1
|
Xu S, Liu Z, Ren P, Liu Y, Xiao F, Li W. BmfR, a novel GntR family regulator, regulates biofilm formation in marine-derived, Bacillus methylotrophicus B-9987. Microbiol Res 2024; 287:127859. [PMID: 39098095 DOI: 10.1016/j.micres.2024.127859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2024] [Revised: 07/21/2024] [Accepted: 07/24/2024] [Indexed: 08/06/2024]
Abstract
Biofilms are common living states for microorganisms, allowing them to adapt to environmental changes. Numerous Bacillus strains can form complex biofilms that play crucial roles in biocontrol processes. However, our current understanding of the molecular mechanisms of biofilm formation in Bacillus is mainly based on studies of Bacillus subtilis. Knowledge regarding the biofilm formation of other Bacillus species remains limited. In this study, we identified a novel transcriptional regulator, BmfR, belonging to the GntR family, that regulates biofilm formation in marine-derived Bacillus methylotrophicus B-9987. We demonstrated that BmfR induces biofilm formation by activating the extracellular polysaccharide structural genes epsA-O and negatively regulating the matrix gene repressor, SinR; of note it positively affects the expression of the master regulator of sporulation, Spo0A. Furthermore, database mining for BmfR homologs has revealed their widespread distribution among many bacterial species, mainly Firmicutes and Proteobacteria. This study advances our understanding of the biofilm regulatory network of Bacillus strains, and provides a new target for exploiting and manipulating biofilm formation.
Collapse
Affiliation(s)
- Shanshan Xu
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Zengzhi Liu
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Pengfei Ren
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Yang Liu
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Fei Xiao
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China
| | - Wenli Li
- Key Laboratory of Marine Drugs, Ministry of Education, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China; State Key Laboratory for Crop Stress Resistance and High-Efficiency Production, Shaanxi Key Laboratory of Natural Products & Chemical Biology, College of Chemistry & Pharmacy, Northwest A&F University, Yangling, Shannxi 712100, China.
| |
Collapse
|
2
|
Puri D, Allison KR. Escherichia coli self-organizes developmental rosettes. Proc Natl Acad Sci U S A 2024; 121:e2315850121. [PMID: 38814871 PMCID: PMC11161754 DOI: 10.1073/pnas.2315850121] [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: 09/12/2023] [Accepted: 05/01/2024] [Indexed: 06/01/2024] Open
Abstract
Rosettes are self-organizing, circular multicellular communities that initiate developmental processes, like organogenesis and embryogenesis, in complex organisms. Their formation results from the active repositioning of adhered sister cells and is thought to distinguish multicellular organisms from unicellular ones. Though common in eukaryotes, this multicellular behavior has not been reported in bacteria. In this study, we found that Escherichia coli forms rosettes by active sister-cell repositioning. After division, sister cells "fold" to actively align at the 2- and 4-cell stages of clonal division, thereby producing rosettes with characteristic quatrefoil configuration. Analysis revealed that folding follows an angular random walk, composed of ~1 µm strokes and directional randomization. We further showed that this motion was produced by the flagellum, the extracellular tail whose rotation generates swimming motility. Rosette formation was found to require de novo flagella synthesis suggesting it must balance the opposing forces of Ag43 adhesion and flagellar propulsion. We went on to show that proper rosette formation was required for subsequent morphogenesis of multicellular chains, rpoS gene expression, and formation of hydrostatic clonal-chain biofilms. Moreover, we found self-folding rosette-like communities in the standard motility assay, indicating that this behavior may be a general response to hydrostatic environments in E. coli. These findings establish self-organization of clonal rosettes by a prokaryote and have implications for evolutionary biology, synthetic biology, and medical microbiology.
Collapse
Affiliation(s)
- Devina Puri
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA30322
| | - Kyle R. Allison
- Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, GA30322
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA30322
| |
Collapse
|
3
|
Raz C, Shemesh M, Argov-Argaman N. The role of milk fat globule size in modulating the composition of postbiotics produced by Bacillus subtilis and their effect on mammary epithelial cells. Food Chem 2023; 427:136730. [PMID: 37392632 DOI: 10.1016/j.foodchem.2023.136730] [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] [Received: 04/16/2023] [Revised: 06/15/2023] [Accepted: 06/24/2023] [Indexed: 07/03/2023]
Abstract
Milk lipids are secreted into the milk collecting ducts as milk fat globule (MFG) where they are exposed to microflora of the udder. We hypothesized that MFG size modulates the metabolic fingerprint of B. subtilis. Accordingly, small and large (2.3 and 7.0 µm, respectively) MFG were isolated from cow milk and used as a substrate for B. subtilis. Small MFG enhanced growth, whereas large MFG enhanced biofilm formation. Bacteria incubated with small MFG had increased concentration of metabolites related to energy production whereas metabolome of the bacteria incubated with large MFG had reduced concentrations of metabolites important for biofilm formation. Postbiotics from bacteria grown on large MFG exacerbated the proinflammatory response of MEC to LPS, and changed the expression of key enzymes involved in lipid and protein synthesis. Our results suggest that MFG size modulate growth trajectories and metabolome of B. subtilis, and consequently the stress response of host cells.
Collapse
Affiliation(s)
- Chen Raz
- Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Israel; Department of Food Sciences, Institute of Postharvest Technology and Food Sciences, Agricultural Research Organization, The Volcani Institute, Rishon LeZion 7528809, Israel.
| | - Moshe Shemesh
- Department of Food Sciences, Institute of Postharvest Technology and Food Sciences, Agricultural Research Organization, The Volcani Institute, Rishon LeZion 7528809, Israel.
| | - Nurit Argov-Argaman
- Department of Animal Sciences, The Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Israel.
| |
Collapse
|
4
|
Gallegos-Monterrosa R, Mendiola RO, Nuñez Y, Auvynet C, Kumar KM, Tang B, Ruiz-Ortega LI, Bustamante VH. Antibacterial and antibiofilm activities of ZIF-67. J Antibiot (Tokyo) 2023; 76:603-612. [PMID: 37337088 PMCID: PMC10522484 DOI: 10.1038/s41429-023-00637-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/05/2023] [Accepted: 05/20/2023] [Indexed: 06/21/2023]
Abstract
Currently, antibiotic-resistant bacteria represent a serious threat to public health worldwide. Biofilm formation potentiates both virulence and antibiotic resistance of bacteria. Therefore, the discovery of new antibacterial and antibiofilm compounds is an issue of paramount importance to combat and prevent hard-to-treat bacterial infections. Zeolitic-imidazolate-frameworks (ZIFs) are metallo-organic compounds known to have various interesting chemical and biological applications, including antibacterial properties. In this study, we synthesized ZIF-67 nanoparticles, formed by imidazolate anions and cobalt cations, and found that they inhibit the growth of Acinetobacter baumannii, Pseudomonas aeruginosa, and Staphylococcus aureus. Sub-inhibitory concentrations of ZIF-67 were also able to significantly reduce the biomass of pre-established biofilms of these pathogenic bacteria. On the other hand, the ZIF-67 nanoparticles had null or low cytotoxicity in mammalian cells at those concentrations showing antibacterial or antibiofilm activities. Thus, our results reveal the potential of ZIF-67 nanoparticles to be used against pathogenic bacteria.
Collapse
Affiliation(s)
- Ramses Gallegos-Monterrosa
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México
| | - Rodrigo Orozco Mendiola
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México
| | - Yoselin Nuñez
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México
| | - Constance Auvynet
- Departamento de Medicina Molecular y Bioprocesos, Instituto de Biotecnología, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México
| | - Kesarla Mohan Kumar
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México
| | - Bin Tang
- Department of Biomedical Engineering, Southern University of Science and Technology, 1088 Xueyuan Avenue, Shenzhen, 518055, PR China
| | - Leonardo I Ruiz-Ortega
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México.
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, C.P. 62210, Cuernavaca, Morelos, México.
| |
Collapse
|
5
|
Shen G, Yang L, Lv X, Zhang Y, Hou X, Li M, Zhou M, Pan L, Chen A, Zhang Z. Antibiofilm Activity and Mechanism of Linalool against Food Spoilage Bacillus amyloliquefaciens. Int J Mol Sci 2023; 24:10980. [PMID: 37446158 DOI: 10.3390/ijms241310980] [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: 05/26/2023] [Revised: 06/20/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023] Open
Abstract
Pellicle biofilm-forming bacteria Bacillus amyloliquefaciens are the major spoilage microorganisms of soy products. Due to their inherent resistance to antibiotics and disinfectants, pellicle biofilms formed are difficult to eliminate and represent a threat to food safety. Here, we assessed linalool's ability to prevent the pellicle of two spoilage B. amyloliquefaciens strains. The minimum biofilm inhibitory concentration (MBIC) of linalool against B. amyloliquefaciens DY1a and DY1b was 4 μL/mL and 8 μL/mL, respectively. The MBIC of linalool had a considerable eradication rate of 77.15% and 83.21% on the biofilm of the two strains, respectively. Scanning electron microscopy observations revealed that less wrinkly and thinner pellicle biofilms formed on a medium supplemented with 1/2 MBIC and 1/4 MBIC linalool. Also, linalool inhibited cell motility and the production of extracellular polysaccharides and proteins of the biofilm matrix. Furthermore, linalool exposure reduced the cell surface hydrophobicity, zeta potential, and cell auto-aggregation of B. amyloliquefaciens. Molecular docking analysis demonstrated that linalool interacted strongly with quorum-sensing ComP receptor and biofilm matrix assembly TasA through intermolecular hydrogen bonds, hydrophobic contacts, and van der Waals forces interacting with site residues. Overall, our findings suggest that linalool may be employed as a potential antibiofilm agent to control food spoilage B. amyloliquefaciens.
Collapse
Affiliation(s)
- Guanghui Shen
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Lu Yang
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xinyu Lv
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Yingfan Zhang
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Xiaoyan Hou
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Meiliang Li
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Man Zhou
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Le Pan
- Chemical Engineering College, Xinjiang Agricultural University, Urumqi 830052, China
| | - Anjun Chen
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| | - Zhiqing Zhang
- College of Food Science, Sichuan Agricultural University, Ya'an 625014, China
| |
Collapse
|
6
|
Mhade S, Kaushik KS. Tools of the Trade: Image Analysis Programs for Confocal Laser-Scanning Microscopy Studies of Biofilms and Considerations for Their Use by Experimental Researchers. ACS OMEGA 2023; 8:20163-20177. [PMID: 37332792 PMCID: PMC10268615 DOI: 10.1021/acsomega.2c07255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 05/11/2023] [Indexed: 06/20/2023]
Abstract
Confocal laser-scanning microscopy (CLSM) is the bedrock of the microscopic visualization of biofilms. Previous applications of CLSM in biofilm studies have largely focused on observations of bacterial or fungal elements of biofilms, often seen as aggregates or mats of cells. However, the field of biofilm research is moving beyond qualitative observations alone, toward the quantitative analysis of the structural and functional features of biofilms, across clinical, environmental, and laboratory conditions. In recent times, several image analysis programs have been developed to extract and quantify biofilm properties from confocal micrographs. These tools not only vary in their scope and relevance to the specific biofilm features under study but also with respect to the user interface, compatibility with operating systems, and raw image requirements. Understanding these considerations is important when selecting tools for quantitative biofilm analysis, including at the initial experimental stages of image acquisition. In this review, we provide an overview of image analysis programs for confocal micrographs of biofilms, with a focus on tool selection and image acquisition parameters that are relevant for experimental researchers to ensure reliability and compatibility with downstream image processing.
Collapse
Affiliation(s)
- Shreeya Mhade
- Department
of Biotechnology, Savitribai Phule Pune
University, Pune 411007, India
| | - Karishma S Kaushik
- Department
of Biotechnology, Savitribai Phule Pune
University, Pune 411007, India
| |
Collapse
|
7
|
Milton ME, Cavanagh J. The Biofilm Regulatory Network from Bacillus subtilis: A Structure-Function Analysis. J Mol Biol 2023; 435:167923. [PMID: 36535428 DOI: 10.1016/j.jmb.2022.167923] [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: 10/06/2022] [Revised: 12/02/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022]
Abstract
Bacterial biofilms are notorious for their ability to protect bacteria from environmental challenges, most importantly the action of antibiotics. Bacillus subtilis is an extensively studied model organism used to understand the process of biofilm formation. A complex network of principal regulatory proteins including Spo0A, AbrB, AbbA, Abh, SinR, SinI, SlrR, and RemA, work in concert to transition B. subtilis from the free-swimming planktonic state to the biofilm state. In this review, we explore, connect, and summarize decades worth of structural and biochemical studies that have elucidated this protein signaling network. Since structure dictates function, unraveling aspects of protein molecular mechanisms will allow us to devise ways to exploit critical features of the biofilm regulatory pathway, such as possible therapeutic intervention. This review pools our current knowledge base of B. subtilis biofilm regulatory proteins and highlights potential therapeutic intervention points.
Collapse
Affiliation(s)
- Morgan E Milton
- Department of Biochemistry and Molecular Biology, The Brody School of Medicine, East Carolina University, NC 27834, USA.
| | - John Cavanagh
- Department of Biochemistry and Molecular Biology, The Brody School of Medicine, East Carolina University, NC 27834, USA.
| |
Collapse
|
8
|
eDNA Provides a Scaffold for Autoaggregation of B. subtilis in Bacterioplankton Suspension. Microorganisms 2023; 11:microorganisms11020332. [PMID: 36838297 PMCID: PMC9966259 DOI: 10.3390/microorganisms11020332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/20/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
The self-binding of bacterial cells, or autoaggregation, is, together with surface colonization, one of the first steps in the formation of a mature biofilm. In this work, the autoaggregation of B. subtilis in dilute bacterial suspensions was studied. The dynamics of cell lysis, eDNA release, and bacterial autoaggregate assembly were determined and related to the spatial autocorrelation of bacterial cells in dilute planktonic bacterial suspensions. The non-random distribution of cells was associated with an eDNA network, which stabilized the initial bacterial cell-cell aggregates. Upon the addition of DNase I, the aggregates were dispersed. The release of eDNA during cell lysis allows for the entrapment of bacterial drifters at a radius several times the size of the dying bacteria. The size of bacterial aggregates increased from 2 to about 100 μm in diameter in dilute bacterial suspensions. The results suggest that B. subtilis cells form previously unnoticed continuum of autoaggregate structures during planktonic growth.
Collapse
|
9
|
Porous Pellicle Formation of a Filamentous Bacterium, Leptothrix. Appl Environ Microbiol 2022; 88:e0134122. [PMID: 36416549 PMCID: PMC9746318 DOI: 10.1128/aem.01341-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The bacterium Leptothrix cholodnii generates filaments encased in a sheath comprised of woven nanofibrils. In static liquid culture, L. cholodnii moves toward the air-liquid interface, where it forms porous pellicles. Observations of aggregation at the interface reveal that clusters consisting of only a few bacteria primarily grow by netting free cells. These growing clusters hierarchically enlarge through the random docking of other small clusters. We find that the bacteria swim using their polar flagellum toward the interface, where their sheath assists them in intertwining with others and thereby promotes the formation of small clusters. In contrast, sheathless hydrophobic mutant cells get stuck to the interface. We find that the nanofibril sheath is vital for robust pellicle formation as it lowers cell surface hydrophobicity by 60%, thereby reducing their adsorption and enabling cells to move toward and stick together at the air-liquid interface. IMPORTANCE Efficient and sustainable management of water resources is becoming a fundamental issue for supporting growing populations and for developing economic activity. Fundamental to this management is the treatment of wastewater. Microorganisms are the active component of activated sludge that is employed in the biodegradation process of many wastewater treatment facilities. However, uncontrolled growth of filamentous bacteria such as Sphaerotilus often results in filamentous bulking, lowering the efficiency of water treatment systems. To prevent this undesirable condition, strategies based on a fundamental understanding of the ecology of filamentous bacteria are required. Although the filamentous bacterium Leptothrix cholodnii, which is closely related to Sphaerotilus, is a minor inhabitant of activated sludge, its complete genome sequence is known, making gene manipulation relatively easy. Moreover, L. cholodnii generates porous pellicles under static conditions, which may be a characteristic of filamentous bulking. We show that both swimming motility and nanofibril-mediated air-liquid interface attachment are required for porous pellicle formation. These insights are critical for a better understanding of the characteristics of filamentous bulking and might improve strategies to control activated sludge.
Collapse
|
10
|
Fessia A, Sartori M, García D, Fernández L, Ponzio R, Barros G, Nesci A. In vitro studies of biofilm-forming Bacillus strains, biocontrol agents isolated from the maize phyllosphere. Biofilm 2022; 4:100097. [PMID: 36504526 PMCID: PMC9731887 DOI: 10.1016/j.bioflm.2022.100097] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/08/2022] [Accepted: 11/18/2022] [Indexed: 12/12/2022] Open
Abstract
We aimed to assess how biofilm formation by three Bacillus isolates was affected by changes in temperature, water potential, growth media, time, and the combinations between these factors. The strains had been selected as potential biological control agents (BCAs) in earlier studies, and they were identified as B. subtilis and B. velezensis spp. through 16 rRNA sequencing and MALDI-TOF MS. Maize leaves (ML) were used as one of the growth media, since they made it possible to simulate the nutrient content in the maize phyllosphere, from which the bacteria were originally isolated. The strains were able to form biofilm both in ML and biofilm-inducing MSgg after 24, 48, and 72 h. Biofilm development in the form of pellicles and architecturally complex colonies varied morphologically from one strain to another and depended on the conditions mentioned above. In all cases, colonies and pellicles were less complex when both temperature and water potential were lower. Scanning electron microscopy (SEM) revealed that changing levels of complexity in pellicles were correlated with those in colonies. Statistical analyses found that the quantification of biofilm produced by the isolates was influenced by all the conditions tested. In terms of motility (which may contribute to biofilm formation), swimming and swarming were possible for all strains in 0.3 and 0.7% agar, respectively. A more in-depth understanding of how abiotic factors influence biofilm formation can contribute to a more effective use of these biocontrol strains against pathogens in the maize phyllosphere.
Collapse
Affiliation(s)
- Aluminé Fessia
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina,Corresponding author. Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina.
| | - Melina Sartori
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Daiana García
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Luciana Fernández
- Departamento de Física, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, CONICET, X5804BYA, Río Cuarto, Argentina,Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Rodrigo Ponzio
- Departamento de Física, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, CONICET, X5804BYA, Río Cuarto, Argentina,Instituto de Investigaciones en Tecnologías Energéticas y Materiales Avanzados (IITEMA), Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Germán Barros
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| | - Andrea Nesci
- Laboratorio de Ecología Microbiana, Departamento de Microbiología e Inmunología, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Ruta Nacional 36, Km 601, X5804ZAB, Río Cuarto, Córdoba, Argentina,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina
| |
Collapse
|
11
|
de Almeida OGG, Pereira MG, Oxaran V, De Martinis ECP, Alves VF. In silico metatranscriptomic approach for tracking biofilm-related effectors in dairies and its importance for improving food safety. Front Microbiol 2022; 13:928480. [PMID: 36147852 PMCID: PMC9487997 DOI: 10.3389/fmicb.2022.928480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Sessile microorganisms are usually recalcitrant to antimicrobial treatments, and it is possible that finding biofilm-related effectors in metatranscriptomics datasets helps to understand mechanisms for bacterial persistence in diverse environments, by revealing protein-encoding genes that are expressed in situ. For this research, selected dairy-associated metatranscriptomics bioprojects were downloaded from the public databases JGI GOLD and NCBI (eight milk and 45 cheese samples), to screen for sequences encoding biofilm-related effectors. Based on the literature, the selected genetic determinants were related to adhesins, BAP, flagellum-related, intraspecific QS (AHL, HK, and RR), interspecific QS (LuxS), and QQ (AHL-acylases, AHL-lactonases). To search for the mRNA sequences encoding for those effector proteins, a custom database was built from UniprotKB, yielding 1,154,446 de-replicated sequences that were indexed in DIAMOND for alignment. The results revealed that in all the dairy-associated metatranscriptomic datasets obtained, there were reads assigned to genes involved with flagella, adhesion, and QS/QQ, but BAP-reads were found only for milk. Significant Pearson correlations (p < 0.05) were observed for transcripts encoding for flagella, RR, histidine kinases, adhesins, and LuxS, although no other significant correlations were found. In conclusion, the rationale used in this study was useful to demonstrate the presence of biofilm-associated effectors in metatranscriptomics datasets, pointing out to possible regulatory mechanisms in action in dairy-related biofilms, which could be targeted in the future to improve food safety.
Collapse
Affiliation(s)
| | - Marita Gimenez Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Virginie Oxaran
- Department of Biological Sciences, University of Texas, El Paso, El Paso, TX, United States
| | | | | |
Collapse
|
12
|
Xu S, Cao Q, Liu Z, Chen J, Yan P, Li B, Xu Y. Transcriptomic Analysis Reveals the Role of tmRNA on Biofilm Formation in Bacillus subtilis. Microorganisms 2022; 10:microorganisms10071338. [PMID: 35889057 PMCID: PMC9319509 DOI: 10.3390/microorganisms10071338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 06/30/2022] [Accepted: 06/30/2022] [Indexed: 11/16/2022] Open
Abstract
Bacillus strains are widely distributed in terrestrial and marine environments, and some of them are used as biocontrol organisms for their biofilm-formation ability. In Bacillus subtilis, biofilm formation is fine-tuned by a complex network, a clear understanding of which still requires study. In bacteria, tmRNA, encoded by the ssrA gene, catalyzes trans-translation that can rescue ribosomes stalled on mRNA transcripts lacking a functional stop codon. tmRNA also affects physiological bioprocesses in some bacteria. In this study, we constructed a ssrA mutant in B. subtilis and found that the biofilm formation in the ssrA mutant was largely impaired. Moreover, we isolated a biofilm-formation suppressor of ssrA, in which the biofilm formation was restored to a level even stronger than that in the wild type. We further performed RNAseq assays with the wild type, ssrA mutant, and suppressor of ssrA for comparisons of their transcriptomes. By analyzing the transcriptomic data, we predicted the possible functions of some differentially expressed genes (DEGs) in the tmRNA regulation of biofilm formation in B. subtilis. Finally, we found that the overexpression of two DEGs, acoA and yhjR, could restore the biofilm formation in the ssrA mutant, indicating that AcoA and YhjR were immediate regulators involved in the tmRNA regulatory web controlling biofilm formation in B. subtilis. Our data can improve the knowledge about the molecular network involved in Bacillus biofilm formation and provide new targets for manipulation of Bacillus biofilms for future investigation.
Collapse
Affiliation(s)
- Shanshan Xu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China; (S.X.); (Q.C.); (Z.L.); (J.C.)
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;
| | - Qianqian Cao
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China; (S.X.); (Q.C.); (Z.L.); (J.C.)
| | - Zengzhi Liu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China; (S.X.); (Q.C.); (Z.L.); (J.C.)
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;
| | - Junpeng Chen
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China; (S.X.); (Q.C.); (Z.L.); (J.C.)
| | - Peiguang Yan
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;
| | - Bingyu Li
- Guangdong Key Laboratory for Genome Stability and Disease Prevention, Health Science Center, Shenzhen University, Shenzhen 518055, China
- Correspondence: (B.L.); (Y.X.)
| | - Ying Xu
- Shenzhen Key Laboratory of Marine Bioresource and Eco-Environmental Science, Shenzhen Engineering Laboratory for Marine Algal Biotechnology, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, China; (S.X.); (Q.C.); (Z.L.); (J.C.)
- Correspondence: (B.L.); (Y.X.)
| |
Collapse
|
13
|
Smith TM, Youngblom MA, Kernien JF, Mohamed MA, Fry SS, Bohr LL, Mortimer TD, O'Neill MB, Pepperell CS. Rapid adaptation of a complex trait during experimental evolution of Mycobacterium tuberculosis. eLife 2022; 11:e78454. [PMID: 35726854 PMCID: PMC9213004 DOI: 10.7554/elife.78454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 05/15/2022] [Indexed: 12/30/2022] Open
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tb), is a leading cause of death due to infectious disease. TB is not traditionally associated with biofilms, but M. tb biofilms are linked with drug and immune tolerance and there is increasing recognition of their contribution to the recalcitrance of TB infections. Here, we used M. tb experimental evolution to investigate this complex phenotype and identify candidate loci controlling biofilm formation. We identified novel candidate loci, adding to our understanding of the genetic architecture underlying M. tb biofilm development. Under selective pressure to grow as a biofilm, regulatory mutations rapidly swept to fixation and were associated with changes in multiple traits, including extracellular matrix production, cell size, and growth rate. Genetic and phenotypic paths to enhanced biofilm growth varied according to the genetic background of the parent strain, suggesting that epistatic interactions are important in M. tb adaptation to changing environments.
Collapse
Affiliation(s)
| | - Madison A Youngblom
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
- Microbiology Doctoral Training Program, University of Wisconsin-MadisonMadisonUnited States
| | - John F Kernien
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Mohamed A Mohamed
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Sydney S Fry
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| | - Lindsey L Bohr
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
- Microbiology Doctoral Training Program, University of Wisconsin-MadisonMadisonUnited States
| | - Tatum D Mortimer
- Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public HealthBostonUnited States
| | - Mary B O'Neill
- Laboratoire de Biochimie (LBC), Chimie Biologie et Innovation, ESPCI Paris, PSL UniversitéParisFrance
| | - Caitlin S Pepperell
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
- Department of Medicine (Infectious Diseases), School of Medicine and Public Health, University of Wisconsin-MadisonMadisonUnited States
| |
Collapse
|
14
|
Comerci CJ, Gillman AL, Galera-Laporta L, Gutierrez E, Groisman A, Larkin JW, Garcia-Ojalvo J, Süel GM. Localized electrical stimulation triggers cell-type-specific proliferation in biofilms. Cell Syst 2022; 13:488-498.e4. [PMID: 35512710 PMCID: PMC9233089 DOI: 10.1016/j.cels.2022.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 12/20/2021] [Accepted: 04/11/2022] [Indexed: 01/18/2023]
Abstract
Biological systems ranging from bacteria to mammals utilize electrochemical signaling. Although artificial electrochemical signals have been utilized to characterize neural tissue responses, the effects of such stimuli on non-neural systems remain unclear. To pursue this question, we developed an experimental platform that combines a microfluidic chip with a multielectrode array (MiCMA) to enable localized electrochemical stimulation of bacterial biofilms. The device also allows for the simultaneous measurement of the physiological response within the biofilm with single-cell resolution. We find that the stimulation of an electrode locally changes the ratio of the two major cell types comprising Bacillus subtilis biofilms, namely motile and extracellular-matrix-producing cells. Specifically, stimulation promotes the proliferation of motile cells but not matrix cells, even though these two cell types are genetically identical and reside in the same microenvironment. Our work thus reveals that an electronic interface can selectively target bacterial cell types, enabling the control of biofilm composition and development.
Collapse
Affiliation(s)
- Colin J Comerci
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Alan L Gillman
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Leticia Galera-Laporta
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Edgar Gutierrez
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Alex Groisman
- Department of Physics, University of California San Diego, La Jolla, CA 92093, USA
| | - Joseph W Larkin
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
| | - Gürol M Süel
- Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California San Diego, La Jolla, CA 92093, USA.
| |
Collapse
|
15
|
Systems view of Bacillus subtilis pellicle development. NPJ Biofilms Microbiomes 2022; 8:25. [PMID: 35414070 PMCID: PMC9005697 DOI: 10.1038/s41522-022-00293-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 03/19/2022] [Indexed: 11/08/2022] Open
Abstract
In this study, we link pellicle development at the water-air interface with the vertical distribution and viability of the individual B. subtilis PS-216 cells throughout the water column. Real-time interfacial rheology and time-lapse confocal laser scanning microscopy were combined to correlate mechanical properties with morphological changes (aggregation status, filament formation, pellicle thickness, spore formation) of the growing pellicle. Six key events were identified in B. subtilis pellicle formation that are accompanied by a major change in viscoelastic and morphology behaviour of the pellicle. The results imply that pellicle development is a multifaceted response to a changing environment induced by bacterial growth that causes population redistribution within the model system, reduction of the viable habitat to the water-air interface, cell development, and morphogenesis. The outcome is a build-up of mechanical stress supporting structure that eventually, due to nutrient deprivation, reaches the finite thickness. After prolonged incubation, the formed pellicle collapses, which correlates with the spore releasing process. The pellicle loses the ability to support mechanical stress, which marks the end of the pellicle life cycle and entry of the system into the dormant state.
Collapse
|
16
|
Ivo Ganchev. Role of Multispecies Biofilms with a Dominance of Bacillus subtilis in the Rhizosphere. BIOL BULL+ 2022. [DOI: 10.1134/s1062359021150061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
17
|
Stress Dependent Biofilm Formation and Bioactive Melanin Pigment Production by a Thermophilic Bacillus Species from Chilean Hot Spring. Polymers (Basel) 2022; 14:polym14040680. [PMID: 35215592 PMCID: PMC8880475 DOI: 10.3390/polym14040680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/05/2022] [Accepted: 02/07/2022] [Indexed: 12/02/2022] Open
Abstract
Thermophilic bacteria able to survive extreme temperature stress are of great biotechnological interest due to their extracellular production of bioactive molecules as a part of a survival strategy, or by intracellular modifications. In the present study, thermophilic Bacillus haynesii CamB6, isolated from a Chilean hot spring, was studied for the formation of different stress response molecules. The polymeric pigment produced by the bacterial strain was characterized by different physicochemical techniques. On exposure to ranges of temperature (50–60 °C), pH (5.0–7.0), and sources of nitrogen and carbon (1–5 g·L−1), the bacteria responded with a biofilm network formation in a hydrophobic polystyrene surface. Biofilm formation under fed-batch conditions was also statistically validated. The bacteria showed a planktonic pellicle network formation in the presence of induced hypoxia and salinity stress (19.45 g·L−1) under static conditions. Salinity stress also resulted in the intracellular response of brown pigment production. The pigment was structurally and functionally characterized by UV-Vis absorbance and the presence of different characteristic peaks via FTIR analysis (bacterial pyomelanin fingerprints) were assessed. A high thermal stability and TGA profile indicated the brown pigment was a probable pyomelanin candidate. Micropyrolysis (Py-GC/MS) showed that isoprene, pyrrole, benzene, pyridine, and their derivatives were the major components detected. In addition, acetic acid, indole, phenol, and its derivatives were observed. The absence of sulfocompounds in the pyrolyzed products agreed with those reported in the literature for pyomelanin. The pigment surface morphology was analyzed via SEM, and the elemental composition via EDS also demonstrated the similarity of the brown pigment to that of the melanin family. The pyomelanin pigment was observed to be bioactive with promising antioxidant capacity (H2O2, Fe2+) compared to the standard antioxidant molecules. In conclusion, B. haynesii CamB6 demonstrated the formation of several biomolecules as a stress response mechanism that is bioactive, showing its probable biotechnological applications in future.
Collapse
|
18
|
Dutta S, Lee YH. High-throughput identification of genes influencing the competitive ability to obtain nutrients and performance of biocontrol in Pseudomonas putida JBC17. Sci Rep 2022; 12:872. [PMID: 35042886 PMCID: PMC8766522 DOI: 10.1038/s41598-022-04858-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/11/2021] [Indexed: 11/22/2022] Open
Abstract
Elucidating underlying mechanisms of biocontrol agents (BCAs) could aid in selecting potent BCAs and increasing their biocontrol efficacy. Nutrient competition is an important biocontrol mechanism; however, essential nutrient sources, and contributing genes for nutrient competition still remain to be explored. Pseudomonas putida JBC17 (JBC17WT) suppressed green mold in satsuma mandarins by inhibiting conidial germination of Penicillium digitatum via nutrient competition. To analyze genes essential for biocontrol performance of JBC17WT, we generated a transposon (Tn)-mediated mutant library and selected mutants with the ability to suppress conidial germination. Several mutants in the genes of flagella-formation, including fliR, fliH, and flgG, increased biocontrol performance and enhanced inhibition of conidial germination. They lost swimming motility, exhibited increased growth and rapid carbon and nitrogen utilization than the wild type under nutrient-poor conditions. The nutrient competition assay using polytetrafluoroethylene cylinders revealed that conidial germination was inhibited by nutrient absorption under nutrient-poor conditions. In addition, genes, including amidohydrolase (ytcJ), tonB-dependent receptor (cirA), argininosuccinate synthase (argG), D-3-phosphoglycerate dehydrogenase (serA), and chaperone protein (dnaJ), were involved in the inhibition of conidial germination. The results of this study indicate that rapid and continuous absorption of nutrients by JBC17WT restrict nutrient availability for conidial germination on nutrient-limited fruit surfaces, thereby decreasing the chances of fungal spores infecting fruits. The high-throughput analysis of Tn mutants of this study highlighted the importance of nutrient competition and the genes that influence biocontrol ability, which contributes to the development of biocontrol applications.
Collapse
Affiliation(s)
- Swarnalee Dutta
- Division of Biotechnology, Jeonbuk National University, 79 Gobong-ro, Iksan-si, Jeollabuk-do, 54596, Republic of Korea
| | - Yong Hoon Lee
- Division of Biotechnology, Jeonbuk National University, 79 Gobong-ro, Iksan-si, Jeollabuk-do, 54596, Republic of Korea.
- Advanced Institute of Environment and Bioscience, Plant Medical Research Center, and Institute of Bio-Industry, Jeonbuk National University, Jeonju-si, Republic of Korea.
| |
Collapse
|
19
|
Sanchez-Vizuete P, Dergham Y, Bridier A, Deschamps J, Dervyn E, Hamze K, Aymerich S, Le Coq D, Briandet R. The coordinated population redistribution between Bacillus subtilis submerged biofilm and liquid-air pellicle. Biofilm 2022; 4:100065. [PMID: 35024609 PMCID: PMC8732777 DOI: 10.1016/j.bioflm.2021.100065] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/09/2021] [Accepted: 12/14/2021] [Indexed: 12/15/2022] Open
Abstract
Bacillus subtilis is a widely used bacterial model to decipher biofilm formation, genetic determinants and their regulation. For several years, studies were conducted on colonies or pellicles formed at the interface with air, but more recent works showed that non-domesticated strains were able to form thick and structured biofilms on submerged surfaces. Taking advantage of time-lapse confocal laser scanning microscopy, we monitored bacterial colonization on the surface and observed an unexpected biphasic submerged biofilm development. Cells adhering to the surface firstly form elongated chains before being suddenly fragmented and released as free motile cells in the medium. This switching coincided with an oxygen depletion in the well which preceded the formation of the pellicle at the liquid-air interface. Residual bacteria still associated with the solid surface at the bottom of the well started to express matrix genes under anaerobic metabolism to build the typical biofilm protruding structures.
Collapse
Affiliation(s)
- Pilar Sanchez-Vizuete
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Yasmine Dergham
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France.,Faculty of Science, Lebanese University, 1003, Beirut, Lebanon
| | - Arnaud Bridier
- Fougères Laboratory, Antibiotics, Biocides, Residues and Resistance Unit, Anses, 35300, Fougères, France
| | - Julien Deschamps
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Etienne Dervyn
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Kassem Hamze
- Faculty of Science, Lebanese University, 1003, Beirut, Lebanon
| | - Stéphane Aymerich
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Dominique Le Coq
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France.,Université Paris-Saclay, Centre National de la Recherche Scientifique (CNRS), INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| | - Romain Briandet
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, 78350, Jouy-en-Josas, France
| |
Collapse
|
20
|
Zhang H, Qian Y, Fan D, Tian Y, Huang X. Biofilm formed by Hansschlegelia zhihuaiae S113 on root surface mitigates the toxicity of bensulfuron-methyl residues to maize. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 292:118366. [PMID: 34653590 DOI: 10.1016/j.envpol.2021.118366] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Revised: 09/20/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Bensulfuron-methyl (BSM) residues in soil threaten the rotation of BSM-sensitive crops. Microbial biofilms formed on crop roots could improve the ability of microbes to survive and protect crop roots. However, the research on biofilms with the purpose of mitigating or even eliminating BSM damage to sensitive crops is very limited. In this study, one BSM-degrading bacterium, Hansschlegelia zhihuaiae S113, colonized maize roots by forming a biofilm. Root exudates were associated with increased BSM degradation efficiency with strain S113 in rhizosphere soil relative to bulk soil, so the interactions among BSM degradation, root exudates, and biofilms may provide a new approach for the BSM-contaminated soil bioremediation. Root exudates and their constituent organic acids, including fumaric acid, tartaric acid, and l-malic acid, enhanced biofilm formation with 13.0-22.2% increases, owing to the regulation of genes encoding proteins responsible for cell motility/chemotaxis (fla/che cluster) and materials metabolism, thus promoting S113 population increases. Additionally, root exudates were also able to induce exopolysaccharide production to promote mature biofilm formation. Complete BSM degradation and healthy maize growth were found in BSM-contaminated rhizosphere soil treated with wild strain S113, compared to that treated with loss-of-function mutants ΔcheA-S113 (89.3%, without biofilm formation ability) and ΔsulE-S113 (22.1%, without degradation ability) or sterile water (10.7%, control). Furthermore, the biofilm mediated by organic acids, such as l-malic acid, exhibited a more favorable effect on BSM degradation and maize growth. These results showed that root exudates and their components (such as organic acids) can induce the biosynthesis of the biofilm to promote BSM degradation, emphasizing the contribution of root biofilm in reducing BSM damage to maize.
Collapse
Affiliation(s)
- Hao Zhang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China; College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, PR China; Innovation Center of Water Security for Water Source Region of Mid-route Project of South-North Water Diversion of Henan Province, Nanyang Normal University, Nanyang, 473061, PR China
| | - Yingying Qian
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Dandan Fan
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Yanning Tian
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China
| | - Xing Huang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, PR China.
| |
Collapse
|
21
|
Maan H, Povolotsky TL, Porat Z, Itkin M, Malitsky S, Kolodkin-Gal I. Imaging flow cytometry reveals a dual role for exopolysaccharides in biofilms: To promote self-adhesion while repelling non-self-community members. Comput Struct Biotechnol J 2021; 20:15-25. [PMID: 34976308 PMCID: PMC8666610 DOI: 10.1016/j.csbj.2021.11.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 11/16/2022] Open
Abstract
In nature, bacteria frequently reside in differentiated communities or biofilms. These multicellular communities are held together by self-produced polymers that allow the community members to adhere to the surface as well as to neighbor bacteria. Here, we report that exopolysaccharides prevent Bacillus subtilis from co-aggregating with a distantly related bacterium Bacillus mycoides, while maintaining their role in promoting self-adhesion and co-adhesion with phylogenetically related bacterium, Bacillus atrophaeus. The defensive role of the exopolysaccharides is due to the specific regulation of bacillaene. Single cell analysis of biofilm and free-living bacterial cells using imaging flow cytometry confirmed a specific role for the exopolysaccharides in microbial competition repelling B. mycoides. Unlike exopolysaccharides, the matrix protein TasA induced bacillaene but inhibited the expression of the biosynthetic clusters for surfactin, and therefore its overall effect on microbial competition during floating biofilm formation was neutral. Thus, the exopolysaccharides provide a dual fitness advantage for biofilm-forming cells, as it acts to promote co-aggregation of related species, as well as, a secreted cue for chemical interference with non-compatible partners. These results experimentally demonstrate a general assembly principle of complex communities and provides an appealing explanation for how closely related species are favored during community assembly. Furthermore, the differential regulation of surfactin and bacillaene by the extracellular matrix may explain the spatio-temporal gradients of antibiotic production within biofilms.
Collapse
Affiliation(s)
- Harsh Maan
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | | | - Ziv Porat
- Flow Cytometry Unit, Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot, Israel
| | - Maxim Itkin
- Life Science Core Facilities Weizmann Institute of Science, 234 Herzl Street, Rehovot, Israel
| | - Sergey Malitsky
- Life Science Core Facilities Weizmann Institute of Science, 234 Herzl Street, Rehovot, Israel
| | - Ilana Kolodkin-Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
22
|
Kobayashi K. Diverse LXG toxin and antitoxin systems specifically mediate intraspecies competition in Bacillus subtilis biofilms. PLoS Genet 2021; 17:e1009682. [PMID: 34280190 PMCID: PMC8321402 DOI: 10.1371/journal.pgen.1009682] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 07/29/2021] [Accepted: 06/25/2021] [Indexed: 12/14/2022] Open
Abstract
Biofilms are multispecies communities, in which bacteria constantly compete with one another for resources and niches. Bacteria produce many antibiotics and toxins for competition. However, since biofilm cells exhibit increased tolerance to antimicrobials, their roles in biofilms remain controversial. Here, we showed that Bacillus subtilis produces multiple diverse polymorphic toxins, called LXG toxins, that contain N-terminal LXG delivery domains and diverse C-terminal toxin domains. Each B. subtilis strain possesses a distinct set of LXG toxin–antitoxin genes, the number and variation of which is sufficient to distinguish each strain. The B. subtilis strain NCIB3610 possesses six LXG toxin–antitoxin operons on its chromosome, and five of the toxins functioned as DNase. In competition assays, deletion mutants of any of the six LXG toxin–antitoxin operons were outcompeted by the wild-type strain. This phenotype was suppressed when the antitoxins were ectopically expressed in the deletion mutants. The fitness defect of the mutants was only observed in solid media that supported biofilm formation. Biofilm matrix polymers, exopolysaccharides and TasA protein polymers were required for LXG toxin function. These results indicate that LXG toxin-antitoxin systems specifically mediate intercellular competition between B. subtilis strains in biofilms. Mutual antagonism between some LXG toxin producers drove the spatial segregation of two strains in a biofilm, indicating that LXG toxins not only mediate competition in biofilms, but may also help to avoid warfare between strains in biofilms. LXG toxins from strain NCIB3610 were effective against some natural isolates, and thus LXG toxin–antitoxin systems have ecological impact. B. subtilis possesses another polymorphic toxin, WapA. WapA had toxic effects under planktonic growth conditions but not under biofilm conditions because exopolysaccharides and TasA protein polymers inhibited WapA function. These results indicate that B. subtilis uses two types of polymorphic toxins for competition, depending on the growth mode. Biofilms are surface-associated multispecies communities, in which bacteria are protected by self-produced extracellular polymeric substances. In biofilms, bacteria constantly engage in intra- and interspecies competition. To minimize exploitation by competitors, bacteria produce a variety of antibiotics and toxins for competition. However, since biofilm cells exhibit increased tolerance to antimicrobials, the function of antibiotics and toxins in biofilms remains controversial. Therefore, the mechanisms underlying bacterial competition in biofilms remain to be investigated. We found that the soil bacterium B. subtilis produces polymorphic toxins, termed LXG toxins. LXG toxins are highly diversified among B. subtilis strains, and each B. subtilis strain possesses three to nine different LXG toxins. LXG toxins specifically mediate intraspecies competition in biofilms. Competition between some LXG toxin producers resulted in the spatial segregation of strains in biofilms, indicating that LXG toxins not only mediate competition, but also help to minimize warfare in biofilms. LXG toxins were effective against natural isolates of B. subtilis, suggesting that LXG toxin–antitoxin systems have ecological impact. Our results provide new insights into how bacteria survive competition in biofilms.
Collapse
Affiliation(s)
- Kazuo Kobayashi
- Division of Biological Science, Department of Science and Technology, Nara Institute of Science & Technology, Ikoma, Nara, Japan
- * E-mail:
| |
Collapse
|
23
|
Abstract
The dispersal of bacterial cells from a matured biofilm can be mediated either by active or passive mechanisms. In this issue of the Journal of Bacteriology, Nishikawa and Kobayashi demonstrate that the presence of calcium influences the dispersal of spores from the pellicle biofilm of Bacillus subtilis (M. Nishikawa and K. Kobayashi, J Bacteriol 203:e00114-21, 2021, https://doi.org/10.1128/JB.00114-21). The authors propose that temporal heterogeneity in matrix production and chelation of calcium by dipicolinic acid in spores weakens the biofilm matrix and causes passive dispersal.
Collapse
|
24
|
Abstract
Biofilm dispersion is the final stage of biofilm development, during which biofilm cells actively escape from biofilms in response to deteriorating conditions within the biofilm. Biofilm dispersion allows cells to spread to new locations and form new biofilms in better locations. However, dispersal mechanisms have been elucidated only in a limited number of bacteria. Here, we investigated biofilm dispersion in Bacillus subtilis. Biofilm dispersion was clearly observed when B. subtilis was grown under static conditions in modified LB medium containing glycerol and manganese. Biofilm dispersion was synergistically caused by two mechanisms: decreased expression of the epsA operon encoding exopolysaccharide synthetases and the induction of sporulation. Indeed, constitutive expression of the epsA operon in the sporulation-defective ΔsigK mutant prevented biofilm dispersion. The addition of calcium to the medium prevented biofilm dispersion without significantly affecting the expression of the epsA operon and sporulation genes. In synthetic medium, eliminating calcium did not prevent the expression of biofilm matrix genes and, thereby, biofilm formation, but it attenuated biofilm architecture. These results indicate that calcium structurally stabilizes biofilms and causes resistance to biofilm dispersion mechanisms. Sporulation-dependent biofilm dispersion required the spoVF operon, encoding dipicolinic acid (DPA) synthase. During sporulation, an enormous amount of DPA is synthesized and stored in spores as a chelate with calcium. We speculate that, during sporulation, calcium bound to biofilm matrix components may be transported to spores as a calcium-DPA complex, which weakens biofilm structure and leads to biofilm dispersion. IMPORTANCE Bacteria growing as biofilms are notoriously difficult to eradicate and sometimes pose serious threats to public health. Bacteria escape from biofilms by degrading them when biofilm conditions deteriorate. This process, called biofilm dispersion, has been studied as a promising strategy for safely controlling biofilms. However, the regulation and mechanism of biofilm dispersion has been elucidated only in a limited number of bacteria. Here, we identified two biofilm dispersion mechanisms in the Gram-positive, spore-forming bacterium Bacillus subtilis. The addition of calcium to the medium stabilized biofilms and caused resistance to dispersal mechanisms. Our findings provide new insights into biofilm dispersion and biofilm control.
Collapse
|
25
|
CdgL is a degenerate nucleotide cyclase domain protein affecting flagellin synthesis and motility in Bacillus thuringiensis. Res Microbiol 2021; 172:103850. [PMID: 34082027 DOI: 10.1016/j.resmic.2021.103850] [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: 10/02/2020] [Revised: 02/28/2021] [Accepted: 05/27/2021] [Indexed: 11/23/2022]
Abstract
In Bacillus subtilis, motility genes are expressed in a hierarchical pattern - governed by the σD transcription factor and other proteins such as the EpsE molecular clutch and SlrA/SlrR regulator proteins. In contrast, motile species in the Bacillus cereus group seem to express their motility genes in a non-hierarchical pattern, and less is known about their regulation, also given that no orthologs to σD, EpsE, SlrA or SlrR are found in B. cereus group genomes. Here we show that deletion of cdgL (BTB_RS26690/BTB_c54300) in Bacillus thuringiensis 407 (cry-) resulted in a six-to ten-fold downregulation of the entire motility locus, and loss of flagellar structures and swimming motility. cdgL is unique to the B. cereus group and is found in all phylogenetic clusters in the population except for group I, which comprises isolates of non-motile Bacillus pseudomycoides. Analysis of RNA-Seq data revealed cdgL to be expressed in a three-gene operon with a NupC like nucleoside transporter, and a putative glycosyl transferase for which transposon-based gene inactivation was previously shown to produce a similar phenotype to cdgL deletion. Interestingly, all three proteins were predicted to be membrane-bound and may provide a concerted function in the regulation of B. cereus group motility.
Collapse
|
26
|
Dergham Y, Sanchez-Vizuete P, Le Coq D, Deschamps J, Bridier A, Hamze K, Briandet R. Comparison of the Genetic Features Involved in Bacillus subtilis Biofilm Formation Using Multi-Culturing Approaches. Microorganisms 2021; 9:microorganisms9030633. [PMID: 33803642 PMCID: PMC8003051 DOI: 10.3390/microorganisms9030633] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/12/2021] [Accepted: 03/16/2021] [Indexed: 11/16/2022] Open
Abstract
Surface-associated multicellular assemblage is an important bacterial trait to withstand harsh environmental conditions. Bacillus subtilis is one of the most studied Gram-positive bacteria, serving as a model for the study of genetic pathways involved in the different steps of 3D biofilm formation. B. subtilis biofilm studies have mainly focused on pellicle formation at the air-liquid interface or complex macrocolonies formed on nutritive agar. However, only few studies focus on the genetic features of B. subtilis submerged biofilm formation and their link with other multicellular models at the air interface. NDmed, an undomesticated B. subtilis strain isolated from a hospital, has demonstrated the ability to produce highly structured immersed biofilms when compared to strains classically used for studying B. subtilis biofilms. In this contribution, we have conducted a multi-culturing comparison (between macrocolony, swarming, pellicle, and submerged biofilm) of B. subtilis multicellular communities using the NDmed strain and mutated derivatives for genes shown to be required for motility and biofilm formation in pellicle and macrocolony models. For the 15 mutated NDmed strains studied, all showed an altered phenotype for at least one of the different culture laboratory assays. Mutation of genes involved in matrix production (i.e., tasA, epsA-O, cap, ypqP) caused a negative impact on all biofilm phenotypes but favored swarming motility on semi-solid surfaces. Mutation of bslA, a gene coding for an amphiphilic protein, affected the stability of the pellicle at the air-liquid interface with no impact on the submerged biofilm model. Moreover, mutation of lytF, an autolysin gene required for cell separation, had a greater effect on the submerged biofilm model than that formed at aerial level, opposite to the observation for lytABC mutant. In addition, B. subtilis NDmed with sinR mutation formed wrinkled macrocolony, less than that formed by the wild type, but was unable to form neither thick pellicle nor structured submerged biofilm. The results are discussed in terms of the relevancy to determine whether genes involved in colony and pellicle formation also govern submerged biofilm formation, by regarding the specificities in each model.
Collapse
Affiliation(s)
- Yasmine Dergham
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (Y.D.); (P.S.-V.); (D.L.C.); (J.D.)
- Faculty of Science, Lebanese University, 1003 Beirut, Lebanon;
| | - Pilar Sanchez-Vizuete
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (Y.D.); (P.S.-V.); (D.L.C.); (J.D.)
| | - Dominique Le Coq
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (Y.D.); (P.S.-V.); (D.L.C.); (J.D.)
- Centre National de la Recherche Scientifique (CNRS), Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Julien Deschamps
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (Y.D.); (P.S.-V.); (D.L.C.); (J.D.)
| | - Arnaud Bridier
- Fougères Laboratory, Antibiotics, Biocides, Residues and Resistance Unit, Anses, 35300 Fougères, France;
| | - Kassem Hamze
- Faculty of Science, Lebanese University, 1003 Beirut, Lebanon;
| | - Romain Briandet
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (Y.D.); (P.S.-V.); (D.L.C.); (J.D.)
- Correspondence:
| |
Collapse
|
27
|
Newton R, Amstutz J, Patrick JE. Biofilm formation by Bacillus subtilis is altered in the presence of pesticides. Access Microbiol 2021; 2:acmi000175. [PMID: 33490870 PMCID: PMC7818241 DOI: 10.1099/acmi.0.000175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 10/21/2020] [Indexed: 11/18/2022] Open
Abstract
Bacillus subtilis uses swarming motility and biofilm formation to colonize plant roots and form a symbiotic relationship with the plant. Swarming motility and biofilm formation are group behaviours made possible through the use of chemical messengers. We investigated whether chemicals applied to plants would interfere with the swarming motility and biofilm-forming capabilities of B. subtilis in vitro. We hypothesized that pesticides could act as chemical signals that influence bacterial behaviour; this research investigates whether swarming motility and biofilm formation of B. subtilis is affected by the application of the commercial pesticides with the active ingredients of neem oil, pyrethrin, or malathion. The results indicate that all three pesticides inhibit biofilm formation. Swarming motility is not affected by the application of pyrethrin or malathion, but swarm expansion and pattern is altered in the presence of neem oil. Future studies to investigate the mechanism by which pesticides alter biofilm formation are warranted.
Collapse
Affiliation(s)
- Rachael Newton
- Truman State University, 100 E Normal Kirksville, MO 63501, USA
| | | | - Joyce E Patrick
- Truman State University, 100 E Normal Kirksville, MO 63501, USA
| |
Collapse
|
28
|
Pellicle formation by Escherichia coli K-12: Role of adhesins and motility. J Biosci Bioeng 2021; 131:381-389. [PMID: 33495047 DOI: 10.1016/j.jbiosc.2020.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 11/24/2020] [Accepted: 12/05/2020] [Indexed: 01/01/2023]
Abstract
Initial work to generate physically robust biofilms for biocatalytic applications revealed that Escherichia coli K-12 can form a floating biofilm at the air-liquid interface, commonly referred to as a pellicle. Unlike other species where pellicle formation is well-characterised, such as Bacillus subtilis, there are few reports of E. coli K-12 pellicles in the literature. In order to study pellicle formation, a growth model was developed and pellicle formation was monitored over time. Mechanical forces, both motility and shaking, were shown to have effects on pellicle formation and development. The role and regulation of curli, an amyloid protein adhesin critical in E. coli K-12 biofilm formation, was studied by using promoter-green fluorescent protein reporters; flow cytometry and confocal laser scanning microscopy were used to monitor curli expression over time and in different locations. Curli were found to be not only crucial for pellicle formation, but also heterogeneously expressed within the pellicle. The components of the extracellular polymeric substances (EPS) in pellicles were analysed by confocal microscopy using lectins, revealing distinct pellicle morphology on the air-facing and medium-facing sides, and spatially- and temporally-regulated generation of the EPS components poly-N-acetyl glucosamine and colanic acid. We discuss the difference between pellicles formed by E. coli K-12, pathogenic E. coli strains and other species, and the relationship between E. coli K-12 pellicles and solid surface-attached biofilms.
Collapse
|
29
|
Schiller H, Schulze S, Mutan Z, de Vaulx C, Runcie C, Schwartz J, Rados T, Bisson Filho AW, Pohlschroder M. Haloferax volcanii Immersed Liquid Biofilms Develop Independently of Known Biofilm Machineries and Exhibit Rapid Honeycomb Pattern Formation. mSphere 2020; 5:e00976-20. [PMID: 33328348 PMCID: PMC7771232 DOI: 10.1128/msphere.00976-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/19/2020] [Indexed: 12/21/2022] Open
Abstract
The ability to form biofilms is shared by many microorganisms, including archaea. Cells in a biofilm are encased in extracellular polymeric substances that typically include polysaccharides, proteins, and extracellular DNA, conferring protection while providing a structure that allows for optimal nutrient flow. In many bacteria, flagella and evolutionarily conserved type IV pili are required for the formation of biofilms on solid surfaces or floating at the air-liquid interface of liquid media. Similarly, in many archaea it has been demonstrated that type IV pili and, in a subset of these species, archaella are required for biofilm formation on solid surfaces. Additionally, in the model archaeon Haloferax volcanii, chemotaxis and AglB-dependent glycosylation play important roles in this process. H. volcanii also forms immersed biofilms in liquid cultures poured into petri dishes. This study reveals that mutants of this haloarchaeon that interfere with the biosynthesis of type IV pili or archaella, as well as a chemotaxis-targeting transposon and aglB deletion mutants, lack obvious defects in biofilms formed in liquid cultures. Strikingly, we have observed that these liquid-based biofilms are capable of rearrangement into honeycomb-like patterns that rapidly form upon removal of the petri dish lid, a phenomenon that is not dependent on changes in light or oxygen concentration but can be induced by controlled reduction of humidity. Taken together, this study demonstrates that H. volcanii requires novel, unidentified strategies for immersed liquid biofilm formation and also exhibits rapid structural rearrangements.IMPORTANCE This first molecular biological study of archaeal immersed liquid biofilms advances our basic biological understanding of the model archaeon Haloferax volcanii Data gleaned from this study also provide an invaluable foundation for future studies to uncover components required for immersed liquid biofilms in this haloarchaeon and also potentially for liquid biofilm formation in general, which is poorly understood compared to the formation of biofilms on surfaces. Moreover, this first description of rapid honeycomb pattern formation is likely to yield novel insights into the underlying structural architecture of extracellular polymeric substances and cells within immersed liquid biofilms.
Collapse
Affiliation(s)
- Heather Schiller
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Stefan Schulze
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Zuha Mutan
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Charlotte de Vaulx
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Catalina Runcie
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jessica Schwartz
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Theopi Rados
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Alexandre W Bisson Filho
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts, USA
| | - Mechthild Pohlschroder
- Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| |
Collapse
|
30
|
The phosphorylated regulator of chemotaxis is crucial throughout biofilm biogenesis in Shewanella oneidensis. NPJ Biofilms Microbiomes 2020; 6:54. [PMID: 33188190 PMCID: PMC7666153 DOI: 10.1038/s41522-020-00165-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/13/2020] [Indexed: 02/04/2023] Open
Abstract
The core of the chemotaxis system of Shewanella oneidensis is made of the CheA3 kinase and the CheY3 regulator. When appropriated, CheA3 phosphorylates CheY3, which, in turn, binds to the rotor of the flagellum to modify the swimming direction. In this study, we showed that phosphorylated CheY3 (CheY3-P) also plays an essential role during biogenesis of the solid-surface-associated biofilm (SSA-biofilm). Indeed, in a ΔcheY3 strain, the formation of this biofilm is abolished. Using the phospho-mimetic CheY3D56E mutant, we showed that CheY-P is required throughout the biogenesis of the biofilm but CheY3 phosphorylation is independent of CheA3 during this process. We have recently found that CheY3 interacts with two diguanylate cyclases (DGCs) and with MxdA, the c-di-GMP effector, probably triggering exopolysaccharide synthesis by the Mxd machinery. Here, we discovered two additional DGCs involved in SSA-biofilm development and showed that one of them interacts with CheY3. We therefore propose that CheY3-P acts together with DGCs to control SSA-biofilm formation. Interestingly, two orthologous CheY regulators complement the biofilm defect of a ΔcheY3 strain, supporting the idea that biofilm formation could involve CheY regulators in other bacteria.
Collapse
|
31
|
Ogura M. Glucose-Mediated Protein Arginine Phosphorylation/Dephosphorylation Regulates ylxR Encoding Nucleoid-Associated Protein and Cell Growth in Bacillus subtilis. Front Microbiol 2020; 11:590828. [PMID: 33101263 PMCID: PMC7546277 DOI: 10.3389/fmicb.2020.590828] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/07/2020] [Indexed: 11/13/2022] Open
Abstract
Glucose is the most favorable carbon source for many bacteria, and these bacteria have several glucose-responsive networks. We proposed new glucose responsive system, which includes protein acetylation and probable translation control through TsaEBD, which is a tRNA modification enzyme required for the synthesis of threonylcarbamoyl adenosine (t6A)-tRNA. The system also includes nucleoid-associated protein YlxR, regulating more than 400 genes including many metabolic genes and the ylxR-containing operon driven by the PylxS promoter is induced by glucose. Thus, transposon mutagenesis was performed for searching regulatory factors for PylxS expression. As a result, ywlE was identified. The McsB kinase phosphorylates arginine (Arg) residues of proteins and the YwlE phosphatase counteracts against McsB through Arg-dephosphorylation. Phosphorylated Arg has been known to function as a tag for ClpCP-dependent protein degradation. The previous analysis identified TsaD as an Arg-phosphorylated protein. Our results showed that the McsB/YwlE system regulates PylxS expression through ClpCP-mediated protein degradation of TsaD. In addition, we observed that glucose induced ywlE expression and repressed mcsB expression. It was concluded that these phenomena would cause glucose induction (GI) of PylxS, based on the Western blot analyses of TsaD-FLAG. These observations and the previous those that many glycolytic enzymes are Arg-phosphorylated suggested that the McsB/YwlE system might be involved in cell growth in glucose-containing medium. We observed that the disruption of mcsB and ywlE resulted in an increase of cell mass and delayed growth, respectively, in semi-synthetic medium. These results provide us broader insights to the physiological roles of the McsB/YwlE system and protein Arg-phosphorylation.
Collapse
Affiliation(s)
- Mitsuo Ogura
- Institute of Oceanic Research and Development, Tokai University, Shizuoka, Japan
| |
Collapse
|
32
|
DNA Methylation Epigenetically Regulates Gene Expression in Burkholderia cenocepacia and Controls Biofilm Formation, Cell Aggregation, and Motility. mSphere 2020; 5:5/4/e00455-20. [PMID: 32669472 PMCID: PMC7364216 DOI: 10.1128/msphere.00455-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
CF patients diagnosed with Burkholderia cenocepacia infections often experience rapid deterioration of lung function, known as cepacia syndrome. B. cenocepacia has a large multireplicon genome, and much remains to be learned about regulation of gene expression in this organism. From studies in other (model) organisms, it is known that epigenetic changes through DNA methylation play an important role in this regulation. The identification of B. cenocepacia genes of which the expression is regulated by DNA methylation and identification of the regulatory systems involved in this methylation are likely to advance the biological understanding of B. cenocepacia cell adaptation via epigenetic regulation. In time, this might lead to novel approaches to tackle B. cenocepacia infections in CF patients. Respiratory tract infections by the opportunistic pathogen Burkholderia cenocepacia often lead to severe lung damage in cystic fibrosis (CF) patients. New insights in how to tackle these infections might emerge from the field of epigenetics, as DNA methylation is an important regulator of gene expression. The present study focused on two DNA methyltransferases (MTases) in B. cenocepacia strains J2315 and K56-2 and their role in regulating gene expression. In silico predicted DNA MTase genes BCAL3494 and BCAM0992 were deleted in both strains, and the phenotypes of the resulting deletion mutants were studied: deletion mutant ΔBCAL3494 showed changes in biofilm structure and cell aggregation, while ΔBCAM0992 was less motile. B. cenocepacia wild-type cultures treated with sinefungin, a known DNA MTase inhibitor, exhibited the same phenotype as DNA MTase deletion mutants. Single-molecule real-time sequencing was used to characterize the methylome of B. cenocepacia, including methylation at the origin of replication, and motifs CACAG and GTWWAC were identified as targets of BCAL3494 and BCAM0992, respectively. All genes with methylated motifs in their putative promoter region were identified, and qPCR experiments showed an upregulation of several genes, including biofilm- and motility-related genes, in MTase deletion mutants with unmethylated motifs, explaining the observed phenotypes in these mutants. In summary, our data confirm that DNA methylation plays an important role in regulating the expression of B. cenocepacia genes involved in biofilm formation, cell aggregation, and motility. IMPORTANCE CF patients diagnosed with Burkholderia cenocepacia infections often experience rapid deterioration of lung function, known as cepacia syndrome. B. cenocepacia has a large multireplicon genome, and much remains to be learned about regulation of gene expression in this organism. From studies in other (model) organisms, it is known that epigenetic changes through DNA methylation play an important role in this regulation. The identification of B. cenocepacia genes of which the expression is regulated by DNA methylation and identification of the regulatory systems involved in this methylation are likely to advance the biological understanding of B. cenocepacia cell adaptation via epigenetic regulation. In time, this might lead to novel approaches to tackle B. cenocepacia infections in CF patients.
Collapse
|
33
|
Role of Glutamate Synthase in Biofilm Formation by Bacillus subtilis. J Bacteriol 2020; 202:JB.00120-20. [PMID: 32393519 DOI: 10.1128/jb.00120-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 05/04/2020] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis forms robust biofilms in the presence of large amounts of carbon sources, such as glycerol. However, little is known about the importance of the metabolic systems, or the relationship between metabolic systems and regulatory systems, involved in biofilm formation. Glutamate synthase, encoded by gltAB, is an enzyme that converts 2-ketoglutarate (a tricarboxylic acid [TCA] cycle intermediate) and glutamine into glutamate, which is a general amino group donor in metabolism. Here, we show that a ΔgltA mutant exhibited early arrest of biofilm formation in complex medium containing glycerol. This phenotype was not due to glutamate auxotrophy. Consistent with its biofilm formation phenotype, the ΔgltA mutant exhibited an early decrease in expression of the epsA and tapA operons, which are responsible for production of biofilm matrix polymers. This resulted from decreased activity of their regulator, Spo0A, as evidenced by reduced expression of other Spo0A-regulated genes in the ΔgltA mutant. The ΔgltA mutation prevented biofilm formation only in the presence of large amounts of glycerol. Moreover, limited expression of citrate synthase (but not other TCA enzymes) restored biofilm-forming ability to the ΔgltA mutant. These results indicate that the ΔgltA mutant accumulates an inhibitory intermediate (citrate) in the TCA cycle in the presence of large amounts of glycerol. The ΔgltA mutant formed biofilms when excess iron was added to the medium. Taken together, the data suggest that accumulation of citrate ions by the ΔgltA mutant causes iron shortage due to chelation, which prevents activation of Spo0A and causes defective biofilm formation.IMPORTANCE Bacillus subtilis, a model organism for bacterial biofilm formation, forms robust biofilms in a medium-dependent manner. Although the regulatory network that controls biofilm formation has been well studied, the importance of the underlying metabolic systems remains to be elucidated. The present study demonstrates that a metabolic disorder in a well-conserved metabolic system causes accumulation of an inhibitory metabolic intermediate that prevents activation of the system that regulates biofilm formation. These findings increase our understanding of the coordination between cellular metabolic status and the regulatory networks governing biofilm formation.
Collapse
|
34
|
K R, Y V N, V P V. Acid soluble extracellular matrix confers structural stability to marine Bacillus haynesii pellicle biofilms. Colloids Surf B Biointerfaces 2020; 194:111160. [PMID: 32526635 DOI: 10.1016/j.colsurfb.2020.111160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 04/20/2020] [Accepted: 05/27/2020] [Indexed: 11/26/2022]
Abstract
In natural and engineered settings, bacteria predominantly thrive in biofilms, which are complex microbial communities embedded in a self-produced extracellular polymeric substances (EPSs) matrix. Pellicles are complex macroscopic biofilms floating at air-water interface. Though pellicle formation has been studied in detail in Bacillus subtilis, a soil bacterium, it is not reported in aquatic bacteria, which may use pellicle-growth as survival-strategy. This study shows that Bacillus haynesii isolated from a marine environment forms robust pellicle biofilms at air-water interface. B. haynesii pellicles showed complex architecture, involving dense cell-aggregates with interconnecting thread-like structures in an extracellular matrix. In situ staining by Alcian blue, Concanavalin A and ThioflavinT (ThT), respectively, localized acidic polymers, glycoconjugates and amyloid-like fibers in the pellicle. The pellicle was rigid and not disrupted by common EPS extraction protocols. Hence, a set of reagents and conditions were evaluated for solubilizing the EPS and pellicle. Acetic acid was able to effectively solubilize the structural EPS and pellicle structure. Acid soluble structural EPS contained chemical signatures for both proteins and carbohydrates, as revealed by elemental analysis, Fourier Transform Infrared Spectroscopy and Raman Spectroscopy. Ex situ staining of acid soluble EPS by ThT showed recovery of amyloid-forming proteins from pellicle. Results show that structural stability of the pellicle is mainly conferred by amyloid-like fibers of the EPS matrix. The robust pellicle-growth reported here may represent a survival-strategy in the aquatic bacterium. The findings reported here can support future research on biofilm structure, EPS matrix and its formation, which are critical for understanding how microbes thrive in natural and engineered settings.
Collapse
Affiliation(s)
- Rajitha K
- Biofouling and Biofilm Processes, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, 603102, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai, 400094, India
| | - Nancharaiah Y V
- Biofouling and Biofilm Processes, Water and Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, 603102, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai, 400094, India.
| | - Venugopalan V P
- Homi Bhabha National Institute, Anushakti Nagar, Mumbai, 400094, India; Bioscience Group, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085, India
| |
Collapse
|
35
|
Zhou C, Zhou H, Fang H, Ji Y, Wang H, Liu F, Zhang H, Lu F. Spo0A can efficiently enhance the expression of the alkaline protease gene aprE in Bacillus licheniformis by specifically binding to its regulatory region. Int J Biol Macromol 2020; 159:444-454. [PMID: 32437805 DOI: 10.1016/j.ijbiomac.2020.05.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 02/06/2023]
Abstract
The expression of enzymes in Bacillus licheniformis, such as the valuable extracellular alkaline protease AprE, is highly regulated by a complex transcriptional regulation mechanism. Here, we found that the transcript abundance of aprE varies >343-fold in response to the supply of nutrients or to environmental challenges. To identify the underlying regulatory mechanism, the core promoter of aprE and several important upstream regulatory regions outside the promoter were firstly confirmed by 5'-RACE and mutagenesis experiments. The specific proteins that bind to the identified sequences were subsequently captured by DNA pull-down experiments, which yielded the transcriptional factors (TFs) Spo0A, CggR, FruR, YhcZ, as well as fragments of functionally unassigned proteins. Further electrophoretic mobility shift assay (EMSA) and DNase I foot-printing experiments indicated that Spo0A can directly bind to the region from -92 to -118 nucleotides upstream of the transcription start site, and the deletion of this specific region drastically decreased the production of AprE. Taken together, these results indicated that the expression of aprE was mainly regulated by the interplay between Spo0A and its cognate DNA sequence, which was successfully applied to overproduce AprE in a genetically modified host harboring three aprE expression cassettes. The DNA binding proteins may serve to increase the efficiency of transcription by creating an additional binding site for RNA polymerase. The discovery of this mechanism significantly increases our understanding of the aprE transcription mechanism, which is of great importance for AprE overproduction.
Collapse
Affiliation(s)
- Cuixia Zhou
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China; School of biology and brewing engineering, Taishan University, Taian 271018, PR China
| | - Huiying Zhou
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China
| | - Honglei Fang
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China
| | - Yizhi Ji
- Beijing Key Laboratory of Biomass Waste Resource Utilization, College of Biochemistry and Engineering, Beijing Union University, Beijing 100023, PR China
| | - Hongbin Wang
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China
| | - Fufeng Liu
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China
| | - Huitu Zhang
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China.
| | - Fuping Lu
- Key laboratory of industrial fermentation microbiology, ministry of education, College of biotechnology, Tianjin University of Science &Technology, Tianjin 300450, PR China.
| |
Collapse
|
36
|
Kobayashi K, Ikemoto Y. Biofilm-associated toxin and extracellular protease cooperatively suppress competitors in Bacillus subtilis biofilms. PLoS Genet 2019; 15:e1008232. [PMID: 31622331 PMCID: PMC6818787 DOI: 10.1371/journal.pgen.1008232] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 10/29/2019] [Accepted: 10/04/2019] [Indexed: 12/17/2022] Open
Abstract
In nature, most bacteria live in biofilms where they compete with their siblings and other species for space and nutrients. Some bacteria produce antibiotics in biofilms; however, since the diffusion of antibiotics is generally hindered in biofilms by extracellular polymeric substances, i.e., the biofilm matrix, their function remains unclear. The Bacillus subtilis yitPOM operon is a paralog of the sdpABC operon, which produces the secreted peptide toxin SDP. Unlike sdpABC, yitPOM is induced in biofilms by the DegS-DegU two-component regulatory system. High yitPOM expression leads to the production of a secreted toxin called YIT. Expression of yitQ, which lies upstream of yitPOM, confers resistance to the YIT toxin, suggesting that YitQ is an anti-toxin protein for the YIT toxin. The alternative sigma factor SigW also contributes to YIT toxin resistance. In a mutant lacking yitQ and sigW, the YIT toxin specifically inhibits biofilm formation, and the extracellular neutral protease NprB is required for this inhibition. The requirement for NprB is eliminated by Δeps and ΔbslA mutations, either of which impairs production of biofilm matrix polymers. Overexpression of biofilm matrix polymers prevents the action of the SDP toxin but not the YIT toxin. These results indicate that, unlike the SDP toxin and many conventional antibiotics, the YIT toxin can pass through layers of biofilm matrix polymers to attack cells within biofilms with assistance from NprB. When the wild-type strain and the YIT-sensitive mutant were grown together on a solid medium, the wild-type strain formed biofilms that excluded the YIT-sensitive mutant. This observation suggests that the YIT toxin protects B. subtilis biofilms against competitors. Several bacteria are known to produce antibiotics in biofilms. We propose that some bacteria including B. subtilis may have evolved specialized antibiotics that can function within biofilms. Biofilms are multicellular aggregates of bacteria that are formed on various living and non-living surfaces. Biofilms often cause serious problems, including food contamination and infectious diseases. Since bacteria in biofilms exhibit increased tolerance or resistance to antimicrobials, new agents and treatments for combating biofilm-related problems are required. In this study, we demonstrated that B. subtilis produces a secreted peptide antibiotic called the YIT toxin and its resistant proteins in biofilms. A mutant lacking the resistance genes was defective in biofilm formation. This effect resulted from the ability of the YIT toxin to pass through the biofilm defense barrier and to attack biofilm cells. Thus, unlike many conventional antibiotics, the YIT toxin can penetrate biofilms and suppress the growth of YIT toxin-sensitive cells within biofilms. Some bacteria produce antibiotics in biofilms, some of which can alter the bacterial composition in the biofilms. Taking these observations into consideration, our findings suggest that some bacteria produce special antibiotics that are effective against bacteria in biofilms, and these antibiotics might serve as anti-biofilm agents.
Collapse
Affiliation(s)
- Kazuo Kobayashi
- Division of Biological Science, Nara Institute of Science & Technology, Ikoma, Nara, Japan
- * E-mail:
| | - Yukako Ikemoto
- Division of Biological Science, Nara Institute of Science & Technology, Ikoma, Nara, Japan
| |
Collapse
|
37
|
Lee LM, Rosenberg G, Rubinstein SM. A Sequence of Developmental Events Occurs Underneath Growing Bacillus subtilis Pellicles. Front Microbiol 2019; 10:842. [PMID: 31105657 PMCID: PMC6499031 DOI: 10.3389/fmicb.2019.00842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/02/2019] [Indexed: 01/18/2023] Open
Abstract
Biofilms are structured communities of bacteria that exhibit complex spatio-temporal dynamics. In liquid media, Bacillus subtilis produces an opaque floating biofilm, or a pellicle. Biofilms are generally associated with an interface, but the ability of Bacillus subtilis to swim means the bacteria are additionally able to reside within the liquid phase. However, due to imaging complications associated with the opacity of pellicles, the extent to which bacteria coexist within the liquid bulk as well as their behavior in the liquid is not well studied. We therefore develop a high-throughput imaging system to image underneath developing pellicles. Here we report a well-defined sequence of developmental events that occurs underneath a growing pellicle. Comparison with bacteria deficient in swimming and chemotaxis suggest that these properties enable collective bacterial swimming within the liquid phase which facilitate faster surface colonization. Furthermore, comparison to bacteria deficient in exopolymeric substances (EPS) suggest that the lack of a surface pellicle prevents further developmental steps from occurring within the liquid phase. Our results reveal a sequence of developmental events during pellicle growth, encompassing adhesion, conversion, growth, maturity, and detachment on the interface, which are synchronized with the bacteria in the liquid bulk increasing in density until the formation of a mature surface pellicle, after which the density of bacteria in the liquid drops.
Collapse
Affiliation(s)
- Lisa M Lee
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States.,Kavli Institute for Bionano Science and Technology, Cambridge, MA, United States
| | - Gili Rosenberg
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Shmuel M Rubinstein
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States.,Kavli Institute for Bionano Science and Technology, Cambridge, MA, United States
| |
Collapse
|
38
|
Inactivation of cysL Inhibits Biofilm Formation by Activating the Disulfide Stress Regulator Spx in Bacillus subtilis. J Bacteriol 2019; 201:JB.00712-18. [PMID: 30718304 DOI: 10.1128/jb.00712-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 01/27/2019] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis forms biofilms in response to internal and external stimuli. I previously showed that the cysL deletion mutant was defective in biofilm formation, but the reason for this remains unidentified. CysL is a transcriptional activator of the cysJI operon, which encodes sulfite reductase, an enzyme involved in cysteine biosynthesis. Decreased production of sulfite reductase led to biofilm formation defects in the ΔcysL mutant. The ΔcysL mutation was suppressed by disrupting cysH operon genes, whose products function upstream of sulfite reductase in the cysteine biosynthesis pathway, indicating that defects in cysteine biosynthesis were not a direct cause for the defective biofilm formation observed in the ΔcysL mutant. The cysH gene encodes phosphoadenosine phosphosulfate reductase, which requires a reduced form of thioredoxin (TrxA) as an electron donor. High expression of trxA inhibited biofilm formation in the ΔcysL mutant but not in the wild-type strain. Northern blot analysis showed that trxA transcription was induced in the ΔcysL mutant in a disulfide stress-induced regulator Spx-dependent manner. On the basis of these results, I propose that the ΔcysL mutation causes phosphoadenosine phosphosulfate reductase to consume large amounts of reduced thioredoxin, inducing disulfide stress and activating Spx. The spx mutation restored biofilm formation to the ΔcysL mutant. The ΔcysL mutation reduced expression of the eps operon, which is required for exopolysaccharide production. Moreover, overexpression of the eps operon restored biofilm formation to the ΔcysL mutant. Taken together, these results suggest that the ΔcysL mutation activates Spx, which then inhibits biofilm formation through repression of the eps operon.IMPORTANCE Bacillus subtilis has been studied as a model organism for biofilm formation. In this study, I explored why the cysL deletion mutant was defective in biofilm formation. I demonstrated that the ΔcysL mutation activated the disulfide stress response regulator Spx, which inhibits biofilm formation by repressing biofilm matrix genes. Homologs of Spx are highly conserved among Gram-positive bacteria with low G+C contents. In some pathogens, Spx is also reported to inhibit biofilm formation by repressing biofilm matrix genes, even though these genes and their regulation are quite different from those of B. subtilis Thus, the negative regulation of biofilm formation by Spx is likely to be well conserved across species and may be an appropriate target for control of biofilm formation.
Collapse
|
39
|
Kovács ÁT, Dragoš A. Evolved Biofilm: Review on the Experimental Evolution Studies of Bacillus subtilis Pellicles. J Mol Biol 2019; 431:4749-4759. [PMID: 30769118 DOI: 10.1016/j.jmb.2019.02.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2019] [Revised: 01/21/2019] [Accepted: 02/04/2019] [Indexed: 12/25/2022]
Abstract
For several decades, laboratory evolution has served as a powerful method to manipulate microorganisms and to explore long-term dynamics in microbial populations. Next to canonical Escherichia coli planktonic cultures, experimental evolution has expanded into alternative cultivation methods and species, opening the doors to new research questions. Bacillus subtilis, the spore-forming and root-colonizing bacterium, can easily develop in the laboratory as a liquid-air interface colonizing pellicle biofilm. Here, we summarize recent findings derived from this tractable experimental model. Clonal pellicle biofilms of B. subtilis can rapidly undergo morphological and genetic diversification creating new ecological interactions, for example, exploitation by biofilm non-producers. Moreover, long-term exposure to such matrix non-producers can modulate cooperation in biofilms, leading to different phenotypic heterogeneity pattern of matrix production with larger subpopulation of "ON" cells. Alternatively, complementary variants of biofilm non-producers, each lacking a distinct matrix component, can engage in a genetic division of labor, resulting in superior biofilm productivity compared to the "generalist" wild type. Nevertheless, inter-genetic cooperation appears to be evanescent and rapidly vanquished by individual biofilm formation strategies altering the amount or the properties of the remaining matrix component. Finally, fast-evolving mobile genetic elements can unpredictably shift intra-species interactions in B. subtilis biofilms. Understanding evolution in clonal biofilm populations will facilitate future studies in complex multispecies biofilms that are more representative of nature.
Collapse
Affiliation(s)
- Ákos T Kovács
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| | - Anna Dragoš
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kongens Lyngby, Denmark.
| |
Collapse
|
40
|
Environmental conditions shape the biofilm of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125. Microbiol Res 2018; 218:66-75. [PMID: 30454660 DOI: 10.1016/j.micres.2018.09.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/24/2018] [Accepted: 09/28/2018] [Indexed: 11/21/2022]
Abstract
Biofilms are the most widely distributed and successful microbial modes of life. The capacity of bacteria to colonize surfaces provides stability in the growth environment, allows the capturing of nutrients and affords protection from a range of environmental challenges and stress. Bacteria living in cold environments, like Antarctica, can be found as biofilms, even though the mechanisms of how this lifestyle is related to their environmental adaptation have been poorly investigated. In this paper, the biofilm of Pseudoalteromonas haloplanktis TAC125, one of the model organisms of cold-adapted bacteria, has been characterized in terms of biofilm typology and matrix composition. The characterization was performed on biofilms produced by the bacterium in response to different nutrient abundance and temperatures; in particular, this is the first report describing the structure of a biofilm formed at 0 °C. The results reported demonstrate that PhTAC125 produces biofilms in different amount and endowed with different physico-chemical properties, like hydrophobicity and roughness, by modulating the relative amount of the different macromolecules present in the biofilm matrix. The capability of PhTAC125 to adopt different biofilm structures in response to environment changes appears to be an interesting adaptation strategy and gives the first hints about the biofilm formation in cold environments.
Collapse
|
41
|
Basarab VY, Voronkova OS, Voronkova YS, Severynovska OV. The Characteristics of Growth of Bacilli Formed Fouling on Wooden Constructions. INTERNATIONAL LETTERS OF NATURAL SCIENCES 2018. [DOI: 10.56431/p-h657vz] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Problem of biofilm formation have a great significance for environmental microbiological research. Biospheric microorganisms can form biofilm, that provide bacteria resistance to influence of different environmental factors. Some of the most common bacteria in biosphere are bacilli, among them there are film-forming strains. Bacillus spp. ia a well-known film forming microorganisms that colonize environmental objects. The biofilm fouling of underwater elements of small wooden constructions located on the Dnieper River near the city of the Dnipro (Ukraine) was studied. It was found that biofilms from surfaces of water constructions include bacilli. It is established that the mean values of CFU in samples from running and still water were (1.81±0.52)×108 and (1.83±0.53)×108 CFU / ml respectively per area of wooden sample approximately 1 cm2, while during the laboratory cultivation of the film, formed by these cultures on the plate, the number of cells was (4.90±0.93)×107 and (4.60±1.07)×107 CFU / ml per 1 cm2 of the well’s bottom, which was an approximate limit of the content of cells of the Bacillus spp. film per unit of area.
Collapse
|
42
|
Basarab VY, Voronkova OS, Voronkova YS, Severynovska OV. The Characteristics of Growth of Bacilli Formed Fouling on Wooden Constructions. INTERNATIONAL LETTERS OF NATURAL SCIENCES 2018. [DOI: 10.18052/www.scipress.com/ilns.70.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Problem of biofilm formation have a great significance for environmental microbiological research. Biospheric microorganisms can form biofilm, that provide bacteria resistance to influence of different environmental factors. Some of the most common bacteria in biosphere are bacilli, among them there are film-forming strains.Bacillus spp.ia a well-known film forming microorganisms that colonize environmental objects. The biofilm fouling of underwater elements of small wooden constructions located on the Dnieper River near the city of the Dnipro (Ukraine) was studied. It was found that biofilms from surfaces of water constructions include bacilli. It is established that the mean values of CFU in samples from running and still water were (1.81±0.52)×108and (1.83±0.53)×108CFU / ml respectively per area of wooden sample approximately 1 cm2, while during the laboratory cultivation of the film, formed by these cultures on the plate, the number of cells was (4.90±0.93)×107and (4.60±1.07)×107CFU / ml per 1 cm2of the well’s bottom, which was an approximate limit of the content of cells of theBacillus spp.film per unit of area.
Collapse
|
43
|
Luo Y, Cheng Y, Yi J, Zhang Z, Luo Q, Zhang D, Li Y. Complete Genome Sequence of Industrial Biocontrol Strain Paenibacillus polymyxa HY96-2 and Further Analysis of Its Biocontrol Mechanism. Front Microbiol 2018; 9:1520. [PMID: 30050512 PMCID: PMC6052121 DOI: 10.3389/fmicb.2018.01520] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 06/19/2018] [Indexed: 12/17/2022] Open
Abstract
Paenibacillus polymyxa (formerly known as Bacillus polymyxa) has been extensively studied for agricultural applications as a plant-growth-promoting rhizobacterium and is also an important biocontrol agent. Our team has developed the P. polymyxa strain HY96-2 from the tomato rhizosphere as the first microbial biopesticide based on P. polymyxa for controlling plant diseases around the world, leading to the commercialization of this microbial biopesticide in China. However, further research is essential for understanding its precise biocontrol mechanisms. In this paper, we report the complete genome sequence of HY96-2 and the results of a comparative genomic analysis between different P. polymyxa strains. The complete genome size of HY96-2 was found to be 5.75 Mb and 5207 coding sequences were predicted. HY96-2 was compared with seven other P. polymyxa strains for which complete genome sequences have been published, using phylogenetic tree, pan-genome, and nucleic acid co-linearity analysis. In addition, the genes and gene clusters involved in biofilm formation, antibiotic synthesis, and systemic resistance inducer production were compared between strain HY96-2 and two other strains, namely, SC2 and E681. The results revealed that all three of the P. polymyxa strains have the ability to control plant diseases via the mechanisms of colonization (biofilm formation), antagonism (antibiotic production), and induced resistance (systemic resistance inducer production). However, the variation of the corresponding genes or gene clusters between the three strains may lead to different antimicrobial spectra and biocontrol efficacies. Two possible pathways of biofilm formation in P. polymyxa were reported for the first time after searching the KEGG database. This study provides a scientific basis for the further optimization of the field applications and quality standards of industrial microbial biopesticides based on HY96-2. It may also serve as a reference for studying the differences in antimicrobial spectra and biocontrol capability between different biocontrol agents.
Collapse
Affiliation(s)
| | | | | | | | | | - Daojing Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Yuanguang Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| |
Collapse
|
44
|
von Bronk B, Götz A, Opitz M. Complex microbial systems across different levels of description. Phys Biol 2018; 15:051002. [PMID: 29757151 DOI: 10.1088/1478-3975/aac473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Complex biological systems offer a variety of interesting phenomena at the different physical scales. With increasing abstraction, details of the microscopic scales can often be extrapolated to average or typical macroscopic properties. However, emergent properties and cross-scale interactions can impede naïve abstractions and necessitate comprehensive investigations of these complex systems. In this review paper, we focus on microbial communities, and first, summarize a general hierarchy of relevant scales and description levels to understand these complex systems: (1) genetic networks, (2) single cells, (3) populations, and (4) emergent multi-cellular properties. Second, we employ two illustrating examples, microbial competition and biofilm formation, to elucidate how cross-scale interactions and emergent properties enrich the observed multi-cellular behavior in these systems. Finally, we conclude with pointing out the necessity of multi-scale investigations to understand complex biological systems and discuss recent investigations.
Collapse
Affiliation(s)
- Benedikt von Bronk
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, D-80539 Munich, Germany
| | | | | |
Collapse
|
45
|
Steinberg N, Rosenberg G, Keren-Paz A, Kolodkin-Gal I. Collective Vortex-Like Movement of Bacillus subtilis Facilitates the Generation of Floating Biofilms. Front Microbiol 2018; 9:590. [PMID: 29651280 PMCID: PMC5884953 DOI: 10.3389/fmicb.2018.00590] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/14/2018] [Indexed: 12/29/2022] Open
Abstract
Bacteria in nature are usually found in complex multicellular structures, called biofilms. One common form of a biofilm is pellicle—a floating mat of bacteria formed in the water-air interphase. So far, our knowledge on the basic mechanisms underlying the formation of biofilms at air-liquid interfaces is not complete. In particular, the co-occurrence of motile cells and extracellular matrix producers has not been studied. In addition, the potential involvement of chemical communication in pellicle formation remained largely undefined. Our results indicate that vortex-like collective motility by aggregates of motile cells and EPS producers accelerate the formation of floating biofilms. Successful aggregation and migration to the water-air interphase depend on the chemical communication signal autoinducer 2 (AI-2). This ability of bacteria to form a biofilm in a preferable niche ahead of their potential rivals would provide a fitness advantage in the context of inter-species competition.
Collapse
Affiliation(s)
- Nitai Steinberg
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Gili Rosenberg
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Alona Keren-Paz
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Ilana Kolodkin-Gal
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
46
|
Okshevsky M, Louw MG, Lamela EO, Nilsson M, Tolker‐Nielsen T, Meyer RL. A transposon mutant library of Bacillus cereus ATCC 10987 reveals novel genes required for biofilm formation and implicates motility as an important factor for pellicle-biofilm formation. Microbiologyopen 2018; 7:e00552. [PMID: 29164822 PMCID: PMC5911993 DOI: 10.1002/mbo3.552] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/18/2017] [Indexed: 11/16/2022] Open
Abstract
Bacillus cereus is one of the most common opportunistic pathogens causing foodborne illness, as well as a common source of contamination in the dairy industry. B. cereus can form robust biofilms on food processing surfaces, resulting in food contamination due to shedding of cells and spores. Despite the medical and industrial relevance of this species, the genetic basis of biofilm formation in B. cereus is not well studied. In order to identify genes required for biofilm formation in this bacterium, we created a library of 5000 + transposon mutants of the biofilm-forming strain B. cereusATCC 10987, using an unbiased mariner transposon approach. The mutant library was screened for the ability to form a pellicle biofilm at the air-media interface, as well as a submerged biofilm at the solid-media interface. A total of 91 genes were identified as essential for biofilm formation. These genes encode functions such as chemotaxis, amino acid metabolism and cellular repair mechanisms, and include numerous genes not previously known to be required for biofilm formation. Although the majority of disrupted genes are not directly responsible for motility, further investigations revealed that the vast majority of the biofilm-deficient mutants were also motility impaired. This observation implicates motility as a pivotal factor in the formation of a biofilm by B. cereus. These results expand our knowledge of the fundamental molecular mechanisms of biofilm formation by B. cereus.
Collapse
Affiliation(s)
- Mira Okshevsky
- Interdisciplinary Nanoscience CenterAarhus UniversityAarhusDenmark
| | | | | | - Martin Nilsson
- Department of Immunology and MicrobiologyUniversity of CopenhagenCopenhagenDenmark
| | - Tim Tolker‐Nielsen
- Department of Immunology and MicrobiologyUniversity of CopenhagenCopenhagenDenmark
| | - Rikke Louise Meyer
- Interdisciplinary Nanoscience CenterAarhus UniversityAarhusDenmark
- Department of BioscienceAarhus UniversityAarhusDenmark
| |
Collapse
|
47
|
FtsEX-CwlO regulates biofilm formation by a plant-beneficial rhizobacterium Bacillus velezensis SQR9. Res Microbiol 2018; 169:166-176. [PMID: 29427638 DOI: 10.1016/j.resmic.2018.01.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 01/23/2018] [Accepted: 01/29/2018] [Indexed: 12/23/2022]
Abstract
Bacillus velezensis strain SQR9 is a well-investigated rhizobacterium with an outstanding ability to colonize roots, enhance plant growth and suppress soil-borne diseases. The recognition that biofilm formation by plant-beneficial bacteria is crucial for their root colonization and function has resulted in increased interest in understanding molecular mechanisms related to biofilm formation. Here, we report that the gene ftsE, encoding the ATP-binding protein of an FtsEX ABC transporter, is required for efficient SQR9 biofilm formation. FtsEX has been reported to regulate the atolysin CwlO. We provided evidence that FtsEX-CwlO was involved in the regulation of SQR9 biofilm formation; however, this effect has little to do with CwlO autolysin activity. We propose that regulation of biofilm formation by CwlO was exerted through the spo0A pathway, since transcription of spo0A cascade genes was altered and their downstream extracellular matrix genes were downregulated in SQR9 ftsE/cwlO deletion mutants. CwlO was also shown to interact physically with KinB/KinD. CwlO may therefore interact with KinB/KinD to interfere with the spo0A pathway. This study revealed that FtsEX-CwlO plays a previously undiscovered regulatory role in biofilm formation by SQR9 that may enhance root colonization and plant-beneficial functions of SQR9 and other beneficial rhizobacteria as well.
Collapse
|
48
|
Visualizing Bacterial Colony Morphologies Using Time-Lapse Imaging Chamber MOCHA. J Bacteriol 2017; 200:JB.00413-17. [PMID: 29084858 PMCID: PMC5738739 DOI: 10.1128/jb.00413-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 10/19/2017] [Indexed: 02/05/2023] Open
Abstract
Capturing microbial growth on a macroscopic scale is of great importance to further our understanding of microbial life. However, methods for imaging microbial life on a scale of millimeters to centimeters are often limited by designs that have poor environmental control, resulting in dehydration of the agar plate within just a few days. Here, we created MOCHA (microbial chamber), a simple but effective chamber that allows users to study microbial growth for extended periods (weeks) in a stable environment. Agar hydration is maintained with a double-decker design, in which two glass petri dishes are connected by a wick, allowing the lower plate to keep the upper plate hydrated. This flexible chamber allows the observation of a variety of microbiological phenomena, such as the growth and development of single bacterial and fungal colonies, interspecies interactions, swarming motility, and pellicle formation.IMPORTANCE Detailed study of microbial life on the colony scale of millimeters to centimeters has been lagging considerably behind microscopic inspection of microbes. One major reason for this is the lack of inexpensive instrumentation that can reproducibly capture images in a controlled environment. In this study, we present the design and use of a unique chamber that was used to produce several time-lapse movies that aimed to capture the diversity of microbial colony phenotypes over long periods.
Collapse
|
49
|
Lysinibacillus fusiformis M5 Induces Increased Complexity in Bacillus subtilis 168 Colony Biofilms via Hypoxanthine. J Bacteriol 2017; 199:JB.00204-17. [PMID: 28583948 DOI: 10.1128/jb.00204-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/30/2017] [Indexed: 12/18/2022] Open
Abstract
In recent years, biofilms have become a central subject of research in the fields of microbiology, medicine, agriculture, and systems biology, among others. The sociomicrobiology of multispecies biofilms, however, is still poorly understood. Here, we report a screening system that allowed us to identify soil bacteria which induce architectural changes in biofilm colonies when cocultured with Bacillus subtilis We identified the soil bacterium Lysinibacillus fusiformis M5 as an inducer of wrinkle formation in B. subtilis colonies mediated by a diffusible signaling molecule. This compound was isolated by bioassay-guided chromatographic fractionation. The elicitor was identified to be the purine hypoxanthine using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. We show that the induction of wrinkle formation by hypoxanthine is not dependent on signal recognition by the histidine kinases KinA, KinB, KinC, and KinD, which are generally involved in phosphorylation of the master regulator Spo0A. Likewise, we show that hypoxanthine signaling does not induce the expression of biofilm matrix-related operons epsABCDEFGHIJKLMNO and tasA-sipW-tapA Finally, we demonstrate that the purine permease PbuO, but not PbuG, is necessary for hypoxanthine to induce an increase in wrinkle formation of B. subtilis biofilm colonies. Our results suggest that hypoxanthine-stimulated wrinkle development is not due to a direct induction of biofilm-related gene expression but rather is caused by the excess of hypoxanthine within B. subtilis cells, which may lead to cell stress and death.IMPORTANCE Biofilms are a bacterial lifestyle with high relevance regarding diverse human activities. Biofilms can be beneficial, for instance, in crop protection. In nature, biofilms are commonly found as multispecies communities displaying complex social behaviors and characteristics. The study of interspecies interactions will thus lead to a better understanding and use of biofilms as they occur outside laboratory conditions. Here, we present a screening method suitable for the identification of multispecies interactions and showcase L. fusiformis as a soil bacterium that is able to live alongside B. subtilis and modify the architecture of its biofilms.
Collapse
|
50
|
Films of bacteria at interfaces. Adv Colloid Interface Sci 2017; 247:561-572. [PMID: 28778342 DOI: 10.1016/j.cis.2017.07.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 11/21/2022]
Abstract
Bacteria are often discussed as active colloids, self-propelled organisms whose collective motion can be studied in the context of non-equilibrium statistical mechanics. In such studies, the behavior of bacteria confined to interfaces or in the proximity of an interface plays an important role. For instance, many studies have probed collective behavior of bacteria in quasi two-dimensional systems such as soap films. Since fluid interfaces can adsorb surfactants and other materials, the stress and velocity boundary conditions at interfaces can alter bacteria motion; hydrodynamic studies of interfaces with differing boundary conditions are reviewed. Also, bacteria in bulk can become trapped at or near fluid interfaces, where they colonize and form structures comprising secretions like exopolysaccharides, surfactants, living and dead bacteria, thereby creating Films of Bacteria at Interfaces (FBI). The formation of FBI is discussed at air-water, oil-water, and water-water interfaces, with an emphasis on film mechanics, and with some allusion to genetic functions guiding bacteria to restructure fluid interfaces. At air-water interfaces, bacteria form pellicles or interfacial biofilms. Studies are reviewed that reveal that pellicle material properties differ for different strains of bacteria, and that pellicle physicochemistry can act as a feedback mechanism to regulate film formation. At oil-water interfaces, a range of FBI form, depending on bacteria strain. Some bacteria-laden interfaces age from an initial active film, with dynamics dominated by motile bacteria, through viscoelastic states, to form an elastic film. Others remain active with no evidence of elastic film formation even at significant interface ages. Finally, bacteria can adhere to and colonize ultra-low surface tension interfaces such as aqueous-aqueous systems common in food industries. Relevant literature is reviewed, and areas of interest for potential application are discussed, ranging from health to bioremediation.
Collapse
|