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Hubert A, Tabuteau H, Farasin J, Loncar A, Dufresne A, Méheust Y, Le Borgne T. Fluid flow drives phenotypic heterogeneity in bacterial growth and adhesion on surfaces. Nat Commun 2024; 15:6161. [PMID: 39039040 PMCID: PMC11263347 DOI: 10.1038/s41467-024-49997-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 06/25/2024] [Indexed: 07/24/2024] Open
Abstract
Bacteria often thrive in surface-attached communities, where they can form biofilms affording them multiple advantages. In this sessile form, fluid flow is a key component of their environments, renewing nutrients and transporting metabolic products and signaling molecules. It also controls colonization patterns and growth rates on surfaces, through bacteria transport, attachment and detachment. However, the current understanding of bacterial growth on surfaces neglects the possibility that bacteria may modulate their division behavior as a response to flow. Here, we employed single-cell imaging in microfluidic experiments to demonstrate that attached Escherichia coli cells can enter a growth arrest state while simultaneously enhancing their adhesion underflow. Despite utilizing clonal populations, we observed a non-uniform response characterized by bistable dynamics, with co-existing subpopulations of non-dividing and actively dividing bacteria. As the proportion of non-dividing bacteria increased with the applied flow rate, it resulted in a reduction in the average growth rate of bacterial populations on flow-exposed surfaces. Dividing bacteria exhibited asymmetric attachment, whereas non-dividing counterparts adhered to the surface via both cell poles. Hence, this phenotypic diversity allows bacterial colonies to combine enhanced attachment with sustained growth, although at a reduced rate, which may be a significant advantage in fluctuating flow conditions.
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Affiliation(s)
- Antoine Hubert
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Hervé Tabuteau
- Institut de Physique de Rennes, UMR 6251 University of Rennes and CNRS, Rennes, France.
| | - Julien Farasin
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Aleksandar Loncar
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Alexis Dufresne
- ECOBIO, UMR 6553 University of Rennes and CNRS, Rennes, France
| | - Yves Méheust
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France
| | - Tanguy Le Borgne
- Géosciences Rennes, UMR 6118 University of Rennes and CNRS, Rennes, France.
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Wen K, Gorbushina AA, Schwibbert K, Bell J. Microfluidic Platform with Precisely Controlled Hydrodynamic Parameters and Integrated Features for Generation of Microvortices to Accurately Form and Monitor Biofilms in Flow. ACS Biomater Sci Eng 2024; 10:4626-4634. [PMID: 38904279 PMCID: PMC11234330 DOI: 10.1021/acsbiomaterials.4c00101] [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] [Indexed: 06/22/2024]
Abstract
Microorganisms often live in habitats characterized by fluid flow, and their adhesion to surfaces in industrial systems or clinical settings may lead to pipe clogging, microbially influenced corrosion, material deterioration, food spoilage, infections, and human illness. Here, a novel microfluidic platform was developed to investigate biofilm formation under precisely controlled (i) cell concentration, (ii) temperature, and (iii) flow conditions. The developed platform central unit is a single-channel microfluidic flow cell designed to ensure ultrahomogeneous flow and condition in its central area, where features, e.g., with trapping properties, can be incorporated. In comparison to static and macroflow chamber assays for biofilm studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes and have better environment control and smaller sample requirements. Flow simulations and experiments with fluorescent particles were used to simulate bacteria flow in the platform cell for calculating flow velocity and direction at the microscale level. The combination of flow analysis and fluorescent strain injection in the cell showed that microtraps placed at the center of the channel were efficient in capturing bacteria at determined positions and to study how flow conditions, especially microvortices, can affect biofilm formation. The microfluidic platform exhibited improved performances in terms of homogeneity and robustness for in vitro biofilm formation. We anticipate the presented platform to be suitable for broad, versatile, and high-throughput biofilm studies at the microscale level.
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Affiliation(s)
- Keqing Wen
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
- Freie Universität Berlin, Kaiserswerther Str. 16-18, Berlin 14195, Germany
| | - Anna A Gorbushina
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
- Freie Universität Berlin, Kaiserswerther Str. 16-18, Berlin 14195, Germany
| | - Karin Schwibbert
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
| | - Jérémy Bell
- Bundesanstalt für Materialforschung und -prüfung (BAM), Unter den Eichen 87, Berlin 12205, Germany
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Hoagland B, Rasmussen KL, Singha K, Spear JR, Navarre-Sitchler A. Metal-oxide precipitation influences microbiome structure in hyporheic zones receiving acid rock drainage. Appl Environ Microbiol 2024; 90:e0198723. [PMID: 38391193 PMCID: PMC10952486 DOI: 10.1128/aem.01987-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/14/2024] [Indexed: 02/24/2024] Open
Abstract
Streams impacted by historic mining activity are characterized by acidic pH, unique microbial communities, and abundant metal-oxide precipitation, all of which can influence groundwater-surface water exchange. We investigate how metal-oxide precipitates and hyporheic mixing mediate the composition of microbial communities in two streams receiving acid-rock and mine drainage near Silverton, Colorado, USA. A large, neutral pH hyporheic zone facilitated the precipitation of metal particles/colloids in hyporheic porewaters. A small, low pH hyporheic zone, limited by the presence of a low-permeability, iron-oxyhydroxide layer known as ferricrete, led to the formation of steep geochemical gradients and high dissolved-metal concentrations. To determine how these two hyporheic systems influence microbiome composition, we installed well clusters and deployed in situ microcosms in each stream to sample porewaters and sediments for 16S rRNA gene sequencing. Results indicated that distinct hydrogeochemical conditions were present above and below the ferricrete in the low pH system. A positive feedback loop may be present in the low pH stream where microbially mediated precipitation of iron-oxides contributes to additional clogging of hyporheic pore spaces, separating abundant, iron-oxidizing bacteria (Gallionella spp.) above the ferricrete from rare, low-abundance bacteria below the ferricrete. Metal precipitates and colloids that formed in the neutral pH hyporheic zone were associated with a more diverse phylogenetic community of nonmotile, nutrient-cycling bacteria that may be transported through hyporheic pore spaces. In summary, biogeochemical conditions influence, and are influenced by, hyporheic mixing, which mediates the distribution of micro-organisms and, thus, the cycling of metals in streams receiving acid-rock and mine drainage. IMPORTANCE In streams receiving acid-rock and mine drainage, the abundant precipitation of iron minerals can alter how groundwater and surface water mix along streams (in what is known as the "hyporheic zone") and may shape the distribution of microbial communities. The findings presented here suggest that neutral pH streams with large, well-mixed hyporheic zones may harbor and transport diverse microorganisms attached to particles/colloids through hyporheic pore spaces. In acidic streams where metal oxides clog pore spaces and limit hyporheic exchange, iron-oxidizing bacteria may dominate and phylogenetic diversity becomes low. The abundance of iron-oxidizing bacteria in acid mine drainage streams has the potential to contribute to additional clogging of hyporheic pore spaces and the accumulation of toxic metals in the hyporheic zone. This research highlights the dynamic interplay between hydrology, geochemistry, and microbiology at the groundwater-surface water interface of acid mine drainage streams.
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Affiliation(s)
- Beth Hoagland
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
- S.S. Papadopulos & Associates, Inc., Rockville, Maryland, USA
| | - Kalen L. Rasmussen
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Kamini Singha
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, Colorado, USA
| | - Alexis Navarre-Sitchler
- Department of Geology and Geological Engineering, Hydrologic Science and Engineering Program, Colorado School of Mines, Golden, Colorado, USA
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Ugolini GS, Wang M, Secchi E, Pioli R, Ackermann M, Stocker R. Microfluidic approaches in microbial ecology. LAB ON A CHIP 2024; 24:1394-1418. [PMID: 38344937 PMCID: PMC10898419 DOI: 10.1039/d3lc00784g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Microbial life is at the heart of many diverse environments and regulates most natural processes, from the functioning of animal organs to the cycling of global carbon. Yet, the study of microbial ecology is often limited by challenges in visualizing microbial processes and replicating the environmental conditions under which they unfold. Microfluidics operates at the characteristic scale at which microorganisms live and perform their functions, thus allowing for the observation and quantification of behaviors such as growth, motility, and responses to external cues, often with greater detail than classical techniques. By enabling a high degree of control in space and time of environmental conditions such as nutrient gradients, pH levels, and fluid flow patterns, microfluidics further provides the opportunity to study microbial processes in conditions that mimic the natural settings harboring microbial life. In this review, we describe how recent applications of microfluidic systems to microbial ecology have enriched our understanding of microbial life and microbial communities. We highlight discoveries enabled by microfluidic approaches ranging from single-cell behaviors to the functioning of multi-cellular communities, and we indicate potential future opportunities to use microfluidics to further advance our understanding of microbial processes and their implications.
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Affiliation(s)
- Giovanni Stefano Ugolini
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Laura-Hezner-Weg 7, 8093 Zurich, Switzerland.
| | - Miaoxiao Wang
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland
| | - Eleonora Secchi
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Laura-Hezner-Weg 7, 8093 Zurich, Switzerland.
| | - Roberto Pioli
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Laura-Hezner-Weg 7, 8093 Zurich, Switzerland.
| | - Martin Ackermann
- Institute of Biogeochemistry and Pollutant Dynamics, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, Duebendorf, Switzerland
- Laboratory of Microbial Systems Ecology, School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédéral de Lausanne (EPFL), Lausanne, Switzerland
| | - Roman Stocker
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Laura-Hezner-Weg 7, 8093 Zurich, Switzerland.
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5
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Kogay R, Zhaxybayeva O. Co-evolution of gene transfer agents and their alphaproteobacterial hosts. J Bacteriol 2024; 206:e0039823. [PMID: 38240570 PMCID: PMC10883770 DOI: 10.1128/jb.00398-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 12/19/2023] [Indexed: 02/23/2024] Open
Abstract
Gene transfer agents (GTAs) are enigmatic elements that resemble small viruses and are known to be produced during nutritional stress by some bacteria and archaea. The production of GTAs is regulated by quorum sensing, under which a small fraction of the population acts as GTA producers, while the rest becomes GTA recipients. In contrast to canonical viruses, GTAs cannot propagate themselves because they package pieces of the producing cell's genome. In alphaproteobacteria, GTAs are mostly vertically inherited and reside in their hosts' genomes for hundreds of millions of years. While GTAs' ability to transfer genetic material within a population and their long-term preservation suggest an increased fitness of GTA-producing microbes, the associated benefits and type of selection that maintains GTAs are poorly understood. By comparing rates of evolutionary change in GTA genes to the rates in gene families abundantly present across 293 alphaproteobacterial genomes, we detected 59 gene families that likely co-evolve with GTA genes. These gene families are predominantly involved in stress response, DNA repair, and biofilm formation. We hypothesize that biofilm formation enables the physical proximity of GTA-producing cells, limiting GTA-derived benefits only to a group of closely related cells. We further conjecture that the population structure of biofilm-forming sub-populations ensures that the trait of GTA production is maintained despite the inevitable rise of "cheating" genotypes. Because release of GTA particles kills the producing cell, maintenance of GTAs is an exciting example of social evolution in a microbial population.IMPORTANCEGene transfer agents (GTAs) are viruses domesticated by some archaea and bacteria as vehicles for carrying pieces of the host genome. Produced under certain environmental conditions, GTA particles can deliver DNA to neighboring, closely related cells. The function of GTAs remains uncertain. While making GTAs is suicidal for a cell, GTA-encoding genes are widespread in genomes of alphaproteobacteria. Such GTA persistence implies functional benefits but raises questions about how selection maintains this lethal trait. By showing that GTA genes co-evolve with genes involved in stress response, DNA repair, and biofilm formation, we provide support for the hypothesis that GTAs facilitate DNA exchange during the stress conditions and present a model for how GTAs persist in biofilm-forming bacterial populations despite being lethal.
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Affiliation(s)
- Roman Kogay
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Olga Zhaxybayeva
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
- Department of Computer Science, Dartmouth College, Hanover, New Hampshire, USA
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6
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Cheng JH, Du R, Sun DW. Regulating bacterial biofilms in food and biomedicine: unraveling mechanisms and Innovating strategies. Crit Rev Food Sci Nutr 2024:1-17. [PMID: 38384205 DOI: 10.1080/10408398.2024.2312539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Bacterial biofilm has brought a lot of intractable problems in food and biomedicine areas. Conventional biofilm control mainly focuses on inactivation and removal of biofilm. However, with robust construction and enhanced resistance, the established biofilm is extremely difficult to eradicate. According to the mechanism of biofilm development, biofilm formation can be modulated by intervening in the key factors and regulatory systems. Therefore, regulation of biofilm formation has been proposed as an alternative way for effective biofilm control. This review aims to provide insights into the regulation of biofilm formation in food and biomedicine. The underlying mechanisms for early-stage biofilm establishment are summarized based on the key factors and correlated regulatory networks. Recent developments and applications of novel regulatory strategies such as anti/pro-biofilm agents, nanomaterials, functionalized surface materials and physical strategies are also discussed. The current review indicates that these innovative methods have contributed to effective biofilm control in a smart, safe and eco-friendly way. However, standard methodology for regulating biofilm formation in practical use is still missing. As biofilm formation in real-world systems could be far more complicated, further studies and interdisciplinary collaboration are still needed for simulation and experiments in the industry and other open systems.
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Affiliation(s)
- Jun-Hu Cheng
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, China
- Engineering and Technological Research Centre of Guangdong Province on Intelligent Sensing and Process Control of Cold Chain Foods, & Guangdong Province Engineering Laboratory for Intelligent Cold Chain Logistics Equipment for Agricultural Products, Guangzhou Higher Education Mega Centre, Guangzhou, China
| | - Rong Du
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, China
- Engineering and Technological Research Centre of Guangdong Province on Intelligent Sensing and Process Control of Cold Chain Foods, & Guangdong Province Engineering Laboratory for Intelligent Cold Chain Logistics Equipment for Agricultural Products, Guangzhou Higher Education Mega Centre, Guangzhou, China
| | - Da-Wen Sun
- School of Food Science and Engineering, South China University of Technology, Guangzhou, China
- Academy of Contemporary Food Engineering, South China University of Technology, Guangzhou Higher Education Mega Centre, Guangzhou, China
- Engineering and Technological Research Centre of Guangdong Province on Intelligent Sensing and Process Control of Cold Chain Foods, & Guangdong Province Engineering Laboratory for Intelligent Cold Chain Logistics Equipment for Agricultural Products, Guangzhou Higher Education Mega Centre, Guangzhou, China
- Food Refrigeration and Computerized Food Technology (FRCFT), Agriculture and Food Science Centre, University College Dublin, National University of Ireland, Dublin 4, Ireland
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Barnes J, Balestra B, Knee KL, Frederick JA, Landaverde N, Meiller J. Freshwater algal biofilm assemblages are more effective than invertebrate assemblages at aggregating microplastics. Heliyon 2024; 10:e23239. [PMID: 38163167 PMCID: PMC10754882 DOI: 10.1016/j.heliyon.2023.e23239] [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: 08/15/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Microplastics, plastic particles less than 5 mm in length, are a ubiquitous pollutant in the environment, but research on freshwater microplastic contamination is lacking. A possible fate of microplastics in freshwater environments is to become entangled or aggregated in biofilms, which are matrices of algae, bacteria, and micro invertebrates that grow on underwater surfaces, following a progression of settling algae, periphyton, and finally invertebrate colonization. This in-situ study at the Oasis Marina at National Harbor in Oxon Hill, Maryland, examined how the taxonomic assemblages of freshwater biofilms in the Potomac River are associated with the number of microplastics aggregated within them. Aluminum discs, acting as artificial substrate for biofilm growth, were deployed at the water's surface and at 2 m depth to survey biofilm assemblage and were sampled monthly from October 2021-October 2022. Microplastic abundances in the water column were measured every 2 weeks over the same period. Spatial and temporal trends in trapped and suspended microplastics, water quality parameters (temperature, dissolved oxygen, pH, salinity, conductivity, turbidity, ammonia, nitrate, and phosphate), and biofilm assemblages were measured and compared to explore factors affecting the abundance of microplastics and their partitioning between the water column and biofilms. Water quality had no measurable impact on microplastic abundance in the water column at either depth, but temperature was negatively correlated to microplastic abundance in biofilms. As the weather warmed and biofilms progressed to invertebrate settling, they tended to contain fewer microplastics. This may have occurred because less biologically rich biofilms, primarily composed of unicellular algal colonies, provide a favorable surface for microplastic deposition. Understanding seasonal changes in biofilm assemblage and microplastic abundance may help track the fate of microplastics in freshwater systems, particularly in their interactions with lower trophic organisms.
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Affiliation(s)
- Joseph Barnes
- American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA
| | - Barbara Balestra
- American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA
- Paleobiology Department, National Museum of Natural History (NMNH), Smithsonian, Washington, DC, 20560, USA
| | - Karen L. Knee
- American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA
| | - J. Adam Frederick
- Maryland Sea Grant, 5825 University Research Ct Suite 1350, College Park, MD 20740, USA
| | - Natalie Landaverde
- American University, 4400 Massachusetts Ave NW, Washington, DC 20016, USA
| | - Jesse Meiller
- The Earth Commons—Georgetown University's Institute for Environment & Sustainability, Washington, DC, 20007, USA
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Odermatt PD, Nussbaum P, Monnappa S, Talà L, Li Z, Sivabalasarma S, Albers SV, Persat A. Archaeal type IV pili stabilize Haloferax volcanii biofilms in flow. Curr Biol 2023; 33:3265-3271.e4. [PMID: 37473762 DOI: 10.1016/j.cub.2023.06.055] [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: 01/23/2023] [Revised: 05/01/2023] [Accepted: 06/20/2023] [Indexed: 07/22/2023]
Abstract
Multicellular communities of contiguous cells attached to solid surfaces called biofilms represent a common microbial strategy to improve resilience in adverse environments.1,2,3 While bacterial biofilms have been under intense investigation, whether archaeal biofilms follow similar assembly rules remains unknown.4,5Haloferax volcanii is an extremely halophilic euryarchaeon that commonly colonizes salt crust surfaces. H. volcanii produces long and thin appendages called type IV pili (T4Ps). These play a role in surface attachment and biofilm formation in both archaea and bacteria. In this study, we employed biophysical experiments to identify the function of T4Ps in H. volcanii biofilm morphogenesis. H. volcanii expresses not one but six types of major pilin subunits that are predicted to compose T4Ps. Non-invasive imaging of T4Ps in live cells using interferometric scattering (iSCAT) microscopy reveals that piliation varies across mutants expressing single major pilin isoforms. T4Ps are necessary to secure attachment of single cells to surfaces, and the adhesive strength of pilin mutants correlates with their level of piliation. In flow, H. volcanii forms clonal biofilms that extend in three dimensions. Notably, the expression of PilA2, a single pilin isoform, is sufficient to maintain levels of piliation, surface attachment, and biofilm formation that are indistinguishable from the wild type. Furthermore, we discovered that fluid flow stabilizes biofilm integrity; as in the absence of flow, biofilms tend to lose cohesion and disperse in a density-dependent manner. Overall, our results demonstrate that T4P-surface and possibly T4P-T4P interactions promote biofilm formation and integrity and that flow is a key factor regulating archaeal biofilm formation.
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Affiliation(s)
- Pascal D Odermatt
- Global Health Institute and Institute for Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Phillip Nussbaum
- Molecular Biology of Archaea, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Sourabh Monnappa
- Global Health Institute and Institute for Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Lorenzo Talà
- Global Health Institute and Institute for Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland
| | - Zhengqun Li
- Molecular Biology of Archaea, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Shamphavi Sivabalasarma
- Molecular Biology of Archaea, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
| | - Alexandre Persat
- Global Health Institute and Institute for Bioengineering, School of Life Sciences, EPFL, 1015 Lausanne, Switzerland.
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Material Substrate Physical Properties Control Pseudomonas aeruginosa Biofilm Architecture. mBio 2023; 14:e0351822. [PMID: 36786569 PMCID: PMC10127718 DOI: 10.1128/mbio.03518-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
In the wild, bacteria are most frequently found in the form of multicellular structures called biofilms. Biofilms grow at the surface of abiotic and living materials with wide-ranging mechanical properties. The opportunistic pathogen Pseudomonas aeruginosa forms biofilms on indwelling medical devices and on soft tissues, including burn wounds and the airway mucosa. Despite the critical role of substrates in the foundation of biofilms, we still lack a clear understanding of how material mechanics regulate their architecture and the physiology of resident bacteria. Here, we demonstrate that physical properties of hydrogel material substrates define P. aeruginosa biofilm architecture. We show that hydrogel mesh size regulates twitching motility, a surface exploration mechanism priming biofilms, ultimately controlling the organization of single cells in the multicellular community. The resulting architectural transitions increase P. aeruginosa's tolerance to colistin, a last-resort antibiotic. In addition, mechanical regulation of twitching motility affects P. aeruginosa clonal lineages, so that biofilms are more mixed on relatively denser materials. Our results thereby establish material properties as a factor that dramatically affects biofilm architecture, antibiotic efficacy, and evolution of the resident population. IMPORTANCE The biofilm lifestyle is the most widespread survival strategy in the bacterial world. Pseudomonas aeruginosa biofilms cause chronic infections and are highly recalcitrant to antimicrobials. The genetic requirements allowing P. aeruginosa to grow into biofilms are known, but not the physical stimuli that regulate their formation. Despite colonizing biological tissues, investigations of biofilms on soft materials are limited. In this work, we show that biofilms take unexpected forms when growing on soft substrates. The physical properties of the material shape P. aeruginosa biofilms by regulating surface-specific twitching motility. Physical control of biofilm morphogenesis ultimately influences the resilience of biofilms to antimicrobials, linking physical environment with tolerance to treatment. Altogether, our work established that the physical properties of a surface are a critical environmental regulator of biofilm biogenesis and evolution.
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10
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Berne C, Zappa S, Brun YV. eDNA-stimulated cell dispersion from Caulobacter crescentus biofilms upon oxygen limitation is dependent on a toxin-antitoxin system. eLife 2023; 12:80808. [PMID: 36475544 PMCID: PMC9851616 DOI: 10.7554/elife.80808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
In their natural environment, most bacteria preferentially live as complex surface-attached multicellular colonies called biofilms. Biofilms begin with a few cells adhering to a surface, where they multiply to form a mature colony. When conditions deteriorate, cells can leave the biofilm. This dispersion is thought to be an important process that modifies the overall biofilm architecture and that promotes colonization of new environments. In Caulobacter crescentus biofilms, extracellular DNA (eDNA) is released upon cell death and prevents newborn cells from joining the established biofilm. Thus, eDNA promotes the dispersal of newborn cells and the subsequent colonization of new environments. These observations suggest that eDNA is a cue for sensing detrimental environmental conditions in the biofilm. Here, we show that the toxin-antitoxin system (TAS) ParDE4 stimulates cell death in areas of a biofilm with decreased O2 availability. In conditions where O2 availability is low, eDNA concentration is correlated with cell death. Cell dispersal away from biofilms is decreased when parDE4 is deleted, probably due to the lower local eDNA concentration. Expression of parDE4 is positively regulated by O2 and the expression of this operon is decreased in biofilms where O2 availability is low. Thus, a programmed cell death mechanism using an O2-regulated TAS stimulates dispersal away from areas of a biofilm with decreased O2 availability and favors colonization of a new, more hospitable environment.
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Affiliation(s)
- Cecile Berne
- Département de microbiologie, infectiologie et immunologie, Université de MontréalMontréalCanada
| | - Sébastien Zappa
- Département de microbiologie, infectiologie et immunologie, Université de MontréalMontréalCanada
| | - Yves V Brun
- Département de microbiologie, infectiologie et immunologie, Université de MontréalMontréalCanada
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11
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Abstract
Biofilm formation is an important and ubiquitous mode of growth among bacteria. Central to the evolutionary advantage of biofilm formation is cell-cell and cell-surface adhesion achieved by a variety of factors, some of which are diffusible compounds that may operate as classical public goods-factors that are costly to produce but may benefit other cells. An outstanding question is how diffusible matrix production, in general, can be stable over evolutionary timescales. In this work, using Vibrio cholerae as a model, we show that shared diffusible biofilm matrix proteins are indeed susceptible to cheater exploitation and that the evolutionary stability of producing these matrix components fundamentally depends on biofilm spatial structure, intrinsic sharing mechanisms of these components, and flow conditions in the environment. We further show that exploitation of diffusible adhesion proteins is localized within a well-defined spatial range around cell clusters that produce them. Based on this exploitation range and the spatial distribution of cell clusters, we constructed a model of costly diffusible matrix production and related these length scales to the relatedness coefficient in social evolution theory. Our results show that production of diffusible biofilm matrix components is evolutionarily stable under conditions consistent with natural biofilm habitats and host environments. We expect the mechanisms revealed in this study to be relevant to other secreted factors that operate as cooperative public goods in bacterial communities and the concept of exploitation range and the associated analysis tools to be generally applicable.
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12
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Lissens M, Joos M, Lories B, Steenackers HP. Evolution-proof inhibitors of public good cooperation: a screening strategy inspired by social evolution theory. FEMS Microbiol Rev 2022; 46:6604382. [PMID: 35675280 PMCID: PMC9616471 DOI: 10.1093/femsre/fuac019] [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: 12/14/2021] [Revised: 04/22/2022] [Indexed: 01/07/2023] Open
Abstract
Interference with public good cooperation provides a promising novel antimicrobial strategy since social evolution theory predicts that resistant mutants will be counter-selected if they share the public benefits of their resistance with sensitive cells in the population. Although this hypothesis is supported by a limited number of pioneering studies, an extensive body of more fundamental work on social evolution describes a multitude of mechanisms and conditions that can stabilize public behaviour, thus potentially allowing resistant mutants to thrive. In this paper we theorize on how these different mechanisms can influence the evolution of resistance against public good inhibitors. Based hereon, we propose an innovative 5-step screening strategy to identify novel evolution-proof public good inhibitors, which involves a systematic evaluation of the exploitability of public goods under the most relevant experimental conditions, as well as a careful assessment of the most optimal way to interfere with their action. Overall, this opinion paper is aimed to contribute to long-term solutions to fight bacterial infections.
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Affiliation(s)
- Maries Lissens
- Centre of Microbial and Plant Genetics (CMPG), Department of Microbial and Molecular Systems, KU Leuven, Leuven, B-3001, Belgium
| | - Mathieu Joos
- Centre of Microbial and Plant Genetics (CMPG), Department of Microbial and Molecular Systems, KU Leuven, Leuven, B-3001, Belgium
| | - Bram Lories
- Centre of Microbial and Plant Genetics (CMPG), Department of Microbial and Molecular Systems, KU Leuven, Leuven, B-3001, Belgium
| | - Hans P Steenackers
- Corresponding author: Centre of Microbial and Plant Genetics (CMPG), Kasteelpark Arenberg 20 – Box 2460, B-3001 Leuven, Belgium. E-mail:
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13
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Singh C. Guided run-and-tumble active particles: wall accumulation and preferential deposition. SOFT MATTER 2021; 17:8858-8866. [PMID: 34541594 DOI: 10.1039/d1sm00775k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Bacterial biofilms cost an enormous amount of resources in the health, medical, and industrial sectors. To understand early biofilm formation, beginning from planktonic states of active suspensions (such as Escherichia coli) to micro-colonization, it is vital to study the mechanics of cell accumulation near surfaces and subsequent deposition. Variability in bacterial motion strategies and the presence of taxis fields make the problem even more multifaceted. In this study, analytical expressions for the density and angular distributions, mean orientation, and deposition rates in such bacterial suspensions are derived, with and without the effects of external guiding or taxis fields. The derived results are closely verified by simulations of confined active particles using run-and-tumble statistics from multiple past experiments and utilizing a preferential sticking probability model for deposition. The behavioral changes in cell running strategies are modeled by varying the run-time distribution from an exponential to a heavy-tailed one. It is found that the deposition rates can be altered significantly by a guiding torque but are less affected by a change in the cell running behavior. However, both the mechanisms alter the pair correlation function of the deposited structures. The factor behind the changes in the architecture of deposited biomass under a torque generating guiding field turns out to be an asymmetrical rotational drift of planktonic cells, which can be an important physical mechanism behind the organization in confined active particle suspensions.
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Affiliation(s)
- Chamkor Singh
- Department of Physics, Central University of Punjab, Bathinda 151401, India.
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208, USA
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14
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Both Pseudomonas aeruginosa and Candida albicans Accumulate Greater Biomass in Dual-Species Biofilms under Flow. mSphere 2021; 6:e0041621. [PMID: 34160236 PMCID: PMC8265656 DOI: 10.1128/msphere.00416-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Microbe-microbe interactions can strongly influence growth and biofilm formation kinetics. For Pseudomonas aeruginosa and Candida albicans, which are found together in diverse clinical sites, including urinary and intravenous catheters and the lungs of individuals with cystic fibrosis (CF), we compared the kinetics of biofilm formation by each species in dual-species and single-species biofilms. We engineered fluorescent protein constructs for P. aeruginosa (producing mKO-κ) and C. albicans (producing mKate2) that did not alter growth and enabled single-cell resolution imaging by live-sample microscopy. Using these strains in an optically clear derivative of synthetic CF sputum medium, we found that both P. aeruginosa and C. albicans displayed increased biovolume accumulation—by three- and sixfold, respectively—in dual-species biofilms relative to single-species biofilms. This result was specific to the biofilm environment, as enhanced growth was not observed in planktonic cocultures. Stimulation of C. albicans biofilm formation occurred regardless of whether P. aeruginosa was added at the time of fungal inoculation or 24 h after the initiation of biofilm development. P. aeruginosa biofilm increases in cocultures did not require the Pel extracellular polysaccharide, phenazines, and siderophores known to influence C. albicans. P. aeruginosa mutants lacking Anr, LasR, and BapA were not significantly stimulated by C. albicans, but they still promoted a significant enhancement of biofilm development of the fungus, suggesting a fungal response to the presence of bacteria. Last, we showed that a set of P. aeruginosa clinical isolates also prompted an increase of biovolume by C. albicans in coculture. IMPORTANCE There is an abundance of work on both P. aeruginosa and C. albicans in isolation, and quite some work as well on the way these two microbes interact. These studies do not, however, consider biofilm environments under flow, and our results here show that the expected outcome of interaction between these two pathogens can actually be reversed under flow, from pure antagonism to an increase in biomass on the part of both. Our work also highlights the importance of cellular-scale spatial structure in biofilms for understanding multispecies population dynamics.
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15
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Abstract
Bacteria use intercellular signaling, or quorum sensing (QS), to share information and respond collectively to aspects of their surroundings. The autoinducers that carry this information are exposed to the external environment; consequently, they are affected by factors such as removal through fluid flow, a ubiquitous feature of bacterial habitats ranging from the gut and lungs to lakes and oceans. To understand how QS genetic architectures in cells promote appropriate population-level phenotypes throughout the bacterial life cycle requires knowledge of how these architectures determine the QS response in realistic spatiotemporally varying flow conditions. Here we develop and apply a general theory that identifies and quantifies the conditions required for QS activation in fluid flow by systematically linking cell- and population-level genetic and physical processes. We predict that when a subset of the population meets these conditions, cell-level positive feedback promotes a robust collective response by overcoming flow-induced autoinducer concentration gradients. By accounting for a dynamic flow in our theory, we predict that positive feedback in cells acts as a low-pass filter at the population level in oscillatory flow, allowing a population to respond only to changes in flow that occur over slow enough timescales. Our theory is readily extendable and provides a framework for assessing the functional roles of diverse QS network architectures in realistic flow conditions.
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Affiliation(s)
- Mohit P Dalwadi
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, United Kingdom;
| | - Philip Pearce
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115
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16
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Depetris A, Peter H, Bordoloi AD, Bernard H, Niayifar A, Kühl M, de Anna P, Battin TJ. Morphogenesis and oxygen dynamics in phototrophic biofilms growing across a gradient of hydraulic conditions. iScience 2021; 24:102067. [PMID: 33598641 PMCID: PMC7868926 DOI: 10.1016/j.isci.2021.102067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 12/11/2020] [Accepted: 01/11/2021] [Indexed: 10/25/2022] Open
Abstract
Biofilms are surface-attached and matrix-enclosed microbial communities that dominate microbial life in numerous ecosystems. Using flumes and automated optical coherence tomography, we studied the morphogenesis of phototrophic biofilms along a gradient of hydraulic conditions. Compact and coalescent biofilms formed under elevated bed shear stress, whereas protruding clusters separated by troughs formed under reduced shear stress. This morphological differentiation did not linearly follow the hydraulic gradient, but a break point emerged around a shear stress of ~0.08 Pa. While community composition did not differ between high and low shear environments, our results suggest that the morphological differentiation was linked to biomass displacement and reciprocal interactions between the biofilm structure and hydraulics. Mapping oxygen concentrations within and around biofilm structures, we provide empirical evidence for biofilm-induced alterations of oxygen mass transfer. Our findings suggest that architectural plasticity, efficient mass transfer, and resistance to shear stress contribute to the success of phototrophic biofilms.
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Affiliation(s)
- Anna Depetris
- Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Hannes Peter
- Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Ankur Deep Bordoloi
- Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland
| | - Hippolyte Bernard
- Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Amin Niayifar
- Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Michael Kühl
- Marine Biological Section, Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Pietro de Anna
- Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland
| | - Tom Jan Battin
- Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, 1015 Lausanne, Switzerland
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17
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Uppal G, Bahcecioglu G, Zorlutuna P, Vural DC. Tissue Failure Propagation as Mediated by Circulatory Flow. Biophys J 2020; 119:2573-2583. [PMID: 33189679 DOI: 10.1016/j.bpj.2020.11.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 10/06/2020] [Accepted: 11/05/2020] [Indexed: 01/09/2023] Open
Abstract
Aging is driven by subcellular processes that are relatively well understood. However, the qualitative mechanisms and quantitative dynamics of how these micro-level failures cascade to a macro-level catastrophe in a tissue or organs remain largely unexplored. Here, we experimentally and theoretically study how cell failure propagates in an engineered tissue in the presence of advective flow. We argue that cells secrete cooperative factors, thereby forming a network of interdependence governed by diffusion and flow, which fails with a propagating front parallel to advective circulation.
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Affiliation(s)
- Gurdip Uppal
- Department of Physics, University of Notre Dame, Notre Dame, Indiana
| | - Gokhan Bahcecioglu
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana
| | - Pinar Zorlutuna
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, Indiana.
| | - Dervis Can Vural
- Department of Physics, University of Notre Dame, Notre Dame, Indiana.
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18
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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: 14] [Impact Index Per Article: 3.5] [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.
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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.
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19
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Mechanomicrobiology: how bacteria sense and respond to forces. Nat Rev Microbiol 2020; 18:227-240. [DOI: 10.1038/s41579-019-0314-2] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2019] [Indexed: 12/26/2022]
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20
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Li X, Wang X, Lee DJ, Yan WM. Highly heterogeneous interior structure of biofilm wastewater for enhanced pollutant removals. BIORESOURCE TECHNOLOGY 2019; 291:121919. [PMID: 31376667 DOI: 10.1016/j.biortech.2019.121919] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/24/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Biofilm processes are widely used in wastewater treatment. The biofilm has highly heterogeneous interior structure, which can significantly affect the transport processes and the biological reactions over the biofilm. This study for the first time detailed the complicated velocity and concentration fields of substrate in a real biofilm structure. With a real biofilm interior being profiled and meshed to numerical solutions, the flow-through mode has significant distortion of inflow velocity fields and concentration distributions, which lead to enhanced biological reactions at regimes nearby major pores. Conversely, the crossflow mode depends weakly on the biofilm interior structure. The uniform biofilm model fails to describe the real biofilm processes. Future research needs based on real biofilm structures were discussed.
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Affiliation(s)
- Xianyang Li
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China; School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Xiaodong Wang
- Research Center of Engineering Thermophysics, North China Electric Power University, Beijing 102206, China; School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
| | - Duu-Jong Lee
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan; Department of Chemical Engineering, National Taiwan University of Science and Technology, National Taiwan University of Science and Technology, Taipei 10607, Taiwan; College of Engineering, Tunghai University, Taichung 40704, Taiwan
| | - Wei-Mon Yan
- Department of Energy and Refrigerating Air-Conditioning Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
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21
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Vibrio cholerae filamentation promotes chitin surface attachment at the expense of competition in biofilms. Proc Natl Acad Sci U S A 2019; 116:14216-14221. [PMID: 31239347 PMCID: PMC6628660 DOI: 10.1073/pnas.1819016116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The human pathogen Vibrio cholerae, when not inside of a host, grows in cell clusters (biofilms) on pieces of detritus in aquatic environments. Here we discovered that some isolates of V. cholerae can change their shape from small comma-shaped cells to long filaments in seawater. This altered cell shape allows cells to make new types of biofilms, and provides an advantage in quickly colonizing particles in seawater, at the expense of longer-term competitive ability. The filamentous cell-shape strategy is particularly effective at competing in environments with quick turnover of chitin particles. This result showcases how bacterial cell shape can be coupled to environmental success during surface occupation, competition within biofilms, and dispersal to new resource patches. Collective behavior in spatially structured groups, or biofilms, is the norm among microbes in their natural environments. Though biofilm formation has been studied for decades, tracing the mechanistic and ecological links between individual cell morphologies and the emergent features of cell groups is still in its infancy. Here we use single-cell–resolution confocal microscopy to explore biofilms of the human pathogen Vibrio cholerae in conditions mimicking its marine habitat. Prior reports have noted the occurrence of cellular filamentation in V. cholerae, with variable propensity to filament among both toxigenic and nontoxigenic strains. Using a filamenting strain of V. cholerae O139, we show that cells with this morphotype gain a profound competitive advantage in colonizing and spreading on particles of chitin, the material many marine Vibrio species depend on for growth in seawater. Furthermore, filamentous cells can produce biofilms that are independent of primary secreted components of the V. cholerae biofilm matrix; instead, filamentous biofilm architectural strength appears to derive at least in part from the entangled mesh of cells themselves. The advantage gained by filamentous cells in early chitin colonization and growth is countered in long-term competition experiments with matrix-secreting V. cholerae variants, whose densely packed biofilm structures displace competitors from surfaces. Overall, our results reveal an alternative mode of biofilm architecture that is dependent on filamentous cell morphology and advantageous in environments with rapid chitin particle turnover. This insight provides an environmentally relevant example of how cell morphology can impact bacterial fitness.
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22
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Fuqua C, Filloux A, Ghigo JM, Visick KL. Biofilms 2018: A diversity of microbes and mechanisms. J Bacteriol 2019; 201:JB.00118-19. [PMID: 30782638 PMCID: PMC6707918 DOI: 10.1128/jb.00118-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The 8th ASM Conference on Biofilms was held in Washington D.C. on October 7-11, 2018. This very highly subscribed meeting represented a wide breadth of current research in biofilms, and included over 500 attendees, 12 sessions with 64 oral presentations, and four poster sessions with about 400 posters.
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Affiliation(s)
- Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Alain Filloux
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College, London, United Kingdom
| | - Jean-Marc Ghigo
- Institut Pasteur, Unité de Génétique des Biofilms, Département de Microbiologie, Paris, France
| | - Karen L. Visick
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
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