2018; 112:84-90. [DOI: 10.1016/j.micron.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Revised: 05/04/2018] [Accepted: 05/04/2018] [Indexed: 01/05/2023]
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Time-Resolved Imaging of Bacterial Surfaces Using Atomic Force Microscopy. Methods Mol Biol 2018. [PMID: 29956245 DOI: 10.1007/978-1-4939-8591-3_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Time-resolved atomic force microscopy (AFM) offers countless new modes by which to study bacterial cell physiology on relevant time scales, from mere milliseconds to hours and days on end. In addition, time-lapse AFM acts as a complementary tool to optical fluorescence microscopy (OFM), for which the combination offers a correlative link between the physical manifestation of bacterial phenotypes and molecular mechanisms obeying those principles. Herein we describe the essential materials and methods necessary for conducting time-resolved AFM and dual AFM/OFM experiments on bacteria.
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Xing Y, Xu M, Gui X, Cao Y, Babel B, Rudolph M, Weber S, Kappl M, Butt HJ. The application of atomic force microscopy in mineral flotation. Adv Colloid Interface Sci 2018; 256:373-392. [PMID: 29559086 DOI: 10.1016/j.cis.2018.01.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 01/29/2018] [Accepted: 01/29/2018] [Indexed: 11/30/2022]
Abstract
During the past years, atomic force microscopy (AFM) has matured to an indispensable tool to characterize nanomaterials in colloid and interface science. For imaging, a sharp probe mounted near to the end of a cantilever scans over the sample surface providing a high resolution three-dimensional topographic image. In addition, the AFM tip can be used as a force sensor to detect local properties like adhesion, stiffness, charge etc. After the invention of the colloidal probe technique it has also become a major method to measure surface forces. In this review, we highlight the advances in the application of AFM in the field of mineral flotation, such as mineral morphology imaging, water at mineral surface, reagent adsorption, inter-particle force, and bubble-particle interaction. In the coming years, the complementary characterization of chemical composition such as using infrared spectroscopy and Raman spectroscopy for AFM topography imaging and the synchronous measurement of the force and distance involving deformable bubble as a force sensor will further assist the fundamental understanding of flotation mechanism.
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Affiliation(s)
- Yaowen Xing
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China; Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mengdi Xu
- School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou 221116, China
| | - Xiahui Gui
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China; Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | - Yijun Cao
- Chinese National Engineering Research Center of Coal Preparation and Purification, China University of Mining and Technology, Xuzhou 221116, China; Henan Province Industrial Technology Research Institute of Resources and Materials, Zhengzhou University, Zhengzhou 450001, China.
| | - Bent Babel
- Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Chemnitzer Str. 40, 09599 Freiberg, Germany
| | - Martin Rudolph
- Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Chemnitzer Str. 40, 09599 Freiberg, Germany
| | - Stefan Weber
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Michael Kappl
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
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Palankar R, Kohler TP, Krauel K, Wesche J, Hammerschmidt S, Greinacher A. Platelets kill bacteria by bridging innate and adaptive immunity via platelet factor 4 and FcγRIIA. J Thromb Haemost 2018; 16:1187-1197. [PMID: 29350833 DOI: 10.1111/jth.13955] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Indexed: 12/15/2022]
Abstract
Essentials Human platelets specifically interact with IgG opsonized bacteria through FcγRIIA. Platelet factor 4 (PF4) binds to polyanions (P) and undergoes a conformational change. Anti-PF4/P IgG opsonizes PF4-coated Gram-positive and Gram-negative bacteria. Platelets specifically kill E.coli opsonized with PF4 and human anti-PF4/P IgG. SUMMARY Background Activated platelets release the chemokine platelet factor 4 (PF4) stored in their granules. PF4 binds to polyanions (P) on bacteria, undergoes a conformational change and exposes neoepitopes. These neoepitopes induce production of anti-PF4/P antibodies. As PF4 binds to a variety of bacteria, anti-PF4/P IgG can bind and opsonize several bacterial species. Objective Here we investigated whether platelets are able to kill bacteria directly after recognizing anti-PF4/P IgG opsonized bacteria in the presence of PF4 via their FcγRIIA. Methods Using platelet-bacteria suspension co-culture experiments and micropatterns with immobilized viable bacteria, in combination with pharmacological inhibitors and human anti- PF4/P IgG we analyzed the role of platelet-mediated killing of bacteria. Results In the presence of PF4, human anti-PF4/P IgG and platelets, E. coli killing (> 50%) with colony forming units (CFU mL-1 ) 0.71 × 104 ± 0.19 was observed compared with controls incubated only with anti-PF4/P IgG (CFU mL-1 3.4 × 104 ± 0.38). Blocking of platelet FcγRIIA using mAb IV.3 (CFU mL-1 2.5 × 104 ± 0.45), or integrin αIIbβ3 (CFU mL-1 2.26 × 104 ± 0.31), or disruption of cytoskeletal functions (CFU mL-1 2.7 × 104 ± 0.4) markedly reduced E. coli killing by this mechanism. Our observation of E. coli killing by platelets on micropatterned arrays is compatible with the model that platelets kill bacteria by covering them, actively concentrating them into the area under their granulomere and then releasing antimicrobial substances of platelet α-granules site directed towards bacteria. Conclusion These findings collectively indicate that by bridging of innate and adaptive immune mechanisms, platelets and anti-PF4/polyanion antibodies cooperate in an antibacterial host response.
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Affiliation(s)
- R Palankar
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - T P Kohler
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - K Krauel
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - J Wesche
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - S Hammerschmidt
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - A Greinacher
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
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Rončević T, Vukičević D, Ilić N, Krce L, Gajski G, Tonkić M, Goić-Barišić I, Zoranić L, Sonavane Y, Benincasa M, Juretić D, Maravić A, Tossi A. Antibacterial Activity Affected by the Conformational Flexibility in Glycine–Lysine Based α-Helical Antimicrobial Peptides. J Med Chem 2018; 61:2924-2936. [DOI: 10.1021/acs.jmedchem.7b01831] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomislav Rončević
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Damir Vukičević
- Department of Mathematics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Nada Ilić
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Lucija Krce
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Goran Gajski
- Mutagenesis Unit, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia
| | - Marija Tonkić
- Department of Clinical Microbiology, University Hospital of Split, 21000 Split, Croatia
- School of Medicine, University of Split, 21000 Split, Croatia
| | - Ivana Goić-Barišić
- Department of Clinical Microbiology, University Hospital of Split, 21000 Split, Croatia
- School of Medicine, University of Split, 21000 Split, Croatia
| | - Larisa Zoranić
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Yogesh Sonavane
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
| | - Monica Benincasa
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
| | - Davor Juretić
- Department of Physics, Faculty of Science, University of Split, 21000 Split, Croatia
- Mediterranean Institute for Life Sciences, 21000 Split, Croatia
| | - Ana Maravić
- Department of Biology, Faculty of Science, University of Split, Ruđera Boškovića 33, 21000 Split, Croatia
| | - Alessandro Tossi
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy
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Nazemi E, Hassen WM, Frost EH, Dubowski JJ. Growth of Escherichia coli on the GaAs (001) surface. Talanta 2018; 178:69-77. [PMID: 29136882 DOI: 10.1016/j.talanta.2017.08.097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 10/18/2022]
Abstract
Detection of pathogenic bacteria and monitoring their susceptibility to antibiotics are of great importance in the fields of medicine, pharmaceutical research, as well as water and food industries. In order to develop a photonic biosensor for detection of bacteria by taking advantage of photoluminescence (PL) of GaAs-based devices, we have investigated the capture and growth of Escherichia coli K12 on bare and biofunctionalized surfaces of GaAs (001) - a material of interest for capping different semiconductor microstructures. The results were compared with the capture and growth of Escherichia coli K12 on Au surfaces that have commonly been applied for studying a variety of biological and biochemical reactions. We found that neither GaAs nor Au-coated glass wafers placed in Petri dishes inoculated with bacteria inhibited bacterial growth in nutrient agar, regardless of the wafers being bare or biofunctionalized. However, the capture and growth of bacteria on biofunctionalized surfaces of GaAs and Au wafers kept in a flow cell and exposed to different concentrations of bacteria and growth medium revealed that the initial surface coverage and the subsequent bacterial growth were dependent on the biofunctionalization architecture, with antibody-coated surfaces clearly being most efficient in capturing bacteria and offering better conditions for growth of bacteria. We have observed that, as long as the GaAs wafers were exposed to bacterial suspensions at concentrations of at least 105 CFU/mL, bacteria could grow on the surface of wafers, regardless of the type of biofunctionalization architecture used to capture the bacteria. These results provide important insight towards the successful development of GaAs-based devices designed for photonic monitoring of bacterial reactions to different biochemical environments.
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Affiliation(s)
- Elnaz Nazemi
- Interdisciplinary Institute for Technological Innovation (3IT), CNRS UMI-3463, Department of Electrical and Computer Engineering, Faculty of Engineering, Université de Sherbrooke, 3000, boul. de l'Université, Sherbrooke, Québec, Canada J1K 0A5.
| | - Walid M Hassen
- Interdisciplinary Institute for Technological Innovation (3IT), CNRS UMI-3463, Department of Electrical and Computer Engineering, Faculty of Engineering, Université de Sherbrooke, 3000, boul. de l'Université, Sherbrooke, Québec, Canada J1K 0A5.
| | - Eric H Frost
- Interdisciplinary Institute for Technological Innovation (3IT), CNRS UMI-3463, Department of Electrical and Computer Engineering, Faculty of Engineering, Université de Sherbrooke, 3000, boul. de l'Université, Sherbrooke, Québec, Canada J1K 0A5; Department of Microbiology and Infectiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, Québec, Canada J1H 5N4.
| | - Jan J Dubowski
- Interdisciplinary Institute for Technological Innovation (3IT), CNRS UMI-3463, Department of Electrical and Computer Engineering, Faculty of Engineering, Université de Sherbrooke, 3000, boul. de l'Université, Sherbrooke, Québec, Canada J1K 0A5.
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40
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Buszewski B, Railean-Plugaru V, Pomastowski P, Rafińska K, Szultka-Mlynska M, Golinska P, Wypij M, Laskowski D, Dahm H. Antimicrobial activity of biosilver nanoparticles produced by a novel Streptacidiphilus durhamensis strain. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2018; 51:45-54. [DOI: 10.1016/j.jmii.2016.03.002] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/20/2016] [Accepted: 03/09/2016] [Indexed: 01/24/2023]
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Bhat SV, Kamencic B, Körnig A, Shahina Z, Dahms TES. Exposure to Sub-lethal 2,4-Dichlorophenoxyacetic Acid Arrests Cell Division and Alters Cell Surface Properties in Escherichia coli. Front Microbiol 2018; 9:44. [PMID: 29472899 PMCID: PMC5810288 DOI: 10.3389/fmicb.2018.00044] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/09/2018] [Indexed: 11/13/2022] Open
Abstract
Escherichia coli is a robust, easily adaptable and culturable bacterium in vitro, and a model bacterium for studying the impact of xenobiotics in the environment. We have used correlative atomic force – laser scanning confocal microscopy (AFM-LSCM) to characterize the mechanisms of cellular response to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). One of the most extensively used herbicides world-wide, 2,4-D is known to cause hazardous effects in diverse non-target organisms. Sub-lethal concentrations of 2,4-D caused DNA damage in E. coli WM1074 during short exposure periods which increased significantly over time. In response to 2,4-D, FtsZ and FtsA relocalized within seconds, coinciding with the complete inhibition of cell septation and cell elongation. Exposure to 2,4-D also resulted in increased activation of the SOS response. Changes to cell division were accompanied by concomitant changes to surface roughness, elasticity and adhesion in a time-dependent manner. This is the first study describing the mechanistic details of 2,4-D at sub-lethal levels in bacteria. Our study suggests that 2,4-D arrests E. coli cell division within seconds after exposure by disrupting the divisome complex, facilitated by dissipation of membrane potential. Over longer exposures, 2,4-D causes filamentation as a result of an SOS response to oxidative stress induced DNA damage.
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Affiliation(s)
- Supriya V Bhat
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
| | - Belma Kamencic
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
| | | | - Zinnat Shahina
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
| | - Tanya E S Dahms
- Department of Chemistry and Biochemistry, University of Regina, Regina, SK, Canada
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42
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Assessment of the Scales of Gilthead Seabream (Sparus aurata L.) by Image Analysis and Atomic Force Microscopy. FISHES 2018. [DOI: 10.3390/fishes3010009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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43
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Westmeier D, Hahlbrock A, Reinhardt C, Fröhlich-Nowoisky J, Wessler S, Vallet C, Pöschl U, Knauer SK, Stauber RH. Nanomaterial–microbe cross-talk: physicochemical principles and (patho)biological consequences. Chem Soc Rev 2018; 47:5312-5337. [DOI: 10.1039/c6cs00691d] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
NPs’ characteristics impact their spontaneous binding to microbes, which may affect the (patho)biological identity of both NP and microbes.
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Affiliation(s)
- D. Westmeier
- Department of Nanobiomedicine/ENT
- University Medical Center of Mainz
- 55101 Mainz
- Germany
| | - A. Hahlbrock
- Department of Nanobiomedicine/ENT
- University Medical Center of Mainz
- 55101 Mainz
- Germany
| | - C. Reinhardt
- Center for Thrombosis and Hemostasis
- University Medical Center Mainz
- 55101 Mainz
- Germany
| | - J. Fröhlich-Nowoisky
- Multiphase Chemistry Department
- Max Planck Institute for Chemistry
- 55128 Mainz
- Germany
| | - S. Wessler
- Department of Molecular Biology
- Paris-Lodron University of Salzburg
- A-5020 Salzburg
- Austria
| | - C. Vallet
- Institute for Molecular Biology
- CENIDE
- University Duisburg-Essen
- 45117 Essen
- Germany
| | - U. Pöschl
- Multiphase Chemistry Department
- Max Planck Institute for Chemistry
- 55128 Mainz
- Germany
| | - S. K. Knauer
- Institute for Molecular Biology
- CENIDE
- University Duisburg-Essen
- 45117 Essen
- Germany
| | - R. H. Stauber
- Department of Nanobiomedicine/ENT
- University Medical Center of Mainz
- 55101 Mainz
- Germany
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Doxorubicin-conjugated Escherichia coli Nissle 1917 swimmers to achieve tumor targeting and responsive drug release. J Control Release 2017; 268:390-399. [DOI: 10.1016/j.jconrel.2017.10.041] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 09/26/2017] [Accepted: 10/30/2017] [Indexed: 12/11/2022]
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45
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Zorila FL, Ionescu C, Craciun LS, Zorila B. Atomic force microscopy study of morphological modifications induced by different decontamination treatments on Escherichia coli. Ultramicroscopy 2017; 182:226-232. [PMID: 28728044 DOI: 10.1016/j.ultramic.2017.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 04/30/2017] [Indexed: 10/19/2022]
Abstract
In this paper we used atomic force microscopy (AFM) to investigate the surface morphology of Escherichia coli, after being subjected to decontamination treatments, at sub-MICs levels (minimal inhibitory concentrations), with different disinfectants used in hospitals, pharmaceutical, food industry and even in our home, as an essential means to prevent the spreading of microorganisms. This article focuses on different morphological modifications adopted by E. coli cells as responses to the different modes of action of these substances. For high-resolution AFM images bacterial cells were immobilized on mica (Muscovite) disks. Each kind of treatment induces its distinct morphological changes, due to different mechanisms of action.
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Affiliation(s)
- Florina Lucica Zorila
- "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, 077125 Bucharest, Magurele, Romania; Department of Genetics, Faculty of Biology, University of Bucharest, Bucharest, Romania.
| | - Cristina Ionescu
- "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, 077125 Bucharest, Magurele, Romania
| | - Liviu Stefan Craciun
- "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, 077125 Bucharest, Magurele, Romania
| | - Bogdan Zorila
- "Horia Hulubei" National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, 077125 Bucharest, Magurele, Romania; Department of Electricity, Solid Physics and Biophysics, Faculty of Physics, University of Bucharest, Magurele, Romania
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Abstract
Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.
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Affiliation(s)
- George K Auer
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Douglas B Weibel
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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47
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Monitoring growth and antibiotic susceptibility of Escherichia coli with photoluminescence of GaAs/AlGaAs quantum well microstructures. Biosens Bioelectron 2017; 93:234-240. [DOI: 10.1016/j.bios.2016.08.112] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 08/17/2016] [Accepted: 08/31/2016] [Indexed: 12/31/2022]
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Formosa-Dague C, Duval RE, Dague E. Cell biology of microbes and pharmacology of antimicrobial drugs explored by Atomic Force Microscopy. Semin Cell Dev Biol 2017; 73:165-176. [PMID: 28668355 DOI: 10.1016/j.semcdb.2017.06.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 06/22/2017] [Accepted: 06/26/2017] [Indexed: 01/03/2023]
Abstract
Antimicrobial molecules have been used for more than 50 years now and are the basis of modern medicine. No surgery can nowdays be imagined to be performed without antibiotics; dreadful diseases like tuberculosis, leprosis, siphilys, and more broadly all microbial induced diseases, can be cured only through the use of antimicrobial treatments. However, the situation is becoming more and more complex because of the ability of microbes to adapt, develop, acquire, and share mechanisms of resistance to antimicrobial agents. We choose to introduce this review by briefly drawing the panorama of antimicrobial discovery and development, but also of the emergence of microbial resistance. Then we describe how Atomic Force Microscopy (AFM) can be used to provide a better understanding of the mechanisms of action of these drugs at the nanoscale level on microbial interfaces. In this section, we will address these questions: (1) how does drug treatment affect the morphology of single microbes?; (2) do antimicrobial molecules modify the nanomechanical properties of microbes, or do the nanomechanical properties of microbes play a role in antimicrobial activity and efficiency?; and (3) how are the adhesive abilitites of microbes affected by antimicrobial drugs treatment? Finally, in a second part of this review we focus on recent studies aimed at changing the paradigm of the single molecule/cell technology that AFM typically represents. Recent work dealing with the creation of a microbe array which can be explored by AFM will be presented, as these developments constitute the first steps toward transforming AFM into a higher throughput technology. We also discuss papers using AFM as NanoMechnanicalSensors (NEMS), and demonstrate the interest of such approaches in clinical microbiology to detect quickly and with high accuracy microbial resistance.
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Affiliation(s)
- Cécile Formosa-Dague
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France; CNRS, UMR 7565, SRSMC, F-54506 Vandœuvre-lès-Nancy, France; Université de Lorraine, UMR 7565, SRSMC, Faculté de Pharmacie, F-54001 Nancy, France.
| | - Raphaël Emmanuel Duval
- CNRS, UMR 7565, SRSMC, F-54506 Vandœuvre-lès-Nancy, France; Université de Lorraine, UMR 7565, SRSMC, Faculté de Pharmacie, F-54001 Nancy, France; ABC Platform(®), F-54001 Nancy, France
| | - Etienne Dague
- LAAS-CNRS, Université de Toulouse, CNRS, Toulouse, France.
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Wang C, Stanciu CE, Ehrhardt CJ, Yadavalli VK. Nanoscale characterization of forensically relevant epithelial cells and surface associated extracellular DNA. Forensic Sci Int 2017; 277:252-258. [PMID: 28672218 DOI: 10.1016/j.forsciint.2017.06.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/18/2017] [Accepted: 06/18/2017] [Indexed: 01/03/2023]
Abstract
Atomic force microscopy provides a novel morphological and physico-chemical perspective to analyze epithelial cell samples in forensic investigations. As a nanoscale, single cell tool, it allows the investigation of scarce samples in a non-destructive fashion. Using chemical force spectroscopy, it permits the identification of specific functional groups or surface molecules. Of specific interest is the presence of extracellular DNA (eDNA) on the surface of epithelial cells that line the exterior skin and interior cavities of human bodies, and can transfer onto surfaces through contact with skin and saliva. To date, this eDNA has only been measured a bulk level. Here, using nanoscale imaging, we first describe the unique differences between keratinized epithelial cells and non-keratinized buccal cells. Then via a force mapping technique, we show how eDNA can be spatially located and quantified on the cell surface. Our results suggest that presence and relative quantity of surface-associated, extracellular DNA signatures can be analyzed on individual epithelial cells from different tissue sources, providing a new tool in the forensic analysis of touch samples.
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Affiliation(s)
- Congzhou Wang
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Cristina E Stanciu
- Department of Forensic Science, Virginia Commonwealth University, Richmond, VA, USA
| | | | - Vamsi K Yadavalli
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA, USA.
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Fu Q, Zhang K, Gao D, Wang L, Yang F, Liu Y, Xia Z. Escherichia coli adhesive coating as a chiral stationary phase for open tubular capillary electrochromatography enantioseparation. Anal Chim Acta 2017; 969:63-71. [PMID: 28411631 DOI: 10.1016/j.aca.2017.03.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Revised: 03/03/2017] [Accepted: 03/20/2017] [Indexed: 10/19/2022]
Abstract
Bacteria, the microorganism with intrinsic chirality, have numerous fascinating chiral phenomena such as various chirality-triggered biological processes and behaviors. Herein, bacteria were firstly explored as novel chiral stationary phases in open-tubular capillary electrochromatography (OT-CEC) for enantioseparation of fluoroquinolone enantiomers and simultaneous separation of six fluoroquinolone antibiotics. The model strain, i.e. non-pathogenic Escherichia coli (E. coli) DH5α, was adhered onto the inner surface of positively charged polyethyleneimine (PEI) modified capillaries based on the bacterial adhesion characteristics and strong electrostatic interaction. The morphology and thickness of the bacteria adhesive coatings in the capillary were characterized by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Baseline separation of ofloxacin and partial separation of lomefloxacin enantiomers could be achieved by the E. coli coated columns. The preparation parameters including the coating time and concentration of bacteria that affecting the chiral resolution were intensively investigated. The electrophoretic parameters, including pH, buffer concentration and applied voltage, were also optimized. The developed method was validated (linearity, LOD, LOQ, intra-day, inter-day and column-to-column repeatability and recovery) and successfully utilized for the quantitative analysis of ofloxacin enantiomers in the ofloxacin tablets. Moreover, only a slight decrease in the separation efficiency was observed after 90 consecutive runs on the E. coli@capillary. These results demonstrated that bacteria are promising stationary phases for chiral separation in CEC.
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Affiliation(s)
- Qifeng Fu
- Department of Medicinal Chemistry, Southwest Medical University, Luzhou 646000, China.
| | - Kailian Zhang
- Department of Medicinal Chemistry, Southwest Medical University, Luzhou 646000, China
| | - Die Gao
- Department of Medicinal Chemistry, Southwest Medical University, Luzhou 646000, China
| | - Lujun Wang
- Department of Medicinal Chemistry, Southwest Medical University, Luzhou 646000, China
| | - Fengqing Yang
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030, China
| | - Yao Liu
- School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030, China
| | - Zhining Xia
- Innovative Drug Research Centre and School of Pharmaceutical Sciences, Chongqing University, Chongqing 400030, China; School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400030, China.
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