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Gómez-Bolívar J, Warburton MP, Mumford AD, Mujica-Alarcón JF, Anguilano L, Onwukwe U, Barnes J, Chronopoulou M, Ju-Nam Y, Thornton SF, Rolfe SA, Ojeda JJ. Spectroscopic and Microscopic Characterization of Microbial Biofouling on Aircraft Fuel Tanks. Langmuir 2024. [PMID: 38319653 PMCID: PMC10883048 DOI: 10.1021/acs.langmuir.3c02803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Avoiding microbial contamination and biofilm formation on the surfaces of aircraft fuel tanks is a major challenge in the aviation industry. The inevitable presence of water in fuel systems and nutrients provided by the fuel makes an ideal environment for bacteria, fungi, and yeast to grow. Understanding how microbes grow on different fuel tank materials is the first step to control biofilm formation in aviation fuel systems. In this study, biofilms of Pseudomonas putida, a model Gram-negative bacterium previously found in aircraft fuel tanks, were characterized on aluminum 7075-T6 surfaces, which is an alloy used by the aviation industry due to favorable properties including high strength and fatigue resistance. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray (EDX) showed that extracellular polymeric substances (EPS) produced by P. putida were important components of biofilms with a likely role in biofilm stability and adhesion to the surfaces. EDX analysis showed that the proportion of phosphorus with respect to nitrogen is higher in the EPS than in the bacterial cells. Additionally, different morphologies in biofilm formation were observed in the fuel phase compared to the water phase. Micro-Fourier transform infrared spectroscopy (micro-FTIR) analysis suggested that phosphoryl and carboxyl functional groups are fundamental for the irreversible attachment between the EPS of bacteria and the aluminum surface, by the formation of hydrogen bonds and inner-sphere complexes between the macromolecules and the aluminum surface. Based on the hypothesis that nucleic acids (particularly DNA) are an important component of EPS in P. putida biofilms, the impact of degrading extracellular DNA was tested. Treatment with the enzyme DNase I affected both water and fuel phase biofilms─with the cell structure disrupted in the aqueous phase, but cells remained attached to the aluminum coupons.
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Affiliation(s)
- Jaime Gómez-Bolívar
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, U.K
| | - Martin P Warburton
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, U.K
| | - Adam D Mumford
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, U.K
| | | | - Lorna Anguilano
- Experimental Techniques Centre, Brunel University London, Uxbridge UB8 3PH, U.K
| | - Uchechukwu Onwukwe
- Experimental Techniques Centre, Brunel University London, Uxbridge UB8 3PH, U.K
| | - James Barnes
- Airbus Operations Ltd, Pegasus House, Aerospace Avenue, Filton, Bristol BS34 7PA, U.K
| | | | - Yon Ju-Nam
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, U.K
| | - Steven F Thornton
- Groundwater Protection and Restoration Group, Department of Civil & Structural Engineering, Broad Lane, University of Sheffield, Sheffield S3 7HQ, U.K
| | - Stephen A Rolfe
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Jesús J Ojeda
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, U.K
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Martínez-Rodríguez P, Sánchez-Castro I, Ojeda JJ, Abad MM, Descostes M, Merroun ML. Effect of different phosphate sources on uranium biomineralization by the Microbacterium sp. Be9 strain: A multidisciplinary approach study. Front Microbiol 2023; 13:1092184. [PMID: 36699588 PMCID: PMC9868770 DOI: 10.3389/fmicb.2022.1092184] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/16/2022] [Indexed: 01/11/2023] Open
Abstract
Introduction Industrial activities related with the uranium industry are known to generate hazardous waste which must be managed adequately. Amongst the remediation activities available, eco-friendly strategies based on microbial activity have been investigated in depth in the last decades and biomineralization-based methods, mediated by microbial enzymes (e.g., phosphatase), have been proposed as a promising approach. However, the presence of different forms of phosphates in these environments plays a complicated role which must be thoroughly unraveled to optimize results when applying this remediation process. Methods In this study, we have looked at the effect of different phosphate sources on the uranium (U) biomineralization process mediated by Microbacterium sp. Be9, a bacterial strain previously isolated from U mill tailings. We applied a multidisciplinary approach (cell surface characterization, phosphatase activity, inorganic phosphate release, cell viability, microscopy, etc.). Results and Discussion It was clear that the U removal ability and related U interaction mechanisms by the strain depend on the type of phosphate substrate. In the absence of exogenous phosphate substrate, the cells interact with U through U phosphate biomineralization with a 98% removal of U within the first 48 h. However, the U solubilization process was the main U interaction mechanism of the cells in the presence of inorganic phosphate, demonstrating the phosphate solubilizing potential of the strain. These findings show the biotechnological use of this strain in the bioremediation of U as a function of phosphate substrate: U biomineralization (in a phosphate free system) and indirectly through the solubilization of orthophosphate from phosphate (P) containing waste products needed for U precipitation.
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Affiliation(s)
- Pablo Martínez-Rodríguez
- Department of Microbiology, University of Granada, Granada, Spain,*Correspondence: Pablo Martínez-Rodríguez, ✉
| | | | - Jesús J. Ojeda
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea, United Kingdom
| | - María M. Abad
- Centro de Instrumentación Científica (CIC), University of Granada, Granada, Spain
| | - Michael Descostes
- Environmental R&D Department, ORANO Mining, Chatillon, France,Centre de Géosciences, MINES Paris, PSL University, Fontainebleau, France
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Tagg AS, Sperlea T, Labrenz M, Harrison JP, Ojeda JJ, Sapp M. Year-Long Microbial Succession on Microplastics in Wastewater: Chaotic Dynamics Outweigh Preferential Growth. Microorganisms 2022; 10:microorganisms10091775. [PMID: 36144377 PMCID: PMC9506493 DOI: 10.3390/microorganisms10091775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Microplastics are a globally-ubiquitous aquatic pollutant and have been heavily studied over the last decade. Of particular interest are the interactions between microplastics and microorganisms, especially the pursuit to discover a plastic-specific biome, the so-called plastisphere. To follow this up, a year-long microcosm experimental setup was deployed to expose five different microplastic types (and silica beads control) to activated aerobic wastewater in controlled conditions, with microbial communities being measured four times over the course of the year using 16S rDNA (bacterial) and ITS (fungal) amplicon sequencing. The biofilm community shows no evidence of a specific plastisphere, even after a year of incubation. Indeed, the microbial communities (particularly bacterial) show a clear trend of increasing dissimilarity between plastic types as time increases. Despite little evidence for a plastic-specific community, there was a slight grouping observed for polyolefins (PE and PP) in 6–12-month biofilms. Additionally, an OTU assigned to the genus Devosia was identified on many plastics, increasing over time while showing no growth on silicate (natural particle) controls, suggesting this could be either a slow-growing plastic-specific taxon or a symbiont to such. Both substrate-associated findings were only possible to observe in samples incubated for 6–12 months, which highlights the importance of studying long-term microbial community dynamics on plastic surfaces.
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Affiliation(s)
- Alexander S. Tagg
- Leibniz-Institut für Ostseeforschung Warnemünde, Seestraße 15, 18119 Rostock, Germany
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK
- Correspondence:
| | - Theodor Sperlea
- Leibniz-Institut für Ostseeforschung Warnemünde, Seestraße 15, 18119 Rostock, Germany
| | - Matthias Labrenz
- Leibniz-Institut für Ostseeforschung Warnemünde, Seestraße 15, 18119 Rostock, Germany
| | - Jesse P. Harrison
- CSC—IT Center for Science Ltd., P.O. Box 405, FI-02101 Espoo, Finland
| | - Jesús J. Ojeda
- Department of Chemical Engineering, Faculty of Science and Engineering, Swansea University, Swansea SA1 8EN, UK
| | - Melanie Sapp
- Institute of Human Genetics, University Hospital Düsseldorf, Heinrich Heine University, Moorenstrasse 5, 40225 Düsseldorf, Germany
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Mulligan S, Ojeda JJ, Kakonyi G, Thornton SF, Moharamzadeh K, Martin N. Characterisation of Microparticle Waste from Dental Resin-Based Composites. Materials (Basel) 2021; 14:ma14164440. [PMID: 34442963 PMCID: PMC8402022 DOI: 10.3390/ma14164440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 01/05/2023]
Abstract
Clinical applications of resin-based composite (RBC) generate environmental pollution in the form of microparticulate waste. Methods: SEM, particle size and specific surface area analysis, FT-IR and potentiometric titrations were used to characterise microparticles arising from grinding commercial and control RBCs as a function of time, at time of generation and after 12 months ageing in water. The RBCs were tested in two states: (i) direct-placement materials polymerised to simulate routine clinical use and (ii) pre-polymerised CAD/CAM ingots milled using CAD/CAM technology. Results: The maximum specific surface area of the direct-placement commercial RBC was seen after 360 s of agitation and was 1290 m2/kg compared with 1017 m2/kg for the control material. The median diameter of the direct-placement commercial RBC was 6.39 μm at 360 s agitation and 9.55 μm for the control material. FTIR analysis confirmed that microparticles were sufficiently unique to be identified after 12 months ageing and consistent alteration of the outermost surfaces of particles was observed. Protonation-deprotonation behaviour and the pH of zero proton charge (pHzpc) ≈ 5–6 indicated that the particles are negatively charged at neutral pH7. Conclusion: The large surface area of RBC microparticles allows elution of constituent monomers with potential environmental impacts. Characterisation of this waste is key to understanding potential mitigation strategies.
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Affiliation(s)
- Steven Mulligan
- Academic Unit of Restorative Dentistry, School of Clinical Dentistry, Claremont Crescent, The University of Sheffield, Sheffield S10 2TA, UK;
- Correspondence:
| | - Jesús J. Ojeda
- Systems and Process Engineering Centre, College of Engineering, Swansea University, Swansea SA1 8EN, UK;
| | - Gabriella Kakonyi
- Groundwater Protection and Restoration Group, Department of Civil and Structural Engineering, Sir Frederick Mappin Building, Mappin Street, The University of Sheffield, Sheffield S1 3JD, UK; (G.K.); (S.F.T.)
| | - Steven F. Thornton
- Groundwater Protection and Restoration Group, Department of Civil and Structural Engineering, Sir Frederick Mappin Building, Mappin Street, The University of Sheffield, Sheffield S1 3JD, UK; (G.K.); (S.F.T.)
| | - Keyvan Moharamzadeh
- Hamdan Bin Mohammed College of Dental Medicine (HBMCDM), Mohammed Bin Rashid University of Medicine and Health Sciences (MBRU), Dubai P.O. Box 505055, United Arab Emirates;
| | - Nicolas Martin
- Academic Unit of Restorative Dentistry, School of Clinical Dentistry, Claremont Crescent, The University of Sheffield, Sheffield S10 2TA, UK;
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Harrison JP, Hoellein TJ, Sapp M, Tagg AS, Ju-Nam Y, Ojeda JJ. Microplastic-Associated Biofilms: A Comparison of Freshwater and Marine Environments. The Handbook of Environmental Chemistry 2018. [DOI: 10.1007/978-3-319-61615-5_9] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Tagg AS, Sapp M, Harrison JP, Ojeda JJ. Identification and Quantification of Microplastics in Wastewater Using Focal Plane Array-Based Reflectance Micro-FT-IR Imaging. Anal Chem 2015; 87:6032-40. [DOI: 10.1021/acs.analchem.5b00495] [Citation(s) in RCA: 351] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alexander S. Tagg
- Brunel University London, Experimental Techniques
Centre, Institute of Materials and Manufacturing, Bragg Building, Kingston Lane,
Uxbridge, Middlesex, United Kingdom, UB8 3PH
| | - Melanie Sapp
- Fera Science Ltd., Sand Hutton, York, United Kingdom, YO41 1LZ
| | - Jesse P. Harrison
- The University of Edinburgh, School of Physics
and Astronomy, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, United Kingdom, EH9 3FD
| | - Jesús J. Ojeda
- Brunel University London, Experimental Techniques
Centre, Institute of Materials and Manufacturing, Bragg Building, Kingston Lane,
Uxbridge, Middlesex, United Kingdom, UB8 3PH
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Attard-Montalto N, Ojeda JJ, Reynolds A, Ismail M, Bailey M, Doodkorte L, de Puit M, Jones BJ. Determining the chronology of deposition of natural fingermarks and inks on paper using secondary ion mass spectrometry. Analyst 2014; 139:4641-53. [DOI: 10.1039/c4an00811a] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study thoroughly explores the use of time-of-flight secondary ion mass spectrometry (ToF-SIMS) for determining the deposition sequence of fingermarks and ink on a porous paper surface.
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Affiliation(s)
| | - Jesús J. Ojeda
- Experimental Techniques Centre (ETCbrunel)
- Brunel University
- Uxbridge, UK
| | - Alan Reynolds
- Experimental Techniques Centre (ETCbrunel)
- Brunel University
- Uxbridge, UK
| | - Mahado Ismail
- Department of Chemistry
- University of Surrey
- Guildford, UK
| | - Melanie Bailey
- Department of Chemistry
- University of Surrey
- Guildford, UK
| | | | - Marcel de Puit
- Netherlands Forensic Institute (NFI)
- The Hague, The Netherlands
| | - Benjamin J. Jones
- School of Applied Sciences
- University of Huddersfield
- Huddersfield, UK
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8
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Attard Montalto N, Ojeda JJ, Jones BJ. Determining the order of deposition of natural latent fingerprints and laser printed ink using chemical mapping with secondary ion mass spectrometry. Sci Justice 2013; 53:2-7. [DOI: 10.1016/j.scijus.2012.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 10/28/2022]
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Harrison JP, Ojeda JJ, Romero-González ME. The applicability of reflectance micro-Fourier-transform infrared spectroscopy for the detection of synthetic microplastics in marine sediments. Sci Total Environ 2012; 416:455-63. [PMID: 22221871 DOI: 10.1016/j.scitotenv.2011.11.078] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/28/2011] [Accepted: 11/29/2011] [Indexed: 05/16/2023]
Abstract
Synthetic microplastics (≤5-mm fragments) are globally distributed contaminants within coastal sediments that may transport organic pollutants and additives into food webs. Although micro-Fourier-transform infrared (micro-FT-IR) spectroscopy represents an ideal method for detecting microplastics in sediments, this technique lacks a standardized operating protocol. Herein, an optimized method for the micro-FT-IR analysis of microplastics in vacuum-filtered sediment retentates was developed. Reflectance micro-FT-IR analyses of polyethylene (PE) were compared with attenuated total reflectance FT-IR (ATR-FT-IR) measurements. Molecular mapping as a precursor to the imaging of microplastics was explored in the presence and absence of 150-μm PE fragments, added to sediment at concentrations of 10, 100, 500 and 1000ppm. Subsequently, polymer spectra were assessed across plastic-spiked sediments from fifteen offshore sites. While all spectra obtained of evenly shaped plastics were typical to PE, reflectance micro-FT-IR measurements of irregularly shaped materials must account for refractive error. Additionally, we provide the first evidence that mapping successfully detects microplastics without their visual selection for characterization, despite this technique relying on spectra from small and spatially separated locations. Flotation of microplastics from sediments only enabled a fragment recovery rate of 61 (±31 S.D.) %. However, mapping 3-mm(2) areas (within 47-mm filters) detected PE at spiking concentrations of 100ppm and above, displaying 69 (±12 S.D.) % of the fragments in these locations. Additionally, mapping detected a potential PE fragment in a non-spiked retentate. These data have important implications for research into the imaging of microplastics. Specifically, the sensitivity and spatial resolution of the present protocol may be improved by visualizing the entire filter with high-throughput detection techniques (e.g., focal plane array-based imaging). Additionally, since micro-FT-IR analyses depend on methods of sample collection, our results emphasize the urgency of developing efficient and reproducible techniques to separate microplastics from sediments.
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Affiliation(s)
- Jesse P Harrison
- Department of Animal and Plant Sciences, The University of Sheffield, Western Bank, Sheffield S10 2TN, UK.
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10
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Abstract
A rapid and inexpensive method to characterise chemical cell properties and identify the functional groups present in the cell wall is Fourier transform infrared spectroscopy (FTIR). Infrared spectroscopy is a well-established technique to identify functional groups in organic molecules based on their vibration modes at different infrared wave numbers. The presence or absence of functional groups, their protonation states, or any changes due to new interactions can be monitored by analysing the position and intensity of the different infrared absorption bands. Additionally, infrared spectroscopy is non-destructive and can be used to monitor the chemistry of living cells. Despite the complexity of the spectra, the elucidation of functional groups on Gram-negative and Gram-positive bacteria has been already well documented in the literature. Recent advances in detector sensitivity have allowed the use of micro-FTIR spectroscopy as an important analytical tool to analyse biofilm samples without the need of previous treatment. Using FTIR spectroscopy, the infrared bands corresponding to proteins, lipids, polysaccharides, polyphosphate groups, and other carbohydrate functional groups on the bacterial cells can now be identified and compared along different conditions. Despite some differences in FTIR spectra among bacterial strains, experimental conditions, or changes in microbiological parameters, the IR absorption bands between approximately 4,000 and 400 cm(-1) are mainly due to fundamental vibrational modes and can often be assigned to the same particular functional groups. In this chapter, an overview covering the different sample preparation protocols for infrared analysis of bacterial cells is given, alongside the basic principles of the technique, the procedures for calculating vibrational frequencies based on simple harmonic motion, and the advantages and disadvantages of FTIR spectroscopy for the analysis of microorganisms.
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Affiliation(s)
- Jesús J Ojeda
- Experimental Techniques Centre, Brunel University, Uxbridge, Middlesex, UK.
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Ojeda JJ, Romero-González ME, Banwart SA. Analysis of Bacteria on Steel Surfaces Using Reflectance Micro-Fourier Transform Infrared Spectroscopy. Anal Chem 2009; 81:6467-73. [DOI: 10.1021/ac900841c] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jesús J. Ojeda
- Cell-Mineral Research Center, Kroto Research Institute, The University of Sheffield, Broad Lane, Sheffield S3 7HQ, U.K
| | - María E. Romero-González
- Cell-Mineral Research Center, Kroto Research Institute, The University of Sheffield, Broad Lane, Sheffield S3 7HQ, U.K
| | - Steven A. Banwart
- Cell-Mineral Research Center, Kroto Research Institute, The University of Sheffield, Broad Lane, Sheffield S3 7HQ, U.K
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Geoghegan M, Andrews JS, Biggs CA, Eboigbodin KE, Elliott DR, Rolfe S, Scholes J, Ojeda JJ, Romero-González ME, Edyvean RGJ, Swanson L, Rutkaite R, Fernando R, Pen Y, Zhang Z, Banwart SA. The polymer physics and chemistry of microbial cell attachment and adhesion. Faraday Discuss 2009; 139:85-103; discussion 105-28, 419-20. [PMID: 19048992 DOI: 10.1039/b717046g] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The attachment of microbial cells to solid substrata is a primary ecological strategy for the survival of species and the development of specific activity and function within communities. An hypothesis arising from a biological sciences perspective may be stated as follows: The attachment of microbes to interfaces is controlled by the macromolecular structure of the cell wall and the functional genes that are induced for its biological synthesis. Following logically from this is the view that diverse attached cell behaviour is mediated by the physical and chemical interactions of these macromolecules in the interfacial region and with other cells. This aspect can be reduced to its simplest form by treating physico-chemical interactions as colloidal forces acting between an isolated cell and a solid or pseudo solid substratum. These forces can be analysed by established methods rooted in DLVO (Derjaguin, Landau, Verwey and Overbeek) theory. Such a methodology provides little insight into what governs changes in the behaviour of the cell wall attached to surfaces, or indeed other cells. Nor does it shed any light on the expulsion of macromolecules that modify the interface such as formation of slime layers. These physical and chemical problems must be treated at the more fundamental level of the structure and behaviour of the individual components of the cell wall, for example biosurfactants and extracellular polysaccharides. This allows us to restate the above hypothesis in physical sciences terms: Cell attachment and related cell growth behaviour is mediated by macromolecular physics and chemistry in the interfacial environment. Ecological success depends on the genetic potential to favourably influence the interface through adaptation of the macromolecular structure, We present research that merges these two perspectives. This is achieved by quantifying attached cell growth for genetically diverse model organisms, building chemical models that capture the variations in interfacial structure and quantifying the resulting physical interactions. Experimental observations combine aqueous chemistry techniques with surface spectroscopy in order to elucidate the cell wall structure. Atomic force microscopy methods quantify the physical interactions between the solid substrata and key components of the cell wall such as macromolecular biosurfactants. Our current approach focuses on considering individually mycolic acids or longer chain polymers harvested from cells, as well as characterised whole cells. This approach allows us to use a multifactorial approach to address the relative impact of the individual components of the cell wall in contact with model surfaces. We then combine these components to increase complexity step-wise, while comparing with the behaviour of entire cells. Eventually, such an approach should allow us to estimate and understand the primary factors governing microbial cell adhesion. Although the work addresses the cell-mineral interface at a fundamental level, the research is driven by a range of technology needs. The initial rationale was improved prediction of contaminant degradation in natural environments (soils, sediments, aquifers) for environmental cleanup. However, this area of research addresses a wide range of biotechnology areas including improved understanding of pathogen survival (e.g., in surgical environments), better process intensification in biomanufacturing (biofilm technologies) and new product development.
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Affiliation(s)
- Mark Geoghegan
- Department of Physics and Astronomy, The University of Sheffield, Sheffield, UK S3 7RH.
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Ojeda JJ, Romero-Gonzalez ME, Bachmann RT, Edyvean RGJ, Banwart SA. Characterization of the cell surface and cell wall chemistry of drinking water bacteria by combining XPS, FTIR spectroscopy, modeling, and potentiometric titrations. Langmuir 2008; 24:4032-4040. [PMID: 18302422 DOI: 10.1021/la702284b] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Aquabacterium commune, a predominant member of European drinking water biofilms, was chosen as a model bacterium to study the role of functional groups on the cell surface that control the changes in the chemical cell surface properties in aqueous electrolyte solutions at different pH values. Cell surface properties of A. commune were examined by potentiometric titrations, modeling, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. By combining FTIR data at different pH values and potentiometric titration data with thermodynamic model optimization, the presence, concentration, and changes of organic functional groups on the cell surface (e.g., carboxyl, phosphoryl, and amine groups) were inferred. The pH of zero proton charge, pH(zpc) = 3.7, found from titrations of A. commune at different electrolyte concentrations and resulting from equilibrium speciation calculations suggests that the net surface charge is negative at drinking water pH in the absence of other charge determining ions. In situ FTIR was used to describe and monitor chemical interactions between bacteria and liquid solutions at different pH in real time. XPS analysis was performed to quantify the elemental surface composition, to assess the local chemical environment of carbon and oxygen at the cell wall, and to calculate the overall concentrations of polysaccharides, peptides, and hydrocarbon compounds of the cell surface. Thermodynamic parameters for proton adsorption are compared with parameters for other gram-negative bacteria. This work shows how the combination of potentiometric titrations, modeling, XPS, and FTIR spectroscopy allows a more comprehensive characterization of bacterial cell surfaces and cell wall reactivity as the initial step to understand the fundamental mechanisms involved in bacterial adhesion to solid surfaces and transport in aqueous systems.
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Affiliation(s)
- Jesús J Ojeda
- Cell-Mineral Interface Research Programme, Kroto Research Institute, The University of Sheffield, Broad Lane, Sheffield, United Kingdom
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