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Wu J, Li X, Kong R, Wang J, Wang X. Analysis of biofilm expansion rate of Bacillus subtilis (MTC871) on agar substrates with different stiffness. Can J Microbiol 2023; 69:479-487. [PMID: 37379574 DOI: 10.1139/cjm-2022-0259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
The surface morphology of mature biofilms is heterogeneous and can be divided into concentric rings wrinkles (I), labyrinthine networks wrinkles (II), radial ridges wrinkles (III), and branches wrinkles (IV), according to surface wrinkle structure and distribution characteristics. Due to the wrinkle structures, channels are formed between the biofilm and substrate and transport nutrients, water, metabolic products, etc. We find that expansion rate variations of biofilms growing on substrates with high and low agar concentrations (1.5, 2.0, 2.5 wt.%) are not in the same phase. In the first 3 days' growth, the interaction stress between biofilm and each agar substrate increases, which makes the biofilm expansion rate decreases before wrinkle pattern IV (branches) comes up. After 3 days, in the later growth stage after wrinkle pattern IV appears, the biofilm has larger expansion rate growing on 2.0 wt.% agar concentration, which has the larger wrinkle distance in wrinkle pattern IV reducing energy consumption. Our study shows that the stiff substrate does not always inhibit the biofilm expansion, although it does in the earlier stage; after that, mature biofilms acquire larger expansion rate by adjusting the growth mode through the wrinkle evolution even in nutrient extremely depletion.
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Affiliation(s)
- Jin Wu
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Xianyong Li
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Rui Kong
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Jiankun Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Xiaoling Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing 100083, China
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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2
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Bera P, Wasim A, Ghosh P. Interplay of cell motility and self-secreted extracellular polymeric substance induced depletion effects on spatial patterning in a growing microbial colony. SOFT MATTER 2023; 19:8136-8149. [PMID: 37847026 DOI: 10.1039/d3sm01144e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Reproducing bacteria self-organize to develop patterned biofilms in various conditions. Various factors contribute to the shaping of a multicellular bacterial organization. Here we investigate how motility force and self-secreted extracellular polymeric substances (EPS) influence bacterial cell aggregation, leading to phase-separated colonies using a particle-based/individual-based model. Our findings highlight the critical role of the interplay between motility force and depletion effects in regulating phase separation within a growing colony under far-from-equilibrium conditions. We observe that increased motility force hinders depletion-induced cell aggregation and phase segregation, necessitating a higher depletion effect for highly motile bacteria to undergo phase separation within a growing biofilm. We present a phase diagram illustrating the systematic variation of motility force and repulsive mechanical force, shedding light on the combined contributions of these two factors: self-propulsive motion and aggregation due to the depletion effect, resulting in the presence of small to large bacterial aggregates. Furthermore, our study reveals the dynamic nature of clustering, marked by changes in cluster size over time. Additionally, our findings suggest that differential dispersion among the components can lead to the localization of EPS at the periphery of a growing colony. Our study enhances the understanding of the collective dynamics of motile bacterial cells within a growing colony, particularly in the presence of a self-secreted polymer-driven depletion effect.
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Affiliation(s)
- Palash Bera
- Tata Institute of Fundamental Research Hyderabad, Telangana 500046, India
| | - Abdul Wasim
- Tata Institute of Fundamental Research Hyderabad, Telangana 500046, India
| | - Pushpita Ghosh
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala, 695551, India.
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3
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Li X, Kong R, Wang J, Wu J, Wang X. Matrix Producing Cells Induce the Morphological Difference in the Bacillus subtilis Biofilm. Indian J Microbiol 2023; 63:197-207. [PMID: 37325022 PMCID: PMC10267082 DOI: 10.1007/s12088-023-01073-w] [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: 10/29/2022] [Accepted: 02/24/2023] [Indexed: 03/09/2023] Open
Abstract
There is a 'coffee ring' in the Bacillus subtilis biofilm center, and the colony biofilm morphologies are distinct inside and outside the 'coffee ring'. In this paper, we study this morphological difference and explain the reasons of the 'coffee ring' formation and further the causes to the morphological variation. We developed a quantitative method to characterize the surface morphology, the outer area is thicker than the inner area of the 'coffee ring', and the thickness amplitude in outer area is larger than inner area of the 'coffee ring'. We adopt a logistic growth model to obtain how the environmental resistance influence the colony biofilm thickness. Dead cells provide gaps for stress release and make folds formation in colony biofilm. we developed a technique for optical imaging and matching cells with the BRISK algorithm to capture the distribution and movement of motile cells and matrix producing cells in the colony biofilm. Matrix producing cells are mainly distribute in the outside of the 'coffee ring', and the extracellular matrix (ECM) prevents the motile cells moving outward from center. Motile cells mainly locate inside the ring, a small amount of dead motile cells outside the 'coffee ring' give rise to radial folds formation. There are no ECM blocking cell movements inside the ring, which result in uniform folds formation. The distribution of ECM and different phenotypes lead to the formation of the 'coffee ring', which is verified by using eps and flagellar mutants.
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Affiliation(s)
- Xianyong Li
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083 China
| | - Rui Kong
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083 China
| | - Jiankun Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083 China
| | - Jin Wu
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083 China
| | - Xiaoling Wang
- School of Mechanical Engineering, University of Science and Technology Beijing, Beijing, 100083 China
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 USA
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4
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Bera P, Wasim A, Ghosh P. A mechanistic understanding of microcolony morphogenesis: coexistence of mobile and sessile aggregates. SOFT MATTER 2023; 19:1034-1045. [PMID: 36648295 DOI: 10.1039/d2sm01365g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Most bacteria in the natural environment self-organize into collective phases such as cell clusters, swarms, patterned colonies, or biofilms. Several intrinsic and extrinsic factors, such as growth, motion, and physicochemical interactions, govern the occurrence of different phases and their coexistence. Hence, predicting the conditions under which a collective phase emerges due to individual-level interactions is crucial. Here we develop a particle-based biophysical model of bacterial cells and self-secreted extracellular polymeric substances (EPS) to decipher the interplay of growth, motility-mediated dispersal, and mechanical interactions during microcolony morphogenesis. We show that the microcolony dynamics and architecture significantly vary depending upon the heterogeneous EPS production. In particular, microcolony shows the coexistence of both motile and sessile aggregates rendering a transition towards biofilm formation. We identified that the interplay of differential dispersion and the mechanical interactions among the components of the colony determines the fate of the colony morphology. Our results provide a significant understanding of the mechano-self-regulation during biofilm morphogenesis and open up possibilities of designing experiments to test the predictions.
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Affiliation(s)
- Palash Bera
- Tata Institute of Fundamental Research Hyderabad, Telangana, 500046, India
| | - Abdul Wasim
- Tata Institute of Fundamental Research Hyderabad, Telangana, 500046, India
| | - Pushpita Ghosh
- School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala, 695551, India.
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5
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Artificial Human Sweat as a Novel Growth Condition for Clinically Relevant Pathogens on Hospital Surfaces. Microbiol Spectr 2022; 10:e0213721. [PMID: 35357242 PMCID: PMC9045197 DOI: 10.1128/spectrum.02137-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The emergence of biofilms on dry hospital surfaces has led to the development of numerous models designed to challenge the efficacious properties of common antimicrobial agents used in cleaning. This is in spite of limited research defining how dry surfaces are able to facilitate biofilm growth and formation in such desiccating and nutrient-deprived environments. While it is well established that the phenotypical response of biofilms is dependent on the conditions in which they are formed, most models incorporate a nutrient-enriched, hydrated environment dissimilar to the clinical setting. In this study, we piloted a novel culture medium, artificial human sweat (AHS), which is perceived to be more indicative of the nutrient sources available on hospital surfaces, particularly those in close proximity to patients. AHS was capable of sustaining the proliferation of four clinically relevant multidrug-resistant pathogens (Acinetobacter baumannii, Staphylococcus aureus, Enterococcus faecalis, and Pseudomonas aeruginosa) and achieved biofilm formation at concentration levels equivalent to those found in situ (average, 6.00 log10 CFU/cm2) with similar visual characteristics upon microscopy. The AHS model presented here could be used for downstream applications, including efficacy testing of hospital cleaning products, due to its resemblance to clinical biofilms on dry surfaces. This may contribute to a better understanding of the true impact these products have on surface hygiene. IMPORTANCE Precise modeling of dry surface biofilms in hospitals is critical for understanding their role in hospital-acquired infection transmission and surface contamination. Using a representative culture condition which includes a nutrient source is key to developing a phenotypically accurate biofilm community. This will enable accurate laboratory testing of cleaning products and their efficacy against dry surface biofilms.
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Bhowmik P, Rajagopal S, Hmar RV, Singh P, Saxena P, Amar P, Thomas T, Ravishankar R, Nagaraj S, Katagihallimath N, Sarangapani RK, Ramachandran V, Datta S. Validated In Silico Model for Biofilm Formation in Escherichia coli. ACS Synth Biol 2022; 11:713-731. [PMID: 35025506 DOI: 10.1021/acssynbio.1c00445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using Escherichia coli as the representative biofilm former, we report here the development of an in silico model built by simulating events that transform a free-living bacterial entity into self-encased multicellular biofilms. Published literature on ∼300 genes associated with pathways involved in biofilm formation was curated, static maps were created, and suitably interconnected with their respective metabolites using ordinary differential equations. Precise interplay of genetic networks that regulate the transitory switching of bacterial growth pattern in response to environmental changes and the resultant multicomponent synthesis of the extracellular matrix were appropriately represented. Subsequently, the in silico model was analyzed by simulating time-dependent changes in the concentration of components by using the R and python environment. The model was validated by simulating and verifying the impact of key gene knockouts (KOs) and systematic knockdowns on biofilm formation, thus ensuring the outcomes were comparable with the reported literature. Similarly, specific gene KOs in laboratory and pathogenic E. coli were constructed and assessed. MiaA, YdeO, and YgiV were found to be crucial in biofilm development. Furthermore, qRT-PCR confirmed the elevation of expression in biofilm-forming clinical isolates. Findings reported in this study offer opportunities for identifying biofilm inhibitors with applications in multiple industries. The application of this model can be extended to the health care sector specifically to develop novel adjunct therapies that prevent biofilms in medical implants and reduce emergence of biofilm-associated resistant polymicrobial-chronic infections. The in silico framework reported here is open source and accessible for further enhancements.
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Affiliation(s)
- Purnendu Bhowmik
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Sreenath Rajagopal
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Rothangamawi Victoria Hmar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Purnima Singh
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Pragya Saxena
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Prakruthi Amar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Teby Thomas
- St. John’s Research Institute, Bengaluru, Karnataka 560034, India
| | - Rajani Ravishankar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Savitha Nagaraj
- St. John’s Medical College, Bengaluru, Karnataka 560034, India
| | - Nainesh Katagihallimath
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Ramanujan Kadambi Sarangapani
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Vasanthi Ramachandran
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Santanu Datta
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
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7
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Bera P, Wasim A, Mondal J, Ghosh P. Mechanistic underpinning of cell aspect ratio-dependent emergent collective motions in swarming bacteria. SOFT MATTER 2021; 17:7322-7331. [PMID: 34286783 DOI: 10.1039/d1sm00311a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Self-propelled bacteria can exhibit a large variety of non-equilibrium self-organized phenomena. Swarming is one such fascinating dynamical scenario where a number of motile individuals group into dynamical clusters and move in synchronized flows and vortices. While precedent investigations into rod-like particles confirm that an increased aspect-ratio promotes alignment and order, recent experimental studies in bacteria Bacillus subtilis show a non-monotonic dependence of the cell-aspect ratio on their swarming motion. Here, by computer simulations of an agent-based model of self-propelled, mechanically interacting, rod-shaped bacteria under overdamped conditions, we explore the collective dynamics of a bacterial swarm subjected to a variety of cell-aspect ratios. When modeled with an identical self-propulsion speed across a diverse range of cell aspect ratios, simulations demonstrate that both shorter and longer bacteria exhibit slow dynamics whereas the fastest speed is obtained at an intermediate aspect ratio. Our investigation highlights that the origin of this observed non-monotonic trend of bacterial speed and vorticity with the cell-aspect ratio is rooted in the cell-size dependence of motility force. The swarming features remain robust for a wide range of surface density of the cells, whereas asymmetry in friction attributes a distinct effect. Our analysis identifies that at an intermediate aspect ratio, an optimum cell size and motility force promote alignment, which reinforces the mechanical interactions among neighboring cells leading to the overall fastest motion. Mechanistic underpinning of the collective motions reveals that it is a joint venture of the short-range repulsive and the size-dependent motility forces, which determines the characteristics of swarming.
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Affiliation(s)
- Palash Bera
- Tata Institute of Fundamental Research Hyderabad, Telangana 500046, India.
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8
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Grobas I, Polin M, Asally M. Swarming bacteria undergo localized dynamic phase transition to form stress-induced biofilms. eLife 2021; 10:62632. [PMID: 33722344 PMCID: PMC7963483 DOI: 10.7554/elife.62632] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 02/26/2021] [Indexed: 12/23/2022] Open
Abstract
Self-organized multicellular behaviors enable cells to adapt and tolerate stressors to a greater degree than isolated cells. However, whether and how cellular communities alter their collective behaviors adaptively upon exposure to stress is largely unclear. Here, we investigate this question using Bacillus subtilis, a model system for bacterial multicellularity. We discover that, upon exposure to a spatial gradient of kanamycin, swarming bacteria activate matrix genes and transit to biofilms. The initial stage of this transition is underpinned by a stress-induced multilayer formation, emerging from a biophysical mechanism reminiscent of motility-induced phase separation (MIPS). The physical nature of the process suggests that stressors which suppress the expansion of swarms would induce biofilm formation. Indeed, a simple physical barrier also induces a swarm-to-biofilm transition. Based on the gained insight, we propose a strategy of antibiotic treatment to inhibit the transition from swarms to biofilms by targeting the localized phase transition.
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Affiliation(s)
- Iago Grobas
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom
| | - Marco Polin
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom.,Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, United Kingdom.,Physics Department, University of Warwick, Coventry, United Kingdom.,Mediterranean Institute for Advanced Studies (IMEDEA UIB-CSIC), C/ Miquel Marqués, Balearic Islands, Spain
| | - Munehiro Asally
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry, United Kingdom.,Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, United Kingdom.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
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9
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A Dual-Species Biofilm with Emergent Mechanical and Protective Properties. J Bacteriol 2019; 201:JB.00670-18. [PMID: 30833350 DOI: 10.1128/jb.00670-18] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 02/23/2019] [Indexed: 12/14/2022] Open
Abstract
Many microbes coexist within biofilms, or multispecies communities of cells encased in an extracellular matrix. However, little is known about the microbe-microbe interactions relevant for creating these structures. In this study, we explored a striking dual-species biofilm between Bacillus subtilis and Pantoea agglomerans that exhibited characteristics that were not predictable from previous work examining monoculture biofilms. Coculture wrinkle formation required a P. agglomerans exopolysaccharide as well as the B. subtilis amyloid-like protein TasA. Unexpectedly, other B. subtilis matrix components essential for monoculture biofilm formation were not necessary for coculture wrinkling (e.g., the exopolysaccharide EPS, the hydrophobin BslA, and cell chaining). In addition, B. subtilis cell chaining prevented coculture wrinkling, even though chaining was previously associated with more robust monoculture biofilms. We also observed that increasing the relative proportion of P. agglomerans (which forms completely featureless monoculture colonies) increased coculture wrinkling. Using microscopy and rheology, we observed that these two bacteria assemble into an organized layered structure that reflects the physical properties of both monocultures. This partitioning into distinct regions negatively affected the survival of P. agglomerans while also serving as a protective mechanism in the presence of antibiotic stress. Taken together, these data indicate that studying cocultures is a productive avenue to identify novel mechanisms that drive the formation of structured microbial communities.IMPORTANCE In the environment, many microbes form biofilms. However, the interspecies interactions underlying bacterial coexistence within these biofilms remain understudied. Here, we mimic environmentally relevant biofilms by studying a dual-species biofilm formed between Bacillus subtilis and Pantoea agglomerans and subjecting the coculture to chemical and physical stressors that it may experience in the natural world. We determined that both bacteria contribute structural elements to the coculture, which is reflected in its overall viscoelastic behavior. Existence within the coculture can be either beneficial or detrimental depending on the context. Many of the features and determinants of the coculture biofilm appear distinct from those identified in monoculture biofilm studies, highlighting the importance of characterizing multispecies consortia to understand naturally occurring bacterial interactions.
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10
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Brown JR, Jurcisek J, Lakhani V, Snedden A, Ray WC, Mokrzan EM, Bakaletz LO, Das J. In Silico Modeling of Biofilm Formation by Nontypeable Haemophilus influenzae In Vivo. mSphere 2019; 4:e00254-19. [PMID: 31366707 PMCID: PMC6669334 DOI: 10.1128/msphere.00254-19] [Citation(s) in RCA: 10] [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: 04/04/2019] [Accepted: 07/08/2019] [Indexed: 01/08/2023] Open
Abstract
Biofilms formed by nontypeable Haemophilus influenzae (NTHI) bacteria play an important role in multiple respiratory tract diseases. Visual inspection of the morphology of biofilms formed during chronic infections shows distinct differences from biofilms formed in vitro To better understand these differences, we analyzed images of NTHI biofilms formed in the middle ears of Chinchilla lanigera and developed an in silico agent-based model of the formation of NTHI biofilms in vivo We found that, as in vitro, NTHI bacteria are organized in self-similar patterns; however, the sizes of NTHI clusters in vivo are more than 10-fold smaller than their in vitro counterparts. The agent-based model reproduced these patterns and suggested that smaller clusters occur due to elimination of planktonic NTHI cells by the host responses. Estimation of model parameters by fitting simulation results to imaging data showed that the effects of several processes in the model change during the course of the infection.IMPORTANCE Multiple respiratory illnesses are associated with formation of biofilms within the human airway by NTHI. However, a substantial amount of our understanding of the mechanisms that underlie NTHI biofilm formation is obtained from in vitro studies. Our in silico model that describes biofilm formation by NTHI within the middle ears of Chinchilla lanigera will help isolate processes potentially responsible for the differences between the morphologies of biofilms formed in vivo versus those formed in vitro Thus, the in silico model can be used to glean mechanisms that underlie biofilm formation in vivo and connect those mechanisms to those obtained from in vitro experiments. The in silico model developed here can be extended to investigate potential roles of specific host responses (e.g., mucociliary clearance) on NTHI biofilm formation in vivo The developed computational tools can also be used to analyze and describe biofilm formation by other bacterial species in vivo.
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Affiliation(s)
- Jonathan R Brown
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Joseph Jurcisek
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Vinal Lakhani
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Ali Snedden
- High Performance Computing Center, The Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - William C Ray
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, College of Medicine, the Ohio State University, Columbus, Ohio, USA
- Department of Biophysics Graduate Program, the Ohio State University, Columbus, Ohio, USA
| | - Elaine M Mokrzan
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Lauren O Bakaletz
- Department of Pediatrics, College of Medicine, the Ohio State University, Columbus, Ohio, USA
- Center for Microbial Pathogenesis, The Abigail Wexner Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
| | - Jayajit Das
- Battelle Center for Mathematical Medicine, The Research Institute at the Nationwide Children's Hospital, Columbus, Ohio, USA
- Department of Pediatrics, College of Medicine, the Ohio State University, Columbus, Ohio, USA
- Department of Biophysics Graduate Program, the Ohio State University, Columbus, Ohio, USA
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11
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García García T, Ventroux M, Derouiche A, Bidnenko V, Correia Santos S, Henry C, Mijakovic I, Noirot-Gros MF, Poncet S. Phosphorylation of the Bacillus subtilis Replication Controller YabA Plays a Role in Regulation of Sporulation and Biofilm Formation. Front Microbiol 2018; 9:486. [PMID: 29619013 PMCID: PMC5871692 DOI: 10.3389/fmicb.2018.00486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/01/2018] [Indexed: 11/13/2022] Open
Abstract
Bacillus subtilis cells can adopt different life-styles in response to various environmental cues, including planktonic cells during vegetative growth, sessile cells during biofilm formation and sporulation. While switching life-styles, bacteria must coordinate the progression of their cell cycle with their physiological status. Our current understanding of the regulatory pathways controlling the decision-making processes and triggering developmental switches highlights a key role of protein phosphorylation. The regulatory mechanisms that integrate the bacterial chromosome replication status with sporulation involve checkpoint proteins that target the replication initiator DnaA or the kinase phosphorelay controlling the master regulator Spo0A. B. subtilis YabA is known to interact with DnaA to prevent over-initiation of replication during vegetative growth. Here, we report that YabA is phosphorylated by YabT, a Ser/Thr kinase expressed during sporulation and biofilm formation. The phosphorylation of YabA has no effect on replication initiation control but hyper-phosphorylation of YabA leads to an increase in sporulation efficiency and a strong inhibition of biofilm formation. We also provide evidence that YabA phosphorylation affects the level of Spo0A-P in cells. These results indicate that YabA is a multifunctional protein with a dual role in regulating replication initiation and life-style switching, thereby providing a potential mechanism for cross-talk and coordination of cellular processes during adaptation to environmental change.
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Affiliation(s)
| | - Magali Ventroux
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | | | - Vladimir Bidnenko
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sara Correia Santos
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Céline Henry
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Ivan Mijakovic
- Systems and Synthetic Biology, Chalmers University of Technology, Göteborg, Sweden
| | | | - Sandrine Poncet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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12
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Mukherjee M, Ghosh P. Growth-mediated autochemotactic pattern formation in self-propelling bacteria. Phys Rev E 2018; 97:012413. [PMID: 29448366 DOI: 10.1103/physreve.97.012413] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Indexed: 06/08/2023]
Abstract
Bacteria, while developing a multicellular colony or biofilm, can undergo pattern formation by diverse intricate mechanisms. One such route is directional movement or chemotaxis toward or away from self-secreted or externally employed chemicals. In some bacteria, the self-produced signaling chemicals or autoinducers themselves act as chemoattractants or chemorepellents and thereby regulate the directional movements of the cells in the colony. In addition, bacteria follow a certain growth kinetics which is integrated in the process of colony development. Here, we study the interplay of bacterial growth dynamics, cell motility, and autochemotactic motion with respect to the self-secreted diffusive signaling chemicals in spatial pattern formation. Using a continuum model of motile bacteria, we show growth can act as a crucial tuning parameter in determining the spatiotemporal dynamics of a colony. In action of growth dynamics, while chemoattraction toward autoinducers creates arrested phase separation, pattern transitions and suppression can occur for a fixed chemorepulsive strength.
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Affiliation(s)
| | - Pushpita Ghosh
- Tata Institute of Fundamental Research, Hyderabad 500107, India
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Extracellular DNA and Type IV Pilus Expression Regulate the Structure and Kinetics of Biofilm Formation by Nontypeable Haemophilus influenzae. mBio 2017; 8:mBio.01466-17. [PMID: 29259083 PMCID: PMC5736908 DOI: 10.1128/mbio.01466-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Biofilms formed in the middle ear by nontypeable Haemophilus influenzae (NTHI) are central to the chronicity, recurrence, and refractive nature of otitis media (OM). However, mechanisms that underlie the emergence of specific NTHI biofilm structures are unclear. We combined computational analysis tools and in silico modeling rooted in statistical physics with confocal imaging of NTHI biofilms formed in vitro during static culture in order to identify mechanisms that give rise to distinguishing morphological features. Our analysis of confocal images of biofilms formed by NTHI strain 86-028NP using pair correlations of local bacterial densities within sequential planes parallel to the substrate showed the presence of fractal structures of short length scales (≤10 μm). The in silico modeling revealed that extracellular DNA (eDNA) and type IV pilus (Tfp) expression played important roles in giving rise to the fractal structures and allowed us to predict a substantial reduction of these structures for an isogenic mutant (ΔcomE) that was significantly compromised in its ability to release eDNA into the biofilm matrix and had impaired Tfp function. This prediction was confirmed by analysis of confocal images of in vitro ΔcomE strain biofilms. The fractal structures potentially generate niches for NTHI survival in the hostile middle ear microenvironment by dramatically increasing the contact area of the biofilm with the surrounding environment, facilitating nutrient exchange, and by generating spatial positive feedback to quorum signaling. NTHI is a major bacterial pathogen for OM, which is a common ear infection in children worldwide. Chronic OM is associated with bacterial biofilm formation in the middle ear; therefore, knowledge of the mechanisms that underlie NTHI biofilm formation is important for the development of therapeutic strategies for NTHI-associated OM. Our combined approach using confocal imaging of NTHI biofilms formed in vitro and mathematical tools for analysis of pairwise density correlations and agent-based modeling revealed that eDNA and Tfp expression were important factors in the development of fractal structures in NTHI biofilms. These structures may help NTHI survive in hostile environments, such as the middle ear. Our in silico model can be used in combination with laboratory or animal modeling studies to further define the mechanisms that underlie NTHI biofilm development during OM and thereby guide the rational design of, and optimize time and cost for, benchwork and preclinical studies.
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Rana N, Ghosh P, Perlekar P. Spreading of nonmotile bacteria on a hard agar plate: Comparison between agent-based and stochastic simulations. Phys Rev E 2017; 96:052403. [PMID: 29347735 DOI: 10.1103/physreve.96.052403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Indexed: 06/07/2023]
Abstract
We study spreading of a nonmotile bacteria colony on a hard agar plate by using agent-based and continuum models. We show that the spreading dynamics depends on the initial nutrient concentration, the motility, and the inherent demographic noise. Population fluctuations are inherent in an agent-based model, whereas for the continuum model we model them by using a stochastic Langevin equation. We show that the intrinsic population fluctuations coupled with nonlinear diffusivity lead to a transition from a diffusion limited aggregation type of morphology to an Eden-like morphology on decreasing the initial nutrient concentration.
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Affiliation(s)
- Navdeep Rana
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500107, India
| | - Pushpita Ghosh
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500107, India
| | - Prasad Perlekar
- Tata Institute of Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500107, India
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Ghosh P, Levine H. Morphodynamics of a growing microbial colony driven by cell death. Phys Rev E 2017; 96:052404. [PMID: 29347664 DOI: 10.1103/physreve.96.052404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Indexed: 06/07/2023]
Abstract
Bacterial cells can often self-organize into multicellular structures with complex spatiotemporal morphology. In this work, we study the spatiotemporal dynamics of a growing microbial colony in the presence of cell death. We present an individual-based model of nonmotile bacterial cells which grow and proliferate by consuming diffusing nutrients on a semisolid two-dimensional surface. The colony spreads by growth forces and sliding motility of cells and undergoes cell death followed by subsequent disintegration of the dead cells in the medium. We model cell death by considering two possible situations: In one of the cases, cell death occurs in response to the limitation of local nutrients, while the other case corresponds to an active death process, known as apoptotic or programmed cell death. We demonstrate how the colony morphology is influenced by the presence of cell death. Our results show that cell death facilitates transitions from roughly circular to highly branched structures at the periphery of an expanding colony. Interestingly, our results also reveal that for the colonies which are growing in higher initial nutrient concentrations, cell death occurs much earlier compared to the colonies which are growing in lower initial nutrient concentrations. This work provides new insights into the branched patterning of growing bacterial colonies as a consequence of complex interplay among the biochemical and mechanical effects.
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Affiliation(s)
- Pushpita Ghosh
- Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad 500107, India
| | - Herbert Levine
- Center for Theoretical Biological Physics, Rice University, Texas 77005, USA
- Department of Bioengineering, Rice University, Texas 77005, USA
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Azeredo J, Azevedo NF, Briandet R, Cerca N, Coenye T, Costa AR, Desvaux M, Di Bonaventura G, Hébraud M, Jaglic Z, Kačániová M, Knøchel S, Lourenço A, Mergulhão F, Meyer RL, Nychas G, Simões M, Tresse O, Sternberg C. Critical review on biofilm methods. Crit Rev Microbiol 2016; 43:313-351. [PMID: 27868469 DOI: 10.1080/1040841x.2016.1208146] [Citation(s) in RCA: 541] [Impact Index Per Article: 67.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Biofilms are widespread in nature and constitute an important strategy implemented by microorganisms to survive in sometimes harsh environmental conditions. They can be beneficial or have a negative impact particularly when formed in industrial settings or on medical devices. As such, research into the formation and elimination of biofilms is important for many disciplines. Several new methodologies have been recently developed for, or adapted to, biofilm studies that have contributed to deeper knowledge on biofilm physiology, structure and composition. In this review, traditional and cutting-edge methods to study biofilm biomass, viability, structure, composition and physiology are addressed. Moreover, as there is a lack of consensus among the diversity of techniques used to grow and study biofilms. This review intends to remedy this, by giving a critical perspective, highlighting the advantages and limitations of several methods. Accordingly, this review aims at helping scientists in finding the most appropriate and up-to-date methods to study their biofilms.
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Affiliation(s)
- Joana Azeredo
- a CEB ? Centre of Biological Engineering, LIBRO, Laboratórios de Biofilmes Rosário Oliveira, University of Minho Campus de Gualtar , Braga , Portugal
| | - Nuno F Azevedo
- b LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
| | - Romain Briandet
- c Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay , Jouy-en-Josas , France
| | - Nuno Cerca
- a CEB ? Centre of Biological Engineering, LIBRO, Laboratórios de Biofilmes Rosário Oliveira, University of Minho Campus de Gualtar , Braga , Portugal
| | - Tom Coenye
- d Laboratory of Pharmaceutical Microbiology , Ghent University , Ghent , Belgium
| | - Ana Rita Costa
- a CEB ? Centre of Biological Engineering, LIBRO, Laboratórios de Biofilmes Rosário Oliveira, University of Minho Campus de Gualtar , Braga , Portugal
| | - Mickaël Desvaux
- e INRA Centre Auvergne-Rhône-Alpes , UR454 Microbiologie , Saint-Genès Champanelle , France
| | - Giovanni Di Bonaventura
- f Department of Medical, Oral, and Biotechnological Sciences, and Center of Excellence on Aging and Translational Medicine (CeSI-MeT) , "G. d'Annunzio" University of Chieti-Pescara , Chieti , Italy
| | - Michel Hébraud
- e INRA Centre Auvergne-Rhône-Alpes , UR454 Microbiologie , Saint-Genès Champanelle , France
| | - Zoran Jaglic
- g Department of Food and Feed Safety, Laboratory of Food Bacteriology , Veterinary Research Institute , Brno , Czech Republic
| | - Miroslava Kačániová
- h Department of Microbiology, Faculty of Biotechnology and Food Sciences , Slovak University of Agriculture in Nitra , Nitra , Slovakia
| | - Susanne Knøchel
- i Department of Food Science (FOOD) , University of Copenhagen , Frederiksberg C , Denmark
| | - Anália Lourenço
- j Department of Computer Science , University of Vigo , Ourense , Spain
| | - Filipe Mergulhão
- b LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
| | - Rikke Louise Meyer
- k Aarhus University, Interdisciplinary Nanoscience Center (iNANO) , Aarhus , Denmark
| | - George Nychas
- l Agricultural University of Athens, Lab of Microbiology and Biotechnology of Foods , Athens , Greece
| | - Manuel Simões
- b LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
| | - Odile Tresse
- m LUNAM Université, Oniris, SECALIM UMR1024 INRA , Université de Nantes , Nantes , France
| | - Claus Sternberg
- n Department of Biotechnology and Biomedicine , Technical University of Denmark , Lyngby, Denmark
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Patra P, Kissoon K, Cornejo I, Kaplan HB, Igoshin OA. Colony Expansion of Socially Motile Myxococcus xanthus Cells Is Driven by Growth, Motility, and Exopolysaccharide Production. PLoS Comput Biol 2016; 12:e1005010. [PMID: 27362260 PMCID: PMC4928896 DOI: 10.1371/journal.pcbi.1005010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 06/02/2016] [Indexed: 12/21/2022] Open
Abstract
Myxococcus xanthus, a model organism for studies of multicellular behavior in bacteria, moves exclusively on solid surfaces using two distinct but coordinated motility mechanisms. One of these, social (S) motility is powered by the extension and retraction of type IV pili and requires the presence of exopolysaccharides (EPS) produced by neighboring cells. As a result, S motility requires close cell-to-cell proximity and isolated cells do not translocate. Previous studies measuring S motility by observing the colony expansion of cells deposited on agar have shown that the expansion rate increases with initial cell density, but the biophysical mechanisms involved remain largely unknown. To understand the dynamics of S motility-driven colony expansion, we developed a reaction-diffusion model describing the effects of cell density, EPS deposition and nutrient exposure on the expansion rate. Our results show that at steady state the population expands as a traveling wave with a speed determined by the interplay of cell motility and growth, a well-known characteristic of Fisher’s equation. The model explains the density-dependence of the colony expansion by demonstrating the presence of a lag phase–a transient period of very slow expansion with a duration dependent on the initial cell density. We propose that at a low initial density, more time is required for the cells to accumulate enough EPS to activate S-motility resulting in a longer lag period. Furthermore, our model makes the novel prediction that following the lag phase the population expands at a constant rate independent of the cell density. These predictions were confirmed by S motility experiments capturing long-term expansion dynamics. Collective motility is a key mechanism bacteria use to self-organize into multicellular structures and to adapt to various environments. An important example of such behavior is social (S) motility in the gram-negative bacterium Myxococcus xanthus. S-motile cells are restricted to movement in groups and do not move as individual cells. S-motility is powered by type IV pili (TFP)–multi-subunit filaments, which extrude from the cell poles, adhere to the substrate and retract, pulling the cell forward. TFP retraction or adhesion is suggested to be triggered by extracellular exopolysaccharides (EPS) deposited by cells on the substrate. As individual cells synthesize both pili and EPS, it is unclear why S-motile cells only exhibit group movement. Moreover, the experimentally observed initial cell-density dependence of S-motility remains unexplained. To understand these phenomena, we developed a mathematical model for the colony expansion of S-motile cells. Our model hypothesizes that the EPS level regulates the TFP activity that initiates collective cell movements. With this assumption, the model quantitatively matches the density-dependent expansion rate. Moreover, the model predicts two phases during colony expansion: an initial density-dependent lag phase with a slow expansion rate, followed by a faster expansion phase with a density-independent rate. These model predictions were confirmed by long-term colony expansion experiments.
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Affiliation(s)
- Pintu Patra
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
| | - Kimberley Kissoon
- Department of Natural Sciences, Del Mar College, Corpus Christi, Texas, United States of America
| | - Isabel Cornejo
- Department of Natural Sciences, University of Houston-Downtown, Houston, Texas, United States of America
| | - Heidi B. Kaplan
- Department of Microbiology and Molecular Genetics, University of Texas Medical School, Houston, Texas, United States of America
| | - Oleg A. Igoshin
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
- * E-mail:
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Boraey MA, Guaily A, Epstein M. A hybrid model for biofilm growth on a deformable substratum. CAN J CHEM ENG 2015. [DOI: 10.1002/cjce.22172] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Mechanically-driven phase separation in a growing bacterial colony. Proc Natl Acad Sci U S A 2015; 112:E2166-73. [PMID: 25870260 DOI: 10.1073/pnas.1504948112] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Secretion of extracellular polymeric substances (EPSs) by growing bacteria is an integral part of forming biofilm-like structures. In such dense systems, mechanical interactions among the structural components can be expected to significantly contribute to morphological properties. Here, we use a particle-based modeling approach to study the self-organization of nonmotile rod-shaped bacterial cells growing on a solid substrate in the presence of self-produced EPSs. In our simulation, all of the components interact mechanically via repulsive forces, occurring as the bacterial cells grow and divide (via consuming diffusing nutrient) and produce EPSs. Based on our simulation, we show that mechanical interactions control the collective behavior of the system. In particular, we find that the presence of nonadsorbing EPSs can lead to spontaneous aggregation of bacterial cells by a depletion attraction and thereby generates phase separated patterns in the nonequilibrium growing colony. Both repulsive interactions between cell and EPSs and the overall concentration of EPSs are important factors in the self-organization in a nonequilibrium growing colony. Furthermore, we investigate the interplay of mechanics with the nutrient diffusion and consumption by bacterial cells and observe that suppression of branch formation occurs due to EPSs compared with the case where no EPS is produced.
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