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Yuan W, Deng X, Wang Z, Ma T, Yan S, Gao X, Li J, Ma X, Yin J, Hu K, Zhang W, Jiang X. Photochemical Design for Diverse Controllable Patterns in Self-Wrinkling Films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2400849. [PMID: 38567824 DOI: 10.1002/adma.202400849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 03/11/2024] [Indexed: 04/11/2024]
Abstract
Harnessing the spontaneous surface instability of pliable substances to create intricate, well-ordered, and on-demand controlled surface patterns holds great potential for advancing applications in optical, electrical, and biological processes. However, the current limitations stem from challenges in modulating multidirectional stress fields and diverse boundary environments. Herein, this work proposes a universal strategy to achieve arbitrarily controllable wrinkle patterns via the spatiotemporal photochemical boundaries. Utilizing constraints and inductive effects of the photochemical boundaries, the multiple coupling relationship is accomplished among the light fields, stress fields, and morphology of wrinkles in photosensitive polyurethane (PSPU) film. Moreover, employing sequential light-irradiation with photomask enables the attainment of a diverse array of controllable patterns, ranging from highly ordered 2D patterns to periodic or intricate designs. The fundamental mechanics of underlying buckling and the formation of surface features are comprehensively elucidated through theoretical stimulation and finite element analysis. The results reveal the evolution laws of wrinkles under photochemical boundaries and represent a new effective toolkit for fabricating intricate and captivating patterns in single-layer films.
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Affiliation(s)
- Wenqiang Yuan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xinlu Deng
- School of Mechanical Engineering, State Key Laboratory of Mechanical Systems and Vibration, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zehong Wang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Tianjiao Ma
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shuzhen Yan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaxin Gao
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jin Li
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaodong Ma
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jie Yin
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Kaiming Hu
- School of Mechanical Engineering, State Key Laboratory of Mechanical Systems and Vibration, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wenming Zhang
- School of Mechanical Engineering, State Key Laboratory of Mechanical Systems and Vibration, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xuesong Jiang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory for Metal Matrix Composite Materials, Shanghai Jiao Tong University, Shanghai, 200240, China
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2
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Shao L, Shen Z, Li M, Guan C, Fan B, Chai Y, Zhao Y. ccdC Regulates Biofilm Dispersal in Bacillus velezensis FZB42. Int J Mol Sci 2024; 25:5201. [PMID: 38791239 PMCID: PMC11120784 DOI: 10.3390/ijms25105201] [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: 03/14/2024] [Revised: 04/30/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024] Open
Abstract
Bacillus velezensis FZB42 is a plant growth-promoting rhizobacterium (PGPR) and a model microorganism for biofilm studies. Biofilms are required for the colonization and promotion of plant growth in the rhizosphere. However, little is known about how the final stage of the biofilm life cycle is regulated, when cells regain their motility and escape the mature biofilm to spread and colonize new niches. In this study, the non-annotated gene ccdC was found to be involved in the process of biofilm dispersion. We found that the ccdC-deficient strain maintained a wrinkled state at the late stage of biofilm formation in the liquid-gas interface culture, and the bottom solution showed a clear state, indicating that no bacterial cells actively escaped, which was further evidenced by the formation of a cellular ring (biofilm pellicle) located on top of the preformed biofilm. It can be concluded that dispersal, a biofilm property that relies on motility proficiency, is also positively affected by the unannotated gene ccdC. Furthermore, we found that the level of cyclic diguanylate (c-di-GMP) in the ccdC-deficient strain was significantly greater than that in the wild-type strain, suggesting that B. velezensis exhibits a similar mechanism by regulating the level of c-di-GMP, the master regulator of biofilm formation, dispersal, and cell motility, which controls the fitness of biofilms in Pseudomonas aeruginosain. In this study, we investigated the mechanism regulating biofilm dispersion in PGPR.
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Affiliation(s)
- Lin Shao
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Zizhu Shen
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Meiju Li
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
| | - Chenyun Guan
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
| | - Ben Fan
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
- College of Life Science, Nanjing Forestry University, Nanjing 210037, China
| | - Yunrong Chai
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - Yinjuan Zhao
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry and Grass, Nanjing Forestry University, Nanjing 210037, China
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3
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La Corte SG, Stevens CA, Cárcamo-Oyarce G, Ribbeck K, Wingreen NS, Datta SS. Morphogenesis of bacterial colonies in polymeric environments. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.18.590088. [PMID: 38712130 PMCID: PMC11071276 DOI: 10.1101/2024.04.18.590088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Many bacteria live in polymeric fluids, such as mucus, environmental polysaccharides, and extracellular polymers in biofilms. However, lab studies typically focus on cells in polymer-free fluids. Here, we show that interactions with polymers shape a fundamental feature of bacterial life-how they proliferate in space in multicellular colonies. Using experiments, we find that when polymer is sufficiently concentrated, cells generically and reversibly form large serpentine "cables" as they proliferate. By combining experiments with biophysical theory and simulations, we demonstrate that this distinctive form of colony morphogenesis arises from an interplay between polymer-induced entropic attraction between neighboring cells and their hindered ability to diffusely separate from each other in a viscous polymer solution. Our work thus reveals a pivotal role of polymers in sculpting proliferating bacterial colonies, with implications for how they interact with hosts and with the natural environment, and uncovers quantitative principles governing colony morphogenesis in such complex environments.
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Fan J, Jia Y, He S, Tan Z, Li A, Li J, Zhang Z, Li B, Chu H. GlnR activated transcription of nitrogen metabolic pathway genes facilitates biofilm formation by mycobacterium abscessus. Int J Antimicrob Agents 2024; 63:107025. [PMID: 37926271 DOI: 10.1016/j.ijantimicag.2023.107025] [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: 06/12/2023] [Revised: 10/10/2023] [Accepted: 10/31/2023] [Indexed: 11/07/2023]
Abstract
OBJECTIVES Nitrogen is indispensable for the synthesis of biomacromolecules. The correlation between nitrogen metabolism and Mycobacterium abscessus (M. abscessus) biofilm formation is unclear. This study constructed global nitrogen regulator gene GlnR (Mab_0744) knockout (ΔglnR) and complementation (ΔglnR::glnR) M. abscessus strains. METHODS Global nitrogen regulator gene glnR (Mab_0744) knockout (ΔglnR) and complementation (ΔglnR::glnR) M. abscessus strains were constructed. Sauton's medium was used to culture M. abscessus pellicle biofilm. To test the antibiotic susceptibility of pellicle biofilm, clarithromycin, amikacin, cefoxitin or imipenem was added to the medium under biofilms after 14 days of incubation. RT-qPCR and ChIP-qPCR were performed to analyse the transcriptional regulatory function of GlnR. RESULTS GlnR knockout decreased the growth rate of planktonic cells, reduced biofilm mass and wrinkle formation, and diminished the resistance of biofilms to antibiotics. However, the susceptibility of planktonic cells to antibiotics was not changed by glnR knockout. The growth rate of planktonic ΔglnR cells was accelerated by adding nitrogen sources to the medium; the addition of glutamine or sodium glutamate rescued ΔglnR biofilm morphology and resistance to amikacin, cefoxitin, clarithromycin and imipenem. GlnR bound the promoter region and activated the transcription of eight nitrogen metabolic pathway genes (i.e. glnA, amt, ansP, nirB, nirD, glnD, glnK and narK3), which are closely related to glutamine/glutamate biosynthesis and, thus, regulate biofilm formation. CONCLUSION This study provides insights into the mechanisms of M. abscessus biofilm formation and its resistance to antibiotics.
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Affiliation(s)
- Junsheng Fan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Yaping Jia
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Siyuan He
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Zhili Tan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Anqi Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Juan Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Zhemin Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China
| | - Bing Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China.
| | - Haiqing Chu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China; School of Medicine, Tongji University, Shanghai, China; Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China.
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5
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Suñé M, Arratia C, Bonfils AF, Vella D, Wettlaufer JS. Wrinkling composite sheets. SOFT MATTER 2023; 19:8729-8743. [PMID: 37929692 DOI: 10.1039/d3sm00430a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
We examine the buckling shape and critical compression of confined inhomogeneous composite sheets lying on a liquid foundation. The buckling modes are controlled by the bending stiffness of the sheet, the density of the substrate, and the size and the spatially dependent elastic coefficients of the sheet. We solve the beam equation describing the mechanical equilibrium of a sheet when its bending stiffness varies parallel to the direction of confinement. The case of a homogeneous bending stiffness exhibits a degeneracy of wrinkled states for certain lengths of the confined sheet; we explain this degeneracy using an asymptotic analysis valid for long sheets, and show that it corresponds to the switching of the sheet between symmetric and antisymmetric buckling modes. This degeneracy disappears for spatially dependent elastic coefficients. Medium length sheets buckle similarly to their homogeneous counterparts, whereas the wrinkled states in large length sheets concentrate the bending energy towards the soft regions of the sheet.
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Affiliation(s)
- Marc Suñé
- Nordita, Stockholm University and KTH Royal Institute of Technology, Hannes Alfvéns väg 12, SE-106 91 Stockholm, Sweden.
| | - Cristóbal Arratia
- Nordita, Stockholm University and KTH Royal Institute of Technology, Hannes Alfvéns väg 12, SE-106 91 Stockholm, Sweden.
| | - A F Bonfils
- Nordita, Stockholm University and KTH Royal Institute of Technology, Hannes Alfvéns väg 12, SE-106 91 Stockholm, Sweden.
| | - Dominic Vella
- Mathematical Institute, University of Oxford, Woodstock Rd, Oxford, OX2 6GG, UK.
| | - J S Wettlaufer
- Nordita, Stockholm University and KTH Royal Institute of Technology, Hannes Alfvéns väg 12, SE-106 91 Stockholm, Sweden.
- Yale University, New Haven, Connecticut 06520, USA.
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6
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Prasad M, Obana N, Lin SZ, Zhao S, Sakai K, Blanch-Mercader C, Prost J, Nomura N, Rupprecht JF, Fattaccioli J, Utada AS. Alcanivorax borkumensis biofilms enhance oil degradation by interfacial tubulation. Science 2023; 381:748-753. [PMID: 37590351 DOI: 10.1126/science.adf3345] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 06/21/2023] [Indexed: 08/19/2023]
Abstract
During the consumption of alkanes, Alcanivorax borkumensis will form a biofilm around an oil droplet, but the role this plays during degradation remains unclear. We identified a shift in biofilm morphology that depends on adaptation to oil consumption: Longer exposure leads to the appearance of dendritic biofilms optimized for oil consumption effected through tubulation of the interface. In situ microfluidic tracking enabled us to correlate tubulation to localized defects in the interfacial cell ordering. We demonstrate control over droplet deformation by using confinement to position defects, inducing dimpling in the droplets. We developed a model that elucidates biofilm morphology, linking tubulation to decreased interfacial tension and increased cell hydrophobicity.
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Affiliation(s)
- M Prasad
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - N Obana
- Transborder Medical Research Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - S-Z Lin
- Aix Marseille Univ, Université de Toulon, CNRS, CPT (UMR 7332), Turing Centre for Living systems, Marseille, France
| | - S Zhao
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - K Sakai
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL Université, Sorbonne Université, CNRS, 75005 Paris, France
- Institut Pierre-Gilles de Gennes pour la Microfluidique, 75005 Paris, France
| | - C Blanch-Mercader
- Laboratoire Physico-Chimie Curie UMR168, Institut Curie, Paris Sciences et Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, 75248 Paris, France
| | - J Prost
- Laboratoire Physico-Chimie Curie UMR168, Institut Curie, Paris Sciences et Lettres, Centre National de la Recherche Scientifique, Sorbonne Université, 75248 Paris, France
- Mechanobiology Institute, National University of Singapore, 117411 Singapore
| | - N Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
- TARA center, Univeristy of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - J-F Rupprecht
- Aix Marseille Univ, Université de Toulon, CNRS, CPT (UMR 7332), Turing Centre for Living systems, Marseille, France
| | - J Fattaccioli
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL Université, Sorbonne Université, CNRS, 75005 Paris, France
- Institut Pierre-Gilles de Gennes pour la Microfluidique, 75005 Paris, France
| | - A S Utada
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
- Microbiology Research Center for Sustainability (MiCS), University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
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7
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Hallatschek O, Datta SS, Drescher K, Dunkel J, Elgeti J, Waclaw B, Wingreen NS. Proliferating active matter. NATURE REVIEWS. PHYSICS 2023; 5:1-13. [PMID: 37360681 PMCID: PMC10230499 DOI: 10.1038/s42254-023-00593-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 05/02/2023] [Indexed: 06/28/2023]
Abstract
The fascinating patterns of collective motion created by autonomously driven particles have fuelled active-matter research for over two decades. So far, theoretical active-matter research has often focused on systems with a fixed number of particles. This constraint imposes strict limitations on what behaviours can and cannot emerge. However, a hallmark of life is the breaking of local cell number conservation by replication and death. Birth and death processes must be taken into account, for example, to predict the growth and evolution of a microbial biofilm, the expansion of a tumour, or the development from a fertilized egg into an embryo and beyond. In this Perspective, we argue that unique features emerge in these systems because proliferation represents a distinct form of activity: not only do the proliferating entities consume and dissipate energy, they also inject biomass and degrees of freedom capable of further self-proliferation, leading to myriad dynamic scenarios. Despite this complexity, a growing number of studies document common collective phenomena in various proliferating soft-matter systems. This generality leads us to propose proliferation as another direction of active-matter physics, worthy of a dedicated search for new dynamical universality classes. Conceptual challenges abound, from identifying control parameters and understanding large fluctuations and nonlinear feedback mechanisms to exploring the dynamics and limits of information flow in self-replicating systems. We believe that, by extending the rich conceptual framework developed for conventional active matter to proliferating active matter, researchers can have a profound impact on quantitative biology and reveal fascinating emergent physics along the way.
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Affiliation(s)
- Oskar Hallatschek
- Departments of Physics and Integrative Biology, University of California, Berkeley, CA US
- Peter Debye Institute for Soft Matter Physics, Leipzig University, Leipzig, Germany
| | - Sujit S. Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ USA
| | | | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA USA
| | - Jens Elgeti
- Theoretical Physics of Living Matter, Institute of Biological Information Processing, Forschungszentrum Jülich, Jülich, Germany
| | - Bartek Waclaw
- Dioscuri Centre for Physics and Chemistry of Bacteria, Institute of Physical Chemistry PAN, Warsaw, Poland
- School of Physics and Astronomy, The University of Edinburgh, JCMB, Edinburgh, UK
| | - Ned S. Wingreen
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ USA
- Department of Molecular Biology, Princeton University, Princeton, NJ USA
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8
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Novel 3D Flipwell system that models gut mucosal microenvironment for studying interactions between gut microbiota, epithelia and immunity. Sci Rep 2023; 13:870. [PMID: 36650266 PMCID: PMC9845379 DOI: 10.1038/s41598-023-28233-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/16/2023] [Indexed: 01/19/2023] Open
Abstract
Gut mucosa consists of stratified layers of microbes, semi-permeable mucus, epithelium and stroma abundant in immune cells. Although tightly regulated, interactions between gut commensals and immune cells play indispensable roles in homeostasis and cancer pathogenesis in the body. Thus, there is a critical need to develop a robust model for the gut mucosal microenvironment. Here, we report our novel co-culture utilizing 3D Flipwell system for establishing the stratified layers of discrete mucosal components. This method allows for analyzing synchronous effects of test stimuli on gut bacteria, mucus, epithelium and immune cells, as well as their crosstalks. In the present report, we tested the immuno-stimulatory effects of sepiapterin (SEP, the precursor of the cofactor of nitric oxide synthase (NOS)-BH4) on the gut mucosal community. We previously reported that SEP effectively reprogrammed tumor-associated macrophages and inhibited breast tumor cell growth. In our co-cultures, SEP largely promoted mucus integrity, bacterial binding, and M1-like polarization of macrophages. Conversely, these phenomena were absent in control-treated cultures. Our results demonstrate that this novel co-culture may serve as a robust in vitro system to recapitulate the effects of pharmacological agents on the gut mucosal microenvironment, and could potentially be expanded to test the effects outside the gut.
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Shimaya T, Takeuchi KA. Tilt-induced polar order and topological defects in growing bacterial populations. PNAS NEXUS 2022; 1:pgac269. [PMID: 36712383 PMCID: PMC9802490 DOI: 10.1093/pnasnexus/pgac269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 11/30/2022] [Indexed: 12/24/2022]
Abstract
Rod-shaped bacteria, such as Escherichia coli, commonly live forming mounded colonies. They initially grow two-dimensionally on a surface and finally achieve three-dimensional growth. While it was recently reported that three-dimensional growth is promoted by topological defects of winding number +1/2 in populations of motile bacteria, how cellular alignment plays a role in nonmotile cases is largely unknown. Here, we investigate the relevance of topological defects in colony formation processes of nonmotile E. coli populations, and found that both ±1/2 topological defects contribute to the three-dimensional growth. Analyzing the cell flow in the bottom layer of the colony, we observe that +1/2 defects attract cells and -1/2 defects repel cells, in agreement with previous studies on motile cells, in the initial stage of the colony growth. However, later, cells gradually flow toward -1/2 defects as well, exhibiting a sharp contrast to the existing knowledge. By investigating three-dimensional cell orientations by confocal microscopy, we find that vertical tilting of cells is promoted near the defects. Crucially, this leads to the emergence of a polar order in the otherwise nematic two-dimensional cell orientation. We extend the theory of active nematics by incorporating this polar order and the vertical tilting, which successfully explains the influx toward -1/2 defects in terms of a polarity-induced force. Our work reveals that three-dimensional cell orientations may result in qualitative changes in properties of active nematics, especially those of topological defects, which may be generically relevant in active matter systems driven by cellular growth instead of self-propulsion.
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Affiliation(s)
- Takuro Shimaya
- Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan
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10
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Arjes HA, Gui H, Porter R, Atolia E, Peters JM, Gross C, Kearns DB, Huang KC. Fatty Acid Synthesis Knockdown Promotes Biofilm Wrinkling and Inhibits Sporulation in Bacillus subtilis. mBio 2022; 13:e0138822. [PMID: 36069446 PMCID: PMC9600695 DOI: 10.1128/mbio.01388-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/05/2022] [Indexed: 02/05/2023] Open
Abstract
Many bacterial species typically live in complex three-dimensional biofilms, yet much remains unknown about differences in essential processes between nonbiofilm and biofilm lifestyles. Here, we created a CRISPR interference (CRISPRi) library of knockdown strains covering all known essential genes in the biofilm-forming Bacillus subtilis strain NCIB 3610 and investigated growth, biofilm colony wrinkling, and sporulation phenotypes of the knockdown library. First, we showed that gene essentiality is largely conserved between liquid and surface growth and between two media. Second, we quantified biofilm colony wrinkling using a custom image analysis algorithm and found that fatty acid synthesis and DNA gyrase knockdown strains exhibited increased wrinkling independent of biofilm matrix gene expression. Third, we designed a high-throughput screen to quantify sporulation efficiency after essential gene knockdown; we found that partial knockdowns of essential genes remained competent for sporulation in a sporulation-inducing medium, but knockdown of essential genes involved in fatty acid synthesis exhibited reduced sporulation efficiency in LB, a medium with generally lower levels of sporulation. We conclude that a subset of essential genes are particularly important for biofilm structure and sporulation/germination and suggest a previously unappreciated and multifaceted role for fatty acid synthesis in bacterial lifestyles and developmental processes. IMPORTANCE For many bacteria, life typically involves growth in dense, three-dimensional communities called biofilms that contain cells with differentiated roles held together by extracellular matrix. To examine how essential gene function varies between vegetative growth and the developmental states of biofilm formation and sporulation, we created and screened a comprehensive library of strains using CRISPRi to knockdown expression of each essential gene in the biofilm-capable Bacillus subtilis strain 3610. High-throughput assays and computational algorithms identified a subset of essential genes involved in biofilm wrinkling and sporulation and indicated that fatty acid synthesis plays important and multifaceted roles in bacterial development.
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Affiliation(s)
- Heidi A. Arjes
- Department of Bioengineering, Stanford University School of Medicine, Stanford, California, USA
| | - Haiwen Gui
- Department of Bioengineering, Stanford University School of Medicine, Stanford, California, USA
| | - Rachel Porter
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, California, USA
| | - Esha Atolia
- Department of Bioengineering, Stanford University School of Medicine, Stanford, California, USA
| | - Jason M. Peters
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Bacteriology, University of Wisconsin—Madison, Madison, Wisconsin, USA
- Department of Medical Microbiology and Immunology, University of Wisconsin—Madison, Madison, Wisconsin, USA
| | - Carol Gross
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, USA
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California, USA
| | - Daniel B. Kearns
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University School of Medicine, Stanford, California, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
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11
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Quorum-sensing control of matrix protein production drives fractal wrinkling and interfacial localization of Vibrio cholerae pellicles. Nat Commun 2022; 13:6063. [PMID: 36229546 PMCID: PMC9561665 DOI: 10.1038/s41467-022-33816-6] [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: 05/27/2022] [Accepted: 10/04/2022] [Indexed: 12/24/2022] Open
Abstract
Bacterial cells at fluid interfaces can self-assemble into collective communities with stunning macroscopic morphologies. Within these soft, living materials, called pellicles, constituent cells gain group-level survival advantages including increased antibiotic resistance. However, the regulatory and structural components that drive pellicle self-patterning are not well defined. Here, using Vibrio cholerae as our model system, we report that two sets of matrix proteins and a key quorum-sensing regulator jointly orchestrate the sequential mechanical instabilities underlying pellicle morphogenesis, culminating in fractal patterning. A pair of matrix proteins, RbmC and Bap1, maintain pellicle localization at the interface and prevent self-peeling. A single matrix protein, RbmA, drives a morphogenesis program marked by a cascade of ever finer wrinkles with fractal scaling in wavelength. Artificial expression of rbmA restores fractal wrinkling to a ΔrbmA mutant and enables precise tuning of fractal dimensions. The quorum-sensing regulatory small RNAs Qrr1-4 first activate matrix synthesis to launch pellicle primary wrinkling and ridge instabilities. Subsequently, via a distinct mechanism, Qrr1-4 suppress fractal wrinkling to promote fine modulation of pellicle morphology. Our results connect cell-cell signaling and architectural components to morphogenic patterning and suggest that manipulation of quorum-sensing regulators or synthetic control of rbmA expression could underpin strategies to engineer soft biomaterial morphologies on demand.
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An open-source computational tool for measuring bacterial biofilm morphology and growth kinetics upon one-sided exposure to an antimicrobial source. Sci Rep 2022; 12:16125. [PMID: 36167741 PMCID: PMC9515175 DOI: 10.1038/s41598-022-20275-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 09/12/2022] [Indexed: 11/28/2022] Open
Abstract
Bacillus subtilis biofilms are well known for their complex and highly adaptive morphology. Indeed, their phenotypical diversity and intra-biofilm heterogeneity make this gram-positive bacterium the subject of many scientific papers on the structure of biofilms. The “robustness” of biofilms is a term often used to describe their level of susceptibility to antimicrobial agents and various mechanical and molecular inhibition/eradication methods. In this paper, we use computational analytics to quantify Bacillus subtilis morphological response to proximity to an antimicrobial source, in the form of the antiseptic chlorhexidine. Chlorhexidine droplets, placed in proximity to Bacillus subtilis macrocolonies at different distances result in morphological changes, quantified using Python-based code, which we have made publicly available. Our results quantify peripheral and inner core deformation as well as differences in cellular viability of the two regions. The results reveal that the inner core, which is often characterized by the presence of wrinkled formations in the macrocolony, is more preserved than the periphery. Furthermore, the paper describes a crescent-shaped colony morphology which occurs when the distance from the chlorhexidine source is 0.5 cm, as well as changes observed in the growth substrate of macrocolonies exposed to chlorhexidine.
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13
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Li H, Wu Y, Tang Y, Fang B, Luo P, Yang L, Jiang Q. A manganese-oxidizing bacterium-Enterobacter hormaechei strain DS02Eh01: Capabilities of Mn(II) immobilization, plant growth promotion and biofilm formation. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 309:119775. [PMID: 35843452 DOI: 10.1016/j.envpol.2022.119775] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Revised: 07/06/2022] [Accepted: 07/10/2022] [Indexed: 06/15/2023]
Abstract
While biogenic Mn oxides (BioMnOx) generated by Mn(II)-oxidizing bacteria (MOB) have attracted increasing attention, a MOB strain isolated from Mn-polluted sediments was identified and assigned as Enterobacter hormaechei DS02Eh01. Its Mn(II) immobilization activity, plant growth-promoting traits, and biofilm formation capability were investigated. The results showed that strain DS02Eh01 was found to be able to tolerate Mn(II) up to 122 mM. The strain immobilized Mn(II) in aquatic media mainly through extracellular adsorption, bio-oxidation and pH-induced precipitation as well as manganese oxidation. DS02Eh01-derived BioMnOx are negatively charged and have a larger specific surface area (86.70 m2/g) compared to the previously reported BioMnOx. The strain can immobilize Mn(II) at extreme levels, for instance, when it was exposed to 20 mM Mn(II), about 59% of Mn(II) were found immobilized and 17% of Mn(II) were converted to MnOx. The SEM and TEM observation revealed that the DS02Eh01-derived BioMnOx were aggregates doped with granules and microbial pellets. The precipitated Mn(II) and the Mn(III)/Mn(IV) oxides co-existed in BioMnOx, in which Mn(II) and Mn(IV) were found dominant with Mn(II) accounting for 49.6% and Mn(IV) accounting for 41.3%. DS02Eh01 possesses plant growth-promoting traits and biofilm formation capacity even under Mn(II) exposure. Mn(II) exposure at 5 mM was found to stimulate strain DS02Eh01 to form biofilms, from which, the extracted EPS was mainly composed of aromatic proteins. This study reveals that E. hormaechei strain DS02Eh01 possesses the potential in environmental ecoremediation via coupling processes of macrophytes extraction, biochemical immobilization and biosorption.
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Affiliation(s)
- Huilan Li
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
| | - Yu Wu
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
| | - Yankui Tang
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China.
| | - Bo Fang
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
| | - Penghong Luo
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
| | - Luling Yang
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
| | - Qiming Jiang
- Guangxi Key Laboratory of Processing for Non-ferrous Metals and Featured Materials & MOE Key Laboratory of New Processing Technology for Non-ferrous Metals and Materials, School of Resources, Environment and Materials, Guangxi University, Nanning, 530004, China; Key Laboratory of Environmental Protection (Guangxi University), Education Department of Guangxi Zhuang Autonomous Region, Nanning, 530004, China
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Shay R, Wiegand AA, Trail F. Biofilm Formation and Structure in the Filamentous Fungus Fusarium graminearum, a Plant Pathogen. Microbiol Spectr 2022; 10:e0017122. [PMID: 35950855 PMCID: PMC9430603 DOI: 10.1128/spectrum.00171-22] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 07/16/2022] [Indexed: 11/25/2022] Open
Abstract
Biofilms are protective structures for pathogens of plants and animals, in which cells are shielded from host defense responses and antimicrobial treatments. Although biofilms are well studied in bacterial pathogens, their development and structure in filamentous fungi, as well as their role in pathogenicity, are poorly understood. We show that the economically important plant pathogen Fusarium graminearum, a filamentous fungus, forms biofilms in vitro, which adhere to polystyrene, a hydrophobic surface. The biofilms have complex hyphal structures surrounded by a polymeric matrix that consists primarily of polysaccharides and extracellular nucleic acids, and lack lipids. Pellicles are formed in liquid cultures, floating biofilm masses that are common in bacterial biofilms, and noted but undescribed in filamentous fungal biofilms. Commonly, F. graminearum grows as hyphal colonies; however, on media which lack electron acceptors, an altered morphology is formed with predominantly short, bulbous hyphae embedded in the matrix. Supplementation of the biofilm-inducing medium with an electron acceptor restores the filamentous hyphal morphology, demonstrating that the formation of bulbous hyphae is due, at least in part, to oxidative stress. Plant hosts infected with pathogens generally respond by producing reactive oxygen species, commonly produced as a defense response. Thus, the formation of biofilms strongly suggests a role in protecting cells from host responses during the course of plant disease. IMPORTANCE Fusarium graminearum is a filamentous fungal pathogen that causes Fusarium head blight (FHB) in cereal crops, leading to devastating crop losses. We have demonstrated the ability of this pathogen to form biofilms. Biofilms are likely to be important in the disease cycle of F. graminearum and other plant pathogens, protecting cells from plant defenses and environmental conditions. Towards this end, we have characterized the formation of biofilms in F. graminearum in vitro, which, together with ongoing characterization of their association with host plants, provides a basis for understanding the functionality of biofilms in the pathogen disease cycle.
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Affiliation(s)
- Rebecca Shay
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
| | - Aaron A. Wiegand
- High School Honors Science-Engineering-Mathematics Research Program, Michigan State University, East Lansing, Michigan, USA
| | - Frances Trail
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
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15
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Surapaneni VA, Schindler M, Ziege R, de Faria LC, Wölfer J, Bidan CM, Mollen FH, Amini S, Hanna S, Dean MN. Groovy and Gnarly: Surface Wrinkles as a Multifunctional Motif for Terrestrial and Marine Environments. Integr Comp Biol 2022; 62:icac079. [PMID: 35675323 PMCID: PMC9703940 DOI: 10.1093/icb/icac079] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 12/12/2022] Open
Abstract
From large ventral pleats of humpback whales to nanoscale ridges on flower petals, wrinkled structures are omnipresent, multifunctional, and found at hugely diverse scales. Depending on the particulars of the biological system-its environment, morphology, and mechanical properties-wrinkles may control adhesion, friction, wetting, or drag; promote interfacial exchange; act as flow channels; or contribute to stretching, mechanical integrity, or structural color. Undulations on natural surfaces primarily arise from stress-induced instabilities of surface layers (e.g., buckling) during growth or aging. Variation in the material properties of surface layers and in the magnitude and orientation of intrinsic stresses during growth lead to a variety of wrinkling morphologies and patterns which, in turn, reflect the wide range of biophysical challenges wrinkled surfaces can solve. Therefore, investigating how surface wrinkles vary and are implemented across biological systems is key to understanding their structure-function relationships. In this work, we synthesize the literature in a metadata analysis of surface wrinkling in various terrestrial and marine organisms to review important morphological parameters and classify functional aspects of surface wrinkles in relation to the size and ecology of organisms. Building on our previous and current experimental studies, we explore case studies on nano/micro-scale wrinkles in biofilms, plant surfaces, and basking shark filter structures to compare developmental and structure-vs-function aspects of wrinkles with vastly different size scales and environmental demands. In doing this and by contrasting wrinkle development in soft and hard biological systems, we provide a template of structure-function relationships of biological surface wrinkles and an outlook for functionalized wrinkled biomimetic surfaces.
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Affiliation(s)
- Venkata A Surapaneni
- City University of Hong Kong, 31 To Yuen Street, Kowloon, Hong Kong
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, Potsdam, Brandenburg 14476, Germany
| | - Mike Schindler
- City University of Hong Kong, 31 To Yuen Street, Kowloon, Hong Kong
| | - Ricardo Ziege
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, Potsdam, Brandenburg 14476, Germany
| | | | - Jan Wölfer
- Humboldt University of Berlin, Unter den Linden 6, Berlin 10099, Germany
| | - Cécile M Bidan
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, Potsdam, Brandenburg 14476, Germany
| | - Frederik H Mollen
- Elasmobranch Research Belgium, Rehaegenstraat 4, 2820 Bonheiden, Belgium
| | - Shahrouz Amini
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, Potsdam, Brandenburg 14476, Germany
| | - Sean Hanna
- University College London, 14 Upper Woburn Place, London WC1H 0NN, UK
| | - Mason N Dean
- City University of Hong Kong, 31 To Yuen Street, Kowloon, Hong Kong
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, Potsdam, Brandenburg 14476, Germany
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16
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Probing the growth and mechanical properties of Bacillus subtilis biofilms through genetic mutation strategies. Synth Syst Biotechnol 2022; 7:965-971. [PMID: 35756965 PMCID: PMC9194759 DOI: 10.1016/j.synbio.2022.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 12/02/2022] Open
Abstract
Bacterial communities form biofilms on various surfaces by synthesizing a cohesive and protective extracellular matrix, and these biofilms protect microorganisms against harsh environmental conditions. Bacillus subtilis is a widely used experimental species, and its biofilms are used as representative models of beneficial biofilms. Specifically, B. subtilis biofilms are known to be rich in extracellular polymeric substances (EPS) and other biopolymers such as DNA and proteins like the amyloid protein TasA and the hydrophobic protein BslA. These materials, which form an interconnected, cohesive, three-dimensional polymer network, provide the mechanical stability of biofilms and mediate their adherence to surfaces among other functional contributions. Here, we explored how genetically-encoded components specifically contribute to regulate the growth status, mechanical properties, and antibiotic resistance of B. subtilis biofilms, thereby establishing a solid empirical basis for understanding how various genetic engineering efforts are likely to affect the structure and function of biofilms. We noted discrete contributions to biofilm morphology, mechanical properties, and survival from major biofilm components such as EPS, TasA and BslA. For example, EPS plays an important role in maintaining the stability of the mechanical properties and the antibiotic resistance of biofilms, whereas BslA has a significant impact on the resolution that can be obtained for printing applications. This work provides a deeper understanding of the internal interactions of biofilm components through systematic genetic manipulations. It thus not only broadens the application prospects of beneficial biofilms, but also serves as the basis of future strategies for targeting and effectively removing harmful biofilms.
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17
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Day TC, Márquez-Zacarías P, Bravo P, Pokhrel AR, MacGillivray KA, Ratcliff WC, Yunker PJ. Varied solutions to multicellularity: The biophysical and evolutionary consequences of diverse intercellular bonds. BIOPHYSICS REVIEWS 2022; 3:021305. [PMID: 35673523 PMCID: PMC9164275 DOI: 10.1063/5.0080845] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 04/29/2022] [Indexed: 11/16/2022]
Abstract
The diversity of multicellular organisms is, in large part, due to the fact that multicellularity has independently evolved many times. Nonetheless, multicellular organisms all share a universal biophysical trait: cells are attached to each other. All mechanisms of cellular attachment belong to one of two broad classes; intercellular bonds are either reformable or they are not. Both classes of multicellular assembly are common in nature, having independently evolved dozens of times. In this review, we detail these varied mechanisms as they exist in multicellular organisms. We also discuss the evolutionary implications of different intercellular attachment mechanisms on nascent multicellular organisms. The type of intercellular bond present during early steps in the transition to multicellularity constrains future evolutionary and biophysical dynamics for the lineage, affecting the origin of multicellular life cycles, cell-cell communication, cellular differentiation, and multicellular morphogenesis. The types of intercellular bonds used by multicellular organisms may thus result in some of the most impactful historical constraints on the evolution of multicellularity.
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Affiliation(s)
- Thomas C. Day
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | | | | | - Aawaz R. Pokhrel
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | | | - William C. Ratcliff
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Peter J. Yunker
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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18
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Ji Y, Chen L, Cao R, Zhang Z, Zuo P, Xu X, Zhu L. Uncover the secret of the stability and interfacial Gibbs free energy of aerobic granular sludge. ENVIRONMENTAL RESEARCH 2022; 208:112693. [PMID: 35065066 DOI: 10.1016/j.envres.2022.112693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 12/31/2021] [Accepted: 01/04/2022] [Indexed: 06/14/2023]
Abstract
Interfacial Gibbs free energy (IGFE) as a thermodynamic indicator characterize the stability of the natural system. For aerobic granular sludge (AGS), how IGFE determines the stability of sludge remains to be determined. The Gibbs free energy change at the AGS-water interface (ΔGswa) and AGS interfaces (ΔGsc) were selected as the main interfacial thermodynamic factors. Results indicated that the stable AGS was guaranteed with ΔGsc at the range of -31 to - 46 J m-2. Pearson correlation coefficients between ΔGswa/ ΔGsc and relative hydrophobicity, water content, SVI30, integrity coefficient were -0.9, 0.8, 0.85, and 0.84, which illustrated that the IGFE could be a more comprehensive thermodynamic indicator. Microbial community and EPS analysis verified the importance of denitrifiers, Amide III, protein-like substances for AGS stability. This work offers a new insight into the development of AGS stability based on IGFE.
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Affiliation(s)
- Yatong Ji
- Institution of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Linlin Chen
- School of Environmental and Geographical Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Runjuan Cao
- Institution of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Zhiming Zhang
- Institution of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China
| | - Pengxiao Zuo
- Department of Civil and Environmental Engineering, Rice University, Houston, TX, 77005, USA
| | - Xiangyang Xu
- Institution of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China; Zhejiang Provincial Engineering Laboratory of Water Pollution Control, 388 Yuhangtang Road, Hangzhou, 310058, China
| | - Liang Zhu
- Institution of Environment Pollution Control and Treatment, Department of Environmental Engineering, Zhejiang University, Hangzhou, 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou, 310058, China; Zhejiang Provincial Engineering Laboratory of Water Pollution Control, 388 Yuhangtang Road, Hangzhou, 310058, China.
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19
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Systems view of Bacillus subtilis pellicle development. NPJ Biofilms Microbiomes 2022; 8:25. [PMID: 35414070 PMCID: PMC9005697 DOI: 10.1038/s41522-022-00293-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/19/2022] [Indexed: 11/08/2022] Open
Abstract
In this study, we link pellicle development at the water-air interface with the vertical distribution and viability of the individual B. subtilis PS-216 cells throughout the water column. Real-time interfacial rheology and time-lapse confocal laser scanning microscopy were combined to correlate mechanical properties with morphological changes (aggregation status, filament formation, pellicle thickness, spore formation) of the growing pellicle. Six key events were identified in B. subtilis pellicle formation that are accompanied by a major change in viscoelastic and morphology behaviour of the pellicle. The results imply that pellicle development is a multifaceted response to a changing environment induced by bacterial growth that causes population redistribution within the model system, reduction of the viable habitat to the water-air interface, cell development, and morphogenesis. The outcome is a build-up of mechanical stress supporting structure that eventually, due to nutrient deprivation, reaches the finite thickness. After prolonged incubation, the formed pellicle collapses, which correlates with the spore releasing process. The pellicle loses the ability to support mechanical stress, which marks the end of the pellicle life cycle and entry of the system into the dormant state.
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Alric B, Formosa-Dague C, Dague E, Holt LJ, Delarue M. Macromolecular crowding limits growth under pressure. NATURE PHYSICS 2022; 18:411-416. [PMID: 37152719 PMCID: PMC10162713 DOI: 10.1038/s41567-022-01506-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cells that grow in confined spaces eventually build up mechanical compressive stress. This growth-induced pressure (GIP) decreases cell growth. GIP is important in a multitude of contexts from cancer, to microbial infections, to biofouling, yet our understanding of its origin and molecular consequences remains limited. Here, we combine microfluidic confinement of the yeast Saccharomyces cerevisiae, with rheological measurements using genetically encoded multimeric nanoparticles (GEMs) to reveal that growth-induced pressure is accompanied with an increase in a key cellular physical property: macromolecular crowding. We develop a fully calibrated model that predicts how increased macromolecular crowding hinders protein expression and thus diminishes cell growth. This model is sufficient to explain the coupling of growth rate to pressure without the need for specific molecular sensors or signaling cascades. As molecular crowding is similar across all domains of life, this could be a deeply conserved mechanism of biomechanical feedback that allows environmental sensing originating from the fundamental physical properties of cells.
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Affiliation(s)
- Baptiste Alric
- MILE team, CNRS, UPR8001, LAAS-CNRS, 7 Avenue du Colonel Roche, F-31400 Toulouse, France
| | | | - Etienne Dague
- ELIA team, CNRS, UPR8001, LAAS-CNRS, 7 Avenue du Colonel Roche, F-31400 Toulouse, France
| | - Liam J. Holt
- New York University Grossman School of Medicine, Institute for Systems Genetics, 435 E 30th Street, New York, NY, United States
- to whom correspondence should be addressed: ;
| | - Morgan Delarue
- MILE team, CNRS, UPR8001, LAAS-CNRS, 7 Avenue du Colonel Roche, F-31400 Toulouse, France
- to whom correspondence should be addressed: ;
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21
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Patteson AE, Asp ME, Janmey PA. Materials science and mechanosensitivity of living matter. APPLIED PHYSICS REVIEWS 2022; 9:011320. [PMID: 35392267 PMCID: PMC8969880 DOI: 10.1063/5.0071648] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 02/08/2022] [Indexed: 06/14/2023]
Abstract
Living systems are composed of molecules that are synthesized by cells that use energy sources within their surroundings to create fascinating materials that have mechanical properties optimized for their biological function. Their functionality is a ubiquitous aspect of our lives. We use wood to construct furniture, bacterial colonies to modify the texture of dairy products and other foods, intestines as violin strings, bladders in bagpipes, and so on. The mechanical properties of these biological materials differ from those of other simpler synthetic elastomers, glasses, and crystals. Reproducing their mechanical properties synthetically or from first principles is still often unattainable. The challenge is that biomaterials often exist far from equilibrium, either in a kinetically arrested state or in an energy consuming active state that is not yet possible to reproduce de novo. Also, the design principles that form biological materials often result in nonlinear responses of stress to strain, or force to displacement, and theoretical models to explain these nonlinear effects are in relatively early stages of development compared to the predictive models for rubberlike elastomers or metals. In this Review, we summarize some of the most common and striking mechanical features of biological materials and make comparisons among animal, plant, fungal, and bacterial systems. We also summarize some of the mechanisms by which living systems develop forces that shape biological matter and examine newly discovered mechanisms by which cells sense and respond to the forces they generate themselves, which are resisted by their environment, or that are exerted upon them by their environment. Within this framework, we discuss examples of how physical methods are being applied to cell biology and bioengineering.
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Affiliation(s)
- Alison E. Patteson
- Physics Department and BioInspired Institute, Syracuse University, Syracuse NY, 13244, USA
| | - Merrill E. Asp
- Physics Department and BioInspired Institute, Syracuse University, Syracuse NY, 13244, USA
| | - Paul A. Janmey
- Institute for Medicine and Engineering and Departments of Physiology and Physics & Astronomy, University of Pennsylvania, Philadelphia PA, 19104, USA
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22
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Multiscale X-ray study of Bacillus subtilis biofilms reveals interlinked structural hierarchy and elemental heterogeneity. Proc Natl Acad Sci U S A 2022; 119:2118107119. [PMID: 35042817 PMCID: PMC8794879 DOI: 10.1073/pnas.2118107119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2021] [Indexed: 11/24/2022] Open
Abstract
Biofilms are multicellular, soft microbial communities that are able to colonize synthetic surfaces as well as living organisms. To survive sudden environmental changes and efficiently share their common resources, cells in a biofilm divide into subgroups with distinct functions, leading to phenotypic heterogeneity. Here, by studying intact biofilms by synchrotron X-ray diffraction and fluorescence, we revealed correlations between biofilm macroscopic, architectural heterogeneity and the spatiotemporal distribution of extracellular matrix, spores, water, and metal ions. Our findings demonstrate that biofilm heterogeneity is not only affected by local genetic expression and cellular differentiation but also by passive effects resulting from the physicochemical properties of the molecules secreted by the cells, leading to differential distribution of nutrients that propagate through macroscopic length scales. Biofilms are multicellular microbial communities that encase themselves in an extracellular matrix (ECM) of secreted biopolymers and attach to surfaces and interfaces. Bacterial biofilms are detrimental in hospital and industrial settings, but they can be beneficial, for example, in agricultural as well as in food technology contexts. An essential property of biofilms that grants them with increased survival relative to planktonic cells is phenotypic heterogeneity, the division of the biofilm population into functionally distinct subgroups of cells. Phenotypic heterogeneity in biofilms can be traced to the cellular level; however, the molecular structures and elemental distribution across whole biofilms, as well as possible linkages between them, remain unexplored. Mapping X-ray diffraction across intact biofilms in time and space, we revealed the dominant structural features in Bacillus subtilis biofilms, stemming from matrix components, spores, and water. By simultaneously following the X-ray fluorescence signal of biofilms and isolated matrix components, we discovered that the ECM preferentially binds calcium ions over other metal ions, specifically, zinc, manganese, and iron. These ions, remaining free to flow below macroscopic wrinkles that act as water channels, eventually accumulate and may possibly lead to sporulation. The possible link between ECM properties, regulation of metal ion distribution, and sporulation across whole, intact biofilms unravels the importance of molecular-level heterogeneity in shaping biofilm physiology and development.
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23
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Liu Y, Feng Z, Xu C, Chatterjee A, Gorodetsky AA. Reconfigurable Micro- and Nano-Structured Camouflage Surfaces Inspired by Cephalopods. ACS NANO 2021; 15:17299-17309. [PMID: 34633175 DOI: 10.1021/acsnano.0c09990] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Wrinkled surfaces and materials are found throughout the natural world in various plants and animals and are known to improve the performance of emerging optical and electrical technologies. Despite much progress, the reversible post-fabrication tuning of wrinkle sizes and geometries across multiple length scales has remained relatively challenging for some materials, and the development of comprehensive structure-function relationships for optically active wrinkled surfaces has often proven difficult. Herein, by drawing inspiration from natural cephalopod skin and leveraging methodologies established for artificial adaptive infrared platforms, we engineer systems with hierarchically reconfigurable wrinkled surface morphologies and dynamically tunable visible-to-infrared spectroscopic properties. Specifically, we demonstrate architectures for which mechanical actuation changes the surface morphological characteristics; modulates the reflectance, transmittance, and absorptance across a broad spectral window; controls the specular-to-diffuse reflectance ratios; and alters the visible and thermal appearances. Moreover, we demonstrate the incorporation of these architectures into analogous electrically actuated appearance-changing devices that feature competitive figures of merit, such as reasonable maximum areal strains, rapid response times, and good stabilities upon repeated actuation. Overall, our findings constitute another step forward in the continued development of cephalopod-inspired light- and heat-manipulating systems and may facilitate advanced applications in the areas of sensing, electronics, optics, soft robotics, and thermal management.
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Affiliation(s)
- Yinuan Liu
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Zhijing Feng
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Chengyi Xu
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Atrouli Chatterjee
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
| | - Alon A Gorodetsky
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
- Department of Chemical and Biomolecular Engineering, University of California, Irvine, Irvine, California 92697, United States
- Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States
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24
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Nijjer J, Li C, Zhang Q, Lu H, Zhang S, Yan J. Mechanical forces drive a reorientation cascade leading to biofilm self-patterning. Nat Commun 2021; 12:6632. [PMID: 34789754 PMCID: PMC8599862 DOI: 10.1038/s41467-021-26869-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/26/2021] [Indexed: 01/12/2023] Open
Abstract
In growing active matter systems, a large collection of engineered or living autonomous units metabolize free energy and create order at different length scales as they proliferate and migrate collectively. One such example is bacterial biofilms, surface-attached aggregates of bacterial cells embedded in an extracellular matrix that can exhibit community-scale orientational order. However, how bacterial growth coordinates with cell-surface interactions to create distinctive, long-range order during biofilm development remains elusive. Here we report a collective cell reorientation cascade in growing Vibrio cholerae biofilms that leads to a differentially ordered, spatiotemporally coupled core-rim structure reminiscent of a blooming aster. Cell verticalization in the core leads to a pattern of differential growth that drives radial alignment of the cells in the rim, while the growing rim generates compressive stresses that expand the verticalized core. Such self-patterning disappears in nonadherent mutants but can be restored through opto-manipulation of growth. Agent-based simulations and two-phase active nematic modeling jointly reveal the strong interdependence of the driving forces underlying the differential ordering. Our findings offer insight into the developmental processes that shape bacterial communities and provide ways to engineer phenotypes and functions in living active matter.
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Affiliation(s)
- Japinder Nijjer
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Changhao Li
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA
| | - Qiuting Zhang
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Haoran Lu
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Sulin Zhang
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA.
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, USA.
| | - Jing Yan
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
- Quantitative Biology Institute, Yale University, New Haven, CT, USA.
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25
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Rivas DP, Hedgecock ND, Stebe KJ, Leheny RL. Dynamic and mechanical evolution of an oil-water interface during bacterial biofilm formation. SOFT MATTER 2021; 17:8195-8210. [PMID: 34525167 DOI: 10.1039/d1sm00795e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We present an experimental study combining particle tracking, active microrheology, and differential dynamic microscopy (DDM) to investigate the dynamics and rheology of an oil-water interface during biofilm formation by the bacteria Pseudomonas Aeruginosa PA14. The interface transitions from an active fluid dominated by the swimming motion of adsorbed bacteria at early age to an active viscoelastic system at late ages when the biofilm is established. The microrheology measurements using microscale magnetic rods indicate that the biofilm behaves as a viscoelastic solid at late age. The bacteria motility at the interface during the biofilm formation, which is characterized in the DDM measurements, evolves from diffusive motion at early age to constrained, quasi-localized motion at later age. Similarly, the mobility of passively moving colloidal spheres at the interface decreases significantly with increasing interface age and shows a dependence on sphere size after biofilm formation that is orders-of-magnitude larger than that expected in a homogeneous system in equilibrium. We attribute this anomalous size dependence to either length-scale-dependent rheology of the biofilm or widely differing effects of the bacteria activity on the motion of spheres of different sizes.
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Affiliation(s)
- David P Rivas
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Nathan D Hedgecock
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
| | - Kathleen J Stebe
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Robert L Leheny
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, 21218, USA.
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26
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Donnadio A, Roscini L, Di Michele A, Corazzini V, Cardinali G, Ambrogi V. PVC grafted zinc oxide nanoparticles as an inhospitable surface to microbes. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2021; 128:112290. [PMID: 34474841 DOI: 10.1016/j.msec.2021.112290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 06/25/2021] [Accepted: 06/28/2021] [Indexed: 11/27/2022]
Abstract
Antimicrobial Polyvinyl chloride (PVC) was obtained by covalent bonding of zinc oxide nanoparticles, which have gained important achievements in antimicrobial fields because of their auspicious properties. This was achieved by grafting mercaptopropyltrimethoxysilane onto PVC, followed by the growth of zinc oxide nanoparticles covalently bonded on the polymer surface. In this study, the relationship between the physicochemical features of modified-surface PVC and antimicrobial activity on Staphylococcus aureus and Candida albicans was investigated. Zinc oxide with controllable morphologies (rods, rod flowers, and petal flowers) was synthesized on the polymer surface by tuning merely base-type and concentration using a hydrothermal process. The antimicrobial activity was more pronounced for rod flower morphology, because of their differences in microscopic parameters such as specific Zn-polar planes. This work provides an important hint for the safe use of PVC for biomedical devices by the structure surface tuning without injuring polymer bulk properties and a reduced risk of the covalently bonded nanoparticle dispersion in the host and the environment.
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Affiliation(s)
- Anna Donnadio
- Department of Pharmaceutical Sciences, University of Perugia, via del Liceo 1, 06123 Perugia, Italy; Centro di Eccellenza CEMIN - Materiali Innovativi Nanostrutturali per applicazioni Chimica Fisiche e Biomediche, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy.
| | - Luca Roscini
- Department of Pharmaceutical Sciences, University of Perugia, Borgo XX giugno, 06121 Perugia, Italy
| | - Alessandro Di Michele
- Department of Physics and Geology, University of Perugia, Via A. Pascoli, 06123 Perugia, Italy
| | - Valentina Corazzini
- Department of Pharmaceutical Sciences, University of Perugia, via del Liceo 1, 06123 Perugia, Italy
| | - Gianluigi Cardinali
- Department of Pharmaceutical Sciences, University of Perugia, Borgo XX giugno, 06121 Perugia, Italy; Centro di Eccellenza CEMIN - Materiali Innovativi Nanostrutturali per applicazioni Chimica Fisiche e Biomediche, University of Perugia, via Elce di Sotto 8, 06123 Perugia, Italy
| | - Valeria Ambrogi
- Department of Pharmaceutical Sciences, University of Perugia, via del Liceo 1, 06123 Perugia, Italy
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27
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Arnaouteli S, Bamford NC, Stanley-Wall NR, Kovács ÁT. Bacillus subtilis biofilm formation and social interactions. Nat Rev Microbiol 2021; 19:600-614. [PMID: 33824496 DOI: 10.1038/s41579-021-00540-9] [Citation(s) in RCA: 161] [Impact Index Per Article: 53.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/02/2021] [Indexed: 02/03/2023]
Abstract
Biofilm formation is a process in which microbial cells aggregate to form collectives that are embedded in a self-produced extracellular matrix. Bacillus subtilis is a Gram-positive bacterium that is used to dissect the mechanisms controlling matrix production and the subsequent transition from a motile planktonic cell state to a sessile biofilm state. The collective nature of life in a biofilm allows emergent properties to manifest, and B. subtilis biofilms are linked with novel industrial uses as well as probiotic and biocontrol processes. In this Review, we outline the molecular details of the biofilm matrix and the regulatory pathways and external factors that control its production. We explore the beneficial outcomes associated with biofilms. Finally, we highlight major advances in our understanding of concepts of microbial evolution and community behaviour that have resulted from studies of the innate heterogeneity of biofilms.
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Affiliation(s)
- Sofia Arnaouteli
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Natalie C Bamford
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK
| | - Nicola R Stanley-Wall
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee, UK.
| | - Ákos T Kovács
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Kongens Lyngby, Denmark.
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28
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Hierarchical transitions and fractal wrinkling drive bacterial pellicle morphogenesis. Proc Natl Acad Sci U S A 2021; 118:2023504118. [PMID: 33972433 PMCID: PMC8157956 DOI: 10.1073/pnas.2023504118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Multicellular bacterial communities called biofilms and pellicles significantly influence medical infections and industrial biofouling. Biofilms and pellicles often act as reservoirs of toxigenic bacteria. Here, we report a fractal wrinkling morphogenesis program that underlies pellicle formation in the model biofilm former and global pathogen, Vibrio cholerae. Pellicle morphogenesis is marked by the emergence of a cascade of self-similar structures with fractal-like scaling in wavelength, which increases surface area and presumably enhances nutrient transport and signaling among community members. This morphogenesis program can be altered by varying the spatial heterogeneity of the community. Thus, bacterial pellicles could provide tractable model systems to understand overarching principles driving morphogenesis and for engineering of functional soft biomaterials. Bacterial cells can self-organize into structured communities at fluid–fluid interfaces. These soft, living materials composed of cells and extracellular matrix are called pellicles. Cells residing in pellicles garner group-level survival advantages such as increased antibiotic resistance. The dynamics of pellicle formation and, more generally, how complex morphologies arise from active biomaterials confined at interfaces are not well understood. Here, using Vibrio cholerae as our model organism, a custom-built adaptive stereo microscope, fluorescence imaging, mechanical theory, and simulations, we report a fractal wrinkling morphogenesis program that differs radically from the well-known coalescence of wrinkles into folds that occurs in passive thin films at fluid–fluid interfaces. Four stages occur: growth of founding colonies, onset of primary wrinkles, development of secondary curved ridge instabilities, and finally the emergence of a cascade of finer structures with fractal-like scaling in wavelength. The time evolution of pellicle formation depends on the initial heterogeneity of the film microstructure. Changing the starting bacterial seeding density produces three variations in the sequence of morphogenic stages, which we term the bypass, crystalline, and incomplete modes. Despite these global architectural transitions, individual microcolonies remain spatially segregated, and thus, the community maintains spatial and genetic heterogeneity. Our results suggest that the memory of the original microstructure is critical in setting the morphogenic dynamics of a pellicle as an active biomaterial.
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29
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Sharipova MR, Mardanova AM, Rudakova NL, Pudova DS. Bistability and Formation of the Biofilm Matrix as Adaptive Mechanisms during the Stationary Phase of Bacillus subtilis. Microbiology (Reading) 2021. [DOI: 10.1134/s002626172006017x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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30
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Lou SS, Kennard AS, Koslover EF, Gutierrez E, Groisman A, Theriot JA. Elastic wrinkling of keratocyte lamellipodia driven by myosin-induced contractile stress. Biophys J 2021; 120:1578-1591. [PMID: 33631203 DOI: 10.1016/j.bpj.2021.02.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 02/01/2021] [Accepted: 02/03/2021] [Indexed: 11/16/2022] Open
Abstract
During actin-based cell migration, the actin cytoskeleton in the lamellipodium both generates and responds to force, which has functional consequences for the ability of the cell to extend protrusions. However, the material properties of the lamellipodial actin network and its response to stress on the timescale of motility are incompletely understood. Here, we describe a dynamic wrinkling phenotype in the lamellipodium of fish keratocytes, in which the actin sheet buckles upward away from the ventral membrane of the cell, forming a periodic pattern of wrinkles perpendicular to the cell's leading edge. Cells maintain an approximately constant wrinkle wavelength over time despite new wrinkle formation and the lateral movement of wrinkles in the cell frame of reference, suggesting that cells have a preferred or characteristic wrinkle wavelength. Generation of wrinkles is dependent upon myosin contractility, and their wavelength scales directly with the density of the actin network and inversely with cell adhesion. These results are consistent with a simple physical model for wrinkling in an elastic sheet under compression and suggest that the lamellipodial cytoskeleton behaves as an elastic material on the timescale of cell migration despite rapid actin turnover.
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Affiliation(s)
- Sunny S Lou
- Department of Chemical and Systems Biology, Stanford University, Stanford, California
| | - Andrew S Kennard
- Program in Biophysics, Stanford University, Stanford, California; Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington
| | - Elena F Koslover
- Department of Physics, University of California, San Diego, San Diego, California
| | - Edgar Gutierrez
- Department of Physics, University of California, San Diego, San Diego, California
| | - Alexander Groisman
- Department of Physics, University of California, San Diego, San Diego, California
| | - Julie A Theriot
- Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington.
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31
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Newton R, Amstutz J, Patrick JE. Biofilm formation by Bacillus subtilis is altered in the presence of pesticides. Access Microbiol 2021; 2:acmi000175. [PMID: 33490870 PMCID: PMC7818241 DOI: 10.1099/acmi.0.000175] [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: 03/05/2020] [Accepted: 10/21/2020] [Indexed: 11/18/2022] Open
Abstract
Bacillus subtilis uses swarming motility and biofilm formation to colonize plant roots and form a symbiotic relationship with the plant. Swarming motility and biofilm formation are group behaviours made possible through the use of chemical messengers. We investigated whether chemicals applied to plants would interfere with the swarming motility and biofilm-forming capabilities of B. subtilis in vitro. We hypothesized that pesticides could act as chemical signals that influence bacterial behaviour; this research investigates whether swarming motility and biofilm formation of B. subtilis is affected by the application of the commercial pesticides with the active ingredients of neem oil, pyrethrin, or malathion. The results indicate that all three pesticides inhibit biofilm formation. Swarming motility is not affected by the application of pyrethrin or malathion, but swarm expansion and pattern is altered in the presence of neem oil. Future studies to investigate the mechanism by which pesticides alter biofilm formation are warranted.
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Affiliation(s)
- Rachael Newton
- Truman State University, 100 E Normal Kirksville, MO 63501, USA
| | | | - Joyce E Patrick
- Truman State University, 100 E Normal Kirksville, MO 63501, USA
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32
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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.
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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
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33
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Holland MA, Budday S, Li G, Shen D, Goriely A, Kuhl E. Folding drives cortical thickness variations. THE EUROPEAN PHYSICAL JOURNAL. SPECIAL TOPICS 2020; 229:2757-2778. [PMID: 37275766 PMCID: PMC10237175 DOI: 10.1140/epjst/e2020-000001-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/27/2020] [Indexed: 06/07/2023]
Abstract
The cortical thickness is a characteristic biomarker for a wide variety of neurological disorders. While the structural organization of the cerebral cortex is tightly regulated and evolutionarily preserved, its thickness varies widely between 1.5 and 4.5 mm across the healthy adult human brain. It remains unclear whether these thickness variations are a cause or consequence of cortical development. Recent studies suggest that cortical thickness variations are primarily a result of genetic effects. Previous studies showed that a simple homogeneous bilayered system with a growing layer on an elastic substrate undergoes a unique symmetry breaking into a spatially heterogeneous system with discrete gyri and sulci. Here, we expand on that work to explore the evolution of cortical thickness variations over time to support our finding that cortical pattern formation and thickness variations can be explained - at least in part - by the physical forces that emerge during cortical folding. Strikingly, as growth progresses, the developing gyri universally thicken and the sulci thin, even in the complete absence of regional information. Using magnetic resonance images, we demonstrate that these naturally emerging thickness variations agree with the cortical folding pattern in n = 9 healthy adult human brains, in n = 564 healthy human brains ages 7-64, and in n = 73 infant brains scanned at birth, and at ages one and two. Additionally, we show that cortical organoids develop similar patterns throughout their growth. Our results suggest that genetic, geometric, and physical events during brain development are closely interrelated. Understanding regional and temporal variations in cortical thickness can provide insight into the evolution and causative factors of neurological disorders, inform the diagnosis of neurological conditions, and assess the efficacy of treatment options.
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Affiliation(s)
- Maria A. Holland
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Silvia Budday
- Department of Mechanical Engineering, Friedrich-Alexander University, 91058 Erlangen, Germany
| | - Gang Li
- Department of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Dinggang Shen
- Department of Radiology and Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alain Goriely
- Mathematical Institute, University of Oxford, Oxford, UK
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA
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34
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Cont A, Rossy T, Al-Mayyah Z, Persat A. Biofilms deform soft surfaces and disrupt epithelia. eLife 2020; 9:56533. [PMID: 33025904 PMCID: PMC7556879 DOI: 10.7554/elife.56533] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 08/23/2020] [Indexed: 12/12/2022] Open
Abstract
During chronic infections and in microbiota, bacteria predominantly colonize their hosts as multicellular structures called biofilms. A common assumption is that biofilms exclusively interact with their hosts biochemically. However, the contributions of mechanics, while being central to the process of biofilm formation, have been overlooked as a factor influencing host physiology. Specifically, how biofilms form on soft, tissue-like materials remains unknown. Here, we show that biofilms of the pathogens Vibrio cholerae and Pseudomonas aeruginosa can induce large deformations of soft synthetic hydrogels. Biofilms buildup internal mechanical stress as single cells grow within the elastic matrix. By combining mechanical measurements and mutations in matrix components, we found that biofilms deform by buckling, and that adhesion transmits these forces to their substrates. Finally, we demonstrate that V. cholerae biofilms can generate sufficient mechanical stress to deform and even disrupt soft epithelial cell monolayers, suggesting a mechanical mode of infection.
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Affiliation(s)
- Alice Cont
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Tamara Rossy
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Zainebe Al-Mayyah
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Alexandre Persat
- Institute of Bioengineering and Global Health Institute, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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35
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Pandit S, Fazilati M, Gaska K, Derouiche A, Nypelö T, Mijakovic I, Kádár R. The Exo-Polysaccharide Component of Extracellular Matrix is Essential for the Viscoelastic Properties of Bacillus subtilis Biofilms. Int J Mol Sci 2020; 21:ijms21186755. [PMID: 32942569 PMCID: PMC7555405 DOI: 10.3390/ijms21186755] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/17/2022] Open
Abstract
Bacteria are known to form biofilms on various surfaces. Biofilms are multicellular aggregates, held together by an extracellular matrix, which is composed of biological polymers. Three principal components of the biofilm matrix are exopolysaccharides (EPS), proteins, and nucleic acids. The biofilm matrix is essential for biofilms to remain organized under mechanical stress. Thanks to their polymeric nature, biofilms exhibit both elastic and viscous mechanical characteristics; therefore, an accurate mechanical description needs to take into account their viscoelastic nature. Their viscoelastic properties, including during their growth dynamics, are crucial for biofilm survival in many environments, particularly during infection processes. How changes in the composition of the biofilm matrix affect viscoelasticity has not been thoroughly investigated. In this study, we used interfacial rheology to study the contribution of the EPS component of the matrix to viscoelasticity of Bacillus subtilis biofilms. Two strategies were used to specifically deplete the EPS component of the biofilm matrix, namely (i) treatment with sub-lethal doses of vitamin C and (ii) seamless inactivation of the eps operon responsible for biosynthesis of the EPS. In both cases, the obtained results suggest that the EPS component of the matrix is essential for maintaining the viscoelastic properties of bacterial biofilms during their growth. If the EPS component of the matrix is depleted, the mechanical stability of biofilms is compromised and the biofilms become more susceptible to eradication by mechanical stress.
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Affiliation(s)
- Santosh Pandit
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Göteborg, Sweden; (S.P.); (A.D.)
| | - Mina Fazilati
- Department of Industrial and Materials Science, Chalmers University of Technology, 412 96 Göteborg, Sweden;
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden;
| | - Karolina Gaska
- Department of Aerospace Engineering, University of Bristol, Bristol BS8 1TR, UK;
| | - Abderahmane Derouiche
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Göteborg, Sweden; (S.P.); (A.D.)
| | - Tiina Nypelö
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Göteborg, Sweden;
- Wallenberg Wood Science Center, Chalmers, 412 96 Göteborg, Sweden
| | - Ivan Mijakovic
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96 Göteborg, Sweden; (S.P.); (A.D.)
- Correspondence: (I.M.); (R.K.)
| | - Roland Kádár
- Department of Industrial and Materials Science, Chalmers University of Technology, 412 96 Göteborg, Sweden;
- Wallenberg Wood Science Center, Chalmers, 412 96 Göteborg, Sweden
- Correspondence: (I.M.); (R.K.)
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36
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Ido N, Lybman A, Hayet S, Azulay DN, Ghrayeb M, Liddawieh S, Chai L. Bacillus subtilis biofilms characterized as hydrogels. Insights on water uptake and water binding in biofilms. SOFT MATTER 2020; 16:6180-6190. [PMID: 32567645 DOI: 10.1039/d0sm00581a] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biofilms are aggregates of cells that form on surfaces or at the air-water interface. Cells in a biofilm are encased in a self-secreted extracellular matrix (ECM) that provides them with mechanical stability and protects them from antibiotic treatment. From a soft matter perspective, biofilms are regarded as colloidal hydrogels, with the cells playing the role of colloids and the ECM compared with a cross-linked hydrogel. Here, we examined whole biofilms of the soil bacterium Bacillus subtilis utilizing methods that are commonly used to characterize hydrogels in order to evaluate the uptake of water and the water properties in the biofilms. Specifically, we studied wild-type as well ECM mutants, lacking the protein TasA and the exopolysaccharide (EPS). We characterized the morphology and mesh size of biofilms using electron microscopy, studied the state of water in the biofilms using differential scanning calorimetry, and finally, we tested the biofilms' swelling properties. Our study revealed that Bacillus subtilis biofilms resemble cross-linked hydrogels in their morphology and swelling properties. Strikingly, we discovered that all the water in biofilms was bound water and there was no free water in the biofilms. Water binding was mostly related with the presence of solutes and much less so with the major ECM components, the protein TasA and the polysaccharide EPS. This study sheds light on water uptake and water binding in biofilms and it is therefore important for the understanding of solute transport and enzymatic function inside biofilms.
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Affiliation(s)
- Nir Ido
- The Israel Institute for Biological Research, Ness Ziona, Israel
| | - Amir Lybman
- The Israel Institute for Biological Research, Ness Ziona, Israel
| | - Shahar Hayet
- Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, Jerusalem 91904, Israel.
| | - David N Azulay
- Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, Jerusalem 91904, Israel.
| | - Mnar Ghrayeb
- Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, Jerusalem 91904, Israel.
| | - Sajeda Liddawieh
- Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, Jerusalem 91904, Israel.
| | - Liraz Chai
- Institute of Chemistry, The Hebrew University of Jerusalem and The Center for Nanoscience and Nanotechnology, Edmond J. Safra Campus, Jerusalem 91904, Israel.
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Tan Y, Hu B, Song J, Chu Z, Wu W. Bioinspired Multiscale Wrinkling Patterns on Curved Substrates: An Overview. NANO-MICRO LETTERS 2020; 12:101. [PMID: 34138101 PMCID: PMC7770713 DOI: 10.1007/s40820-020-00436-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/14/2020] [Indexed: 05/23/2023]
Abstract
The surface wrinkling of biological tissues is ubiquitous in nature. Accumulating evidence suggests that the mechanical force plays a significant role in shaping the biological morphologies. Controlled wrinkling has been demonstrated to be able to spontaneously form rich multiscale patterns, on either planar or curved surfaces. The surface wrinkling on planar substrates has been investigated thoroughly during the past decades. However, most wrinkling morphologies in nature are based on the curved biological surfaces and the research of controllable patterning on curved substrates still remains weak. The study of wrinkling on curved substrates is critical for understanding the biological growth, developing three-dimensional (3D) or four-dimensional (4D) fabrication techniques, and creating novel topographic patterns. In this review, fundamental wrinkling mechanics and recent advances in both fabrications and applications of the wrinkling patterns on curved substrates are summarized. The mechanics behind the wrinkles is compared between the planar and the curved cases. Beyond the film thickness, modulus ratio, and mismatch strain, the substrate curvature is one more significant parameter controlling the surface wrinkling. Curved substrates can be both solid and hollow with various 3D geometries across multiple length scales. Up to date, the wrinkling morphologies on solid/hollow core-shell spheres and cylinders have been simulated and selectively produced. Emerging applications of the curved topographic patterns have been found in smart wetting surfaces, cell culture interfaces, healthcare materials, and actuators, which may accelerate the development of artificial organs, stimuli-responsive devices, and micro/nano fabrications with higher dimensions.
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Affiliation(s)
- Yinlong Tan
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, 410073, People's Republic of China
| | - Biru Hu
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, 410073, People's Republic of China
| | - Jia Song
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, 410073, People's Republic of China
| | - Zengyong Chu
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, 410073, People's Republic of China.
| | - Wenjian Wu
- College of Liberal Arts and Science, National University of Defense Technology, Changsha, 410073, People's Republic of China.
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38
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Galdino RV, Benevides CA, Tenório RP. Diffusion maps of Bacillus subtilis biofilms via magnetic resonance imaging highlight a complex network of channels. Colloids Surf B Biointerfaces 2020; 190:110905. [PMID: 32143011 DOI: 10.1016/j.colsurfb.2020.110905] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 10/24/2022]
Abstract
Bacillus subtilis microorganism when cultivated under chemically-defined conditions developed a biofilm with an unusual pattern of wrinkles on the surface. Some questions were raised about whether there was a special function of these wrinkles for the biofilm itself, since they resembled microchannels that could be involved in the transport of nutrients within the biofilm. Since the diffusion is the main mechanism for nutrient transport to biofilm from the medium, the role of these wrinkled structures in the whole diffusion within the biofilm was investigated using diffusion-weighted magnetic resonance imaging (DW-MRI). Data from these diffusion images was used to generate 2D diffusion maps which highlighted the striking channel features of the biofilm surface. The diffusion maps revealed a network of interconnected channels, with self-diffusion coefficients higher in the microchannels than in other regions of the biofilms. Polar plots made from 2D diffusion maps obtained from the plane of the biofilm show an anisotropy of the diffusion inside the microchannels, with the diffusion higher when along the principal direction of the microchannels. These results agree with the model, that the buckling of the biofilm surface from the B. subtilis creates microchannels that can enhance diffusion throughout the biofilm.
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Affiliation(s)
- Ramon V Galdino
- Centro Regional de Ciências Nucleares do Nordeste, Comissão Nacional de Energia Nuclear, Av. Prof. Luiz Freire, 200, Cidade Universitária, 50740-545 Recife, Pernambuco, Brazil; Agência Pernambucana de Vigilância Sanitária, Secretaria Estadual de Saúde de Pernambuco, Praça Osvaldo Cruz, s/n, Boa Vista, 50050-210 Recife, Pernambuco, Brazil
| | - Clayton A Benevides
- Centro Regional de Ciências Nucleares do Nordeste, Comissão Nacional de Energia Nuclear, Av. Prof. Luiz Freire, 200, Cidade Universitária, 50740-545 Recife, Pernambuco, Brazil
| | - Rômulo P Tenório
- Centro Regional de Ciências Nucleares do Nordeste, Comissão Nacional de Energia Nuclear, Av. Prof. Luiz Freire, 200, Cidade Universitária, 50740-545 Recife, Pernambuco, Brazil.
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39
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Xiong L, Cao Y, Cooper R, Rappel WJ, Hasty J, Tsimring L. Flower-like patterns in multi-species bacterial colonies. eLife 2020; 9:e48885. [PMID: 31933477 PMCID: PMC6959979 DOI: 10.7554/elife.48885] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 11/16/2019] [Indexed: 11/13/2022] Open
Abstract
Diverse interactions among species within bacterial colonies lead to intricate spatiotemporal dynamics, which can affect their growth and survival. Here, we describe the emergence of complex structures in a colony grown from mixtures of motile and non-motile bacterial species on a soft agar surface. Time-lapse imaging shows that non-motile bacteria 'hitchhike' on the motile bacteria as the latter migrate outward. The non-motile bacteria accumulate at the boundary of the colony and trigger an instability that leaves behind striking flower-like patterns. The mechanism of the front instability governing this pattern formation is elucidated by a mathematical model for the frictional motion of the colony interface, with friction depending on the local concentration of the non-motile species. A more elaborate two-dimensional phase-field model that explicitly accounts for the interplay between growth, mechanical stress from the motile species, and friction provided by the non-motile species, fully reproduces the observed flower-like patterns.
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Affiliation(s)
- Liyang Xiong
- Department of PhysicsUniversity of California, San DiegoLa JollaUnited States
- BioCircuits InstituteUniversity of California, San DiegoLa JollaUnited States
| | - Yuansheng Cao
- Department of PhysicsUniversity of California, San DiegoLa JollaUnited States
| | - Robert Cooper
- BioCircuits InstituteUniversity of California, San DiegoLa JollaUnited States
| | - Wouter-Jan Rappel
- Department of PhysicsUniversity of California, San DiegoLa JollaUnited States
| | - Jeff Hasty
- BioCircuits InstituteUniversity of California, San DiegoLa JollaUnited States
- The San Diego Center for Systems BiologySan DiegoUnited States
- Molecular Biology Section, Division of Biological SciencesUniversity of California, San DiegoLa JollaUnited States
- Department of BioengineeringUniversity of California, San DiegoLa JollaUnited States
| | - Lev Tsimring
- BioCircuits InstituteUniversity of California, San DiegoLa JollaUnited States
- The San Diego Center for Systems BiologySan DiegoUnited States
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40
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Gingichashvili S, Duanis-Assaf D, Shemesh M, Featherstone JDB, Feuerstein O, Steinberg D. The Adaptive Morphology of Bacillus subtilis Biofilms: A Defense Mechanism against Bacterial Starvation. Microorganisms 2019; 8:microorganisms8010062. [PMID: 31905847 PMCID: PMC7023499 DOI: 10.3390/microorganisms8010062] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Revised: 12/25/2019] [Accepted: 12/28/2019] [Indexed: 12/20/2022] Open
Abstract
Biofilms are commonly defined as accumulations of microbes, embedded in a self-secreted, polysaccharide-rich extra-cellular matrix. This study aimed to characterize specific morphological changes that occur in Bacillus subtilis biofilms under nutrient-limiting growth conditions. Under varying levels of nutrient depletion, colony-type biofilms were found to exhibit different rates of spatial expansion and green fluorescent protein production. Specifically, colony-type biofilms grown on media with decreased lysogeny broth content exhibited increased spatial expansion and more stable GFP production over the entire growth period. By modeling the surface morphology of colony-type biofilms using confocal and multiphoton microscopy, we analyzed the appearance of distinctive folds or "wrinkles" that form as a result of lysogeny broth content reduction in the solid agar growth media. When subjected to varying nutritional conditions, the channel-like folds were shown to alter their morphology; growth on nutrient-depleted media was found to trigger the formation of large and straight wrinkles connecting the colony core to its periphery. To test a possible functional role of the formed channels, a fluorescent analogue of glucose was used to demonstrate preferential native uptake of the molecules into the channels' interiors which supports their possible role in the transport of molecules throughout biofilm structures.
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Affiliation(s)
- Sarah Gingichashvili
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, Hebrew University-Hadassah, Jerusalem 9112001, Israel; (D.D.-A.); (D.S.)
- Faculty of Dental Medicine, Department of Prosthodontics, Hebrew University-Hadassah, Jerusalem 9112001, Israel;
- Correspondence:
| | - Danielle Duanis-Assaf
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, Hebrew University-Hadassah, Jerusalem 9112001, Israel; (D.D.-A.); (D.S.)
- Department of Food Quality and Safety, Institute for Postharvest Technology and Food Sciences, Agricultural Research Organization (ARO), The Volcani Center, Rishon LeZion 7528809, Israel;
| | - Moshe Shemesh
- Department of Food Quality and Safety, Institute for Postharvest Technology and Food Sciences, Agricultural Research Organization (ARO), The Volcani Center, Rishon LeZion 7528809, Israel;
| | | | - Osnat Feuerstein
- Faculty of Dental Medicine, Department of Prosthodontics, Hebrew University-Hadassah, Jerusalem 9112001, Israel;
| | - Doron Steinberg
- Biofilm Research Laboratory, Institute of Dental Sciences, Faculty of Dental Medicine, Hebrew University-Hadassah, Jerusalem 9112001, Israel; (D.D.-A.); (D.S.)
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41
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A Dual-Species Biofilm with Emergent Mechanical and Protective Properties. J Bacteriol 2019; 201:JB.00670-18. [PMID: 30833350 DOI: 10.1128/jb.00670-18] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 02/23/2019] [Indexed: 12/14/2022] Open
Abstract
Many microbes coexist within biofilms, or multispecies communities of cells encased in an extracellular matrix. However, little is known about the microbe-microbe interactions relevant for creating these structures. In this study, we explored a striking dual-species biofilm between Bacillus subtilis and Pantoea agglomerans that exhibited characteristics that were not predictable from previous work examining monoculture biofilms. Coculture wrinkle formation required a P. agglomerans exopolysaccharide as well as the B. subtilis amyloid-like protein TasA. Unexpectedly, other B. subtilis matrix components essential for monoculture biofilm formation were not necessary for coculture wrinkling (e.g., the exopolysaccharide EPS, the hydrophobin BslA, and cell chaining). In addition, B. subtilis cell chaining prevented coculture wrinkling, even though chaining was previously associated with more robust monoculture biofilms. We also observed that increasing the relative proportion of P. agglomerans (which forms completely featureless monoculture colonies) increased coculture wrinkling. Using microscopy and rheology, we observed that these two bacteria assemble into an organized layered structure that reflects the physical properties of both monocultures. This partitioning into distinct regions negatively affected the survival of P. agglomerans while also serving as a protective mechanism in the presence of antibiotic stress. Taken together, these data indicate that studying cocultures is a productive avenue to identify novel mechanisms that drive the formation of structured microbial communities.IMPORTANCE In the environment, many microbes form biofilms. However, the interspecies interactions underlying bacterial coexistence within these biofilms remain understudied. Here, we mimic environmentally relevant biofilms by studying a dual-species biofilm formed between Bacillus subtilis and Pantoea agglomerans and subjecting the coculture to chemical and physical stressors that it may experience in the natural world. We determined that both bacteria contribute structural elements to the coculture, which is reflected in its overall viscoelastic behavior. Existence within the coculture can be either beneficial or detrimental depending on the context. Many of the features and determinants of the coculture biofilm appear distinct from those identified in monoculture biofilm studies, highlighting the importance of characterizing multispecies consortia to understand naturally occurring bacterial interactions.
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42
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Forth J, Kim PY, Xie G, Liu X, Helms BA, Russell TP. Building Reconfigurable Devices Using Complex Liquid-Fluid Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1806370. [PMID: 30828869 DOI: 10.1002/adma.201806370] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/12/2018] [Indexed: 06/09/2023]
Abstract
Liquid-fluid interfaces provide a platform both for structuring liquids into complex shapes and assembling dimensionally confined, functional nanomaterials. Historically, attention in this area has focused on simple emulsions and foams, in which surface-active materials such as surfactants or colloids stabilize structures against coalescence and alter the mechanical properties of the interface. In recent decades, however, a growing body of work has begun to demonstrate the full potential of the assembly of nanomaterials at liquid-fluid interfaces to generate functionally advanced, biomimetic systems. Here, a broad overview is given, from fundamentals to applications, of the use of liquid-fluid interfaces to generate complex, all-liquid devices with a myriad of potential applications.
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Affiliation(s)
- Joe Forth
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Paul Y Kim
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Ganhua Xie
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
- Polymer Science and Engineering Department, University of Massachusetts, 120 Governors Drive, Conte Center for Polymer Research, Amherst, MA, 01003, USA
| | - Xubo Liu
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
| | - Brett A Helms
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Thomas P Russell
- Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
- Polymer Science and Engineering Department, University of Massachusetts, 120 Governors Drive, Conte Center for Polymer Research, Amherst, MA, 01003, USA
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China
- WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba, Sendai, 980-8577, Japan
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43
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Jeckel H, Matthey N, Drescher K. Common concepts for bacterial collectives. eLife 2019; 8:e47019. [PMID: 31038120 PMCID: PMC6491033 DOI: 10.7554/elife.47019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 04/17/2019] [Indexed: 11/30/2022] Open
Abstract
The expansion of bacterial swarms and the spreading of biofilms can be described by a unified biophysical theory that involves both active and passive processes.
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Affiliation(s)
- Hannah Jeckel
- Max Planck Institute for Terrestrial MicrobiologyMarburgGermany
- Department of PhysicsPhilipps-Universität MarburgMarburgGermany
| | - Noémie Matthey
- School of Life SciencesSwiss Federal Institute of Technology LausanneLausanneSwitzerland
| | - Knut Drescher
- Max Planck Institute for Terrestrial MicrobiologyMarburgGermany
- Department of PhysicsPhilipps-Universität MarburgMarburgGermany
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44
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Hartmann R, Singh PK, Pearce P, Mok R, Song B, Díaz-Pascual F, Dunkel J, Drescher K. Emergence of three-dimensional order and structure in growing biofilms. NATURE PHYSICS 2019; 15:251-256. [PMID: 31156716 PMCID: PMC6544526 DOI: 10.1038/s41567-018-0356-9] [Citation(s) in RCA: 156] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 10/19/2018] [Indexed: 05/22/2023]
Abstract
Surface-attached bacterial biofilms are self-replicating active liquid crystals and the dominant form of bacterial life on earth (1-4). In conventional liquid crystals and solid-state materials, the interaction potentials between the molecules that comprise the system determine the material properties. However, for growth-active biofilms it is unclear whether potential-based descriptions can account for the experimentally observed morphologies, and which potentials would be relevant. Here, we overcame previous limitations of single-cell imaging techniques (5,6) to reconstruct and track all individual cells inside growing three-dimensional (3D) biofilms with up to 10,000 individuals. Based on these data, we identify, constrain, and provide a microscopic basis for an effective cell-cell interaction potential, which captures and predicts the growth dynamics, emergent architecture, and local liquid crystalline order of Vibrio cholerae biofilms. Furthermore, we show how external fluid flows control the microscopic structure and 3D morphology of biofilms. Our analysis implies that local cellular order and global biofilm architecture in these active bacterial communities can arise from mechanical cell-cell interactions, which cells can modulate by regulating the production of particular matrix components. These results establish an experimentally validated foundation for improved continuum theories of active matter and thereby contribute to solving the important problem of controlling biofilm growth.
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Affiliation(s)
- Raimo Hartmann
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg,
DE
- Department of Physics, Philipps-Universität Marburg, 35032
Marburg, DE
| | - Praveen K. Singh
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg,
DE
| | - Philip Pearce
- Department of Mathematics, Massachusetts Institute of Technology,
Cambridge, MA 02139, USA
| | - Rachel Mok
- Department of Mathematics, Massachusetts Institute of Technology,
Cambridge, MA 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of
Technology, Cambridge, MA 02139, USA
| | - Boya Song
- Department of Mathematics, Massachusetts Institute of Technology,
Cambridge, MA 02139, USA
| | | | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology,
Cambridge, MA 02139, USA
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg,
DE
- Department of Physics, Philipps-Universität Marburg, 35032
Marburg, DE
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45
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Srinivasan S, Vladescu ID, Koehler SA, Wang X, Mani M, Rubinstein SM. Matrix Production and Sporulation in Bacillus subtilis Biofilms Localize to Propagating Wave Fronts. Biophys J 2019; 114:1490-1498. [PMID: 29590605 DOI: 10.1016/j.bpj.2018.02.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 12/31/2022] Open
Abstract
Bacterial biofilms are surface-attached microbial communities encased in self-produced extracellular polymeric substances. Here we demonstrate that during the development of Bacillus subtilis biofilms, matrix production is localized to an annular front propagating at the periphery and sporulation to a second front at a fixed distance at the interior. We show that within these fronts, cells switch off matrix production and transition to sporulation after a set time delay of ∼100 min. Correlation analyses of fluctuations in fluorescence reporter activity reveal that the fronts emerge from a pair of gene-expression waves of matrix production and sporulation. The localized expression waves travel across cells that are immobilized in the biofilm matrix in contrast to active cell migration or horizontal colony spreading. Our results suggest that front propagation arises via a local developmental program occurring at the level of individual bacterial cells, likely driven by nutrient depletion and metabolic by-product accumulation. A single-length scale and timescale couples the spatiotemporal propagation of both fronts throughout development. As a result, gene expression patterns within the advancing fronts collapse to self-similar expression profiles. Our findings highlight the key role of the localized cellular developmental program associated with the propagating front in describing biofilm growth.
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Affiliation(s)
- Siddarth Srinivasan
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts.
| | - Ioana D Vladescu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Stephan A Koehler
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Xiaoling Wang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, China
| | - Madhav Mani
- Department of Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, Illinois
| | - Shmuel M Rubinstein
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; School of Engineering and Applied Sciences and Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, Massachusetts.
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46
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Gordon VD, Wang L. Bacterial mechanosensing: the force will be with you, always. J Cell Sci 2019; 132:132/7/jcs227694. [PMID: 30944157 DOI: 10.1242/jcs.227694] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Whether bacteria are in the planktonic state, free-swimming or free-floating in liquid, or in the biofilm state, sessile on surfaces, they are always subject to mechanical forces. The long, successful evolutionary history of bacteria implies that they are capable of adapting to varied mechanical forces, and probably even actively respond to mechanical cues in their changing environments. However, the sensing of mechanical cues by bacteria, or bacterial mechanosensing, has been under-investigated. This leaves the mechanisms underlying how bacteria perceive and respond to mechanical cues largely unknown. In this Review, we first examine the surface-associated behavior of bacteria, outline the clear evidence for bacterial mechanosensing and summarize the role of flagella, type-IV pili, and envelope proteins as potential mechanosensors, before presenting indirect evidence for mechanosensing in bacteria. The general themes underlying bacterial mechanosensing that we highlight here may provide a framework for future research.
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Affiliation(s)
- Vernita D Gordon
- Department of Physics and Center for Nonlinear Dynamics, The University of Texas at Austin, Austin, TX 78712, USA .,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
| | - Liyun Wang
- Department of Physics and Center for Nonlinear Dynamics, The University of Texas at Austin, Austin, TX 78712, USA
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47
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Corte L, Casagrande Pierantoni D, Tascini C, Roscini L, Cardinali G. Biofilm Specific Activity: A Measure to Quantify Microbial Biofilm. Microorganisms 2019; 7:microorganisms7030073. [PMID: 30866438 PMCID: PMC6463164 DOI: 10.3390/microorganisms7030073] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 02/23/2019] [Accepted: 03/04/2019] [Indexed: 12/21/2022] Open
Abstract
Microbes growing onto solid surfaces form complex 3-D biofilm structures characterized by the production of extracellular polymeric compounds and an increased resistance to drugs. The quantification of biofilm relays currently on a number of different approaches and techniques, often leading to different evaluations of the ability to form biofilms of the studied microbial strains. Measures of biofilm biomass were carried out with crystal violet (CV) and a direct reading at 405 nm, whereas the activity was assessed with the XTT ((2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) method. The strains of four pathogenic species of the genus Candida (C. albicans, C. glabrata, C. parapsilosis and C. tropicalis) and of Staphylococcus aureus were employed to determine the effective relatedness among techniques and the specific activity of the biofilm, as a ratio between the XTT and the CV outcomes. Since the ability to form biomass and to be metabolically active are not highly related, their simultaneous use allowed for a categorization of the strains. This classification is putatively amenable of further study by comparing the biofilm type and the medical behavior of the strains.
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Affiliation(s)
- Laura Corte
- Department of Pharmaceutical Sciences⁻Microbiology, University of Perugia, 06123 Perugia, Italy.
| | | | - Carlo Tascini
- First Division of Infectious Diseases, Cotugno Hospital, 80181 Naples, Italy.
| | - Luca Roscini
- CEMIN-Excellence Research Center, University of Perugia, 06123 Perugia, Italy.
| | - Gianluigi Cardinali
- Department of Pharmaceutical Sciences⁻Microbiology, University of Perugia, 06123 Perugia, Italy.
- CEMIN-Excellence Research Center, University of Perugia, 06123 Perugia, Italy.
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48
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Circular pellicles formed by Pseudomonas alkylphenolica KL28 are a sophisticated architecture principally designed by matrix substance. J Microbiol 2018; 56:790-797. [PMID: 30353464 DOI: 10.1007/s12275-018-8252-7] [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: 05/08/2018] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 10/28/2022]
Abstract
The colonization of liquid surfaces as floating biofilms or pellicles is a bacterial adaptation to optimally occupy the airliquid (A-L) niche. In aerobic heterotrophs, pellicle formation is beneficial for the utilization of O2 and nonpolar organic compounds. Pseudomonas alkylphenolica KL28, an alkylphenol degrader, forms flat circular pellicles that are 0.3-0.5 mm in diameter. In this study, we first monitored the pellicle developmental patterns of multicellular organization from the initial settlement stage. The pellicles developed by clonal growth and mutants for flagella and pilus formation established normal pellicles. In contrast, the mutants of an epm gene cluster for biosynthesis of alginate-like polymer were incompetent in cell alignment for initial two-dimensional (2D) pellicle growth, suggesting the role of the Epm polymer as a structural scaffold for pellicle biofilms. Microscopic observation revealed that the initial 2D growth transited to multilayers by an accumulated self-produced extracellular polymeric substance that may exert a constraint force. Electron microscopy and confocal laser scanning microscopy revealed that the fully matured pellicle structures were densly packed with matrix-encased cells displaying distinct arrangements. The cells on the surface of the pellicle were relatively flat, and those inside were longitudinally cross-packed. The extracellular polysaccharide stained by Congo red was denser on the pellicle rim and a thin film was observed in the open spaces, indicative of its role in pellicle flotation. Our results demonstrate that P. alkylphenolica KL28 coordinately dictates the cell arrangements of pellicle biofilms by the controlled growth of constituent cells that accumulate extracellular polymeric substances.
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Towards standardized mechanical characterization of microbial biofilms: analysis and critical review. NPJ Biofilms Microbiomes 2018; 4:17. [PMID: 30131867 PMCID: PMC6102240 DOI: 10.1038/s41522-018-0062-5] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 02/05/2023] Open
Abstract
Developing reliable anti-biofilm strategies or efficient biofilm-based bioprocesses strongly depends on having a clear understanding of the mechanisms underlying biofilm development, and knowledge of the relevant mechanical parameters describing microbial biofilm behavior. Many varied mechanical testing methods are available to assess these parameters. The mechanical properties thus identified can then be used to compare protocols such as antibiotic screening. However, the lack of standardization in both mechanical testing and the associated identification methods for a given microbiological goal remains a blind spot in the biofilm community. The pursuit of standardization is problematic, as biofilms are living structures, i.e., both complex and dynamic. Here, we review the main available methods for characterizing the mechanical properties of biofilms through the lens of the relationship linking experimental testing to the identification of mechanical parameters. We propose guidelines for characterizing biofilms according to microbiological objectives that will help the reader choose an appropriate test and a relevant identification method for measuring any given mechanical parameter. The use of a common methodology for the mechanical characterization of biofilms will enable reliable analysis and comparison of microbiological protocols needed for improvement of engineering process and screening.
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WANG XIAOLING, ZHAO KAI, ZHAO HUI. FINITE ELEMENT SIMULATION OF BIOFILM VISCOELASTIC BEHAVIOR UNDER VARIOUS LOADINGS. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519418500562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Experiments showed that biofilms exhibit viscoelasticity under both displacement and stress loadings, irrespective of pellicles at liquid–air interface or biofilms at solid–liquid interface. However, the general theoretical models are lacking inuniformly and quantitatively describing biofilms’ viscoelastic behavior under various loading conditions. We use the linear viscoelastic theory — Generalized Maxwell model to describe the viscoelastic mechanical properties of biofilms, and study the responses of biofilms under different loadings, including various strain/stress loading rates and cyclic loadings, by finite element method. The results can capture the typical viscoelastic characteristics of biofilms, such as creep, hysteresis, energy dissipation and loading rate-dependent behavior. Our work provides a simple viscoelastic model not only for bacterial biofilms but also for other biological materials.
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Affiliation(s)
- XIAOLING WANG
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
- School of Engineering and Applied Sciences, Harvard University, 02138 Cambridge MA, USA
| | - KAI ZHAO
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, P. R. China
| | - HUI ZHAO
- Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, No. 105, North Road of West 3rd Ring Road, Haidian District, Beijing 100048, China
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