1
|
Ranieri L, Esposito R, Nunes SP, Vrouwenvelder JS, Fortunato L. Biofilm rigidity, mechanics and composition in seawater desalination pretreatment employing ultrafiltration and microfiltration membranes. WATER RESEARCH 2024; 253:121282. [PMID: 38341976 DOI: 10.1016/j.watres.2024.121282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 02/02/2024] [Accepted: 02/05/2024] [Indexed: 02/13/2024]
Abstract
The choice of appropriate biofilm control strategies in membrane systems for seawater desalination pretreatment relies on understanding the properties of the biofilm formed on the membrane. This study reveals how the biofilm composition, including both organic and inorganic, influenced the biofilm behavior under mechanical loading. The investigation was conducted on two Gravity-Driven Membrane reactors employing Microfiltration (MF) and Ultrafiltration (UF) membrane for the pretreatment of raw seawater. After a stabilization period of 20 days (Phase I), a biofilm behavior test was introduced (Phase II) to evaluate (i) biofilm deformation during the absence of permeation (i.e., relaxation) and (ii) biofilm resistance to detachment forces (i.e., air scouring). The in-situ monitoring investigation using Optical Coherence Tomography (OCT) revealed that the biofilms developed on MF and UF membrane presented a rigid structure in absence of filtration forces, limiting the application of relaxation and biofilm expansion necessary for cleaning. Moreover, under shear stress conditions, a higher reduction in biofilm thickness was observed for MF (-60%, from 84 to 34 µm) compared to UF (-30%, from 64 to 45 µm), leading to an increase of permeate flux (+60%, from 9.1 to 14.9 L/m2/h and +20 % from 7.8 to 9.5 L/m2/h, respectively). The rheometric analysis indicated that the biofilm developed on MF membrane had weaker mechanical strength, displaying lower storage modulus (-50 %) and lower loss modulus (-55 %) compared to UF. These differences in mechanical properties were linked to the lower concentration of polyvalent ions and the distribution of organic foulants (i.e., BB, LMW-N) found in the biofilm on the MF membrane. Moreover, in the presence of air scouring led to a slight difference in microbial community between UF and MF. Our findings provide valuable insight for future investigations aimed at engineer biofilm composition to optimize biofilm control strategies in membrane systems for seawater desalination pretreatment.
Collapse
Affiliation(s)
- Luigi Ranieri
- Environmental Science & Engineering Program (EnSE), Biological and Environmental Science & Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Rebecca Esposito
- Environmental Science & Engineering Program (EnSE), Biological and Environmental Science & Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; Advanced Membranes and Porous Materials (AMPM) Center, King Abdullah University of Science and Technology (KAUST), Saudi Arabia
| | - Suzana P Nunes
- Environmental Science & Engineering Program (EnSE), Biological and Environmental Science & Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; Chemistry Program and Chemical Engineering Program, Physical Science and Engineering Division (BESE), King Abdullah University of Science and Technology (KAUST), 23955-6900 Thuwal, Saudi Arabia; Advanced Membranes and Porous Materials (AMPM) Center, King Abdullah University of Science and Technology (KAUST), Saudi Arabia
| | - Johannes S Vrouwenvelder
- Environmental Science & Engineering Program (EnSE), Biological and Environmental Science & Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Luca Fortunato
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia; MANN+HUMMEL Water & Fluid Solutions S.p.A., Italy.
| |
Collapse
|
2
|
Pechaud Y, Derlon N, Queinnec I, Bessiere Y, Paul E. Modelling biofilm development: The importance of considering the link between EPS distribution, detachment mechanisms and physical properties. WATER RESEARCH 2024; 250:120985. [PMID: 38118257 DOI: 10.1016/j.watres.2023.120985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 12/02/2023] [Accepted: 12/06/2023] [Indexed: 12/22/2023]
Abstract
In industry, treatments against biofilms need to be optimized and, in the wastewater treatment field, biofilm composition needs to be controlled. Therefore, describing the biochemical and physical structures of biofilms is now required to better understand the influence of operating parameters and treatment on biofilms. The present study aims to investigate how growth conditions influence EPS composition, biofilm physical properties and volume detachment using a 1D biofilm model. Two types of EPS are considered in the present model, proteins and polysaccharides. The main hypotheses are that: (i) the production of polysaccharides occurs mainly under strong nutrient limitation(s) while the production of proteins is coupled to both the substrate uptake rate and the lysis process; (ii) the local biofilm porosity depends on the local biofilm composition. Both volume and surface detachment occur in biofilms and volume detachment extent depends on the biofilm local cohesion and thus on the local composition of biofilms for a given shear stress. The model is based on experimental trends and aims to represent these observations on the basis of biochemical and physical processes. Four case studies covering a wide range of contrasting growth conditions such as different COD/N ratios, applied SOLR and shear stresses are investigated. The model predicts how the biochemical and physical biofilm structures change as a result of contrasting growth conditions. More precisely simulation results are in good agreement with the main experimental observations reported in the literature, such as: (i) a strong nitrogen limitation of growth induces an important accumulation of polysaccharides leading to a more porous and homogenous biofilm, (ii) a high applied surface organic loading load allows to obtain a high biofilm thickness, (iii) a strong shear stress applied during the biofilm growth leads to a reduction of the biofilm thickness and to a consolidation of the biofilm structure. Overall, this model represents a relevant decision tool for the selection of appropriate enzymatic treatments in the context of negative biofilm control. From our results, it appears that protease based treatments should be more appropriate for biofilms developed under low COD/N ratios (about 20 gCOD/gN) whereas both glucosidases and proteases based treatments should be more appropriate for biofilms developed under high COD/N ratio (about 70 gCOD/gN). In addition, the model could be useful for other applications such as resource recovery in biofilms or granules, and help to better understand biological membrane fouling.
Collapse
Affiliation(s)
- Y Pechaud
- TBI, CNRS, INRAE, INSA, Université de Toulouse, 35 avenue de Rangueil, Toulouse 31077, France; Laboratoire Géomatériaux et Environnement (EA 4508), Université Gustave Eiffel, Marne-la-Vallée 77454, France.
| | - N Derlon
- EAWAG, Ueberlandstrasse 133, P.O Box 611, Dübendorf 8600, Switzerland
| | - I Queinnec
- CNRS, LAAS, 7 avenue du Colonel Roche, Toulouse F-31400, France
| | - Y Bessiere
- TBI, CNRS, INRAE, INSA, Université de Toulouse, 35 avenue de Rangueil, Toulouse 31077, France
| | - E Paul
- TBI, CNRS, INRAE, INSA, Université de Toulouse, 35 avenue de Rangueil, Toulouse 31077, France.
| |
Collapse
|
3
|
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.
Collapse
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.
| |
Collapse
|
4
|
Li M, Nahum Y, Matouš K, Stoodley P, Nerenberg R. Effects of biofilm heterogeneity on the apparent mechanical properties obtained by shear rheometry. Biotechnol Bioeng 2023; 120:553-561. [PMID: 36305479 DOI: 10.1002/bit.28276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 09/30/2022] [Accepted: 10/24/2022] [Indexed: 01/13/2023]
Abstract
Rheometry is an experimental technique widely used to determine the mechanical properties of biofilms. However, it characterizes the bulk mechanical behavior of the whole biofilm. The effects of biofilm mechanical heterogeneity on rheometry measurements are not known. We used laboratory experiments and computer modeling to explore the effects of biofilm mechanical heterogeneity on the results obtained by rheometry. A synthetic biofilm with layered mechanical properties was studied, and a viscoelastic biofilm theory was employed using the Kelvin-Voigt model. Agar gels with different concentrations were used to prepare the layered, heterogeneous biofilm, which was characterized for mechanical properties in shear mode with a rheometer. Both experiments and simulations indicated that the biofilm properties from rheometry were strongly biased by the weakest portion of the biofilm. The simulation results using linearly stratified mechanical properties from a previous study also showed that the weaker portions of the biofilm dominated the mechanical properties in creep tests. We note that the model can be used as a predictive tool to explore the mechanical behavior of complex biofilm structures beyond those accessible to experiments. Since most biofilms display some degree of mechanical heterogeneity, our results suggest caution should be used in the interpretation of rheometry data. It does not necessarily provide the "average" mechanical properties of the entire biofilm if the mechanical properties are stratified.
Collapse
Affiliation(s)
- Mengfei Li
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Yanina Nahum
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Karel Matouš
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana, USA
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio, USA.,National Biofilm Innovation Centre (NBIC) and National Centre for Advanced Tribology at Southampton (nCATS), Mechanical Engineering, University of Southampton, Southampton, United Kingdom
| | - Robert Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| |
Collapse
|
5
|
Flemming HC, van Hullebusch ED, Neu TR, Nielsen PH, Seviour T, Stoodley P, Wingender J, Wuertz S. The biofilm matrix: multitasking in a shared space. Nat Rev Microbiol 2023; 21:70-86. [PMID: 36127518 DOI: 10.1038/s41579-022-00791-0] [Citation(s) in RCA: 101] [Impact Index Per Article: 101.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2022] [Indexed: 01/20/2023]
Abstract
The biofilm matrix can be considered to be a shared space for the encased microbial cells, comprising a wide variety of extracellular polymeric substances (EPS), such as polysaccharides, proteins, amyloids, lipids and extracellular DNA (eDNA), as well as membrane vesicles and humic-like microbially derived refractory substances. EPS are dynamic in space and time and their components interact in complex ways, fulfilling various functions: to stabilize the matrix, acquire nutrients, retain and protect eDNA or exoenzymes, or offer sorption sites for ions and hydrophobic substances. The retention of exoenzymes effectively renders the biofilm matrix an external digestion system influencing the global turnover of biopolymers, considering the ubiquitous relevance of biofilms. Physico-chemical and biological interactions and environmental conditions enable biofilm systems to morph into films, microcolonies and macrocolonies, films, ridges, ripples, columns, pellicles, bubbles, mushrooms and suspended aggregates - in response to the very diverse conditions confronting a particular biofilm community. Assembly and dynamics of the matrix are mostly coordinated by secondary messengers, signalling molecules or small RNAs, in both medically relevant and environmental biofilms. Fully deciphering how bacteria provide structure to the matrix, and thus facilitate and benefit from extracellular reactions, remains the challenge for future biofilm research.
Collapse
Affiliation(s)
- Hans-Curt Flemming
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore.
| | | | - Thomas R Neu
- Department of River Ecology, Helmholtz Centre for Environmental Research - UFZ, Magdeburg, Germany
| | - Per H Nielsen
- Center for Microbial Communities, Department of Chemistry and Bioscience, Aalborg University, Aalborg, Denmark
| | - Thomas Seviour
- Aarhus University Centre for Water Technology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA.,Department of Orthopaedics, The Ohio State University, Columbus, OH, USA
| | - Jost Wingender
- University of Duisburg-Essen, Biofilm Centre, Department of Aquatic Microbiology, Essen, Germany
| | - Stefan Wuertz
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| |
Collapse
|
6
|
Dynamic Changes in Biofilm Structures under Dynamic Flow Conditions. Appl Environ Microbiol 2022; 88:e0107222. [PMID: 36300948 PMCID: PMC9680615 DOI: 10.1128/aem.01072-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Detachment is an important process determining the structure and function of bacterial biofilm, which has significant implications for biogeochemical cycling of elements, biofilm application, and infection control in clinical settings. Quantifying the responses of biofilm structure to hydrodynamics is crucial for understanding biofilm detachment mechanisms in aquatic environments.
Collapse
|
7
|
Ranieri L, Vrouwenvelder JS, Fortunato L. Periodic fouling control strategies in gravity-driven membrane bioreactors (GD-MBRs): Impact on treatment performance and membrane fouling properties. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:156340. [PMID: 35654208 DOI: 10.1016/j.scitotenv.2022.156340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 05/12/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
This study aims to assess the effects of periodic membrane fouling control strategies in Gravity-Driven Membrane Bioreactor (GD-MBR) treating primary wastewater. The impact of each control strategy on the reactor performance (permeate flux and water quality), biomass morphology, and fouling composition were evaluated. The application of air scouring coupled with intermittent filtration resulted in the highest permeate flux (4 LMH) compared to only intermittent filtration (i.e., relaxation) (1 LMH) and air scouring under continuous filtration (2.5 LMH). Air scouring coupled with relaxation led to a thin (~50 μm) but with more porous fouling layer and low hydraulic resistance, presenting the lowest concentration of extracellular polymeric substance (EPS) in the biomass. Air scouring under continuous filtration led to a thin (~50 μm), dense, compact, and less porous fouling layer with the highest specific hydraulic resistance. The employment of only relaxation led to the highest fouling formation (~280 μm) on the membrane surface. The highest TN removal (~62%) was achieved in the reactor with only relaxation (no aeration) due to the anoxic condition in the filtration tank, while the highest COD removal (~ 60%) was achieved with air scouring under continuous filtration due to the longer aeration time and the denser fouling layer. The results highlighted the importance of performing in-depth fouling characterization to link the membrane fouling properties to the hydraulic resistance and membrane bioreactor performances (i.e., water quality and water production). Moreover, this work proven the versatility of the GD-MBR, where the choice of the appropriate operation and fouling control strategy relies on the eventual discharge or reuse of the treated effluent.
Collapse
Affiliation(s)
- Luigi Ranieri
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Biological & Environmental Science & Engineering Division (BESE), Thuwal 23955-6900, Saudi Arabia
| | - Johannes S Vrouwenvelder
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Biological & Environmental Science & Engineering Division (BESE), Thuwal 23955-6900, Saudi Arabia
| | - Luca Fortunato
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Biological & Environmental Science & Engineering Division (BESE), Thuwal 23955-6900, Saudi Arabia.
| |
Collapse
|
8
|
Savorana G, Słomka J, Stocker R, Rusconi R, Secchi E. A microfluidic platform for characterizing the structure and rheology of biofilm streamers. SOFT MATTER 2022; 18:3878-3890. [PMID: 35535650 PMCID: PMC9131465 DOI: 10.1039/d2sm00258b] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Biofilm formation is the most successful survival strategy for bacterial communities. In the biofilm lifestyle, bacteria embed themselves in a self-secreted matrix of extracellular polymeric substances (EPS), which acts as a shield against mechanical and chemical insults. When ambient flow is present, this viscoelastic scaffold can take a streamlined shape, forming biofilm filaments suspended in flow, called streamers. Streamers significantly disrupt the fluid flow by causing rapid clogging and affect transport in aquatic environments. Despite their relevance, the structural and rheological characterization of biofilm streamers is still at an early stage. In this work, we present a microfluidic platform that allows the reproducible growth of biofilm streamers in controlled physico-chemical conditions and the characterization of their biochemical composition, morphology, and rheology in situ. We employed isolated micropillars as nucleation sites for the growth of single biofilm streamers under the continuous flow of a diluted bacterial suspension. By combining fluorescent staining of the EPS components and epifluorescence microscopy, we were able to characterize the biochemical composition and morphology of the streamers. Additionally, we optimized a protocol to perform hydrodynamic stress tests in situ, by inducing controlled variations of the fluid shear stress exerted on the streamers by the flow. Thus, the reproducibility of the formation process and the testing protocol make it possible to perform several consistent experimental replicates that provide statistically significant information. By allowing the systematic investigation of the role of biochemical composition on the structure and rheology of streamers, this platform will advance our understanding of biofilm formation.
Collapse
Affiliation(s)
- Giovanni Savorana
- Institute of Environmental Engineering, ETH Zürich, 8093, Zürich, Switzerland.
| | - Jonasz Słomka
- Institute of Environmental Engineering, ETH Zürich, 8093, Zürich, Switzerland.
| | - Roman Stocker
- Institute of Environmental Engineering, ETH Zürich, 8093, Zürich, Switzerland.
| | - Roberto Rusconi
- Department of Biomedical Sciences, Humanitas University, 20072, Pieve Emanuele, MI, Italy
- IRCCS Humanitas Research Hospital, 20089, Rozzano, MI, Italy
| | - Eleonora Secchi
- Institute of Environmental Engineering, ETH Zürich, 8093, Zürich, Switzerland.
| |
Collapse
|
9
|
Fortune GT, Oliveira NM, Goldstein RE. Biofilm Growth under Elastic Confinement. PHYSICAL REVIEW LETTERS 2022; 128:178102. [PMID: 35570462 DOI: 10.1103/physrevlett.128.178102] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Accepted: 04/06/2022] [Indexed: 06/15/2023]
Abstract
Bacteria often form surface-bound communities, embedded in a self-produced extracellular matrix, called biofilms. Quantitative studies of bioflim growth have typically focused on unconfined expansion above solid or semisolid surfaces, leading to exponential radial growth. This geometry does not accurately reflect the natural or biomedical contexts in which biofilms grow in confined spaces. Here, we consider one of the simplest confined geometries: a biofilm growing laterally in the space between a solid surface and an overlying elastic sheet. A poroelastic framework is utilized to derive the radial growth rate of the biofilm; it reveals an additional self-similar expansion regime, governed by the Poisson's ratio of the matrix, leading to a finite maximum radius, consistent with our experimental observations of growing Bacillus subtilis biofilms confined by polydimethylsiloxane.
Collapse
Affiliation(s)
- George T Fortune
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | - Nuno M Oliveira
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
| | - Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| |
Collapse
|
10
|
Borges MMB, Dijkstra RJB, Andrade FB, Duarte MAH, Versluis M, van der Sluis LWM, Petridis X. The response of dual-species bacterial biofilm to 2% and 5% NaOCl mixed with etidronic acid: a laboratory real-time evaluation using optical coherence tomography. Int Endod J 2022; 55:758-771. [PMID: 35470434 PMCID: PMC9325035 DOI: 10.1111/iej.13754] [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: 12/31/2021] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 11/29/2022]
Abstract
Aim The addition of etidronic acid (HEDP) to sodium hypochlorite (NaOCl) could increase the antibiofilm potency of the irrigant, whilst maintaining the benefits of continuous chelation. Studies conducted so far have shown that mixing HEDP with NaOCl solutions of relatively low concentration does not compromise the antibiofilm efficacy of the irrigant. However, the working lifespan of NaOCl may decrease resulting in a reduction of its antibiofilm efficacy over time (efficiency). In this regard, continuous irrigant replenishment needs to be examined. This study investigated the response of a dual‐species biofilm when challenged with 2% and 5% NaOCl mixed with HEDP for a prolonged timespan and under steady laminar flow. Methodology Dual‐species biofilms comprised of Streptococcus oralis J22 and Actinomyces naeslundii T14V‐J1 were grown on human dentine discs in a constant depth film fermenter (CDFF) for 96 h. Biofilms were treated with 2% and 5% NaOCl, alone or mixed with HEDP. Irrigants were applied under steady laminar flow for 8 min. Biofilm response was evaluated by means of optical coherence tomography (OCT). Biofilm removal, biofilm disruption, rate of biofilm loss and disruption as well as bubble formation were assessed. One‐way anova, Wilcoxon's signed‐rank test and Kruskal–Wallis H test were performed for statistical analysis of the data. The level of significance was set at a ≤.05. Results Increasing NaOCl concentration resulted in increased biofilm removal and disruption, higher rate of biofilm loss and disruption and increased bubble formation. Mixing HEDP with NaOCl caused a delay in the antibiofilm action of the latter, without compromising its antibiofilm efficacy. Conclusions NaOCl concentration dictates the biofilm response irrespective of the presence of HEDP. The addition of HEDP resulted in a delay in the antibiofilm action of NaOCl. This delay affects the efficiency, but not the efficacy of the irrigant over time.
Collapse
Affiliation(s)
- M M B Borges
- Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - R J B Dijkstra
- Department of Conservative Dentistry, Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - F B Andrade
- Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - M A H Duarte
- Department of Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil
| | - M Versluis
- Physics of Fluids group, Technical Medical (TechMed) Center and MESA+ Institute for Nanotechnology, University of Twente, Enschede
| | - L W M van der Sluis
- Department of Conservative Dentistry, Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - X Petridis
- Department of Conservative Dentistry, Center for Dentistry and Oral Hygiene, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| |
Collapse
|
11
|
Narciso DAC, Pereira A, Dias NO, Melo LF, Martins FG. Characterization of biofilm structure and properties via processing of 2D optical coherence tomography images in BISCAP. Bioinformatics 2022; 38:1708-1715. [PMID: 34986264 DOI: 10.1093/bioinformatics/btac002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/21/2021] [Accepted: 01/03/2022] [Indexed: 02/03/2023] Open
Abstract
MOTIVATION Processing of Optical Coherence Tomography (OCT) biofilm images is currently restricted to a set of custom-made MATLAB scripts. None of the tools currently available for biofilm image processing (including those developed for Confocal Laser Scanning Microscopy-CLSM) enable a fully automatic processing of 2D OCT images. RESULTS A novel software tool entitled Biofilm Imaging and Structure Classification Automatic Processor (BISCAP) is presented. It was developed specifically for the automatic processing of 2D OCT biofilm images. The proposed approach makes use of some of the key principles used in CLSM image processing, and introduces a novel thresholding algorithm and substratum detection strategy. Two complementary pixel continuity checks are executed, enabling very detailed pixel characterizations. BISCAP delivers common structural biofilm parameters and a set of processed images for biofilm analysis. A novel biofilm 'compaction parameter' is suggested. The proposed strategy was tested on a set of 300 images with highly satisfactory results obtained. BISCAP is a Python-based standalone application, not requiring any programming knowledge or property licenses, and where all operations are managed via an intuitive Graphical User Interface. The automatic nature of this image processing strategy decreases biasing problems associated to human-perception and allows a reliable comparison of outputs. AVAILABILITY AND IMPLEMENTATION BISCAP and a collection of biofilm images obtained from OCT scans can be found at: https://github.com/diogonarciso/BISCAP. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
Collapse
Affiliation(s)
- Diogo A C Narciso
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
| | - Ana Pereira
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
| | - Nuno O Dias
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
| | - Luis F Melo
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
| | - F G Martins
- LEPABE - Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal
| |
Collapse
|
12
|
Cross flow frequency determines the physical structure and cohesion of membrane biofilms developed during gravity-driven membrane ultrafiltration of river water: Implication for hydraulic resistance. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2021.120079] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
13
|
Li M, Matouš K, Nerenberg R. Data-driven modeling of heterogeneous viscoelastic biofilms. Biotechnol Bioeng 2022; 119:1301-1313. [PMID: 35129209 DOI: 10.1002/bit.28056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/21/2022] [Accepted: 01/30/2022] [Indexed: 11/06/2022]
Abstract
Biofilms are typically heterogeneous in morphology, structure, and composition, resulting in non-uniform mechanical properties. The distribution of mechanical properties, in turn, determines the biofilm behavior, such as deformation and detachment. Most biofilm models neglect biofilm heterogeneity, especially at the microscale. In this study, an image-based modeling approach was developed to transform two-dimensional optical coherence tomography (OCT) biofilm images to a pixel-scale non-Newtonian viscosity map of the biofilm. The map was calibrated using the bulk viscosity data from rheometer tests, based on assumed maximum and minimum viscosities and a relationship between OCT image intensity signals and non-Newtonian viscosity. While not quantitatively measuring biofilm viscosity for each pixel, it allows a rational spatial allocation of viscosities within the biofilm: areas with lower cell density, e.g., voids, are assigned lower viscosities, and areas with high cell densities are assigned higher viscosities. The spatial distribution of non-Newtonian viscosity was applied in an established Oldroyd-B constitutive model and implemented using the phase-field continuum approach for the deformation and stress analysis. The heterogeneous model was able to predict deformations more accurately than a homogenous one. Stress distribution in the heterogeneous biofilm displayed better characteristics than that in the homogeneous one, because it is highly dependent on the viscosity distribution. This work, using a pixel-scale, image-based approach to map the mechanical heterogeneity of biofilms for computational deformation and stress analysis, provides a novel modeling approach that allows the consideration of biofilm structural and mechanical heterogeneity. Future research should better characterize the relationship between OCT signal and viscosity, and consider other constitutive models for biofilm mechanical behavior. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Mengfei Li
- University of Notre Dame, Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, Notre Dame, IN, 46556, USA
| | - Karel Matouš
- University of Notre Dame, Department of Aerospace and Mechanical Engineering, Notre Dame, IN, 46556, USA
| | - Robert Nerenberg
- University of Notre Dame, Department of Civil and Environmental Engineering and Earth Sciences, 156 Fitzpatrick Hall, Notre Dame, IN, 46556, USA
| |
Collapse
|
14
|
Insights into the Development of Phototrophic Biofilms in a Bioreactor by a Combination of X-ray Microtomography and Optical Coherence Tomography. Microorganisms 2021; 9:microorganisms9081743. [PMID: 34442822 PMCID: PMC8398007 DOI: 10.3390/microorganisms9081743] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/06/2021] [Accepted: 08/12/2021] [Indexed: 11/29/2022] Open
Abstract
As productive biofilms are increasingly gaining interest in research, the quantitative monitoring of biofilm formation on- or offline for the process remains a challenge. Optical coherence tomography (OCT) is a fast and often used method for scanning biofilms, but it has difficulty scanning through more dense optical materials. X-ray microtomography (μCT) can measure biofilms in most geometries but is very time-consuming. By combining both methods for the first time, the weaknesses of both methods could be compensated. The phototrophic cyanobacterium Tolypothrix distorta was cultured in a moving bed photobioreactor inside a biocarrier with a semi-enclosed geometry. An automated workflow was developed to process µCT scans of the biocarriers. This allowed quantification of biomass volume and biofilm-coverage on the biocarrier, both globally and spatially resolved. At the beginning of the cultivation, a growth limitation was detected in the outer region of the carrier, presumably due to shear stress. In the later phase, light limitations could be found inside the biocarrier. µCT data and biofilm thicknesses measured by OCT displayed good correlation. The latter could therefore be used to rapidly measure the biofilm formation in a process. The methods presented here can help gain a deeper understanding of biofilms inside a process and detect any limitations.
Collapse
|
15
|
Biofilm viscoelasticity and nutrient source location control biofilm growth rate, migration rate, and morphology in shear flow. Sci Rep 2021; 11:16118. [PMID: 34373534 PMCID: PMC8352988 DOI: 10.1038/s41598-021-95542-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023] Open
Abstract
We present a numerical model to simulate the growth and deformation of a viscoelastic biofilm in shear flow under different nutrient conditions. The mechanical interaction between the biofilm and the fluid is computed using the Immersed Boundary Method with viscoelastic parameters determined a priori from measurements reported in the literature. Biofilm growth occurs at the biofilm-fluid interface by a stochastic rule that depends on the local nutrient concentration. We compare the growth, migration, and morphology of viscoelastic biofilms with a common relaxation time of 18 min over the range of elastic moduli 10-1000 Pa in different nearby nutrient source configurations. Simulations with shear flow and an upstream or a downstream nutrient source indicate that soft biofilms grow more if nutrients are downstream and stiff biofilms grow more if nutrients are upstream. Also, soft biofilms migrate faster than stiff biofilms toward a downstream nutrient source, and although stiff biofilms migrate toward an upstream nutrient source, soft biofilms do not. Simulations without nutrients show that on the time scale of several hours, soft biofilms develop irregular structures at the biofilm-fluid interface, but stiff biofilms deform little. Our results agree with the biophysical principle that biofilms can adapt to their mechanical and chemical environment by modulating their viscoelastic properties. We also compare the behavior of a purely elastic biofilm to a viscoelastic biofilm with the same elastic modulus of 50 Pa. We find that the elastic biofilm underestimates growth rates and downstream migration rates if the nutrient source is downstream, and it overestimates growth rates and upstream migration rates if the nutrient source is upstream. Future modeling can use our comparison to identify errors that can occur by simulating biofilms as purely elastic structures.
Collapse
|
16
|
Zabiegaj D, Hajirasouliha F, Duilio A, Guido S, Caserta S, Kostoglou M, Petala M, Karapantsios T, Trybala A. Wetting/spreading on porous media and on deformable, soluble structured substrates as a model system for studying the effect of morphology on biofilms wetting and for assessing anti-biofilm methods. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101426] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
17
|
Lequette K, Ait-Mouheb N, Adam N, Muffat-Jeandet M, Bru-Adan V, Wéry N. Effects of the chlorination and pressure flushing of drippers fed by reclaimed wastewater on biofouling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 758:143598. [PMID: 33213927 DOI: 10.1016/j.scitotenv.2020.143598] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 10/29/2020] [Accepted: 10/29/2020] [Indexed: 06/11/2023]
Abstract
Milli-channel baffle labyrinths are widely used in drip irrigation systems. They induce a pressure drop enabling drip irrigation. However, with a section thickness that is measured in mm2, they are sensitive to clogging, which reduces the performance and service life of a drip irrigation system. The impact of chlorination (1.5 ppm of free chlorine during 1 h application) and pressure flushing (0.18 MPa) on the biofouling of non-pressure-compensating drippers, fed by real reclaimed wastewater, was studied at lab scale using optical coherence tomography. The effect of these treatments on microbial composition (bacteria and eukaryotes) was also investigated by High-throughput DNA sequencing. Biofouling was mainly observed in the inlet, outlet and return areas of the milli-labyrinth channel from drippers. Chlorination reduced biofilm development, particularly in the mainstream of the milli-labyrinth channel, and it was more efficient when combined with pressure flushing. Moreover, chlorination was more efficient in maintaining water distribution uniformity (CU < 95% compared to less than 85% for unchlorinated lines). It reduced more efficiently the bacterial concentration (≈1 log) and the diversity of the bacterial community in the dripper biofilms compared to the pressure flushing method. Chlorination significantly modified the microbial communities, promoting chlorine-resistant bacteria such as Comamonadaceae or Azospira. Inversely, several bacterial groups were identified as sensitive to chlorination such as Chloroflexi and Planctomycetes. Nevertheless, one month after stopping the treatments bacterial diversity recovered and the chlorine-sensitive bacteria such as Chloroflexi phylum and the Saprospiraceae, Spirochaetaceae, Christensenellaceae and Hydrogenophilaceae families re-emerged in conjunction with the growth of biofouling, highlighting the resilience of the bacteria originating from drippers. Based on PCoA analyses, the structure of the bacterial communities still clustered separately from non-chlorinated drippers, showing that the effect of chlorination was still detectable one month after stopping the treatment.
Collapse
Affiliation(s)
- Kévin Lequette
- INRAE, University of Montpellier, LBE, 102, Avenue des Etangs, 11100 Narbonne, France; INRAE, University of Montpellier, UMR G-EAU, Avenue Jean-François Breton, 34000 Montpellier, France
| | - Nassim Ait-Mouheb
- INRAE, University of Montpellier, UMR G-EAU, Avenue Jean-François Breton, 34000 Montpellier, France
| | - Nicolas Adam
- University of Toulouse, Centre de recherche Cerveau et Cognition, 31000 Toulouse, France
| | - Marine Muffat-Jeandet
- INRAE, University of Montpellier, UMR G-EAU, Avenue Jean-François Breton, 34000 Montpellier, France
| | - Valérie Bru-Adan
- INRAE, University of Montpellier, LBE, 102, Avenue des Etangs, 11100 Narbonne, France
| | - Nathalie Wéry
- INRAE, University of Montpellier, LBE, 102, Avenue des Etangs, 11100 Narbonne, France.
| |
Collapse
|
18
|
Pavissich JP, Li M, Nerenberg R. Spatial distribution of mechanical properties in Pseudomonas aeruginosa biofilms, and their potential impacts on biofilm deformation. Biotechnol Bioeng 2021; 118:1564-1575. [PMID: 33415727 DOI: 10.1002/bit.27671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/01/2021] [Accepted: 01/04/2021] [Indexed: 11/08/2022]
Abstract
The mechanical properties of biofilms can be used to predict biofilm deformation under external forces, for example, under fluid flow. We used magnetic tweezers to spatially map the compliance of Pseudomonas aeruginosa biofilms at the microscale, then applied modeling to assess its effects on biofilm deformation. Biofilms were grown in capillary flow cells with Reynolds numbers (Re) ranging from 0.28 to 13.9, bulk dissolved oxygen (DO) concentrations from 1 mg/L to 8 mg/L, and bulk calcium ion (Ca2+ ) concentrations of 0 and 100 mg CaCl2 /L. Higher Re numbers resulted in more uniform biofilm morphologies. The biofilm was stiffer at the center of the flow cell than near the walls. Lower bulk DO led to more stratified biofilms. Higher Ca2+ concentrations led to increased stiffness and more uniform mechanical properties. Using the experimental mechanical properties, fluid-structure interaction models predicted up to 64% greater deformation for heterogeneous biofilms, compared with a homogeneous biofilms with the same average properties. However, the deviation depended on the biofilm morphology and flow regime. Our results show significant spatial mechanical variability exists at the microscale, and that this variability can potentially affect biofilm deformation. The average biofilm mechanical properties, provided in many studies, should be used with caution when predicting biofilm deformation.
Collapse
Affiliation(s)
- Juan P Pavissich
- Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Santiago, Chile.,Center of Applied Ecology and Sustainability (CAPES), Santiago, Chile.,Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Mengfei Li
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Robert Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| |
Collapse
|
19
|
Karimifard S, Li X, Elowsky C, Li Y. Modeling the impact of evolving biofilms on flow in porous media inside a microfluidic channel. WATER RESEARCH 2021; 188:116536. [PMID: 33125999 DOI: 10.1016/j.watres.2020.116536] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/22/2020] [Accepted: 10/18/2020] [Indexed: 06/11/2023]
Abstract
This study integrates microfluidic experiments and mathematical modeling to study the impacts of biofilms on flow in porous media and to explore approaches to simplify modeling permeability with complicated biofilm geometries. E. coli biofilms were grown in a microfluidic channel packed with a single layer of glass beads to reach three biofilm levels: low, intermediate, and high, with biofilm ratios (βr) of 2.7%, 17.6%, and 55.2%, respectively. Two-dimensional biofilm structures and distributions in the porous medium were modeled by digitizing confocal images and considering broad ranges of biofilm permeability (kb) (from 10-15 m2 to 10-7 m2) and biofilm porosity (εb) (from 0.2 to 0.8). The overall permeability of the porous medium (k), the flow pathways and the overall/local pressure gradients were found to be highly dependent on βr and kb but were moderately impacted by εb when the biofilm levels were high and intermediate with kb>10-11 m2. When biofilm structures are well developed, simplified biofilm geometries, such as uniform coating and symmetric contact filling, can provide reasonable approximations of k.
Collapse
Affiliation(s)
- Shahab Karimifard
- Department of Civil and Environmental Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, United States
| | - Xu Li
- Department of Civil and Environmental Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, United States
| | - Christian Elowsky
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, United States
| | - Yusong Li
- Department of Civil and Environmental Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, United States.
| |
Collapse
|
20
|
Grobas I, Bazzoli DG, Asally M. Biofilm and swarming emergent behaviours controlled through the aid of biophysical understanding and tools. Biochem Soc Trans 2020; 48:2903-2913. [PMID: 33300966 PMCID: PMC7752047 DOI: 10.1042/bst20200972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 02/06/2023]
Abstract
Bacteria can organise themselves into communities in the forms of biofilms and swarms. Through chemical and physical interactions between cells, these communities exhibit emergent properties that individual cells alone do not have. While bacterial communities have been mainly studied in the context of biochemistry and molecular biology, recent years have seen rapid advancements in the biophysical understanding of emergent phenomena through physical interactions in biofilms and swarms. Moreover, new technologies to control bacterial emergent behaviours by physical means are emerging in synthetic biology. Such technologies are particularly promising for developing engineered living materials (ELM) and devices and controlling contamination and biofouling. In this minireview, we overview recent studies unveiling physical and mechanical cues that trigger and affect swarming and biofilm development. In particular, we focus on cell shape, motion and density as the key parameters for mechanical cell-cell interactions within a community. We then showcase recent studies that use physical stimuli for patterning bacterial communities, altering collective behaviours and preventing biofilm formation. Finally, we discuss the future potential extension of biophysical and bioengineering research on microbial communities through computational modelling and deeper investigation of mechano-electrophysiological coupling.
Collapse
Affiliation(s)
- Iago Grobas
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K
- Warwick Medical School, University of Warwick, Coventry CV4 7AL, U.K
| | - Dario G. Bazzoli
- School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, U.K
| | - Munehiro Asally
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry CV4 7AL, U.K
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, U.K
| |
Collapse
|
21
|
Gloag ES, Fabbri S, Wozniak DJ, Stoodley P. Biofilm mechanics: Implications in infection and survival. Biofilm 2020; 2:100017. [PMID: 33447803 PMCID: PMC7798440 DOI: 10.1016/j.bioflm.2019.100017] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 12/18/2022] Open
Abstract
It has long been recognized that biofilms are viscoelastic materials, however the importance of this attribute to the survival and persistence of these microbial communities is yet to be fully realized. Here we review work, which focuses on understanding biofilm mechanics and put this knowledge in the context of biofilm survival, particularly for biofilm-associated infections. We note that biofilm viscoelasticity may be an evolved property of these communities, and that the production of multiple extracellular polymeric slime components may be a way to ensure the development of biofilms with complex viscoelastic properties. We discuss viscoelasticity facilitating biofilm survival in the context of promoting the formation of larger and stronger biofilms when exposed to shear forces, promoting fluid-like behavior of the biofilm and subsequent biofilm expansion by viscous flow, and enabling resistance to both mechanical and chemical methods of clearance. We conclude that biofilm viscoelasticity contributes to the virulence of chronic biofilm infections.
Collapse
Affiliation(s)
- Erin S. Gloag
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
| | | | - Daniel J. Wozniak
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
| | - Paul Stoodley
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, 43210, USA
- Department of Microbiology, The Ohio State University, Columbus, OH, 43210, USA
- Department of Orthopedics, The Ohio State University, Columbus, OH, 43210, USA
- National Biofilm Innovation Centre (NBIC) and National Centre for Advanced Tribology at Southampton (nCATS), University of Southampton, Southampton, SO17 1BJ, UK
| |
Collapse
|
22
|
Gerbersdorf SU, Koca K, de Beer D, Chennu A, Noss C, Risse-Buhl U, Weitere M, Eiff O, Wagner M, Aberle J, Schweikert M, Terheiden K. Exploring flow-biofilm-sediment interactions: Assessment of current status and future challenges. WATER RESEARCH 2020; 185:116182. [PMID: 32763530 DOI: 10.1016/j.watres.2020.116182] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 06/19/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Biofilm activities and their interactions with physical, chemical and biological processes are of great importance for a variety of ecosystem functions, impacting hydrogeomorphology, water quality and aquatic ecosystem health. Effective management of water bodies requires advancing our understanding of how flow influences biofilm-bound sediment and ecosystem processes and vice-versa. However, research on this triangle of flow-biofilm-sediment is still at its infancy. In this Review, we summarize the current state of the art and methodological approaches in the flow-biofilm-sediment research with an emphasis on biostabilization and fine sediment dynamics mainly in the benthic zone of lotic and lentic environments. Example studies of this three-way interaction across a range of spatial scales from cell (nm - µm) to patch scale (mm - dm) are highlighted in view of the urgent need for interdisciplinary approaches. As a contribution to the review, we combine a literature survey with results of a pilot experiment that was conducted in the framework of a joint workshop to explore the feasibility of asking interdisciplinary questions. Further, within this workshop various observation and measuring approaches were tested and the quality of the achieved results was evaluated individually and in combination. Accordingly, the paper concludes by highlighting the following research challenges to be considered within the forthcoming years in the triangle of flow-biofilm-sediment: i) Establish a collaborative work among hydraulic and sedimentation engineers as well as ecologists to study mutual goals with appropriate methods. Perform realistic experimental studies to test hypotheses on flow-biofilm-sediment interactions as well as structural and mechanical characteristics of the bed. ii) Consider spatially varying characteristics of flow at the sediment-water interface. Utilize combinations of microsensors and non-intrusive optical methods, such as particle image velocimetry and laser scanner to elucidate the mechanism behind biofilm growth as well as mass and momentum flux exchanges between biofilm and water. Use molecular approaches (DNA, pigments, staining, microscopy) for sophisticated community analyses. Link varying flow regimes to microbial communities (and processes) and fine sediment properties to explore the role of key microbial players and functions in enhancing sediment stability (biostabilization). iii) Link laboratory-scale observations to larger scales relevant for management of water bodies. Conduct field experiments to better understand the complex effects of variable flow and sediment regimes on biostabilization. Employ scalable and informative observation techniques (e.g., hyperspectral imaging, particle tracking) that can support predictions on the functional aspects, such as metabolic activity, bed stability, nutrient fluxes under variable regimes of flow-biofilm-sediment.
Collapse
Affiliation(s)
- Sabine Ulrike Gerbersdorf
- University of Stuttgart, Institute for Modelling Hydraulic and Environmental Systems, Pfaffenwaldring 61, 70569 Stuttgart, Germany.
| | - Kaan Koca
- University of Stuttgart, Institute for Modelling Hydraulic and Environmental Systems, Pfaffenwaldring 61, 70569 Stuttgart, Germany.
| | - Dirk de Beer
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany.
| | - Arjun Chennu
- Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany; Leibniz Center for Tropical Marine Research, Fahrenheitstraße 6, 28359 Bremen, Germany.
| | - Christian Noss
- University of Koblenz-Landau, Institute for Environmental Sciences, Fortstraße 7, 76829 Landau, Germany; Federal Waterways Engineering and Research Institute, Hydraulic Engineering in Inland Areas, Kußmaulstraße 17, 76187 Karlsruhe, Germany.
| | - Ute Risse-Buhl
- Helmholtz Centre for Environmental Research - UFZ, Department of River Ecology, Brückstraße 3a, 39114 Magdeburg, Germany.
| | - Markus Weitere
- Helmholtz Centre for Environmental Research - UFZ, Department of River Ecology, Brückstraße 3a, 39114 Magdeburg, Germany.
| | - Olivier Eiff
- KIT Karlsruhe Institute of Technology, Institute for Hydromechanics, Otto-Ammann Platz 1, 76131 Karlsruhe, Germany.
| | - Michael Wagner
- KIT Karlsruhe Institute of Technology, Engler-Bunte-Institute, Water Chemistry and Water Technology, Engler-Bunte-Ring 9a, 76131 Karlsruhe, Germany.
| | - Jochen Aberle
- Technische Universität Braunschweig, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Beethovenstraße 51a, 38106 Braunschweig, Germany.
| | - Michael Schweikert
- University of Stuttgart, Institute of Biomaterials and Biomolecular Systems, Pfaffenwaldring 57, 70569 Stuttgart, Germany.
| | - Kristina Terheiden
- University of Stuttgart, Institute for Modelling Hydraulic and Environmental Systems, Pfaffenwaldring 61, 70569 Stuttgart, Germany.
| |
Collapse
|
23
|
A Review of CFD Modelling and Performance Metrics for Osmotic Membrane Processes. MEMBRANES 2020; 10:membranes10100285. [PMID: 33076290 PMCID: PMC7602433 DOI: 10.3390/membranes10100285] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/28/2020] [Accepted: 08/28/2020] [Indexed: 01/10/2023]
Abstract
Simulation via Computational Fluid Dynamics (CFD) offers a convenient way for visualising hydrodynamics and mass transport in spacer-filled membrane channels, facilitating further developments in spiral wound membrane (SWM) modules for desalination processes. This paper provides a review on the use of CFD modelling for the development of novel spacers used in the SWM modules for three types of osmotic membrane processes: reverse osmosis (RO), forward osmosis (FO) and pressure retarded osmosis (PRO). Currently, the modelling of mass transfer and fouling for complex spacer geometries is still limited. Compared with RO, CFD modelling for PRO is very rare owing to the relative infancy of this osmotically driven membrane process. Despite the rising popularity of multi-scale modelling of osmotic membrane processes, CFD can only be used for predicting process performance in the absence of fouling. This paper also reviews the most common metrics used for evaluating membrane module performance at the small and large scales.
Collapse
|
24
|
Pham DQ, Bryant SJ, Cheeseman S, Huang LZY, Bryant G, Dupont MF, Chapman J, Berndt CC, Vongsvivut JP, Crawford RJ, Truong VK, Ang ASM, Elbourne A. Micro- to nano-scale chemical and mechanical mapping of antimicrobial-resistant fungal biofilms. NANOSCALE 2020; 12:19888-19904. [PMID: 32985644 DOI: 10.1039/d0nr05617k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A fungal biofilm refers to the agglomeration of fungal cells surrounded by a polymeric extracellular matrix (ECM). The ECM is composed primarily of polysaccharides that facilitate strong surface adhesion, proliferation, and cellular protection from the surrounding environment. Biofilms represent the majority of known microbial communities, are ubiquitous, and are found on a multitude of natural and synthetic surfaces. The compositions, and in-turn nanomechanical properties, of fungal biofilms remain poorly understood, because these systems are complex, composed of anisotropic cellular and extracellular material, and importantly are species and environment dependent. Therefore, genomic variation, and/or mutations, as well as environmental and growth factors can change the composition of a fungal cell's biofilm. In this work, we probe the physico-mechanical and biochemical properties of two fungal species, Candida albicans (C. albicans) and Cryptococcus neoformans (C. neoformans), as well as two antifungal resistant sub-species of C. neoformans, fluconazole-resistant C. neoformans (FlucRC. neoformans) and amphotericin B-resistant C. neoformans (AmBRC. neoformans). A new experimental methodology of characterization is proposed, employing a combination of atomic force microscopy (AFM), instrumented nanoindentation, and Synchrotron ATR-FTIR measurements. This allowed the nano-mechanical and chemical characterisation of each fungal biofilm.
Collapse
Affiliation(s)
- Duy Quang Pham
- Surface Engineering for Advanced Materials (SEAM), Department of Mechanical and Production Design Engineering, Swinburne University of Technology, Hawthorn, Australia.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Abstract
Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective. The extent of senescence due to damage accumulation—or aging—is evidently evolvable as it differs hugely between species and is not universal, suggesting that its fitness advantages depend on life history and environment. In contrast, repair of damage is present in all organisms studied. Despite the fundamental trade-off between investing resources into repair or into growth, repair and segregation of damage have not always been considered alternatives. For unicellular organisms, unrepaired damage could be divided asymmetrically between daughter cells, leading to senescence of one and rejuvenation of the other. Repair of “unicells” has been predicted to be advantageous in well-mixed environments such as chemostats. Most microorganisms, however, live in spatially structured systems, such as biofilms, with gradients of environmental conditions and cellular physiology as well as a clonal population structure. To investigate whether this clonal structure might favor senescence by damage segregation (a division-of-labor strategy akin to the germline-soma division in multicellular organisms), we used an individual-based computational model and developed an adaptive repair strategy where cells respond to their current intracellular damage levels by investing into repair machinery accordingly. Our simulations showed that the new adaptive repair strategy was advantageous provided that growth was limited by substrate availability, which is typical for biofilms. Thus, biofilms do not favor a germline-soma-like division of labor between daughter cells in terms of damage segregation. We suggest that damage segregation is beneficial only when extrinsic mortality is high, a degree of multicellularity is present, and an active mechanism makes segregation effective. IMPORTANCE Damage is an inevitable consequence of life. For unicellular organisms, this leads to a trade-off between allocating resources into damage repair or into growth coupled with segregation of damage upon cell division, i.e., aging and senescence. Few studies considered repair as an alternative to senescence. None considered biofilms, where the majority of unicellular organisms live, although fitness advantages in well-mixed systems often turn into disadvantages in spatially structured systems such as biofilms. We compared the fitness consequences of aging versus an adaptive repair mechanism based on sensing damage, using an individual-based model of a generic unicellular organism growing in biofilms. We found that senescence is not beneficial provided that growth is limited by substrate availability. Instead, it is useful as a stress response to deal with damage that failed to be repaired when (i) extrinsic mortality was high; (ii) a degree of multicellularity was present; and (iii) damage segregation was effective.
Collapse
|
26
|
Biofilm as a live and in-situ formed membrane for solids separation in bioreactors: Biofilm succession governs resistance variation demonstrated during the start-up period. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2020.118197] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
27
|
Li M, Matouš K, Nerenberg R. Predicting biofilm deformation with a viscoelastic phase‐field model: Modeling and experimental studies. Biotechnol Bioeng 2020; 117:3486-3498. [DOI: 10.1002/bit.27491] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 06/18/2020] [Accepted: 07/10/2020] [Indexed: 01/27/2023]
Affiliation(s)
- Mengfei Li
- Department of Civil and Environmental Engineering and Earth Sciences University of Notre Dame Notre Dame Indiana
| | - Karel Matouš
- Department of Aerospace and Mechanical Engineering University of Notre Dame Notre Dame Indiana
| | - Robert Nerenberg
- Department of Civil and Environmental Engineering and Earth Sciences University of Notre Dame Notre Dame Indiana
| |
Collapse
|
28
|
Simunič U, Pipp P, Dular M, Stopar D. The limitations of hydrodynamic removal of biofilms from the dead-ends in a model drinking water distribution system. WATER RESEARCH 2020; 178:115838. [PMID: 32361344 DOI: 10.1016/j.watres.2020.115838] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/07/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Biofilm formation and removal from dead-ends is a particularly difficult and understudied area of water distribution system biology. In this work, we have built a model drinking water distribution system to probe the effect of different hydrodynamic flow regimes on biofilm formation and removal in the main pipe and in the dead-end. The test rig was built to include all major drinking water distribution system components with materials and dimensions used in standard plumbing systems. We have simulated the effect of stagnant, laminar, turbulent, and intense turbulent flushing conditions on the growth and removal of biofilms from the main pipe and the dead-end. The growth of the biofilm in the main pipe was not prevented at a volumetric flow rate of 9.4 L min-1 and flow velocity of 2 m s-1. Mature biofilms were more difficult to remove. Biofilms grown under shear stress conditions could withstand significantly higher shear stresses than those to which they were exposed to during growth. The biofilms grew twice as fast in the dead-end when flow in the main pipe was turbulent compared to stagnant conditions. Biofilms in the dead-end were not affected by the flushing conditions in the main pipe (Q = 52 L min-1, Re = 9.0 · 104). The computational fluid dynamics simulation suggests that biofilms cannot be hydrodynamically removed from the dead-end at depths that are larger than one pipe diameter. Biofilms beyond this limit present a possible source for reinoculation and recolonization of the rest of the water distribution system.
Collapse
Affiliation(s)
- Urh Simunič
- University of Ljubljana, Biotechnical Faculty, Jamnikarjeva 101, 1000, Ljubljana, Slovenia
| | - Peter Pipp
- University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, 1000, Ljubljana, Slovenia
| | - Matevž Dular
- University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, 1000, Ljubljana, Slovenia
| | - David Stopar
- University of Ljubljana, Biotechnical Faculty, Jamnikarjeva 101, 1000, Ljubljana, Slovenia.
| |
Collapse
|
29
|
Shi D, Liu Y, Fu W, Li J, Fang Z, Shao S. A combination of membrane relaxation and shear stress significantly improve the flux of gravity-driven membrane system. WATER RESEARCH 2020; 175:115694. [PMID: 32182538 DOI: 10.1016/j.watres.2020.115694] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/29/2020] [Accepted: 03/04/2020] [Indexed: 06/10/2023]
Abstract
Gravity-driven membrane (GDM) filtration system is a promising process for decentralized drinking water treatment. During the operation, membrane relaxation and shear stress could be simply achieved by intermittent filtration and water disturbance (created by occasionally shaking membrane model or stirring water in membrane tank), respectively. To better understand the impact of membrane relaxation and shear stress on the biofouling layer and stable flux in GDM system, action of daily 60-min intermission, daily flushing (cross-flow velocity = 10 cm s-1, 1 min), and the combination of the two (flushed right after the 60-min intermission) were compared. The results showed that membrane relaxation and shear stress lonely was ineffective in improving the stable flux, while their combination enhanced the stable flux by 70%. A more open and spatially heterogeneous biofouling layer with a low extracellular polymeric substance (EPS) content and a high microbial activity was formed under the combination of membrane relaxation and shear stress. In-situ optical coherence tomography (OCT) observation revealed that, during intermission, the absence of pushing force by water flow induced a reversible expansion of biofouling layer, and the biofouling layer restored to its initial state soon after resuming filtration. Shear stress caused abrasion and erosion on the biofouling surface, but it exerted little effect on the interior of biofouling layer. Under the combination, however, both the surface and interior of biofouling layer were disturbed because of 1) the water vortexes caused by rough biofouling layer surface, and 2) the porous structure after 60-min intermission. This disturbance, in turn, helped the biofouling layer maintain its roughness and porosity, thereby improving the stable flux of GDM system.
Collapse
Affiliation(s)
- Danting Shi
- School of Civil Engineering, Wuhan University, PR China.
| | - Yang Liu
- School of Civil Engineering, Wuhan University, PR China
| | - Wenwen Fu
- School of Civil Engineering, Wuhan University, PR China
| | - Jiangyun Li
- School of Civil Engineering, Wuhan University, PR China
| | - Zheng Fang
- School of Civil Engineering, Wuhan University, PR China
| | - Senlin Shao
- School of Civil Engineering, Wuhan University, PR China.
| |
Collapse
|
30
|
Computational and Experimental Investigation of Biofilm Disruption Dynamics Induced by High-Velocity Gas Jet Impingement. mBio 2020; 11:mBio.02813-19. [PMID: 31911489 PMCID: PMC6946800 DOI: 10.1128/mbio.02813-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Knowledge of mechanisms promoting disruption though mechanical forces is essential in optimizing biofilm control strategies which rely on fluid shear. Our results provide insight into how biofilm disruption dynamics is governed by applied forces and fluid properties, revealing a mechanism for ripple formation and fluid-biofilm mixing. These findings have important implications for the rational design of new biofilm cleaning strategies with fluid jets, such as determining optimal parameters (e.g., jet velocity and position) to remove the biofilm from a certain zone (e.g., in dental hygiene or debridement of surgical site infections) or using antimicrobial agents which could increase the interfacial area available for exchange, as well as causing internal mixing within the biofilm matrix, thus disrupting the localized microenvironment which is associated with antimicrobial tolerance. The developed model also has potential application in predicting drag and pressure drop caused by biofilms on bioreactor, pipeline, and ship hull surfaces. Experimental data showed that high-speed microsprays can effectively disrupt biofilms on their support substratum, producing a variety of dynamic reactions such as elongation, displacement, ripple formation, and fluidization. However, the mechanics underlying the impact of high-speed turbulent flows on biofilm structure is complex under such extreme conditions, since direct measurements of viscosity at these high shear rates are not possible using dynamic testing instruments. Here, we used computational fluid dynamics simulations to assess the complex fluid interactions of ripple patterning produced by high-speed turbulent air jets impacting perpendicular to the surface of Streptococcus mutans biofilms, a dental pathogen causing caries, captured by high-speed imaging. The numerical model involved a two-phase flow of air over a non-Newtonian biofilm, whose viscosity as a function of shear rate was estimated using the Herschel-Bulkley model. The simulation suggested that inertial, shear, and interfacial tension forces governed biofilm disruption by the air jet. Additionally, the high shear rates generated by the jet impacts coupled with shear-thinning biofilm property resulted in rapid liquefaction (within milliseconds) of the biofilm, followed by surface instability and traveling waves from the impact site. Our findings suggest that rapid shear thinning under very high shear flows causes the biofilm to behave like a fluid and elasticity can be neglected. A parametric sensitivity study confirmed that both applied force intensity (i.e., high jet nozzle air velocity) and biofilm properties (i.e., low viscosity and low air-biofilm surface tension and thickness) intensify biofilm disruption by generating large interfacial instabilities.
Collapse
|
31
|
Charlton SGV, White MA, Jana S, Eland LE, Jayathilake PG, Burgess JG, Chen J, Wipat A, Curtis TP. Regulating, Measuring, and Modeling the Viscoelasticity of Bacterial Biofilms. J Bacteriol 2019; 201:e00101-19. [PMID: 31182499 PMCID: PMC6707926 DOI: 10.1128/jb.00101-19] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Biofilms occur in a broad range of environments under heterogeneous physicochemical conditions, such as in bioremediation plants, on surfaces of biomedical implants, and in the lungs of cystic fibrosis patients. In these scenarios, biofilms are subjected to shear forces, but the mechanical integrity of these aggregates often prevents their disruption or dispersal. Biofilms' physical robustness is the result of the multiple biopolymers secreted by constituent microbial cells which are also responsible for numerous biological functions. A better understanding of the role of these biopolymers and their response to dynamic forces is therefore crucial for understanding the interplay between biofilm structure and function. In this paper, we review experimental techniques in rheology, which help quantify the viscoelasticity of biofilms, and modeling approaches from soft matter physics that can assist our understanding of the rheological properties. We describe how these methods could be combined with synthetic biology approaches to control and investigate the effects of secreted polymers on the physical properties of biofilms. We argue that without an integrated approach of the three disciplines, the links between genetics, composition, and interaction of matrix biopolymers and the viscoelastic properties of biofilms will be much harder to uncover.
Collapse
Affiliation(s)
- Samuel G V Charlton
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Michael A White
- Interdisciplinary Computing & Complex BioSystems Research Group, School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Saikat Jana
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Lucy E Eland
- Interdisciplinary Computing & Complex BioSystems Research Group, School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - J Grant Burgess
- School of Natural & Environmental Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jinju Chen
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Anil Wipat
- Interdisciplinary Computing & Complex BioSystems Research Group, School of Computing, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Thomas P Curtis
- School of Engineering, Newcastle University, Newcastle upon Tyne, United Kingdom
| |
Collapse
|
32
|
Cattò C, Cappitelli F. Testing Anti-Biofilm Polymeric Surfaces: Where to Start? Int J Mol Sci 2019; 20:E3794. [PMID: 31382580 PMCID: PMC6696330 DOI: 10.3390/ijms20153794] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 08/02/2019] [Indexed: 12/11/2022] Open
Abstract
Present day awareness of biofilm colonization on polymeric surfaces has prompted the scientific community to develop an ever-increasing number of new materials with anti-biofilm features. However, compared to the large amount of work put into discovering potent biofilm inhibitors, only a small number of papers deal with their validation, a critical step in the translation of research into practical applications. This is due to the lack of standardized testing methods and/or of well-controlled in vivo studies that show biofilm prevention on polymeric surfaces; furthermore, there has been little correlation with the reduced incidence of material deterioration. Here an overview of the most common methods for studying biofilms and for testing the anti-biofilm properties of new surfaces is provided.
Collapse
Affiliation(s)
- Cristina Cattò
- Department of Food Environmental and Nutritional Sciences, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy
| | - Francesca Cappitelli
- Department of Food Environmental and Nutritional Sciences, Università degli Studi di Milano, via Celoria 2, 20133 Milano, Italy.
| |
Collapse
|
33
|
Jafari M, Derlon N, Desmond P, van Loosdrecht MCM, Morgenroth E, Picioreanu C. Biofilm compressibility in ultrafiltration: A relation between biofilm morphology, mechanics and hydraulic resistance. WATER RESEARCH 2019; 157:335-345. [PMID: 30965160 DOI: 10.1016/j.watres.2019.03.073] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 02/22/2019] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
Poroelastic fluid-structure interaction models were coupled to experimental data to determine the effects of biofilm spatial distribution of mechanical and hydraulic properties on the biofilm hydraulic resistance and compressibility in membrane filtration processes. Biofilms were cultivated on ultrafiltration membranes for 20 and 30 days under high (0.28 bar) and low (0.06 bar) transmembrane pressure (TMP), in dead-end filtration mode. Subsequently, biofilms were subjected to a compression/relaxation cycles by step-wise TMP changes. Structural deformation of biofilms during compression was observed in-situ using optical coherence tomography. Experimental results show that the observed increase in the biofilm hydraulic resistance during compression is not necessarily accompanied by a detectable biofilm thickness reduction. A dual-layer biofilm model with a dense base and porous top layer could explain these observed results. Because porosity controls indirectly the mechanical response of biofilms under compression, results could be described without assuming a gradient in mechanical properties within the biofilm. The biofilm surface roughness did not significantly influence the water flux in this study. However, the fraction of biofilm base layer directly exposed to bulk liquid could be a good indicator in the determination of water flux. The main implications of this study for the design and operation of low-pressure membrane systems (e.g., MF and UF with fouling layer being the main filtration resistance) lays in the selection of favorable operational TMP and biofilm morphology.
Collapse
Affiliation(s)
- Morez Jafari
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, the Netherlands.
| | - Nicolas Derlon
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland
| | - Peter Desmond
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, the Netherlands
| | - Eberhard Morgenroth
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland; ETH Zürich, Institute of Environmental Engineering, 8093, Zürich, Switzerland
| | - Cristian Picioreanu
- Department of Biotechnology, Faculty of Applied Sciences, Delft University of Technology, Van der Maasweg 9, 2629 HZ, Delft, the Netherlands
| |
Collapse
|
34
|
Biofilm systems as tools in biotechnological production. Appl Microbiol Biotechnol 2019; 103:5095-5103. [PMID: 31079168 DOI: 10.1007/s00253-019-09869-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/23/2019] [Accepted: 04/24/2019] [Indexed: 01/08/2023]
Abstract
The literature provides more and more examples of research projects that develop novel production processes based on microorganisms organized in the form of biofilms. Biofilms are aggregates of microorganisms that are attached to interfaces. These viscoelastic aggregates of cells are held together and are embedded in a matrix consisting of multiple carbohydrate polymers as well as proteins. Biofilms are characterized by a very high cell density and by a natural retentostat behavior. Both factors can contribute to high productivities and a facilitated separation of the desired end-product from the catalytic biomass. Within the biofilm matrix, stable gradients of substrates and products form, which can lead to a differentiation and adaptation of the microorganisms' physiology to the specific process conditions. Moreover, growth in a biofilm state is often accompanied by a higher resistance and resilience towards toxic or growth inhibiting substances and factors. In this short review, we summarize how biofilms can be studied and what most promising niches for their application can be. Moreover, we highlight future research directions that will accelerate the advent of productive biofilms in biology-based production processes.
Collapse
|