1
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Dhar T, Saintillan D. Active transport of a passive colloid in a bath of run-and-tumble particles. Sci Rep 2024; 14:11844. [PMID: 38783044 PMCID: PMC11116446 DOI: 10.1038/s41598-024-62396-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024] Open
Abstract
The dispersion of a passive colloid immersed in a bath of non-interacting and non-Brownian run-and-tumble microswimmers in two dimensions is analyzed using stochastic simulations and an asymptotic theory, both based on a minimal model of swimmer-colloid collisions characterized solely by frictionless steric interactions. We estimate the effective long-time diffusivity D of the suspended colloid resulting from its interaction with the active bath, and elucidate its dependence on the level of activity (persistence length of swimmer trajectories), the mobility ratio of the colloid to a swimmer, and the number density of swimmers in the bath. We also propose a semi-analytical model for the colloid diffusivity in terms of the variance and correlation time of the net fluctuating active force on the colloid resulting from swimmer collisions. Quantitative agreement is found between numerical simulations and analytical results in the experimentally-relevant regime of low swimmer density, low mobility ratio, and high activity.
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Affiliation(s)
- Tanumoy Dhar
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - David Saintillan
- Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
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2
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Kurzthaler C, Zhao Y, Zhou N, Schwarz-Linek J, Devailly C, Arlt J, Huang JD, Poon WCK, Franosch T, Tailleur J, Martinez VA. Characterization and Control of the Run-and-Tumble Dynamics of Escherichia Coli. PHYSICAL REVIEW LETTERS 2024; 132:038302. [PMID: 38307047 DOI: 10.1103/physrevlett.132.038302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 11/29/2023] [Accepted: 12/01/2023] [Indexed: 02/04/2024]
Abstract
We characterize the full spatiotemporal gait of populations of swimming Escherichia coli using renewal processes to analyze the measurements of intermediate scattering functions. This allows us to demonstrate quantitatively how the persistence length of an engineered strain can be controlled by a chemical inducer and to report a controlled transition from perpetual tumbling to smooth swimming. For wild-type E. coli, we measure simultaneously the microscopic motility parameters and the large-scale effective diffusivity, hence quantitatively bridging for the first time small-scale directed swimming and macroscopic diffusion.
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Affiliation(s)
- Christina Kurzthaler
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
- Center for Systems Biology Dresden, 01307 Dresden, Germany
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria
| | - Yongfeng Zhao
- Center for Soft Condensed Matter Physics and Interdisciplinary Research and School of Physical Science and Technology, Soochow University, Suzhou 215006, China
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pok Fu Lam, Hong Kong, China
- Université de Paris, MSC, UMR 7057 CNRS, 75205 Paris, France
- School of Physics and Astronomy and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Nan Zhou
- ZJU-Hangzhou Global Scientific and Technological Innovation Center, Zhejiang University, Hangzhou 311200, China
| | - Jana Schwarz-Linek
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Clemence Devailly
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Jochen Arlt
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Jian-Dong Huang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Pok Fu Lam, Hong Kong, China
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Wilson C K Poon
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Thomas Franosch
- Institut für Theoretische Physik, Universität Innsbruck, Technikerstraße 21A, A-6020 Innsbruck, Austria
| | - Julien Tailleur
- Université de Paris, MSC, UMR 7057 CNRS, 75205 Paris, France
| | - Vincent A Martinez
- School of Physics and Astronomy, University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
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3
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Phan TV, Mattingly HH, Vo L, Marvin JS, Looger LL, Emonet T. Direct measurement of dynamic attractant gradients reveals breakdown of the Patlak-Keller-Segel chemotaxis model. Proc Natl Acad Sci U S A 2024; 121:e2309251121. [PMID: 38194458 PMCID: PMC10801886 DOI: 10.1073/pnas.2309251121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 12/07/2023] [Indexed: 01/11/2024] Open
Abstract
Chemotactic bacteria not only navigate chemical gradients, but also shape their environments by consuming and secreting attractants. Investigating how these processes influence the dynamics of bacterial populations has been challenging because of a lack of experimental methods for measuring spatial profiles of chemoattractants in real time. Here, we use a fluorescent sensor for aspartate to directly measure bacterially generated chemoattractant gradients during collective migration. Our measurements show that the standard Patlak-Keller-Segel model for collective chemotactic bacterial migration breaks down at high cell densities. To address this, we propose modifications to the model that consider the impact of cell density on bacterial chemotaxis and attractant consumption. With these changes, the model explains our experimental data across all cell densities, offering insight into chemotactic dynamics. Our findings highlight the significance of considering cell density effects on bacterial behavior, and the potential for fluorescent metabolite sensors to shed light on the complex emergent dynamics of bacterial communities.
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Affiliation(s)
- Trung V. Phan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT06511
- Quantitative Biology Institute, Yale University, New Haven, CT06511
| | | | - Lam Vo
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT06511
- Quantitative Biology Institute, Yale University, New Haven, CT06511
| | - Jonathan S. Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA20147
| | - Loren L. Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA20147
- HHMI, University of California, San Diego, CA92093
- Department of Neurosciences, University of California, San Diego, CA92093
| | - Thierry Emonet
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT06511
- Quantitative Biology Institute, Yale University, New Haven, CT06511
- Department of Physics, Yale University, New Haven, CT06511
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4
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Dinelli A, O'Byrne J, Curatolo A, Zhao Y, Sollich P, Tailleur J. Non-reciprocity across scales in active mixtures. Nat Commun 2023; 14:7035. [PMID: 37923724 PMCID: PMC10624904 DOI: 10.1038/s41467-023-42713-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2023] [Accepted: 10/19/2023] [Indexed: 11/06/2023] Open
Abstract
In active matter, particles typically experience mediated interactions, which are not constrained by Newton's third law and are therefore generically non-reciprocal. Non-reciprocity leads to a rich set of emerging behaviors that are hard to account for starting from the microscopic scale, due to the absence of a generic theoretical framework out of equilibrium. Here we consider bacterial mixtures that interact via mediated, non-reciprocal interactions (NRI) like quorum-sensing and chemotaxis. By explicitly relating microscopic and macroscopic dynamics, we show that, under conditions that we derive explicitly, non-reciprocity may fade upon coarse-graining, leading to large-scale equilibrium descriptions. In turn, this allows us to account quantitatively, and without fitting parameters, for the rich behaviors observed in microscopic simulations including phase separation, demixing, and multi-phase coexistence. We also derive the condition under which non-reciprocity survives coarse-graining, leading to a wealth of dynamical patterns. Again, our analytical approach allows us to predict the phase diagram of the system starting from its microscopic description. All in all, our work demonstrates that the fate of non-reciprocity across scales is a subtle and important question.
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Affiliation(s)
- Alberto Dinelli
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205, Paris, France
| | - Jérémy O'Byrne
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205, Paris, France
- Department of Applied Maths and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Rd, Cambridge, CB3 0WA, UK
| | - Agnese Curatolo
- John A. Paulson School of Engineering and Applied Sciences and Kavli Institute for Bionano Science and Technology, Harvard University, Cambridge, MA, 02138, USA
| | - Yongfeng Zhao
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, 215006, Suzhou, China
| | - Peter Sollich
- Institute for Theoretical Physics, Georg-August-Universität Göttingen, 37 077, Göttingen, Germany
- Department of Mathematics, King's College London, London, WC2R 2LS, UK
| | - Julien Tailleur
- Université Paris Cité, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205, Paris, France.
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
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5
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Wan KY. Active oscillations in microscale navigation. Anim Cogn 2023; 26:1837-1850. [PMID: 37665482 PMCID: PMC10769930 DOI: 10.1007/s10071-023-01819-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 07/27/2023] [Accepted: 08/12/2023] [Indexed: 09/05/2023]
Abstract
Living organisms routinely navigate their surroundings in search of better conditions, more food, or to avoid predators. Typically, animals do so by integrating sensory cues from the environment with their locomotor apparatuses. For single cells or small organisms that possess motility, fundamental physical constraints imposed by their small size have led to alternative navigation strategies that are specific to the microscopic world. Intriguingly, underlying these myriad exploratory behaviours or sensory functions is the onset of periodic activity at multiple scales, such as the undulations of cilia and flagella, the vibrations of hair cells, or the oscillatory shape modes of migrating neutrophils. Here, I explore oscillatory dynamics in basal microeukaryotes and hypothesize that these active oscillations play a critical role in enhancing the fidelity of adaptive sensorimotor integration.
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Affiliation(s)
- Kirsty Y Wan
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- Department of Mathematics and Statistics, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK.
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6
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Shoup D, Ursell T. Bacterial bioconvection confers context-dependent growth benefits and is robust under varying metabolic and genetic conditions. J Bacteriol 2023; 205:e0023223. [PMID: 37787517 PMCID: PMC10601612 DOI: 10.1128/jb.00232-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 08/17/2023] [Indexed: 10/04/2023] Open
Abstract
Microbes often respond to environmental cues by adopting collective behaviors-like biofilms or swarming-that benefit the population. During "bioconvection," microbes gather in dense groups and plume downward through fluid environments, driving flow and mixing on the scale of millions of cells. Though bioconvection was observed a century ago, the effects of differing physical and chemical inputs and its potential selective advantages for different species of microbes remain largely unexplored. In Bacillus subtilis, vertical oxygen gradients that originate from air-liquid interfaces create cell-density inversions that drive bioconvection. Here, we develop Escherichia coli as a complementary model for the study of bioconvection. In the context of a still fluid, we found that motile and chemotactic genotypes of both E. coli and B. subtilis bioconvect and show increased growth compared to immotile or non-chemotactic genotypes, whereas in a well-mixed fluid, there is no growth advantage to motility or chemotaxis. We found that fluid depth, cell concentration, and carbon availability affect the emergence and timing of bioconvective patterns. Also, whereas B. subtilis requires oxygen gradients to bioconvect, E. coli deficient in aerotaxis (Δaer) or energy-taxis (Δtsr) still bioconvects, as do cultures that lack an air-liquid interface. Thus, in two distantly related microbes, bioconvection may confer context-dependent growth benefits, and E. coli bioconvection is robustly elicited by multiple types of chemotaxis. These results greatly expand the set of physical and metabolic conditions in which this striking collective behavior can be expected and demonstrate its potential to be a generic force for behavioral selection across ecological contexts. IMPORTANCE Individual microorganisms frequently move in response to gradients in their fluid environment, with corresponding metabolic benefits. At a population level, such movements can create density variations in a fluid that couple to gravity and drive large-scale convection and mixing called bioconvection. In this work, we provide evidence that this collective behavior confers a selective benefit on two distantly related species of bacteria. We develop new methods for quantifying this behavior and show that bioconvection in Escherichia coli is surprisingly robust to changes in cell concentration, fluid depth, interface conditions, metabolic sensing, and carbon availability. These results greatly expand the set of conditions known to elicit this collective behavior and indicate its potential to be a selective pressure across ecological contexts.
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Affiliation(s)
- Daniel Shoup
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Rocky Mountain National Laboratories (NIH), Hamilton, Montana, USA
| | - Tristan Ursell
- Department of Physics, University of Oregon, Eugene, Oregon, USA
- Material Science Institute, Eugene, Oregon, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA
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7
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Phan TV, Mattingly HH, Vo L, Marvin JS, Looger LL, Emonet T. Direct measurement of dynamic attractant gradients reveals breakdown of the Patlak-Keller-Segel chemotaxis model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543315. [PMID: 37333331 PMCID: PMC10274659 DOI: 10.1101/2023.06.01.543315] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Chemotactic bacteria not only navigate chemical gradients, but also shape their environments by consuming and secreting attractants. Investigating how these processes influence the dynamics of bacterial populations has been challenging because of a lack of experimental methods for measuring spatial profiles of chemoattractants in real time. Here, we use a fluorescent sensor for aspartate to directly measure bacterially generated chemoattractant gradients during collective migration. Our measurements show that the standard Patlak-Keller-Segel model for collective chemotactic bacterial migration breaks down at high cell densities. To address this, we propose modifications to the model that consider the impact of cell density on bacterial chemotaxis and attractant consumption. With these changes, the model explains our experimental data across all cell densities, offering new insight into chemotactic dynamics. Our findings highlight the significance of considering cell density effects on bacterial behavior, and the potential for fluorescent metabolite sensors to shed light on the complex emergent dynamics of bacterial communities.
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Affiliation(s)
- Trung V. Phan
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT
| | | | - Lam Vo
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT
| | | | - Loren L. Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
- Howard Hughes Medical Institute, Department of Neurosciences, University of California, San Diego, La Jolla, CA
| | - Thierry Emonet
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT
- Quantitative Biology Institute, Yale University, New Haven, CT
- Department of Physics, Yale University, New Haven, CT
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8
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Arellano-Caicedo C, Ohlsson P, Bengtsson M, Beech JP, Hammer EC. Habitat complexity affects microbial growth in fractal maze. Curr Biol 2023; 33:1448-1458.e4. [PMID: 36933553 DOI: 10.1016/j.cub.2023.02.064] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 01/09/2023] [Accepted: 02/21/2023] [Indexed: 03/19/2023]
Abstract
The great variety of earth's microorganisms and their functions are attributed to the heterogeneity of their habitats, but our understanding of the impact of this heterogeneity on microbes is limited at the microscale. In this study, we tested how a gradient of spatial habitat complexity in the form of fractal mazes influenced the growth, substrate degradation, and interactions of the bacterial strain Pseudomonas putida and the fungal strain Coprinopsis cinerea. These strains responded in opposite ways: complex habitats strongly reduced fungal growth but, in contrast, increased the abundance of bacteria. Fungal hyphae did not reach far into the mazes and forced bacteria to grow in deeper regions. Bacterial substrate degradation strongly increased with habitat complexity, even more than bacterial biomass, up to an optimal depth, while the most remote parts of the mazes showed both decreased biomass and substrate degradation. These results suggest an increase in enzymatic activity in confined spaces, where areas may experience enhanced microbial activity and resource use efficiency. Very remote spaces showing a slower turnover of substrates illustrate a mechanism which may contribute to the long-term storage of organic matter in soils. We demonstrate here that the sole effect of spatial microstructures affects microbial growth and substrate degradation, leading to differences in local microscale spatial availability. These differences might add up to considerable changes in nutrient cycling at the macroscale, such as contributing to soil organic carbon storage.
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Affiliation(s)
| | - Pelle Ohlsson
- Department of Biomedical Engineering, Lund University, Ole Römers väg 3, 223 63 Lund, Sweden
| | - Martin Bengtsson
- Department of Biomedical Engineering, Lund University, Ole Römers väg 3, 223 63 Lund, Sweden
| | - Jason P Beech
- Division of Solid State Physics, Lund University, Sölvegatan 16, 223 63 Lund, Sweden
| | - Edith C Hammer
- Department of Biology, Lund University, Sölvegatan 35, 223 62 Lund, Sweden; Centre for Environmental and Climate Science, CEC, Lund University, Sölvegatan 37, 223 62 Lund, Sweden
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9
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Villa-Torrealba A, Navia S, Soto R. Kinetic modeling of the chemotactic process in run-and-tumble bacteria. Phys Rev E 2023; 107:034605. [PMID: 37072994 DOI: 10.1103/physreve.107.034605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 03/14/2023] [Indexed: 04/20/2023]
Abstract
The chemotactic process of run-and-tumble bacteria results from modulating the tumbling rate in response to changes in chemoattractant gradients felt by the bacteria. The response has a characteristic memory time and is subject to important fluctuations. These ingredients are considered in a kinetic description of chemotaxis, allowing the computation of the stationary mobility and the relaxation times needed to reach the steady state. For large memory times, these relaxation times become large, implying that finite-time measurements give rise to nonmonotonic currents as a function of the imposed chemoattractant gradient, contrary to the stationary regime where the response is monotonic. The case of an inhomogeneous signal is analyzed. Contrary to the usual Keller-Segel model, the response is nonlocal, and the bacterial profile is smoothed with a characteristic length that grows with the memory time. Finally, the case of traveling signals is considered, where appreciable differences appear compared to memoryless chemotactic descriptions.
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Affiliation(s)
- Andrea Villa-Torrealba
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Blanco Encalada 2008, Santiago, Chile
| | - Simón Navia
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Blanco Encalada 2008, Santiago, Chile
| | - Rodrigo Soto
- Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Avenida Blanco Encalada 2008, Santiago, Chile
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10
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Ji F, Wu Y, Pumera M, Zhang L. Collective Behaviors of Active Matter Learning from Natural Taxes Across Scales. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2203959. [PMID: 35986637 DOI: 10.1002/adma.202203959] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/23/2022] [Indexed: 06/15/2023]
Abstract
Taxis orientation is common in microorganisms, and it provides feasible strategies to operate active colloids as small-scale robots. Collective taxes involve numerous units that collectively perform taxis motion, whereby the collective cooperation between individuals enables the group to perform efficiently, adaptively, and robustly. Hence, analyzing and designing collectives is crucial for developing and advancing microswarm toward practical or clinical applications. In this review, natural taxis behaviors are categorized and synthetic microrobotic collectives are discussed as bio-inspired realizations, aiming at closing the gap between taxis strategies of living creatures and those of functional active microswarms. As collective behaviors emerge within a group, the global taxis to external stimuli guides the group to conduct overall tasks, whereas the local taxis between individuals induces synchronization and global patterns. By encoding the local orientations and programming the global stimuli, various paradigms can be introduced for coordinating and controlling such collective microrobots, from the viewpoints of fundamental science and practical applications. Therefore, by discussing the key points and difficulties associated with collective taxes of different paradigms, this review potentially offers insights into mimicking natural collective behaviors and constructing intelligent microrobotic systems for on-demand control and preassigned tasks.
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Affiliation(s)
- Fengtong Ji
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 999077, China
| | - Yilin Wu
- Department of Physics, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 999077, China
| | - Martin Pumera
- Faculty of Electrical Engineering and Computer Science, VSB - Technical University of Ostrava, 17. listopadu 2172/15, Ostrava, 70800, Czech Republic
- Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 03722, Korea
| | - Li Zhang
- Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, 999077, China
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11
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Zhang Y, Wei D, Wang X, Wang B, Li M, Fang H, Peng Y, Fan Q, Ye F. Run-and-Tumble Dynamics and Mechanotaxis Discovered in Microglial Migration. RESEARCH (WASHINGTON, D.C.) 2023; 6:0063. [PMID: 36939442 PMCID: PMC10013966 DOI: 10.34133/research.0063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 01/09/2023] [Indexed: 01/22/2023]
Abstract
Microglia are resident macrophage cells in the central nervous system that search for pathogens or abnormal neural activities and migrate to resolve the issues. The effective search and targeted motion of macrophages mean dearly to maintaining a healthy brain, yet little is known about their migration dynamics. In this work, we study microglial motion with and without the presence of external mechanostimuli. We discover that the cells are promptly attracted by the applied forces (i.e., mechanotaxis), which is a tactic behavior as yet unconfirmed in microglia. Meanwhile, in both the explorative and the targeted migration, microglia display dynamics that is strikingly analogous to bacterial run-and-tumble motion. A closer examination reveals that microglial run-and-tumble is more sophisticated, e.g., they display a short-term memory when tumbling and rely on active steering during runs to achieve mechanotaxis, probably via the responses of mechanosensitive ion channels. These differences reflect the sharp contrast between microglia and bacteria cells (eukaryotes vs. prokaryotes) and their environments (compact tissue vs. fluid). Further analyses suggest that the reported migration dynamics has an optimal search efficiency and is shared among a subset of immune cells (human monocyte and macrophage). This work reveals a fruitful analogy between the locomotion of 2 remote systems and provides a framework for studying immune cells exploring complex environments.
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Affiliation(s)
- Yiyu Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences,
University of Chinese Academy of Sciences, Beijing 100049, China
| | - Da Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaochen Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences,
University of Chinese Academy of Sciences, Beijing 100049, China
- Wenzhou Institute,
University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| | - Boyi Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences,
University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ming Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Haiping Fang
- Wenzhou Institute,
University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
- School of Science,
East China University of Science and Technology, Shanghai 200237, China
| | - Yi Peng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences,
University of Chinese Academy of Sciences, Beijing 100049, China
- Address correspondence to: (F.Y.); (Y.P.); (Q.F.)
| | - Qihui Fan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- Address correspondence to: (F.Y.); (Y.P.); (Q.F.)
| | - Fangfu Ye
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics,
Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences,
University of Chinese Academy of Sciences, Beijing 100049, China
- Wenzhou Institute,
University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
- Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou, Zhejiang 325000, China
- Address correspondence to: (F.Y.); (Y.P.); (Q.F.)
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12
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Wetherington MT, Nagy K, Dér L, Ábrahám Á, Noorlag J, Galajda P, Keymer JE. Ecological succession and the competition-colonization trade-off in microbial communities. BMC Biol 2022; 20:262. [PMID: 36447225 PMCID: PMC9710175 DOI: 10.1186/s12915-022-01462-5] [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: 02/04/2022] [Accepted: 11/09/2022] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND During range expansion in spatially distributed habitats, organisms differ from one another in terms of their patterns of localization versus propagation. To exploit locations or explore the landscape? This is the competition-colonization trade-off, a dichotomy at the core of ecological succession. In bacterial communities, this trade-off is a fundamental mechanism towards understanding spatio-temporal fluxes in microbiome composition. RESULTS Using microfluidics devices as structured bacterial habitats, we show that, in a synthetic two-species community of motile strains, Escherichia coli is a fugitive species, whereas Pseudomonas aeruginosa is a slower colonizer but superior competitor. We provide evidence highlighting the role of succession and the relevance of this trade-off in the community assembly of bacteria in spatially distributed patchy landscapes. Furthermore, aggregation-dependent priority effects enhance coexistence which is not possible in well-mixed environments. CONCLUSIONS Our findings underscore the interplay between micron-scale landscape structure and dispersal in shaping biodiversity patterns in microbial ecosystems. Understanding this interplay is key to unleash the technological revolution of microbiome applications.
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Affiliation(s)
- Miles T. Wetherington
- grid.7870.80000 0001 2157 0406Department of Ecology, School of Biological Sciences, P. Catholic University of Chile, Santiago, Chile ,grid.481813.7Biological Research Centre, Institute of Biophysics, Szeged, Hungary ,grid.5386.8000000041936877XSchool of Applied and Engineering Physics, Cornell University, Ithaca, USA
| | - Krisztina Nagy
- grid.481813.7Biological Research Centre, Institute of Biophysics, Szeged, Hungary
| | - László Dér
- grid.481813.7Biological Research Centre, Institute of Biophysics, Szeged, Hungary
| | - Ágnes Ábrahám
- grid.481813.7Biological Research Centre, Institute of Biophysics, Szeged, Hungary ,grid.9008.10000 0001 1016 9625Doctoral School of Multidisciplinary Medical Sciences, University of Szeged, Szeged, Hungary
| | - Janneke Noorlag
- grid.7870.80000 0001 2157 0406Department of Ecology, School of Biological Sciences, P. Catholic University of Chile, Santiago, Chile ,grid.501187.a0000000463647645Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
| | - Peter Galajda
- grid.481813.7Biological Research Centre, Institute of Biophysics, Szeged, Hungary
| | - Juan E. Keymer
- grid.7870.80000 0001 2157 0406Department of Ecology, School of Biological Sciences, P. Catholic University of Chile, Santiago, Chile ,grid.7870.80000 0001 2157 0406Institute of Physics, School of Physics, P. Catholic University of Chile, Santiago, Chile ,grid.501187.a0000000463647645Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
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13
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Honda T, Cremer J, Mancini L, Zhang Z, Pilizota T, Hwa T. Coordination of gene expression with cell size enables Escherichia coli to efficiently maintain motility across conditions. Proc Natl Acad Sci U S A 2022; 119:e2110342119. [PMID: 36067284 PMCID: PMC9478672 DOI: 10.1073/pnas.2110342119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2022] [Indexed: 11/18/2022] Open
Abstract
To swim and navigate, motile bacteria synthesize a complex motility machinery involving flagella, motors, and a sensory system. A myriad of studies has elucidated the molecular processes involved, but less is known about the coordination of motility expression with cellular physiology: In Escherichia coli, motility genes are strongly up-regulated in nutrient-poor conditions compared to nutrient-replete conditions; yet a quantitative link to cellular motility has not been developed. Here, we systematically investigated gene expression, swimming behavior, cell growth, and available proteomics data across a broad spectrum of exponential growth conditions. Our results suggest that cells up-regulate the expression of motility genes at slow growth to compensate for reduction in cell size, such that the number of flagella per cell is maintained across conditions. The observed four or five flagella per cell is the minimum number needed to keep the majority of cells motile. This simple regulatory objective allows E. coli cells to remain motile across a broad range of growth conditions, while keeping the biosynthetic and energetic demands to establish and drive the motility machinery at the minimum needed. Given the strong reduction in flagella synthesis resulting from cell size increases at fast growth, our findings also provide a different physiological perspective on bacterial cell size control: A larger cell size at fast growth is an efficient strategy to increase the allocation of cellular resources to the synthesis of those proteins required for biomass synthesis and growth, while maintaining processes such as motility that are only needed on a per-cell basis.
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Affiliation(s)
- Tomoya Honda
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
- US Department of Energy, Joint Genome Institute, Berkeley, CA 94720
| | - Jonas Cremer
- Department of Physics, University of California at San Diego, La Jolla, CA 92093
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Leonardo Mancini
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom
| | - Zhongge Zhang
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
| | - Teuta Pilizota
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom
| | - Terence Hwa
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
- Department of Physics, University of California at San Diego, La Jolla, CA 92093
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14
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Yasuda S. Numerical Study of the Volcano Effect in Chemotactic Aggregation Based on a Kinetic Transport Equation with Non-instantaneous Tumbling. Bull Math Biol 2022; 84:113. [PMID: 36050510 DOI: 10.1007/s11538-022-01071-x] [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: 04/08/2022] [Accepted: 08/18/2022] [Indexed: 11/29/2022]
Abstract
Aggregation of chemotactic bacteria under a unimodal distribution of chemical cues was investigated by Monte Carlo (MC) simulation based on a kinetic transport equation, which considers an internal adaptation dynamics as well as a finite tumbling duration. It was found that there exist two different regimes of the adaptation time, between which the effect of the adaptation time on the aggregation behavior is reversed; that is, when the adaptation time is as small as the running duration, the aggregation becomes increasingly steeper as the adaptation time increases, while, when the adaptation time is as large as the diffusion time of the population density, the aggregation becomes more diffusive as the adaptation time increases. Moreover, the aggregation profile becomes bimodal (volcano) at the large adaptation-time regime when the tumbling duration is sufficiently large while it is always unimodal at the small adaptation-time regime. A remarkable result of this study is the identification of the parameter regime and scaling for the volcano effect. That is, by comparing the results of MC simulations to the continuum-limit models obtained at each of the small and large adaptation-time scalings, it is clarified that the volcano effect arises due to the coupling of diffusion, adaptation, and finite tumbling duration, which occurs at the large adaptation-time scaling.
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Affiliation(s)
- Shugo Yasuda
- Graduate School of Information Science, University of Hyogo, Kobe, 650-0047, Japan.
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15
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Yu L, Le Nagard L, Barkley S, Smith L, Fradin C. Experimental determination of the propulsion matrix of the body of helical Magnetospirillum magneticum cells. Phys Rev E 2022; 106:034407. [PMID: 36266829 DOI: 10.1103/physreve.106.034407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/07/2022] [Indexed: 06/16/2023]
Abstract
Helical-shaped magnetotactic bacteria provide a rare opportunity to precisely measure both the translational and rotational friction coefficients of micron-sized chiral particles. The possibility to align these cells with a uniform magnetic field allows clearly separating diffusion along and perpendicular to their longitudinal axis. Meanwhile, their corkscrew shape allows detecting rotations around their longitudinal axis, after which orientation correlation analysis can be used to retrieve rotational diffusion coefficients in the two principal directions. Using light microscopy, we measured the four principal friction coefficients of deflagellated Magnetospirillum magneticum cells, and compared our results to that expected for cylinders of comparable size. We show that for rotational motions, the overall dimensions of the cell body are what matters most, while the exact body shape has a larger influence on translational motions. To obtain a full characterization of the friction matrix of these elongated chiral particles, we also quantified the coupling between the rotation around and translation along the longitudinal axis of the cell. Our results suggest that for this bacterial species cell body rotation could significantly contribute to cellular propulsion.
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Affiliation(s)
- Liu Yu
- Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S4M1, Canada
| | - Lucas Le Nagard
- Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S4M1, Canada
| | - Solomon Barkley
- Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S4M1, Canada
| | - Lauren Smith
- Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S4M1, Canada
| | - Cécile Fradin
- Department of Physics and Astronomy, McMaster University, 1280 Main Street W, Hamilton, Ontario L8S4M1, Canada
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16
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Bouvard J, Douarche C, Mergaert P, Auradou H, Moisy F. Direct measurement of the aerotactic response in a bacterial suspension. Phys Rev E 2022; 106:034404. [PMID: 36266851 DOI: 10.1103/physreve.106.034404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 07/29/2022] [Indexed: 06/16/2023]
Abstract
Aerotaxis is the ability of motile cells to navigate toward oxygen. A key question is the dependence of the aerotactic velocity with the local oxygen concentration c. Here we combine simultaneous bacteria tracking and local oxygen concentration measurements using Ruthenium encapsulated in micelles to characterize the aerotactic response of Burkholderia contaminans, a motile bacterium ubiquitous in the environment. In our experiments, an oxygen gradient is produced by the bacterial respiration in a sealed glass capillary permeable to oxygen at one end, producing a bacterial band traveling toward the oxygen source. We compute the aerotactic response χ(c) both at the population scale, from the drift velocity in the bacterial band, and at the bacterial scale, from the angular modulation of the run times. Both methods are consistent with a power-law χ∝c^{-2}, in good agreement with existing models based on the biochemistry of bacterial membrane receptors.
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Affiliation(s)
- J Bouvard
- Université Paris-Saclay, CNRS, FAST, 91405, Orsay, France
| | - C Douarche
- Université Paris-Saclay, CNRS, FAST, 91405, Orsay, France
| | - P Mergaert
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - H Auradou
- Université Paris-Saclay, CNRS, FAST, 91405, Orsay, France
| | - F Moisy
- Université Paris-Saclay, CNRS, FAST, 91405, Orsay, France
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17
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Collective behavior and nongenetic inheritance allow bacterial populations to adapt to changing environments. Proc Natl Acad Sci U S A 2022; 119:e2117377119. [PMID: 35727978 DOI: 10.1073/pnas.2117377119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Collective behaviors require coordination among a group of individuals. As a result, individuals that are too phenotypically different from the rest of the group can be left out, reducing heterogeneity, but increasing coordination. If individuals also reproduce, the offspring can have different phenotypes from their parent(s). This raises the question of how these two opposing processes-loss of diversity by collective behaviors and generation of it through growth and inheritance-dynamically shape the phenotypic composition of an isogenic population. We examine this question theoretically using collective migration of chemotactic bacteria as a model system, where cells of different swimming phenotypes are better suited to navigate in different environments. We find that the differential loss of phenotypes caused by collective migration is environment-dependent. With cell growth, this differential loss enables migrating populations to dynamically adapt their phenotype compositions to the environment, enhancing migration through multiple environments. Which phenotypes are produced upon cell division depends on the level of nongenetic inheritance, and higher inheritance leads to larger composition adaptation and faster migration at steady state. However, this comes at the cost of slower responses to new environments. Due to this trade-off, there is an optimal level of inheritance that maximizes migration speed through changing environments, which enables a diverse population to outperform a nondiverse one. Growing populations might generally leverage the selection-like effects provided by collective behaviors to dynamically shape their own phenotype compositions, without mutations.
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18
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Moore-Ott JA, Chiu S, Amchin DB, Bhattacharjee T, Datta SS. A biophysical threshold for biofilm formation. eLife 2022; 11:76380. [PMID: 35642782 PMCID: PMC9302973 DOI: 10.7554/elife.76380] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 06/01/2022] [Indexed: 11/13/2022] Open
Abstract
Bacteria are ubiquitous in our daily lives, either as motile planktonic cells or as immobilized surface-attached biofilms. These different phenotypic states play key roles in agriculture, environment, industry, and medicine; hence, it is critically important to be able to predict the conditions under which bacteria transition from one state to the other. Unfortunately, these transitions depend on a dizzyingly complex array of factors that are determined by the intrinsic properties of the individual cells as well as those of their surrounding environments, and are thus challenging to describe. To address this issue, here, we develop a generally-applicable biophysical model of the interplay between motility-mediated dispersal and biofilm formation under positive quorum sensing control. Using this model, we establish a universal rule predicting how the onset and extent of biofilm formation depend collectively on cell concentration and motility, nutrient diffusion and consumption, chemotactic sensing, and autoinducer production. Our work thus provides a key step toward quantitatively predicting and controlling biofilm formation in diverse and complex settings.
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Affiliation(s)
- Jenna Anne Moore-Ott
- Department of Chemical and Biological Engineering, Princeton University, Princeton, United States
| | - Selena Chiu
- Department of Chemical and Biological Engineering, Princeton University, Princeton, United States
| | - Daniel B Amchin
- Department of Chemical and Biological Engineering, Princeton University, Princeton, United States
| | - Tapomoy Bhattacharjee
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, United States
| | - Sujit Sankar Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, United States
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19
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Amchin DB, Ott JA, Bhattacharjee T, Datta SS. Influence of confinement on the spreading of bacterial populations. PLoS Comput Biol 2022; 18:e1010063. [PMID: 35533196 PMCID: PMC9119553 DOI: 10.1371/journal.pcbi.1010063] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 05/19/2022] [Accepted: 03/28/2022] [Indexed: 11/25/2022] Open
Abstract
The spreading of bacterial populations is central to processes in agriculture, the environment, and medicine. However, existing models of spreading typically focus on cells in unconfined settings—despite the fact that many bacteria inhabit complex and crowded environments, such as soils, sediments, and biological tissues/gels, in which solid obstacles confine the cells and thereby strongly regulate population spreading. Here, we develop an extended version of the classic Keller-Segel model of bacterial spreading via motility that also incorporates cellular growth and division, and explicitly considers the influence of confinement in promoting both cell-solid and cell-cell collisions. Numerical simulations of this extended model demonstrate how confinement fundamentally alters the dynamics and morphology of spreading bacterial populations, in good agreement with recent experimental results. In particular, with increasing confinement, we find that cell-cell collisions increasingly hinder the initial formation and the long-time propagation speed of chemotactic pulses. Moreover, also with increasing confinement, we find that cellular growth and division plays an increasingly dominant role in driving population spreading—eventually leading to a transition from chemotactic spreading to growth-driven spreading via a slower, jammed front. This work thus provides a theoretical foundation for further investigations of the influence of confinement on bacterial spreading. More broadly, these results help to provide a framework to predict and control the dynamics of bacterial populations in complex and crowded environments. The spreading of bacteria through their environments critically impacts our everyday lives; it can be harmful, underlying the progression of infections and spoilage of foods, or can be beneficial, enabling the delivery of therapeutics, sustaining plant growth, and remediating polluted terrain. In all these cases, bacteria typically inhabit crowded environments, such as soils, sediments, and biological tissues/gels, in which solid obstacles confine the cells and regulate their spreading. However, existing models of spreading typically focus on cells in unconfined settings, and thus are frequently not applicable to cells in more complex environments. Here, we address this gap in knowledge by extending the classic Keller-Segel model of bacterial spreading via motility to also incorporate cellular growth and division, and explicitly consider the influence of confinement. Through numerical simulations of this extended model, we show how confinement fundamentally alters the dynamics and morphology of spreading bacterial populations—in particular, driving a transition from chemotactic spreading of motile cells to growth-driven spreading via a slower, jammed front. These results provide a foundation for further investigations of the influence of confinement on bacterial spreading, both by yielding testable predictions for future experiments, and by providing guidelines to predict and control the dynamics of bacterial populations in complex and crowded environments.
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Affiliation(s)
- Daniel B. Amchin
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States of America
| | - Jenna A. Ott
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States of America
| | - Tapomoy Bhattacharjee
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey, United States of America
| | - Sujit S. Datta
- Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey, United States of America
- * E-mail:
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20
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Wetherington MT, Nagy K, Dér L, Noorlag J, Galajda P, Keymer JE. Variance in Landscape Connectivity Shifts Microbial Population Scaling. Front Microbiol 2022; 13:831790. [PMID: 35464924 PMCID: PMC9020879 DOI: 10.3389/fmicb.2022.831790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 03/10/2022] [Indexed: 12/03/2022] Open
Abstract
Understanding mechanisms shaping distributions and interactions of soil microbes is essential for determining their impact on large scale ecosystem services, such as carbon sequestration, climate regulation, waste decomposition, and nutrient cycling. As the functional unit of soil ecosystems, we focus our attention on the spatial structure of soil macroaggregates. Emulating this complex physico-chemical environment as a patchy habitat landscape we investigate on-chip the effect of changing the connectivity features of this landscape as Escherichia coli forms a metapopulation. We analyze the distributions of E. coli occupancy using Taylor's law, an empirical law in ecology which asserts that the fluctuations in populations is a power law function of the mean. We provide experimental evidence that bacterial metapopulations in patchy habitat landscapes on microchips follow this law. Furthermore, we find that increased variance of patch-corridor connectivity leads to a qualitative transition in the fluctuation scaling. We discuss these results in the context of the spatial ecology of microbes in soil.
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Affiliation(s)
- Miles T. Wetherington
- Department of Ecology, School of Biological Sciences, P. Catholic University of Chile, Santiago, Chile
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
- *Correspondence: Miles T. Wetherington
| | - Krisztina Nagy
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - László Dér
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Janneke Noorlag
- Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
| | - Peter Galajda
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Juan E. Keymer
- Department of Natural Sciences and Technology, University of Aysén, Coyhaique, Chile
- Juan E. Keymer
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21
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Livne N, Vaknin A. Collective responses of bacteria to a local source of conflicting effectors. Sci Rep 2022; 12:4928. [PMID: 35322063 PMCID: PMC8943191 DOI: 10.1038/s41598-022-08762-4] [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: 12/20/2021] [Accepted: 03/09/2022] [Indexed: 12/18/2022] Open
Abstract
To cope in complex environments, motile bacteria have developed a chemosensory system that integrates multiple cues and directs their motion toward regions that it deems favorable. However, we have a limited understanding of the principles that govern bacterial behavior in complex stimuli fields. Here, we followed the spatial redistribution of E. coli cells in perplexing environments created by a local source of both beneficial (nutrients) and hazardous (low pH or indole) effectors. We identified two fundamentally distinct collective responses: a ‘trade-off’ response, in which bacteria sharply accumulated at a distance from the source that reflected a trade-off between the propagating effectors, and a ‘bet-hedging’ response, in which part of the bacteria accumulated away from the source, avoiding the hazardous effector, while the other part evaded the repulsive force and accumulated at the source. In addition, we demonstrate that cells lacking the Tsr sensor swim toward both repellents and, surprisingly, even toward pH values well below 7. Using a numerical analysis, we could correlate the collective bacterial responses with fundamentally distinct chemotactic force fields created along the channel by the propagation of the effectors and their unique perception by the chemosensory system.
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Affiliation(s)
- Nir Livne
- The Racah Institute of Physics, The Hebrew University, Edmond J. Safra Campus, 91904, Jerusalem, Israel
| | - Ady Vaknin
- The Racah Institute of Physics, The Hebrew University, Edmond J. Safra Campus, 91904, Jerusalem, Israel.
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22
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Keegstra JM, Carrara F, Stocker R. The ecological roles of bacterial chemotaxis. Nat Rev Microbiol 2022; 20:491-504. [PMID: 35292761 DOI: 10.1038/s41579-022-00709-w] [Citation(s) in RCA: 62] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2022] [Indexed: 02/08/2023]
Abstract
How bacterial chemotaxis is performed is much better understood than why. Traditionally, chemotaxis has been understood as a foraging strategy by which bacteria enhance their uptake of nutrients and energy, yet it has remained puzzling why certain less nutritious compounds are strong chemoattractants and vice versa. Recently, we have gained increased understanding of alternative ecological roles of chemotaxis, such as navigational guidance in colony expansion, localization of hosts or symbiotic partners and contribution to microbial diversity by the generation of spatial segregation in bacterial communities. Although bacterial chemotaxis has been observed in a wide range of environmental settings, insights into the phenomenon are mostly based on laboratory studies of model organisms. In this Review, we highlight how observing individual and collective migratory behaviour of bacteria in different settings informs the quantification of trade-offs, including between chemotaxis and growth. We argue that systematically mapping when and where bacteria are motile, in particular by transgenerational bacterial tracking in dynamic environments and in situ approaches from guts to oceans, will open the door to understanding the rich interplay between metabolism and growth and the contribution of chemotaxis to microbial life.
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Affiliation(s)
| | - Francesco Carrara
- Institute for Environmental Engineering, ETH Zurich, Zurich, Switzerland
| | - Roman Stocker
- Institute for Environmental Engineering, ETH Zurich, Zurich, Switzerland.
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23
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Bhattacharjee T, Amchin DB, Alert R, Ott JA, Datta SS. Chemotactic smoothing of collective migration. eLife 2022; 11:e71226. [PMID: 35257660 PMCID: PMC8903832 DOI: 10.7554/elife.71226] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Accepted: 01/24/2022] [Indexed: 12/24/2022] Open
Abstract
Collective migration-the directed, coordinated motion of many self-propelled agents-is a fascinating emergent behavior exhibited by active matter with functional implications for biological systems. However, how migration can persist when a population is confronted with perturbations is poorly understood. Here, we address this gap in knowledge through studies of bacteria that migrate via directed motion, or chemotaxis, in response to a self-generated nutrient gradient. We find that bacterial populations autonomously smooth out large-scale perturbations in their overall morphology, enabling the cells to continue to migrate together. This smoothing process arises from spatial variations in the ability of cells to sense and respond to the local nutrient gradient-revealing a population-scale consequence of the manner in which individual cells transduce external signals. Altogether, our work provides insights to predict, and potentially control, the collective migration and morphology of cellular populations and diverse other forms of active matter.
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Affiliation(s)
- Tapomoy Bhattacharjee
- The Andlinger Center for Energy and the Environment, Princeton UniversityPrincetonUnited States
| | - Daniel B Amchin
- Department of Chemical and Biological Engineering, Princeton UniversityPrincetonUnited States
| | - Ricard Alert
- Lewis-Sigler Institute for Integrative Genomics, Princeton UniversityPrincetonUnited States
- Princeton Center for Theoretical Science, Princeton UniversityPrincetonUnited States
| | - Jenna Anne Ott
- Department of Chemical and Biological Engineering, Princeton UniversityPrincetonUnited States
| | - Sujit Sankar Datta
- Department of Chemical and Biological Engineering, Princeton UniversityPrincetonUnited States
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24
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Colin R, Ni B, Laganenka L, Sourjik V. Multiple functions of flagellar motility and chemotaxis in bacterial physiology. FEMS Microbiol Rev 2021; 45:fuab038. [PMID: 34227665 PMCID: PMC8632791 DOI: 10.1093/femsre/fuab038] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/02/2021] [Indexed: 12/13/2022] Open
Abstract
Most swimming bacteria are capable of following gradients of nutrients, signaling molecules and other environmental factors that affect bacterial physiology. This tactic behavior became one of the most-studied model systems for signal transduction and quantitative biology, and underlying molecular mechanisms are well characterized in Escherichia coli and several other model bacteria. In this review, we focus primarily on less understood aspect of bacterial chemotaxis, namely its physiological relevance for individual bacterial cells and for bacterial populations. As evident from multiple recent studies, even for the same bacterial species flagellar motility and chemotaxis might serve multiple roles, depending on the physiological and environmental conditions. Among these, finding sources of nutrients and more generally locating niches that are optimal for growth appear to be one of the major functions of bacterial chemotaxis, which could explain many chemoeffector preferences as well as flagellar gene regulation. Chemotaxis might also generally enhance efficiency of environmental colonization by motile bacteria, which involves intricate interplay between individual and collective behaviors and trade-offs between growth and motility. Finally, motility and chemotaxis play multiple roles in collective behaviors of bacteria including swarming, biofilm formation and autoaggregation, as well as in their interactions with animal and plant hosts.
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Affiliation(s)
- Remy Colin
- Max Planck Institute for Terrestrial Microbiology & Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 16, Marburg D-35043, Germany
| | - Bin Ni
- Max Planck Institute for Terrestrial Microbiology & Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 16, Marburg D-35043, Germany
- College of Resources and Environmental Science, National Academy of Agriculture Green Development, China Agricultural University, Yuanmingyuan Xilu No. 2, Beijing 100193, China
| | - Leanid Laganenka
- Institute of Microbiology, D-BIOL, ETH Zürich, Vladimir-Prelog-Weg 4, Zürich 8093, Switzerland
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology & Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 16, Marburg D-35043, Germany
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25
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Bai Y, He C, Chu P, Long J, Li X, Fu X. Spatial modulation of individual behaviors enables an ordered structure of diverse phenotypes during bacterial group migration. eLife 2021; 10:67316. [PMID: 34726151 PMCID: PMC8563000 DOI: 10.7554/elife.67316] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022] Open
Abstract
Coordination of diverse individuals often requires sophisticated communications and high-order computational abilities. Microbial populations can exhibit diverse individualistic behaviors, and yet can engage in collective migratory patterns with a spatially sorted arrangement of phenotypes. However, it is unclear how such spatially sorted patterns emerge from diverse individuals without complex computational abilities. Here, by investigating the single-cell trajectories during group migration, we discovered that, despite the constant migrating speed of a group, the drift velocities of individual bacteria decrease from the back to the front. With a Langevin-type modeling framework, we showed that this decreasing profile of drift velocities implies the spatial modulation of individual run-and-tumble random motions, and enables the bacterial population to migrate as a pushed wave front. Theoretical analysis and stochastic simulations further predicted that the pushed wave front can help a diverse population to stay in a tight group, while diverse individuals perform the same type of mean reverting processes around centers orderly aligned by their chemotactic abilities. This mechanism about the emergence of orderly collective migration from diverse individuals is experimentally demonstrated by titration of bacterial chemoreceptor abundance. These results reveal a simple computational principle for emergent ordered behaviors from heterogeneous individuals. Organisms living in large groups often have to move together in order to navigate, forage for food, and increase their roaming range. Such groups are often made up of distinct individuals that must integrate their different behaviors in order to migrate in the same direction at a similar pace. For instance, for the bacteria Escherichia coli to travel as a condensed group, they must coordinate their response to a set of chemical signals called chemoattractants that tell them where to go. The chemoattractants surrounding the bacteria are unequally distributed so that there is more of them at the front than the back of the group. During migration, each bacterium moves towards this concentration gradient in a distinct way, spontaneously rotating its direction in a ‘run-and-tumble’ motion that guides it towards areas where there are high levels of these chemical signals. In addition to this variability, how well individual bacteria are able to swim up the gradient also differs within the population. Bacteria that are better at sensing the chemoattractant gradient are placed at the front of the group, while those that are worst are shifted towards the back. This spatial arrangement is thought to help the bacteria migrate together. But how E. coli organize themselves in to this pattern is unclear, especially as they cannot communicate directly with one another and display such diverse, randomized behaviors. To help answer this question, Bai, He et al. discovered a general principle that describes how single bacterial cells move within a group. The results showed that E. coli alter their run-and-tumble motion depending on where they reside within the population: individuals at the rear drift faster so they can catch up with the group, while those leading the group drift slower to draw themselves back. This ‘reversion behavior’ allows the migrating bacteria to travel at a constant speed around a mean position relative to the group. A cell’s drifting speed is determined by how well it moves towards the chemoattractant and its response to the concentration gradient. As a result, the mean position around which the bacterium accelerates or deaccelerates will vary depending on how sensitive it is to the chemoattractant gradient. The E. coli therefore spatially arrange themselves so that the more sensitive bacteria are located at the front of the group where the gradient is shallower; and cells that are less sensitive are located towards the back where the gradient is steeper. These findings suggest a general principle for how bacteria form ordered patterns whilst migrating as a collective group. This behavior could also apply to other populations of distinct individuals, such as ants following a trail or flocks of birds migrating in between seasons.
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Affiliation(s)
- Yang Bai
- CAS Key Laboratory for Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Caiyun He
- CAS Key Laboratory for Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Pan Chu
- CAS Key Laboratory for Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Junjiajia Long
- Yale University, Department of Physics, New Haven, United States
| | - Xuefei Li
- CAS Key Laboratory for Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiongfei Fu
- CAS Key Laboratory for Quantitative Engineering Biology, Guangdong Provincial Key Laboratory of Synthetic Genomics, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.,University of Chinese Academy of Sciences, Beijing, China
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26
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Arellano-Caicedo C, Ohlsson P, Bengtsson M, Beech JP, Hammer EC. Habitat geometry in artificial microstructure affects bacterial and fungal growth, interactions, and substrate degradation. Commun Biol 2021; 4:1226. [PMID: 34702996 PMCID: PMC8548513 DOI: 10.1038/s42003-021-02736-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 10/01/2021] [Indexed: 11/25/2022] Open
Abstract
Microhabitat conditions determine the magnitude and speed of microbial processes but have been challenging to investigate. In this study we used microfluidic devices to determine the effect of the spatial distortion of a pore space on fungal and bacterial growth, interactions, and substrate degradation. The devices contained channels differing in bending angles and order. Sharper angles reduced fungal and bacterial biomass, especially when angles were repeated in the same direction. Substrate degradation was only decreased by sharper angles when fungi and bacteria were grown together. Investigation at the cellular scale suggests that this was caused by fungal habitat modification, since hyphae branched in sharp and repeated turns, blocking the dispersal of bacteria and the substrate. Our results demonstrate how the geometry of microstructures can influence microbial activity. This can be transferable to soil pore spaces, where spatial occlusion and microbial feedback on microstructures is thought to explain organic matter stabilization.
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Affiliation(s)
| | - Pelle Ohlsson
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Martin Bengtsson
- Department of Biomedical Engineering, Lund University, Lund, Sweden
| | - Jason P Beech
- Division of Solid State Physics, Lund University, Lund, Sweden
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27
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Yasuda S. Effects of internal dynamics on chemotactic aggregation of bacteria. Phys Biol 2021; 18. [PMID: 34425564 DOI: 10.1088/1478-3975/ac2048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/23/2021] [Indexed: 11/11/2022]
Abstract
The effects of internal adaptation dynamics on the self-organized aggregation of chemotactic bacteria are investigated by Monte Carlo (MC) simulations based on a two-stream kinetic transport equation coupled with a reaction-diffusion equation of the chemoattractant that bacteria produce. A remarkable finding is a nonmonotonic behavior of the peak aggregation density with respect to the adaptation time; more specifically, aggregation is the most enhanced when the adaptation time is comparable to or moderately larger than the mean run time of bacteria. Another curious observation is the formation of a trapezoidal aggregation profile occurring at a very large adaptation time, where the biased motion of individual cells is rather hindered at the plateau regimes due to the boundedness of the tumbling frequency modulation. Asymptotic analysis of the kinetic transport system is also carried out, and a novel asymptotic equation is obtained at the large adaptation-time regime while the Keller-Segel type equations are obtained when the adaptation time is moderate. Numerical comparison of the asymptotic equations with MC results clarifies that trapezoidal aggregation is well described by the novel asymptotic equation, and the nonmonotonic behavior of the peak aggregation density is interpreted as the transient of the asymptotic solutions between different adaptation time regimes.
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Affiliation(s)
- Shugo Yasuda
- Graduate School of Information Science, University of Hyogo, 650-0047 Kobe, Japan
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28
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Cochet-Escartin O, Demircigil M, Hirose S, Allais B, Gonzalo P, Mikaelian I, Funamoto K, Anjard C, Calvez V, Rieu JP. Hypoxia triggers collective aerotactic migration in Dictyostelium discoideum. eLife 2021; 10:64731. [PMID: 34415238 PMCID: PMC8378850 DOI: 10.7554/elife.64731] [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] [Received: 11/09/2020] [Accepted: 07/30/2021] [Indexed: 01/26/2023] Open
Abstract
Using a self-generated hypoxic assay, we show that the amoeba Dictyostelium discoideum displays a remarkable collective aerotactic behavior. When a cell colony is covered, cells quickly consume the available oxygen (O2) and form a dense ring moving outwards at constant speed and density. To decipher this collective process, we combined two technological developments: porphyrin-based O2 -sensing films and microfluidic O2 gradient generators. We showed that Dictyostelium cells exhibit aerotactic and aerokinetic response in a low range of O2 concentration indicative of a very efficient detection mechanism. Cell behaviors under self-generated or imposed O2 gradients were modeled using an in silico cellular Potts model built on experimental observations. This computational model was complemented with a parsimonious ‘Go or Grow’ partial differential equation (PDE) model. In both models, we found that the collective migration of a dense ring can be explained by the interplay between cell division and the modulation of aerotaxis.
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Affiliation(s)
- Olivier Cochet-Escartin
- Institut Lumière Matière, UMR5306, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
| | - Mete Demircigil
- Institut Camille Jordan, UMR5208, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
| | - Satomi Hirose
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.,Institute of Fluid Science, Tohoku University, Sendai, Japan
| | - Blandine Allais
- Institut Lumière Matière, UMR5306, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
| | - Philippe Gonzalo
- Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, INSERM 1052, CNRS 5286, Université Lyon 1, Université de Lyon, Lyon, France.,Laboratoire de Biochimie et Pharmacologie, Faculté de médecine de Saint-Etienne, CHU de Saint-Etienne, Saint-Etienne, France
| | - Ivan Mikaelian
- Centre Léon Bérard, Centre de recherche en cancérologie de Lyon, INSERM 1052, CNRS 5286, Université Lyon 1, Université de Lyon, Lyon, France
| | - Kenichi Funamoto
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.,Institute of Fluid Science, Tohoku University, Sendai, Japan.,Graduate School of Engineering, Tohoku University, Sendai, Japan
| | - Christophe Anjard
- Institut Lumière Matière, UMR5306, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
| | - Vincent Calvez
- Institut Camille Jordan, UMR5208, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
| | - Jean-Paul Rieu
- Institut Lumière Matière, UMR5306, Université Lyon 1-CNRS, Université de Lyon, Villeurbanne, France
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29
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Caillerie N, Vovelle J. Diffusion-approximation for a kinetic equation with perturbed velocity redistribution process. ANN APPL PROBAB 2021. [DOI: 10.1214/20-aap1619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Nils Caillerie
- Department of Mathematics and Statistics, Georgetown University
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30
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Bhattacharjee T, Amchin DB, Ott JA, Kratz F, Datta SS. Chemotactic migration of bacteria in porous media. Biophys J 2021; 120:3483-3497. [PMID: 34022238 DOI: 10.1016/j.bpj.2021.05.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 03/11/2021] [Accepted: 05/06/2021] [Indexed: 11/16/2022] Open
Abstract
Chemotactic migration of bacteria-their ability to direct multicellular motion along chemical gradients-is central to processes in agriculture, the environment, and medicine. However, current understanding of migration is based on studies performed in bulk liquid, despite the fact that many bacteria inhabit tight porous media such as soils, sediments, and biological gels. Here, we directly visualize the chemotactic migration of Escherichia coli populations in well-defined 3D porous media in the absence of any other imposed external forcing (e.g., flow). We find that pore-scale confinement is a strong regulator of migration. Strikingly, cells use a different primary mechanism to direct their motion in confinement than in bulk liquid. Furthermore, confinement markedly alters the dynamics and morphology of the migrating population-features that can be described by a continuum model, but only when standard motility parameters are substantially altered from their bulk liquid values to reflect the influence of pore-scale confinement. Our work thus provides a framework to predict and control the migration of bacteria, and active matter in general, in complex environments.
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Affiliation(s)
- Tapomoy Bhattacharjee
- Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey
| | - Daniel B Amchin
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Jenna A Ott
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Felix Kratz
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey
| | - Sujit S Datta
- Chemical and Biological Engineering, Princeton University, Princeton, New Jersey.
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31
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Biased reorientation in the chemotaxis of peritrichous bacteria Salmonella enterica serovar Typhimurium. Biophys J 2021; 120:2623-2630. [PMID: 33964275 PMCID: PMC8390861 DOI: 10.1016/j.bpj.2021.04.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/09/2021] [Accepted: 04/26/2021] [Indexed: 11/22/2022] Open
Abstract
Many kinds of peritrichous bacteria that repeat runs and tumbles by using multiple flagella exhibit chemotaxis by sensing a difference in the concentration of the attractant or repellent between two adjacent time points. If a cell senses that the concentration of an attractant has increased, their flagellar motors decrease the switching frequency from counterclockwise to clockwise direction of rotation, which causes a longer run in swimming up the concentration gradient than swimming down. We investigated the turn angle in tumbles of peritrichous bacteria swimming across the concentration gradient of a chemoattractant because the change in the switching frequency in the rotational direction may affect the way tumbles. We tracked several hundreds of runs and tumbles of single cells of Salmonella enterica serovar Typhimurium in the concentration gradient of L-serine and found that the turn angle depends on the concentration gradient that the cell senses just before the tumble. The turn angle is biased toward a smaller value when the cells swim up the concentration gradient, whereas the distribution of the angle is almost uniform (random direction) when the cells swim down the gradient. The effect of the observed bias in the turn angle on the degree of chemotaxis was investigated by random walk simulation. In the concentration field where attractants diffuse concentrically from the point source, we found that this angular distribution clearly affects the reduction of the mean-square displacement of the cell that has started at the attractant source, that is, the bias in the turn angle distribution contributes to chemotaxis in peritrichous bacteria.
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32
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Sathyamoorthy R, Huppert A, Kadouri DE, Jurkevitch E. Effects of the prey landscape on the fitness of the bacterial predators Bdellovibrio and like organisms. FEMS Microbiol Ecol 2021; 97:6178867. [PMID: 33739375 DOI: 10.1093/femsec/fiab047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 03/17/2021] [Indexed: 11/12/2022] Open
Abstract
Bdellovibrio and like organisms (BALOs) are obligate predatory bacteria commonly encountered in the environment. In dual predator-prey cultures, prey accessibility ensures optimal feeding and replication and rapid BALO population growth. However, the environmental prey landscape is complex, as it also incorporates non-prey cells and other particles. These may act as decoys, generating unproductive encounters which in turn may affect both predator and prey population dynamics. In this study, we hypothesized that increasing decoy:prey ratios would bring about increasing costs on the predator's reproductive fitness. We also tested the hypothesis that different BALOs and decoys would have different effects. To this end, we constructed prey landscapes including periplasmic or epibiotic predators including two types of decoy under a large range of initial decoy:prey ratio, and mixed cultures containing multiple predators and prey. We show that as decoy:prey ratios increase, the maximal predator population sizes is reduced and the time to reach it significantly increases. We found that BALOs spent less time handling non-prey (including superinfection-immune invaded prey) than prey cells, and did not differentiate between efficient and less efficient prey. This may explain why in multiple predator and prey cultures, less preferred prey appear to act as decoy.
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Affiliation(s)
- Rajesh Sathyamoorthy
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
| | - Amit Huppert
- Bio-statistical Unit, The Gertner Institute for Epidemiology and Health Policy Research, Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Daniel E Kadouri
- Department of Oral Biology, Rutgers School of Dental Medicine, Newark, NJ, USA
| | - Edouard Jurkevitch
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
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33
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Chatterjee P, Goldenfeld N. Field-theoretic model for chemotaxis in run and tumble particles. Phys Rev E 2021; 103:032603. [PMID: 33862765 DOI: 10.1103/physreve.103.032603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 02/12/2021] [Indexed: 11/07/2022]
Abstract
In this paper, we develop a field-theoretic description for run and tumble chemotaxis, based on a density-functional description of crystalline materials modified to capture orientational ordering. We show that this framework, with its in-built multiparticle interactions, soft-core repulsion, and elasticity, is ideal for describing continuum collective phases with particle resolution, but on diffusive timescales. We show that our model exhibits particle aggregation in an externally imposed constant attractant field, as is observed for phototactic or thermotactic agents. We also show that this model captures particle aggregation through self-chemotaxis, an important mechanism that aids quorum-dependent cellular interactions.
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Affiliation(s)
- Purba Chatterjee
- Department of Physics, University of Illinois at Urbana-Champaign, Loomis Laboratory of Physics, 1110 West Green Street, Urbana, Illinois, 61801-3080, USA
| | - Nigel Goldenfeld
- Department of Physics, University of Illinois at Urbana-Champaign, Loomis Laboratory of Physics, 1110 West Green Street, Urbana, Illinois, 61801-3080, USA
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34
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Naaz F, Agrawal M, Chakraborty S, Tirumkudulu MS, Venkatesh KV. Ligand sensing enhances bacterial flagellar motor output via stator recruitment. eLife 2021; 10:62848. [PMID: 33821791 PMCID: PMC8062133 DOI: 10.7554/elife.62848] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 04/03/2021] [Indexed: 11/13/2022] Open
Abstract
It is well known that flagellated bacteria, such as Escherichia coli, sense chemicals in their environment by a chemoreceptor and relay the signals via a well-characterized signaling pathway to the flagellar motor. It is widely accepted that the signals change the rotation bias of the motor without influencing the motor speed. Here, we present results to the contrary and show that the bacteria is also capable of modulating motor speed on merely sensing a ligand. Step changes in concentration of non-metabolizable ligand cause temporary recruitment of stator units leading to a momentary increase in motor speeds. For metabolizable ligand, the combined effect of sensing and metabolism leads to higher motor speeds for longer durations. Experiments performed with mutant strains delineate the role of metabolism and sensing in the modulation of motor speed and show how speed changes along with changes in bias can significantly enhance response to changes in its environment.
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Affiliation(s)
- Farha Naaz
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Megha Agrawal
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Soumyadeep Chakraborty
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Mahesh S Tirumkudulu
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - K V Venkatesh
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
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35
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Afanzar O, Di Paolo D, Eisenstein M, Levi K, Plochowietz A, Kapanidis AN, Berry RM, Eisenbach M. The switching mechanism of the bacterial rotary motor combines tight regulation with inherent flexibility. EMBO J 2021; 40:e104683. [PMID: 33620739 PMCID: PMC7957414 DOI: 10.15252/embj.2020104683] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 12/17/2020] [Accepted: 01/19/2021] [Indexed: 11/20/2022] Open
Abstract
Regulatory switches are wide spread in many biological systems. Uniquely among them, the switch of the bacterial flagellar motor is not an on/off switch but rather controls the motor’s direction of rotation in response to binding of the signaling protein CheY. Despite its extensive study, the molecular mechanism underlying this switch has remained largely unclear. Here, we resolved the functions of each of the three CheY‐binding sites at the switch in E. coli, as well as their different dependencies on phosphorylation and acetylation of CheY. Based on this, we propose that CheY motor switching activity is potentiated upon binding to the first site. Binding of potentiated CheY to the second site produces unstable switching and at the same time enables CheY binding to the third site, an event that stabilizes the switched state. Thereby, this mechanism exemplifies a unique combination of tight motor regulation with inherent switching flexibility.
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Affiliation(s)
- Oshri Afanzar
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Diana Di Paolo
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Miriam Eisenstein
- Department of Chemical Research Support, The Weizmann Institute of Science, Rehovot, Israel
| | - Kohava Levi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Anne Plochowietz
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Achillefs N Kapanidis
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Richard Michael Berry
- Biological Physics Research Group, Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, UK
| | - Michael Eisenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
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36
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O'Byrne J, Tailleur J. Lamellar to Micellar Phases and Beyond: When Tactic Active Systems Admit Free Energy Functionals. PHYSICAL REVIEW LETTERS 2020; 125:208003. [PMID: 33258650 DOI: 10.1103/physrevlett.125.208003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/14/2020] [Indexed: 06/12/2023]
Abstract
We consider microscopic models of active particles whose velocities, rotational diffusivities, and tumbling rates depend on the gradient of a local field that is either externally imposed or depends on all particle positions. Despite the fundamental differences between active and passive dynamics at the microscopic scale, we show that a large class of such tactic active systems admit fluctuating hydrodynamics equivalent to those of interacting Brownian colloids in equilibrium. We exploit this mapping to show how taxis may lead to the lamellar and micellar phases observed for soft repulsive colloids. In the context of chemotaxis, we show how the competition between chemoattractant and chemorepellent may lead to a bona fide equilibrium liquid-gas phase separation in which a loss of thermodynamic stability of the fluid signals the onset of a chemotactic collapse.
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Affiliation(s)
- J O'Byrne
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
| | - J Tailleur
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
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37
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Kichatov B, Korshunov A, Sudakov V, Kolobov A, Gubernov V, Golubkov A, Kiverin A. Kinetics of cluster formation in active suspension: Coarsening regime. J Chem Phys 2020; 153:084902. [DOI: 10.1063/5.0013665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Boris Kichatov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexey Korshunov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir Sudakov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Andrey Kolobov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Vladimir Gubernov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexandr Golubkov
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Alexey Kiverin
- Moscow State Technical University by N. E. Bauman, 105005 Moscow, Russia
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38
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Bacterial flagellar motor as a multimodal biosensor. Methods 2020; 193:5-15. [PMID: 32640316 DOI: 10.1016/j.ymeth.2020.06.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/04/2020] [Accepted: 06/22/2020] [Indexed: 01/05/2023] Open
Abstract
Bacterial Flagellar Motor is one of nature's rare rotary molecular machines. It enables bacterial swimming and it is the key part of the bacterial chemotactic network, one of the best studied chemical signalling networks in biology, which enables bacteria to direct its movement in accordance with the chemical environment. The network can sense down to nanomolar concentrations of specific chemicals on the time scale of seconds. Motor's rotational speed is linearly proportional to the electrochemical gradients of either proton or sodium driving ions, while its direction is regulated by the chemotactic network. Recently, it has been discovered that motor is also a mechanosensor. Given these properties, we discuss the motor's potential to serve as a multifunctional biosensor and a tool for characterising and studying the external environment, the bacterial physiology itself and single molecular motor biophysics.
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39
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Wang X, Chen Y, Deng W. Theory of relaxation dynamics for anomalous diffusion processes in harmonic potential. Phys Rev E 2020; 101:042105. [PMID: 32422812 DOI: 10.1103/physreve.101.042105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Accepted: 03/10/2020] [Indexed: 11/07/2022]
Abstract
An important physical property for a stochastic process is how it responds to an external force or spatial confinement. This paper aims to study the relaxation dynamics of a generic process confined in a harmonic potential. We find the dependence of ensemble- and time-averaged mean squared displacements of the confined process on the velocity correlation function C(t,t+τ) of the original process without any external force. Combining two kinds of scaling forms of C(t,t+τ) for small τ and large τ, the stationary value and the relaxation behaviors can be immediately obtained. Our results are valid for a large amount of anomalous diffusion processes, including the ones with single-scaled velocity correlation function (such as fractional Brownian motion and scaled Brownian motion) and the multiscaled ones (like Lévy walk with a broad range of power law exponents of flight time distribution). Note that the latter includes a special case with telegraphic active noise, which could take up athermal energy from the environment.
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Affiliation(s)
- Xudong Wang
- School of Mathematics and Statistics, Gansu Key Laboratory of Applied Mathematics and Complex Systems, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Yao Chen
- School of Mathematics and Statistics, Gansu Key Laboratory of Applied Mathematics and Complex Systems, Lanzhou University, Lanzhou 730000, People's Republic of China
| | - Weihua Deng
- School of Mathematics and Statistics, Gansu Key Laboratory of Applied Mathematics and Complex Systems, Lanzhou University, Lanzhou 730000, People's Republic of China
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Tumble Kinematics of Escherichia coli near a Solid Surface. Biophys J 2020; 118:2400-2410. [PMID: 32375021 DOI: 10.1016/j.bpj.2020.03.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/20/2020] [Accepted: 03/23/2020] [Indexed: 11/24/2022] Open
Abstract
Bacteria tumble periodically, following environmental cues. Whether they can tumble near a solid surface is a basic issue for the inception of infection or mineral biofouling. Observing freely swimming Escherichia coli near and parallel to a glass surface imaged at high magnification (×100) and high temporal resolution (500 Hz), we identified tumbles as events starting (or finishing, respectively) in abrupt deceleration (or reacceleration, respectively) of the body motion. Selected events show an equiprobable clockwise (CW) or counterclockwise change in direction that is superimposed on a surface CW path because of persistent propulsion. These tumbles follow a common long (about 300 ± 100 ms, N = 52) deceleration-reorientation-acceleration pattern. A wavelet transform multiscale analysis shows these tumbles cause in-plane diffusive reorientations with 1.5 rad2/s rotational diffusivity, a value that compares with that measured in bulk tumbles. In half of the cases, additional few-millisecond bursts of an almost equiprobable CW or counterclockwise change of direction (12 ± 90°, N = 89) occur within the reorientation stage. The highly dispersed absolute values of change of direction (70 ± 66°, N = 89) of only a few bursts destabilize the cell-swimming direction. These first observations of surface tumbles set a foundation for statistical models of run-and-tumble surface motion different from that in bulk and lend support for chemotaxis near solid surface.
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Bioinspired reorientation strategies for application in micro/nanorobotic control. JOURNAL OF MICRO-BIO ROBOTICS 2020. [DOI: 10.1007/s12213-020-00130-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
AbstractEngineers have recently been inspired by swimming methodologies of microorganisms in creating micro-/nanorobots for biomedical applications. Future medicine may be revolutionized by the application of these small machines in diagnosing, monitoring, and treating diseases. Studies over the past decade have often concentrated on propulsion generation. However, there are many other challenges to address before the practical use of robots at the micro-/nanoscale. The control and reorientation ability of such robots remain as some of these challenges. This paper reviews the strategies of swimming microorganisms for reorientation, including tumbling, reverse and flick, direction control of helical-path swimmers, by speed modulation, using complex flagella, and the help of mastigonemes. Then, inspired by direction change in microorganisms, methods for orientation control for microrobots and possible directions for future studies are discussed. Further, the effects of solid boundaries on the swimming trajectories of microorganisms and microrobots are examined. In addition to propulsion systems for artificial microswimmers, swimming microorganisms are promising sources of control methodologies at the micro-/nanoscale.
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Figueroa-Morales N, Rivera A, Soto R, Lindner A, Altshuler E, Clément É. E. coli "super-contaminates" narrow ducts fostered by broad run-time distribution. SCIENCE ADVANCES 2020; 6:eaay0155. [PMID: 32201716 PMCID: PMC7069694 DOI: 10.1126/sciadv.aay0155] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
One notable feature of bacterial motion is their ability to swim upstream along corners and crevices, by leveraging hydrodynamic interactions. This motion through anatomic ducts or medical devices might be at the origin of serious infections. However, it remains unclear how bacteria can maintain persistent upstream motion while exhibiting run-and-tumble dynamics. Here, we demonstrate that Escherichia coli can travel upstream in microfluidic devices over distances of 15 mm in times as short as 15 min. Using a stochastic model relating the run times to the time that bacteria spend on surfaces, we quantitatively reproduce the evolution of the contamination profiles when considering a broad distribution of run times. The experimental data cannot be reproduced using the usually accepted exponential distribution of run times. Our study demonstrates that the run-and-tumble statistics determine macroscopic bacterial transport properties. This effect, which we name "super-contamination," could explain the fast onset of some life-threatening medical emergencies.
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Affiliation(s)
- Nuris Figueroa-Morales
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, PMMH, ESPCI Paris, PSL University, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
- Department of Biomedical Engineering, The Pennsylvania State University, PA 16802, USA
| | - Aramis Rivera
- Zeolites Engineering Lab, IMRE, University of Havana, 10400 Havana, Cuba
| | - Rodrigo Soto
- Departamento de Física, FCFM, Universidad de Chile, Santiago, Chile
| | - Anke Lindner
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, PMMH, ESPCI Paris, PSL University, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
| | - Ernesto Altshuler
- Group of Complex Systems and Statistical Physics, Physics Faculty, University of Havana, 10400 Havana, Cuba
| | - Éric Clément
- Laboratoire de Physique et Mécanique des Milieux Hétérogènes, PMMH, ESPCI Paris, PSL University, CNRS, Sorbonne Université, Université de Paris, 75005 Paris, France
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Colin R, Drescher K, Sourjik V. Chemotactic behaviour of Escherichia coli at high cell density. Nat Commun 2019; 10:5329. [PMID: 31767843 PMCID: PMC6877613 DOI: 10.1038/s41467-019-13179-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/25/2019] [Indexed: 11/20/2022] Open
Abstract
At high cell density, swimming bacteria exhibit collective motility patterns, self-organized through physical interactions of a however still debated nature. Although high-density behaviours are frequent in natural situations, it remained unknown how collective motion affects chemotaxis, the main physiological function of motility, which enables bacteria to follow environmental gradients in their habitats. Here, we systematically investigate this question in the model organism Escherichia coli, varying cell density, cell length, and suspension confinement. The characteristics of the collective motion indicate that hydrodynamic interactions between swimmers made the primary contribution to its emergence. We observe that the chemotactic drift is moderately enhanced at intermediate cell densities, peaks, and is then strongly suppressed at higher densities. Numerical simulations reveal that this suppression occurs because the collective motion disturbs the choreography necessary for chemotactic sensing. We suggest that this physical hindrance imposes a fundamental constraint on high-density behaviours of motile bacteria, including swarming and the formation of multicellular aggregates and biofilms.
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Affiliation(s)
- Remy Colin
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, Marburg, Germany.
- Loewe Center for Synthetic Microbiology, Karl-von-Frisch-Strasse 16, Marburg, Germany.
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, Marburg, Germany
- Loewe Center for Synthetic Microbiology, Karl-von-Frisch-Strasse 16, Marburg, Germany
- Fachbereich Physik, Philipps-Universität Marburg, Karl-von-Frisch-Str. 16, 35043, Marburg, Germany
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Strasse 10, Marburg, Germany.
- Loewe Center for Synthetic Microbiology, Karl-von-Frisch-Strasse 16, Marburg, Germany.
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Sone K, Ashida Y. Anomalous Topological Active Matter. PHYSICAL REVIEW LETTERS 2019; 123:205502. [PMID: 31809111 DOI: 10.1103/physrevlett.123.205502] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Indexed: 06/10/2023]
Abstract
Active systems exhibit spontaneous flows induced by self-propulsion of microscopic constituents and can reach a nonequilibrium steady state without an external drive. Constructing the analogy between the quantum anomalous Hall insulators and active matter with spontaneous flows, we show that topologically protected sound modes can arise in a steady-state active system in continuum space. We point out that the net vorticity of the steady-state flow, which acts as a counterpart of the gauge field in condensed-matter settings, must vanish under realistic conditions for active systems. The quantum anomalous Hall effect thus provides design principles for realizing topological metamaterials. We propose and analyze the concrete minimal model and numerically calculate its band structure and eigenvectors, demonstrating the emergence of nonzero bulk topological invariants with the corresponding edge sound modes. This new type of topological active systems can potentially expand possibilities for their experimental realizations and may have broad applications to practical active metamaterials. Possible realization of non-Hermitian topological phenomena in active systems is also discussed.
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Affiliation(s)
- Kazuki Sone
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Yuto Ashida
- Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Abstract
Bacterial chemotaxis, the directed movement of cells along gradients of chemoattractants, is among the best-characterized subjects in molecular biology1-10, but much less is known about its physiological roles11. It is commonly seen as a starvation response when nutrients run out, or as an escape response from harmful situations12-16. Here we identify an alternative role of chemotaxis by systematically examining the spatiotemporal dynamics of Escherichia coli in soft agar12,17,18. Chemotaxis in nutrient-replete conditions promotes the expansion of bacterial populations into unoccupied territories well before nutrients run out in the current environment. Low levels of chemoattractants act as aroma-like cues in this process, establishing the direction and enhancing the speed of population movement along the self-generated attractant gradients. This process of navigated range expansion spreads faster and yields larger population gains than unguided expansion following the canonical Fisher-Kolmogorov dynamics19,20 and is therefore a general strategy to promote population growth in spatially extended, nutrient-replete environments.
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Painter KJ. Mathematical models for chemotaxis and their applications in self-organisation phenomena. J Theor Biol 2019; 481:162-182. [DOI: 10.1016/j.jtbi.2018.06.019] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/20/2018] [Accepted: 06/22/2018] [Indexed: 01/31/2023]
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Numerical Simulation of a Multiscale Cell Motility Model Based on the Kinetic Theory of Active Particles. Symmetry (Basel) 2019. [DOI: 10.3390/sym11081003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In this work, we deal with a kinetic model of cell movement that takes into consideration the structure of the extracellular matrix, considering cell membrane reactions, haptotaxis, and chemotaxis, which plays a key role in a number of biological processes such as wound healing and tumor cell invasion. The modeling is performed at a microscopic scale, and then, a scaling limit is performed to derive the macroscopic model. We run some selected numerical experiments aimed at understanding cell movement and adhesion under certain documented situations, and we measure the alignment of the cells and compare it with the pathways determined by the extracellular matrix by introducing new alignment operators.
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Bae GH, Baek SK. Discontinuous phase transition in chemotactic aggregation with density-dependent pressure. Phys Rev E 2019; 100:022605. [PMID: 31574670 DOI: 10.1103/physreve.100.022605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Indexed: 06/10/2023]
Abstract
Many small organisms such as bacteria can attract each other by depositing chemical attractants. At the same time, they exert repulsive force on each other when crowded, which can be modeled by effective pressure as an increasing function of the organisms' density. As the chemical attraction becomes strong compared to the effective pressure, the system will undergo a phase transition from homogeneous distribution to aggregation. In this work, we describe the interplay of organisms and chemicals on a two-dimensional disk with a set of partial differential equations of the Patlak-Keller-Segel type. By analyzing its Lyapunov functional, we show that the aggregation transition occurs discontinuously, forming an aggregate near the boundary of the disk. The result can be interpreted within a thermodynamic framework by identifying the Lyapunov functional with free energy.
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Affiliation(s)
- Gyu Ho Bae
- Department of Physics, Pukyong National University, Busan 48513, Korea
| | - Seung Ki Baek
- Department of Physics, Pukyong National University, Busan 48513, Korea
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50
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Sathyamoorthy R, Maoz A, Pasternak Z, Im H, Huppert A, Kadouri D, Jurkevitch E. Bacterial predation under changing viscosities. Environ Microbiol 2019; 21:2997-3010. [DOI: 10.1111/1462-2920.14696] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 03/23/2019] [Accepted: 05/24/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Rajesh Sathyamoorthy
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment The Hebrew University of Jerusalem Rehovot Israel
| | - Anat Maoz
- Bio‐statistical Unit, The Gertner Institute for Epidemiology and Health Policy Research Chaim Sheba Medical Center Tel Hashomer Israel
| | - Zohar Pasternak
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment The Hebrew University of Jerusalem Rehovot Israel
| | - Hansol Im
- School of Life Sciences Ulsan National Institute of Science & Technology 50 UNIST‐gil Ulju‐gun, Ulsan 44919 Republic of Korea
| | - Amit Huppert
- Bio‐statistical Unit, The Gertner Institute for Epidemiology and Health Policy Research Chaim Sheba Medical Center Tel Hashomer Israel
| | - Daniel Kadouri
- Department of Oral Biology Rutgers School of Dental Medicine Newark NJ USA
| | - Edouard Jurkevitch
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment The Hebrew University of Jerusalem Rehovot Israel
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