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Klopper KB, Bester E, Wolfaardt GM. Listeria monocytogenes Biofilms Are Planktonic Cell Factories despite Peracetic Acid Exposure under Continuous Flow Conditions. Antibiotics (Basel) 2023; 12:antibiotics12020209. [PMID: 36830120 PMCID: PMC9952409 DOI: 10.3390/antibiotics12020209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/07/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023] Open
Abstract
Listeria monocytogenes biofilms are ubiquitous in the food-processing environment, where they frequently show resistance against treatment with disinfectants such as peracetic acid (PAA) due to sub-lethal damage resulting in biofilm persistence or the formation of secondary biofilms. L. monocytogenes serovar ½a EGD-e biofilms were cultivated under continuous flow conditions at 10 °C, 22 °C, and 37 °C and exposed to industrially relevant PAA concentrations. The effect of PAA on biofilm metabolic activity and biomass was monitored in real-time using the CEMS-BioSpec system, in addition to daily measurement of biofilm-derived planktonic cell production. Biofilm-derived planktonic cell yields proved to be consistent with high yields during biofilm establishment (≥106 CFU.mL-1). The exposure of biofilms to the minimum inhibitory PAA concentration (0.16%) resulted in only a brief disruption in whole-biofilm metabolic activity and biofilm biomass accumulation. The recovered biofilm accumulated more biomass and greater activity, but cell yields remained similar. Increasing concentrations of PAA (0.50%, 1.5%, and 4.0%) had a longer-lasting inhibitory effect. Only the maximum dose resulted in a lasting inhibition of biofilm activity and biomass-a factor that needs due consideration in view of dilution in industrial settings. Better disinfection monitoring tools and protocols are required to adequately address the problem of Listeria biofilms in the food-processing environment, and more emphasis should be placed on biofilms serving as a "factory" for cell proliferation rather than only a survival mechanism.
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Affiliation(s)
- Kyle B. Klopper
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Elanna Bester
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
| | - Gideon M. Wolfaardt
- Department of Microbiology, Stellenbosch University, Stellenbosch 7600, South Africa
- Department of Chemistry and Biology, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada
- Correspondence:
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2
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Dhall A, Ramjee R, Oh MJ, Tao K, Hwang G. A 3D-Printed Customizable Platform for Multiplex Dynamic Biofilm Studies. ADVANCED MATERIALS TECHNOLOGIES 2022; 7:2200138. [PMID: 35935146 PMCID: PMC9347831 DOI: 10.1002/admt.202200138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Biofilms are communities of microbes that colonize surfaces. While several biofilm experimental models exist, they often have limited replications of spatiotemporal dynamics surrounding biofilms. For a better understanding dynamic and complex biofilm development, this manuscript presents a customizable platform compatible with off-the-shelf well plates that can monitor microbial adhesion, growth, and associated parameters under various relevant scenarios by taking advantage of 3D printing. The system i) holds any substrate in a stable, vertical position, ii) subjects samples to flow at different angles, iii) switches between static and dynamic modes during an experiment, and iv) allows multiplexing and real-time monitoring of biofilm parameters. Simulated fluid dynamics is employed to estimate flow patterns around discs and shear stresses at disc surfaces. A 3D printed peristaltic pump and a customized pH measurement system for real-time tracking of spent biofilm culture media are equipped with a graphical user interface that grants control over all experimental parameters. The system is tested under static and dynamic conditions with Streptococcus mutans using different carbon sources. By monitoring the effluent pH and characterizing biochemical, microbiological, and morphological properties of cultured biofilms, distinct properties are demonstrated. This novel platform liberates designing experimental strategies for investigations of biofilms under various conditions.
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Affiliation(s)
- Atul Dhall
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravikiran Ramjee
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Min Jun Oh
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Chemical and Biomolecular Engineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kevin Tao
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Geelsu Hwang
- Department of Preventive and Restorative Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Center for Innovation & Precision Dentistry, School of Dental Medicine, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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3
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Ionized jet deposition of antimicrobial and stem cell friendly silver-substituted tricalcium phosphate nanocoatings on titanium alloy. Bioact Mater 2021; 6:2629-2642. [PMID: 34027240 PMCID: PMC8121618 DOI: 10.1016/j.bioactmat.2020.12.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/10/2020] [Accepted: 12/20/2020] [Indexed: 02/07/2023] Open
Abstract
Orthopedic infections pose severe societal and economic burden and interfere with the capability of the implanted devices to integrate in the host bone, thus significantly increasing implants failure rate. To address infection and promote integration, here nanostructured antibacterial and bioactive thin films are proposed, obtained, for the first time, by Ionized Jet Deposition (IJD) of silver-substituted tricalcium phosphate (Ag-TCP) targets on titanium. Coatings morphology, composition and mechanical properties are characterized and proof-of-concept of biocompatibility is shown. Antimicrobial efficacy is investigated against four Gram positive and Gram negative bacterial strains and against C. albicans fungus, by investigating the modifications in planktonic bacterial growth in the absence and presence of silver. Then, for all bacterial strains, the capability of the film to inhibit bacterial adhesion is also tested. Results indicate that IJD permits a fine control over films composition and morphology and deposition of films with suitable mechanical properties. Biological studies show a good efficacy against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis and against fungus Candida albicans, with evidences of efficacy against planktonic growth and significant reduction of bacterial cell adhesion. No cytotoxic effects are evidenced for equine adipose tissue derived mesenchymal stem cells (ADMSCs), as no reductions are caused to cells viability and no interference is assessed in cells differentiation towards osteogenic lineage, in the presence of silver. Instead, thanks to nanostructuration and biomimetic composition, tricalcium phosphate (TCP) coatings favor cells viability, also when silver-substituted. These findings show that silver-substituted nanostructured coatings are promising for orthopedic implant applications. Silver-substituted TCP films on titanium are prepared by Ionized Jet Deposition Films are nanostructured, hard, with submicron thickness Adipose mesenchymal stem cells differentiate into osteogenic lineage on the surface of films Films show antimicrobial and anti-adhesive activity against several microorganisms Films are promising for application in orthopedic titanium implants
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4
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Aqeel H, Liss SN. Autotrophic Fixed-Film Systems Treating High Strength Ammonia Wastewater. Front Microbiol 2020; 11:551925. [PMID: 33013783 PMCID: PMC7506033 DOI: 10.3389/fmicb.2020.551925] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/12/2020] [Indexed: 01/04/2023] Open
Abstract
The aim of the study was enrichment of nitrifying bacteria and to investigate the potential of autotrophic fixed-film and hybrid bioreactors to treat high strength ammonia wastewater (up to 1,000 mg N/L). Two types of fixed-film systems [moving bed biofilm reactor (MBBR) and BioCordTM] in two different configurations [sequencing batch reactor (SBR) and a continuous stirred tank reactor (CSTR)] were operated for 306 days. The laboratory-scale bioreactors were seeded with activated sludge from a municipal wastewater treatment plant and fed synthetic wastewater with no organics. Strategies for acclimation included biomass reseeding (during bioreactor start-up), and gradual increase in the influent ammonia concentration [from 130 to 1,000 mg N/L (10% every 5 days)]. Stable ammonia removal was observed up to 750 mg N/L from 45 to 145 days in the MBBR SBR (94-100%) and CSTR (72-100%), and BioCordTM SBR (96-100%) and CSTR (92-100%). Ammonia removal declined to 87% ± 6, in all bioreactors treating 1,000 mg N/L (on day 185). Following long-term operation at 1,000 mg N/L (on day 306), ammonia removal was 93-94% in both the MBBR SBR and BioCordTM CSTR; whereas, ammonia removal was relatively lower in MBBR CSTR (20-35%) and BioCordTM SBR (45-54%). Acclimation to increasing concentrations of ammonia led to the enrichment of nitrifying (Nitrosomonas, Nitrospira, and Nitrobacter) and denitrifying (Comamonas, OLB8, and Rhodanobacter) bacteria [16S rRNA gene sequencing (Illumina)] in all bioreactors. In the hybrid bioreactor, the nitrifying and denitrifying bacteria were relatively more abundant in flocs and biofilms, respectively. The presence of dead cells (in biofilms) suggests that in the absence of an organic substrate, endogenous decay is a likely contributor of nutrients for denitrifying bacteria. The nitrite accumulation and abundance of denitrifying bacteria indicate partial denitrification in fixed-film bioreactors operated under limited carbon conditions. Further studies are required to assess the contribution of organic material produced in autotrophic biofilms (by endogenous decay and soluble microbial products) to the overall treatment process. Furthermore, the possibility of sustaining autotrophic nitrogen in high strength waste-streams in the presence of organic substrates warrants further investigation.
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Affiliation(s)
- Hussain Aqeel
- School of Environmental Studies, Queen's University, Kingston, ON, Canada
| | - Steven N Liss
- School of Environmental Studies, Queen's University, Kingston, ON, Canada.,Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada.,Department of Microbiology, Stellenbosch University, Stellenbosch, South Africa
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An open-source robotic platform that enables automated monitoring of replicate biofilm cultivations using optical coherence tomography. NPJ Biofilms Microbiomes 2020; 6:18. [PMID: 32238809 PMCID: PMC7113294 DOI: 10.1038/s41522-020-0129-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 03/06/2020] [Indexed: 12/14/2022] Open
Abstract
The paper introduces a fully automated cultivation and monitoring tool to study biofilm development in replicate experiments operated in parallel. To gain a fundamental understanding of the relation between cultivation conditions and biofilm characteristics (e.g., structural, mechanical) a monitoring setup allowing for the standardization of methods is required. Optical coherence tomography (OCT) is an imaging modality ideal for biofilms since it allows for the monitoring of structure in real time. By integrating an OCT device into the open-source robotic platform EvoBot, a fully automated monitoring platform for investigating biofilm development in several flow cells at once was realized. Different positioning scenarios were tested and revealed that the positioning accuracy is within the optical resolution of the OCT. On that account, a reliable and accurate monitoring of biofilm development by means of OCT has become possible. With this robotic platform, reproducible biofilm experiments including a statistical analysis are achievable with only a small investment of operator time. Furthermore, a number of structural parameters calculated within this study confirmed the necessity to perform replicate biofilm cultivations.
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6
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Sou T, Kukavica-Ibrulj I, Levesque RC, Friberg LE, Bergström CA. Model-Informed Drug Development in Pulmonary Delivery: Semimechanistic Pharmacokinetic–Pharmacodynamic Modeling for Evaluation of Treatments against Chronic Pseudomonas aeruginosa Lung Infections. Mol Pharm 2020; 17:1458-1469. [DOI: 10.1021/acs.molpharmaceut.9b00968] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Tomás Sou
- Drug Delivery Group, Department of Pharmacy, Uppsala University, Uppsala 751 23, Sweden
- Pharmacometrics Group, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala 751 05, Sweden
| | - Irena Kukavica-Ibrulj
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec G1V 0A6, Canada
| | - Roger C. Levesque
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec G1V 0A6, Canada
| | - Lena E. Friberg
- Pharmacometrics Group, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala 751 05, Sweden
| | - Christel A.S. Bergström
- Drug Delivery Group, Department of Pharmacy, Uppsala University, Uppsala 751 23, Sweden
- The Swedish Drug Delivery Forum, Department of Pharmacy, Uppsala University, Uppsala 751 05, Sweden
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7
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Pousti M, Lefèvre T, Amirdehi MA, Greener J. A surface spectroscopy study of a Pseudomonas fluorescens biofilm in the presence of an immobilized air bubble. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 222:117163. [PMID: 31177008 DOI: 10.1016/j.saa.2019.117163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/15/2019] [Accepted: 05/26/2019] [Indexed: 06/09/2023]
Abstract
A linear spectral mapping technique was applied to monitor the growth of biomolecular absorption bands at the bio-interface of a nascent Pseudomonas fluorescens biofilm during and after interaction with a surface-adhered air bubble. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectra were obtained in different locations in a microchannel with adequate spatial and temporal resolution to study the effect of a static bubble on the evolution of protein and lipid signals at the ATR crystal surface. The results reveal that the presence of a bubble during the lag phase modified levels of extracellular lipids and affected a surface restructuring process, many hours after the bubble's disappearance.
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Affiliation(s)
- M Pousti
- Département de Chimie, Faculté des sciences et de génie, Université Laval, Québec City, QC, Canada; Centre de recherche sur les matériaux avancés (CERMA), Canada; Centre québécois sur les matériaux fonctionnels (CQMF), Canada
| | - T Lefèvre
- Département de Chimie, Faculté des sciences et de génie, Université Laval, Québec City, QC, Canada; Centre de recherche sur les matériaux avancés (CERMA), Canada; Centre québécois sur les matériaux fonctionnels (CQMF), Canada
| | - M Abbaszadeh Amirdehi
- Département de Chimie, Faculté des sciences et de génie, Université Laval, Québec City, QC, Canada
| | - J Greener
- Département de Chimie, Faculté des sciences et de génie, Université Laval, Québec City, QC, Canada; CHU de Québec, centre de recherche, Université Laval, 10 rue de l'Espinay, Québec, QC, Canada; Centre de recherche sur les matériaux avancés (CERMA), Canada; Centre québécois sur les matériaux fonctionnels (CQMF), Canada.
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8
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Ahmed W, Tian X, Delatolla R. Nitrifying moving bed biofilm reactor: Performance at low temperatures and response to cold-shock. CHEMOSPHERE 2019; 229:295-302. [PMID: 31078886 DOI: 10.1016/j.chemosphere.2019.04.176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/22/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
In contrast with suspended growth systems, attached growth technologies such as the moving bed biofilm reactors (MBBR) have recently demonstrated significant nitrification rates at temperatures as low as 1 °C. The purpose of this study was to investigate the performance of the nitrifying MBBR system at elevated municipal concentrations with exposures to low temperatures and cold-shock conditions down to 1 °C using an enhanced temperature-controlled room. A removal rate of 98.44 ± 4.69 gN·m-3·d-1 was identified as the intrinsic rate of nitrifying MBBR systems at 1 °C and was proposed as the conservative rate for low temperature design. A temperature threshold at which attached growth nitrification displayed a significant decrease in kinetics was identified between 2 °C and 4 °C. Arrhenius correction coefficients of 1.086 and 1.09 previously applied for low temperature nitrifying MBBR systems resulted in conservative modeled removal rates on average 21% lower than the measured rates. Thus, an Arrhenius correction coefficient of 1.049 is proposed between the temperatures of 10 °C and 4 °C and another correction coefficient of 1.149 to model rates at 1 °C. For the transition from 4 °C to 1 °C, the adjustment of a previously reported Theta model is proposed in this study to account for exposure time at low temperatures; with the modified model showing strong correlation with measured rates (R2 = 0.88). Finally, a comparison of nitrification kinetics between MBBR systems acclimatized to 1 °C and systems that are cold-shocked to 1 °C demonstrated that shocked removal rates are 21% lower.
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Affiliation(s)
- Warsama Ahmed
- Department of Civil Engineering, University of Ottawa, Ottawa, ON, 161 Louis Pasteur, K1N 6N5, Canada.
| | - Xin Tian
- Department of Civil Engineering, University of Ottawa, Ottawa, ON, 161 Louis Pasteur, K1N 6N5, Canada.
| | - Robert Delatolla
- Department of Civil Engineering, University of Ottawa, Ottawa, ON, 161 Louis Pasteur, K1N 6N5, Canada.
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9
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Caschera A, Mistry KB, Bedard J, Ronan E, Syed MA, Khan AU, Lough AJ, Wolfaardt G, Foucher DA. Surface-attached sulfonamide containing quaternary ammonium antimicrobials for textiles and plastics. RSC Adv 2019; 9:3140-3150. [PMID: 35518965 PMCID: PMC9059942 DOI: 10.1039/c8ra10173f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 01/13/2019] [Indexed: 11/21/2022] Open
Abstract
With the risks associated with healthcare-associated infections and the rise of antibiotic resistant microorganisms, there is an important need to control the proliferation of these factors in hospitals, retirement homes and other institutions. This work explores the development and application of a novel class of sulfonamide-based quaternary ammonium antimicrobial coatings, anchored to commercially and clinically relevant material surfaces. Synthesized in high yields (60–97%), benzophenone-anchored antimicrobials were spray-coated and UV grafted onto plastic surfaces, while silane-anchored variants were adhered to select textiles via dip-coating. Surface modified samples were characterised by advancing contact angle, anionic dye staining, X-ray photoelectron spectroscopy and atomic force microscopy. After verifying coating quality through the above characterization methods, microbiological testing was performed on batch samples in conditions that simulate the natural inoculation of surfaces and objects (solid/air) and water containers (solid/liquid). Using the previously established Large Drop Inoculum (LDI) protocol at solid/air interfaces, all treated samples showed a full reduction (105–107 CFU) of viable Arthrobacter sp., S. aureus, and E. coli after 3 h of contact time. Additional testing of the walls of plastic LDPE vials treated with a UV-cured sulfonamide antimicrobial at a solid/liquid interface using the newly developed Large Reservoir Inoculum (LRI) protocol under static conditions revealed a complete kill (>106 reduction) of Gram-positive Arthrobacter sp., and a partial kill (>104 reduction) of Gram-negative E. coli within 24–48 h of contact. A series of surface attached silane or benzophenone sulfonamide quaternary ammonium antimicrobials show potent efficacy at solid/air and solid/liquid interfaces.![]()
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Affiliation(s)
- Alexander Caschera
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Kamlesh B Mistry
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Joseph Bedard
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Evan Ronan
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Moiz A Syed
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Aman U Khan
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
| | - Alan J Lough
- Department of Chemistry, University of Toronto 80 St. George Street Toronto Ontario Canada M5S 3H6
| | - Gideon Wolfaardt
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3 .,Stellenbosch University Water Institute Secretariat, Faculty of Natural Science, Stellenbosch University South Africa
| | - Daniel A Foucher
- Department of Chemistry and Biology, Ryerson University 350 Victoria Street Toronto Ontario Canada M5B-2K3
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10
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Pousti M, Zarabadi MP, Abbaszadeh Amirdehi M, Paquet-Mercier F, Greener J. Microfluidic bioanalytical flow cells for biofilm studies: a review. Analyst 2019; 144:68-86. [PMID: 30394455 DOI: 10.1039/c8an01526k] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bacterial biofilms are among the oldest and most prevalent multicellular life forms on Earth and are increasingly relevant in research areas related to industrial fouling, medicine and biotechnology. The main hurdles to obtaining definitive experimental results include time-varying biofilm properties, structural and chemical heterogeneity, and especially their strong sensitivity to environmental cues. Therefore, in addition to judicious choice of measurement tools, a well-designed biofilm study requires strict control over experimental conditions, more so than most chemical studies. Due to excellent control over a host of physiochemical parameters, microfluidic flow cells have become indispensable in microbiological studies. Not surprisingly, the number of lab-on-chip studies focusing on biofilms and other microbiological systems with expanded analytical capabilities has expanded rapidly in the past decade. In this paper, we comprehensively review the current state of microfluidic bioanalytical research applied to bacterial biofilms and offer a perspective on new approaches that are expected to drive continued advances in this field.
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Affiliation(s)
- Mohammad Pousti
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec City, Québec G1 V 0A6, Canada
| | - Mir Pouyan Zarabadi
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec City, Québec G1 V 0A6, Canada
| | - Mehran Abbaszadeh Amirdehi
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec City, Québec G1 V 0A6, Canada
| | - François Paquet-Mercier
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec City, Québec G1 V 0A6, Canada
| | - Jesse Greener
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec City, Québec G1 V 0A6, Canada and CHU de Quebec Research Centre, Laval University, 10 rue de l'Espinay, Quebec City, (QC) G1L 3L5, Canada
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11
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Pousti M, Joly M, Roberge P, Amirdehi MA, Bégin-Drolet A, Greener J. Linear Scanning ATR-FTIR for Chemical Mapping and High-Throughput Studies of Pseudomonas sp. Biofilms in Microfluidic Channels. Anal Chem 2018; 90:14475-14483. [DOI: 10.1021/acs.analchem.8b04279] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Mohammad Pousti
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Maxime Joly
- Département de génie mécanique, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Patrice Roberge
- Département de génie mécanique, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | | | - Andre Bégin-Drolet
- Département de génie mécanique, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
| | - Jesse Greener
- Département de chimie, Faculté des sciences et de génie, Université Laval, Québec, QC G1V 0A6, Canada
- CHU de Quebec Research Centre, Laval University, 10 rue de l’Espinay, Québec, QC G1L 3L5, Canada
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12
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Drinking water microbiome assembly induced by water stagnation. ISME JOURNAL 2018; 12:1520-1531. [PMID: 29588495 PMCID: PMC5955952 DOI: 10.1038/s41396-018-0101-5] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 02/09/2018] [Accepted: 02/20/2018] [Indexed: 01/05/2023]
Abstract
What happens to tap water when you are away from home? Day-to-day water stagnation in building plumbing can potentially result in water quality deterioration (e.g., lead release or pathogen proliferation), which is a major public health concern. However, little is known about the microbial ecosystem processes in plumbing systems, hindering the development of biological monitoring strategies. Here, we track tap water microbiome assembly in situ, showing that bacterial community composition changes rapidly from the city supply following ~6-day stagnation, along with an increase in cell count from 103 cells/mL to upwards of 7.8 × 105 cells/mL. Remarkably, bacterial community assembly was highly reproducible in this built environment system (median Spearman correlation between temporal replicates = 0.78). Using an island biogeography model, we show that neutral processes arising from the microbial communities in the city water supply (i.e., migration and demographic stochasticity) explained the island community composition in proximal pipes (Goodness-of-fit = 0.48), yet declined as water approached the faucet (Goodness-of-fit = 0.21). We developed a size-effect model to simulate this process, which indicated that pipe diameter drove these changes by mediating the kinetics of hypochlorite decay and cell detachment, affecting selection, migration, and demographic stochasticity. Our study challenges current water quality monitoring practice worldwide which ignore biological growth in plumbing, and suggests the island biogeography model as a useful framework to evaluate building water system quality.
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13
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Kotlarz N, Rockey N, Olson TM, Haig SJ, Sanford L, LiPuma JJ, Raskin L. Biofilms in Full-Scale Drinking Water Ozone Contactors Contribute Viable Bacteria to Ozonated Water. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2618-2628. [PMID: 29299927 DOI: 10.1021/acs.est.7b04212] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other ( p = 0.017). The biofilms downstream of the dead zone contained a significantly ( p = 0.036) higher relative abundance of bacteria of the genera Mycobacterium and Legionella than the upstream biofilms. These results have important implications as the effluent from ozone contactors is often treated further in biologically active filters and bacteria in ozonated water continuously seed filter microbial communities.
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Affiliation(s)
- Nadine Kotlarz
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Nicole Rockey
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Terese M Olson
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Sarah-Jane Haig
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Larry Sanford
- Drinking Water Treatment Utility, Ann Arbor , Michigan 48103 , United States
| | - John J LiPuma
- Department of Pediatrics and Communicable Diseases , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | - Lutgarde Raskin
- Department of Civil and Environmental Engineering , University of Michigan , Ann Arbor , Michigan 48109 , United States
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14
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Li J, Feng J, Ma L, de la Fuente Núñez C, Gölz G, Lu X. Effects of meat juice on biofilm formation of Campylobacter and Salmonella. Int J Food Microbiol 2017; 253:20-28. [DOI: 10.1016/j.ijfoodmicro.2017.04.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 03/30/2017] [Accepted: 04/21/2017] [Indexed: 10/19/2022]
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15
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Zarabadi MP, Paquet-Mercier F, Charette SJ, Greener J. Hydrodynamic Effects on Biofilms at the Biointerface Using a Microfluidic Electrochemical Cell: Case Study of Pseudomonas sp. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2041-2049. [PMID: 28147485 DOI: 10.1021/acs.langmuir.6b03889] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The anchoring biofilm layer is expected to exhibit a different response to environmental stresses than for portions in the bulk, due to the protection from other strata and the proximity to the attachment surface. The effect of hydrodynamic stress on surface-adhered biofilm layers was tested using a specially designed microfluidic bio flow cell with an embedded three-electrode detection system. In situ electrochemical impedance spectroscopy (EIS) measurements of biocapacitance and bioresistance of Pseudomonas sp. biofilms were conducted during the growth phase and under different shear flow conditions with verification by other surface sensitive techniques. Distinct, but reversible changes to the amount of biofilm and its structure at the attachment surface were observed during the application of elevated shear stress. In contrast, regular microscopy revealed permanent distortion to the biofilm bulk, in the form of streamers and ripples. Following the application of extreme shear stresses, complete removal of significant portions of biofilm outer layers occurred, but this did not change the measured quantity of biofilm at the electrode attachment surface. The structure of the remaining biofilm, however, appeared to be modified and susceptible to further changes following application of shear stress directly to the unprotected biofilm layers at the attachment surface.
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Affiliation(s)
| | | | - Steve J Charette
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec , Québec City, Québec G1V 4G5, Canada
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16
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Paquet-Mercier F, Parvinzadeh Gashti M, Bellavance J, Taghavi SM, Greener J. Through thick and thin: a microfluidic approach for continuous measurements of biofilm viscosity and the effect of ionic strength. LAB ON A CHIP 2016; 16:4710-4717. [PMID: 27808313 DOI: 10.1039/c6lc01101b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Continuous, non-intrusive measurements of time-varying viscosity of Pseudomonas sp. biofilms are made using a microfluidic method that combines video tracking with a semi-empirical viscous flow model. The approach uses measured velocity and height of tracked biofilm segments, which move under the constant laminar flow of a nutrient solution. Following a low viscosity growth stage, rapid thickening was observed. During this stage, viscosity increased by over an order of magnitude in less than ten hours. The technique was also demonstrated as a promising platform for parallel experiments by subjecting multiple biofilm-laden microchannels to nutrient solutions containing NaCl in the range of 0 to 34 mM. Preliminary data suggest a strong relationship between ionic strength and biofilm properties, such as average viscosity and rapid thickening onset time. The technique opens the way for a combinatorial approach to study the response of biofilm viscosity under well-controlled physical, chemical and biological growth conditions.
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Affiliation(s)
- F Paquet-Mercier
- Département de Chimie, Université Laval, Québec, QC G1V 0A6, Canada.
| | | | - J Bellavance
- Département de Chimie, Université Laval, Québec, QC G1V 0A6, Canada.
| | - S M Taghavi
- Département de Génie Chimique, Université Laval, Québec, QC G1V 0A6, Canada
| | - J Greener
- Département de Chimie, Université Laval, Québec, QC G1V 0A6, Canada.
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17
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Greener J, Parvinzadeh Gashti M, Eslami A, Zarabadi MP, Taghavi SM. A microfluidic method and custom model for continuous, non-intrusive biofilm viscosity measurements under different nutrient conditions. BIOMICROFLUIDICS 2016; 10:064107. [PMID: 27965730 PMCID: PMC5116028 DOI: 10.1063/1.4968522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 11/09/2016] [Indexed: 05/24/2023]
Abstract
Straight, low-aspect ratio micro flow cells are used to support biofilm attachment and preferential accumulation at the short side-wall, which progressively reduces the effective channel width. The biofilm shifts downstream at measurable velocities under the imposed force from the constant laminar co-flowing nutrient stream. The dynamic behaviour of the biofilm viscosity is modeled semi-analytically, based on experimental measurements of biofilm dimensions and velocity as inputs. The technique advances the study of biofilm mechanical properties by strongly limiting biases related to non-Newtonian biofilm properties (e.g., shear dependent viscosity) with excellent time resolution. To demonstrate the proof of principle, young Pseudomonas sp. biofilms were analyzed under different nutrient concentrations and constant micro-flow conditions. The striking results show that large initial differences in biofilm viscosities grown under different nutrient concentrations become nearly identical in less than one day, followed by a continuous thickening process. The technique verifies that in 50 h from inoculation to early maturation stages, biofilm viscosity could grow by over 2 orders of magnitude. The approach opens the way for detailed studies of mechanical properties under a wide variety of physiochemical conditions, such as ionic strength, temperature, and shear stress.
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Affiliation(s)
- J Greener
- Department of Chemistry, Université Laval , 1045 Ave. de la Médecine, Québec, Québec G1V 0A6, Canada
| | - M Parvinzadeh Gashti
- Department of Chemistry, Université Laval , 1045 Ave. de la Médecine, Québec, Québec G1V 0A6, Canada
| | - A Eslami
- Department of Chemical Engineering, Université Laval , Québec, Québec G1V 0A6, Canada
| | - M P Zarabadi
- Department of Chemistry, Université Laval , 1045 Ave. de la Médecine, Québec, Québec G1V 0A6, Canada
| | - S M Taghavi
- Department of Chemical Engineering, Université Laval , Québec, Québec G1V 0A6, Canada
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18
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Droppo IG, Krishnappan BG, Lawrence JR. Microbial interactions with naturally occurring hydrophobic sediments: Influence on sediment and associated contaminant mobility. WATER RESEARCH 2016; 92:121-130. [PMID: 26849315 DOI: 10.1016/j.watres.2016.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/08/2016] [Accepted: 01/17/2016] [Indexed: 06/05/2023]
Abstract
The erosion, transport and fate of sediments and associated contaminants are known to be influenced by both particle characteristics and the flow dynamics imparted onto the sediment. The influential role of bitumen containing hydrophobic sediments and the microbial community on sediment dynamics are however less understood. This study links an experimental evaluation of sediment erosion with measured sediment-associated contaminant concentrations and microbial community analysis to provide an estimate of the potential for sediment to control the erosion, transport and fate of contaminants. Specifically the paper addresses the unique behaviour of hydrophobic sediments and the role that the microbial community associated with hydrophobic sediment may play in the transport of contaminated sediment. Results demonstrate that the hydrophobic cohesive sediment demonstrates unique transport and particle characteristics (poor settling and small floc size). Biofilms were observed to increase with consolidation/biostabilization times and generated a unique microbial consortium relative to the eroded flocs. Natural oil associated with the flocs appeared to be preferentially associated with microbial derived extracellular polymeric substances. While PAHs and naphthenic acid increased with increasing shear (indicative of increasing loads), they tended to decrease with consolidation/biostabilization (CB) time at similar shears suggesting a chemical and/or biological degradation. PAH and napthenic acid degrading microbes decreased with time as well, which may suggest that there was a reduced pool of PAHs and naphthenic acids available resulting in their die off. This study emphasizes the importance that any management strategies and operational assessments for the protection of human and aquatic health incorporate the sediment (suspended and bed sediment) and biological (biofilm) compartments and the energy dynamics within the system in order to better predict contaminant transport.
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Affiliation(s)
- I G Droppo
- Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada.
| | - B G Krishnappan
- Environment Canada, 867 Lakeshore Road, Burlington, Ontario, Canada
| | - J R Lawrence
- Environment Canada, 11 Innovation Blvd., Saskatoon, Saskatchewan, Canada
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19
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Kragh KN, Hutchison JB, Melaugh G, Rodesney C, Roberts AEL, Irie Y, Jensen PØ, Diggle SP, Allen RJ, Gordon V, Bjarnsholt T. Role of Multicellular Aggregates in Biofilm Formation. mBio 2016; 7:e00237. [PMID: 27006463 PMCID: PMC4807362 DOI: 10.1128/mbio.00237-16] [Citation(s) in RCA: 209] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 02/22/2016] [Indexed: 11/25/2022] Open
Abstract
UNLABELLED In traditional models ofin vitrobiofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development ofPseudomonas aeruginosabiofilms. We find that the relative fitness of aggregates depends markedly on the density of surrounding single cells, i.e., the level of competition for growth resources. When competition between aggregates and single cells is low, an aggregate has a growth disadvantage because the aggregate interior has poor access to growth resources. However, if competition is high, aggregates exhibit higher fitness, because extending vertically above the surface gives cells at the top of aggregates better access to growth resources. Other advantages of seeding by aggregates, such as earlier switching to a biofilm-like phenotype and enhanced resilience toward antibiotics and immune response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation. IMPORTANCE During the past decades, there has been a consensus around the model of development of a biofilm, involving attachment of single planktonic bacterial cells to a surface and the subsequent development of a mature biofilm. This study presents results that call for a modification of this rigorous model. We show how free floating biofilm aggregates can have a profound local effect on biofilm development when attaching to a surface. Our findings show that an aggregate landing on a surface will eventually outcompete the biofilm population arising from single cells attached around the aggregate and dominate the local biofilm development. These results point to a regime where preformed biofilm aggregates may have a fitness advantage over planktonic cells when it comes to accessing nutrients. Our findings add to the increasingly prominent comprehension that biofilm lifestyle is the default for bacteria and that planktonic single cells may be only a transition state at the most.
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Affiliation(s)
- Kasper N Kragh
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Jaime B Hutchison
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA
| | - Gavin Melaugh
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Chris Rodesney
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA
| | - Aled E L Roberts
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Yasuhiko Irie
- Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom
| | - Peter Ø Jensen
- Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
| | - Stephen P Diggle
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Rosalind J Allen
- School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom
| | - Vernita Gordon
- Center for Nonlinear Dynamics and Department of Physics, The University of Texas at Austin, Austin, Texas, USA Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA
| | - Thomas Bjarnsholt
- Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark Department of Clinical Microbiology, Rigshospitalet, Copenhagen, Denmark
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20
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Paquet-Mercier F, Karas A, Safdar M, Aznaveh NB, Zarabadi M, Greener J. Development and calibration of a microfluidic biofilm growth cell with flow-templating and multi-modal characterization. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:1557-62. [PMID: 25570268 DOI: 10.1109/embc.2014.6943900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We report the development of a microfluidic flow-templating platform with multi-modal characterization for studies of biofilms and their precursor materials. A key feature is a special three inlet flow-template compartment, which confines and controls the location of biofilm growth against a template wall. Characterization compartments include Raman imaging to study the localization of the nutrient solutions, optical microscopy to quantify biofilm biomass and localization, and cyclic voltammetry for flow velocity measurements. Each compartment is tested and then utilized to make preliminary measurements.
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21
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Gazzola G, Habimana O, Murphy CD, Casey E. Comparison of biomass detachment from biofilms of two different Pseudomonas spp. under constant shear conditions. BIOFOULING 2015; 31:13-18. [PMID: 25563340 DOI: 10.1080/08927014.2014.990962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In the context of biofilm development, detachment is of practical importance when placed in a biofilm management perspective. The objective of the present study was to examine biofilm structure and biofilm detachment under controlled conditions for two distinct microorganisms grown under constant shear conditions. Detached biofilm biomass was regularly collected and analysed over the course of 72 h biofilm growth by Pseudomonas putida and Pseudomonas fluorescens cells, and biofilm structural development assessed using confocal microscopy. The two Pseudomonas spp., which had very similar specific growth rates in planktonic culture, presented notably different characteristics in terms of biofilm morphology but their detachment behaviours over time were very similar. These findings underline the intrinsic complexity of the detachment phenomenon.
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Affiliation(s)
- Giulio Gazzola
- a UCD School of Chemical and Bioprocess Engineering , University College Dublin , Dublin , Ireland
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22
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Aznaveh NB, Safdar M, Wolfaardt G, Greener J. Micropatterned biofilm formations by laminar flow-templating. LAB ON A CHIP 2014; 14:2666-72. [PMID: 24722812 DOI: 10.1039/c4lc00084f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We present a microfluidic device capable of patterning linear biofilm formations using a flow templating approach. We describe the design considerations and fabrication methodology of a two level flow-templating micro-bioreactor (FT-μBR), which generates a biofilm growth stream surrounded on 3 sides by a growth inhibiting confinement stream. Through a combination of experiments and simulations we comprehensively evaluate and exploit control parameters to manipulate the biofilm growth template stream dimensions. The FT-μBR is then used to grow biofilm patterns with controllable dimensions. A proof-of-principle study using the device demonstrates its utility in conducting biofilm growth rate measurements under different shear stress environments. This opens the way for quantitative studies into the effects of the local shear environment on biofilm properties and for the synthesis of a new generation of functional biomaterials with controllable properties.
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Affiliation(s)
- Nahid Babaei Aznaveh
- Département de Chimie, Université Laval, 1045 Avenue de la Médecine, Québec, QC G1V 0A6, Canada.
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23
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Role of force-sensitive amyloid-like interactions in fungal catch bonding and biofilms. EUKARYOTIC CELL 2014; 13:1136-42. [PMID: 24681687 DOI: 10.1128/ec.00068-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The Candida albicans Als adhesin Als5p has an amyloid-forming sequence that is required for aggregation and formation of model biofilms on polystyrene. Because amyloid formation can be triggered by force, we investigated whether laminar flow could activate amyloid formation and increase binding to surfaces. Shearing Saccharomyces cerevisiae cells expressing Als5p or C. albicans at 0.8 dyne/cm(2) increased the quantity and strength of cell-to-surface and cell-to-cell binding compared to that at 0.02 dyne/cm(2). Thioflavin T fluorescence showed that the laminar flow also induced adhesin aggregation into surface amyloid nanodomains in Als5p-expressing cells. Inhibitory concentrations of the amyloid dyes thioflavin S and Congo red or a sequence-specific anti-amyloid peptide decreased binding and biofilm formation under flow. Shear-induced binding also led to formation of robust biofilms. There was less shear-activated increase in adhesion, thioflavin fluorescence, and biofilm formation in cells expressing the amyloid-impaired V326N-substituted Als5p. Similarly, S. cerevisiae cells expressing Flo1p or Flo11p flocculins also showed shear-dependent binding, amyloid formation, biofilm formation, and inhibition by anti-amyloid compounds. Together, these results show that laminar flow activated amyloid formation and led to enhanced adhesion of yeast cells to surfaces and to biofilm formation.
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24
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Paquet-Mercier F, Aznaveh NB, Safdar M, Greener J. A microfluidic bioreactor with in situ SERS imaging for the study of controlled flow patterns of biofilm precursor materials. SENSORS 2013; 13:14714-27. [PMID: 24172286 PMCID: PMC3871105 DOI: 10.3390/s131114714] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 10/19/2013] [Accepted: 10/22/2013] [Indexed: 01/19/2023]
Abstract
A microfluidic bioreactor with an easy to fabricate nano-plasmonic surface is demonstrated for studies of biofilms and their precursor materials via Surface Enhanced Raman Spectroscopy (SERS). The system uses a novel design to induce sheath flow confinement of a sodium citrate biofilm precursor stream against the SERS imaging surface to measure spatial variations in the concentration profile. The unoptimised SERS enhancement was approximately 2.5 × 104, thereby improving data acquisition time, reducing laser power requirements and enabling a citrate detection limit of 0.1 mM, which was well below the concentrations used in biofilm nutrient solutions. The flow confinement was observed by both optical microscopy and SERS imaging with good complementarity. We demonstrate the new bioreactor by growing flow-templated biofilms on the microchannel wall. This work opens the way for in situ spectral imaging of biofilms and their biochemical environment under dynamic flow conditions.
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Affiliation(s)
- François Paquet-Mercier
- Département de Chimie, Université Laval, 1045 Avenue de la Médecine, Québec, QC G1V 0A6, Canada.
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