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Ohmura T, Skinner DJ, Neuhaus K, Choi GPT, Dunkel J, Drescher K. In Vivo Microrheology Reveals Local Elastic and Plastic Responses Inside 3D Bacterial Biofilms. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2314059. [PMID: 38511867 DOI: 10.1002/adma.202314059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/08/2024] [Indexed: 03/22/2024]
Abstract
Bacterial biofilms are highly abundant 3D living materials capable of performing complex biomechanical and biochemical functions, including programmable growth, self-repair, filtration, and bioproduction. Methods to measure internal mechanical properties of biofilms in vivo with spatial resolution on the cellular scale have been lacking. Here, thousands of cells are tracked inside living 3D biofilms of the bacterium Vibrio cholerae during and after the application of shear stress, for a wide range of stress amplitudes, periods, and biofilm sizes, which revealed anisotropic elastic and plastic responses of both cell displacements and cell reorientations. Using cellular tracking to infer parameters of a general mechanical model, spatially-resolved measurements of the elastic modulus inside the biofilm are obtained, which correlate with the spatial distribution of the polysaccharides within the biofilm matrix. The noninvasive microrheology and force-inference approach introduced here provides a general framework for studying mechanical properties with high spatial resolution in living materials.
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Affiliation(s)
- Takuya Ohmura
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, 4056, Switzerland
| | - Dominic J Skinner
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139-4307, USA
- NSF-Simons Center for Quantitative Biology, Northwestern University, Evanston, IL, 60201, USA
| | - Konstantin Neuhaus
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, 4056, Switzerland
- Department of Physics, Philipps-Universität Marburg, Renthof 5, 35032, Marburg, Germany
| | - Gary P T Choi
- Department of Mathematics, The Chinese University of Hong Kong, N.T., Hong Kong
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139-4307, USA
| | - Knut Drescher
- Biozentrum, University of Basel, Spitalstrasse 41, Basel, 4056, Switzerland
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Charlton SG, Bible AN, Secchi E, Morrell‐Falvey JL, Retterer ST, Curtis TP, Chen J, Jana S. Microstructural and Rheological Transitions in Bacterial Biofilms. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2207373. [PMID: 37522628 PMCID: PMC10520682 DOI: 10.1002/advs.202207373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 06/20/2023] [Indexed: 08/01/2023]
Abstract
Biofilms are aggregated bacterial communities structured within an extracellular matrix (ECM). ECM controls biofilm architecture and confers mechanical resistance against shear forces. From a physical perspective, biofilms can be described as colloidal gels, where bacterial cells are analogous to colloidal particles distributed in the polymeric ECM. However, the influence of the ECM in altering the cellular packing fraction (ϕ) and the resulting viscoelastic behavior of biofilm remains unexplored. Using biofilms of Pantoea sp. (WT) and its mutant (ΔUDP), the correlation between biofilm structure and its viscoelastic response is investigated. Experiments show that the reduction of exopolysaccharide production in ΔUDP biofilms corresponds with a seven-fold increase in ϕ, resulting in a colloidal glass-like structure. Consequently, the rheological signatures become altered, with the WT behaving like a weak gel, whilst the ΔUDP displayed a glass-like rheological signature. By co-culturing the two strains, biofilm ϕ is modulated which allows us to explore the structural changes and capture a change in viscoelastic response from a weak to a strong gel, and to a colloidal glass-like state. The results reveal the role of exopolysaccharide in mediating a structural transition in biofilms and demonstrate a correlation between biofilm structure and viscoelastic response.
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Affiliation(s)
- Samuel G.V. Charlton
- Department of Civil, Environmental and Geomatic EngineeringInstitute of Environmental EngineeringETH ZurichZurich8049Switzerland
- School of EngineeringNewcastle UniversityNewcastle Upon TyneNE1 7RUUK
| | - Amber N. Bible
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTN37830USA
| | - Eleonora Secchi
- Department of Civil, Environmental and Geomatic EngineeringInstitute of Environmental EngineeringETH ZurichZurich8049Switzerland
| | | | - Scott T. Retterer
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTN37830USA
- Center for Nanophase Material SciencesOak Ridge National LaboratoryOak RidgeTN37830USA
| | - Thomas P. Curtis
- School of EngineeringNewcastle UniversityNewcastle Upon TyneNE1 7RUUK
| | - Jinju Chen
- School of EngineeringNewcastle UniversityNewcastle Upon TyneNE1 7RUUK
| | - Saikat Jana
- School of EngineeringNewcastle UniversityNewcastle Upon TyneNE1 7RUUK
- School of EngineeringUlster UniversityBelfastBT15 1APUK
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Charlton SGV, Kurz DL, Geisel S, Jimenez-Martinez J, Secchi E. The role of biofilm matrix composition in controlling colony expansion and morphology. Interface Focus 2022; 12:20220035. [PMID: 36330326 PMCID: PMC9560791 DOI: 10.1098/rsfs.2022.0035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 09/09/2022] [Indexed: 08/01/2023] Open
Abstract
Biofilms are biological viscoelastic gels composed of bacterial cells embedded in a self-secreted polymeric extracellular matrix (ECM). In environmental settings, such as in the rhizosphere and phyllosphere, biofilm colonization occurs at the solid-air interface. The biofilms' ability to colonize and expand over these surfaces depends on the formation of osmotic gradients and ECM viscoelastic properties. In this work, we study the influence of biofilm ECM components on its viscoelasticity and expansion, using the model organism Bacillus subtilis and deletion mutants of its three major ECM components, TasA, EPS and BslA. Using a multi-scale approach, we quantified macro-scale viscoelasticity and expansion dynamics. Furthermore, we used a microsphere assay to visualize the micro-scale expansion patterns. We find that the viscoelastic phase angle Φ is likely the best viscoelastic parameter correlating to biofilm expansion dynamics. Moreover, we quantify the sensitivity of the biofilm to changes in substrate water potential as a function of ECM composition. Finally, we find that the deletion of ECM components significantly increases the coherence of micro-scale colony expansion patterns. These results demonstrate the influence of ECM viscoelasticity and substrate water potential on the expansion of biofilm colonies on wet surfaces at the air-solid interface, commonly found in natural environments.
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Affiliation(s)
- Samuel G. V. Charlton
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
| | - Dorothee L. Kurz
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
- Department Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Dübendorf, Switzerland
| | - Steffen Geisel
- Department of Materials, Soft Materials, ETH Zürich, Zürich, Switzerland
| | - Joaquin Jimenez-Martinez
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
- Department Water Resources and Drinking Water, Swiss Federal Institute of Aquatic Science and Technology, Eawag, Dübendorf, Switzerland
| | - Eleonora Secchi
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zürich, Zürich, Switzerland
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4
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Geisel S, Secchi E, Vermant J. Experimental challenges in determining the rheological properties of bacterial biofilms. Interface Focus 2022; 12:20220032. [PMID: 36330324 PMCID: PMC9560794 DOI: 10.1098/rsfs.2022.0032] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 08/03/2022] [Indexed: 08/01/2023] Open
Abstract
Bacterial biofilms are communities living in a matrix consisting of self-produced, hydrated extracellular polymeric substances. Most microorganisms adopt the biofilm lifestyle since it protects by conferring resistance to antibiotics and physico-chemical stress factors. Consequently, mechanical removal is often necessary but rendered difficult by the biofilm's complex, viscoelastic response, and adhesive properties. Overall, the mechanical behaviour of biofilms also plays a role in the spreading, dispersal and subsequent colonization of new surfaces. Therefore, the characterization of the mechanical properties of biofilms plays a crucial role in controlling and combating biofilms in industrial and medical environments. We performed in situ shear rheological measurements of Bacillus subtilis biofilms grown between the plates of a rotational rheometer under well-controlled conditions relevant to many biofilm habitats. We investigated how the mechanical history preceding rheological measurements influenced biofilm mechanics and compared these results to the techniques commonly used in the literature. We also compare our results to measurements using interfacial rheology on bacterial pellicles formed at the air-water interface. This work aims to help understand how different growth and measurement conditions contribute to the large variability of mechanical properties reported in the literature and provide a new tool for the rigorous characterization of matrix components and biofilms.
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Affiliation(s)
- Steffen Geisel
- Laboratory for Soft Materials, Department of Materials, ETH Zurich, Zurich, Switzerland
| | - Eleonora Secchi
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Jan Vermant
- Laboratory for Soft Materials, Department of Materials, ETH Zurich, Zurich, Switzerland
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Schaefer C, McKinley GH, McLeish TCB. Editorial: theme issue on complex rheology in biological systems. Interface Focus 2022. [PMCID: PMC9560783 DOI: 10.1098/rsfs.2022.0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Charley Schaefer
- Department of Physics, University of York, Heslington, York YO10 5DD, UK
| | - Gareth H. McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 01239, USA
| | - Tom C. B. McLeish
- Department of Physics, University of York, Heslington, York YO10 5DD, UK
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