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Jacek P, Ryngajłło M, Bielecki S. Structural changes of bacterial nanocellulose pellicles induced by genetic modification of Komagataeibacter hansenii ATCC 23769. Appl Microbiol Biotechnol 2019; 103:5339-5353. [PMID: 31037382 PMCID: PMC6570709 DOI: 10.1007/s00253-019-09846-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 04/09/2019] [Accepted: 04/10/2019] [Indexed: 01/08/2023]
Abstract
Bacterial nanocellulose (BNC) synthesized by Komagataeibacter hansenii is a polymer that recently gained an attention of tissue engineers, since its features make it a suitable material for scaffolds production. Nevertheless, it is still necessary to modify BNC to improve its properties in order to make it more suitable for biomedical use. One approach to address this issue is to genetically engineer K. hansenii cells towards synthesis of BNC with modified features. One of possible ways to achieve that is to influence the bacterial movement or cell morphology. In this paper, we described for the first time, K. hansenii ATCC 23769 motA+ and motB+ overexpression mutants, which displayed elongated cell phenotype, increased motility, and productivity. Moreover, the mutant cells produced thicker ribbons of cellulose arranged in looser network when compared to the wild-type strain. In this paper, we present a novel development in obtaining BNC membranes with improved properties using genetic engineering tools.
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Affiliation(s)
- Paulina Jacek
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Małgorzata Ryngajłło
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland
| | - Stanisław Bielecki
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland
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Jacek P, Kubiak K, Ryngajłło M, Rytczak P, Paluch P, Bielecki S. Modification of bacterial nanocellulose properties through mutation of motility related genes in Komagataeibacter hansenii ATCC 53582. N Biotechnol 2019; 52:60-68. [PMID: 31096013 DOI: 10.1016/j.nbt.2019.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 05/08/2019] [Accepted: 05/11/2019] [Indexed: 11/17/2022]
Abstract
Bacterial nanocellulose (BNC) produced by Komagataeibacter hansenii has received significant attention due to its unique supernetwork structure and properties. It is nevertheless necessary to modify bacterial nanocellulose to achieve materials with desired properties and thus with broader areas of application. The aim here was to influence the 3D structure of BNC by genetic modification of the cellulose producing K. hansenii strain ATCC 53582. Two genes encoding proteins with homology to the MotA and MotB proteins, which participate in motility and energy transfer, were selected for our studies. A disruption mutant of one or both genes and their respective complementation mutants were created. The phenotype analysis of the disruption mutants showed a reduction in motility, which resulted in higher compaction of nanocellulose fibers and improvement in their mechanical properties. The data strongly suggest that these genes play an important role in the formation of BNC membrane by Komagataeibacter species.
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Affiliation(s)
- Paulina Jacek
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland.
| | - Katarzyna Kubiak
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland.
| | - Małgorzata Ryngajłło
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland.
| | - Przemysław Rytczak
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland.
| | - Piotr Paluch
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland.
| | - Stanisław Bielecki
- Institute of Technical Biochemistry, Lodz University of Technology, B. Stefanowskiego 4/10, 90-924 Lodz, Poland.
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Agrobacterium-mediated horizontal gene transfer: Mechanism, biotechnological application, potential risk and forestalling strategy. Biotechnol Adv 2018; 37:259-270. [PMID: 30579929 DOI: 10.1016/j.biotechadv.2018.12.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 11/20/2022]
Abstract
The extraordinary capacity of Agrobacterium to transfer its genetic material to host cell makes it evolve from phytopathogen to a powerful transgenic vector. Agrobacterium-mediated stable transformation is widely used as the preferred method to create transgenic plants for molecular plant biology research and crop breeding. Recent years, both mechanism and application of Agrobacterium-mediated horizontal gene transfer have made significant progresses, especially Agrobacterium-mediated transient transformation was developed for plant biotechnology industry to produce recombinant proteins. Agrobacterium strains are almost used and saved not only by each of microbiology and molecular plant labs, but also by many of plant biotechnology manufacturers. Agrobacterium is able to transfer its genetic material to a broad range of hosts, including plant and non-plant hosts. As a consequence, the concern of environmental risk associated with the accidental release of genetically modified Agrobacterium arises. In this article, we outline the recent progress in the molecular mechanism of Agrobacterium-meditated gene transfer, focus on the application of Agrobacterium-mediated horizontal gene transfer, and review the potential risk associated with Agrobacterium-meditated gene transfer. Based on the comparison between the infecting process of Agrobacterium as a pathogen and the transgenic process of Agrobacterium as a transgenic vector, we realize that chemotaxis is the distinct difference between these two biological processes and thus discuss the possible role of chemotaxis in forestalling the potential risk of Agrobacterium-meditated horizontal gene transfer to non-target plant species.
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Multiple Flagellin Proteins Have Distinct and Synergistic Roles in Agrobacterium tumefaciens Motility. J Bacteriol 2018; 200:JB.00327-18. [PMID: 30201783 DOI: 10.1128/jb.00327-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 09/01/2018] [Indexed: 11/20/2022] Open
Abstract
Rotary flagella propel bacteria through liquid and across semisolid environments. Flagella are composed of the basal body that constitutes the motor for rotation, the curved hook that connects to the basal body, and the flagellar filament that propels the cell. Flagellar filaments can be composed of a single flagellin protein, such as in Escherichia coli, or made up of multiple flagellins, such as in Agrobacterium tumefaciens The four distinct flagellins FlaA, FlaB, FlaC, and FlaD produced by wild-type A. tumefaciens are not redundant in function but have specific properties. FlaA and FlaB are much more abundant than FlaC and FlaD and are readily observable in mature flagellar filaments, when either FlaA or FlaB is fluorescently labeled. Cells producing FlaA with any one of the other three flagellins can generate functional filaments and thus are motile, but FlaA alone cannot constitute a functional filament. In flaA mutants that manifest swimming deficiencies, there are multiple ways by which these mutations can be phenotypically suppressed. These suppressor mutations primarily occur within or upstream of the flaB flagellin gene or in the transcription factor sciP regulating flagellin expression. The helical conformation of the flagellar filament appears to require a key asparagine residue present in FlaA and absent in other flagellins. However, FlaB can be spontaneously mutated to render helical flagella in the absence of FlaA, reflecting their overall similarity and perhaps the subtle differences in the specific functions they have evolved to fulfill.IMPORTANCE Flagellins are abundant bacterial proteins comprising the flagellar filaments that propel bacterial movement. Several members of the alphaproteobacterial group express multiple flagellins, in contrast to model systems, such as with Escherichia coli, which has one type of flagellin. The plant pathogen Agrobacterium tumefaciens has four flagellins, the abundant and readily detected FlaA and FlaB, and lower levels of FlaC and FlaD. Mutational analysis reveals that FlaA requires at least one of the other flagellins to function, as flaA mutants produce nonhelical flagella and cannot swim efficiently. Suppressor mutations can rescue this swimming defect through mutations in the remaining flagellins, including structural changes imparting helical shape to the flagella, and putative regulators. Our findings shed light on how multiple flagellins contribute to motility.
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Kumar Verma R, Samal B, Chatterjee S. Xanthomonas oryzae pv. oryzae chemotaxis components and chemoreceptor Mcp2 are involved in the sensing of constituents of xylem sap and contribute to the regulation of virulence-associated functions and entry into rice. MOLECULAR PLANT PATHOLOGY 2018; 19:2397-2415. [PMID: 30011125 PMCID: PMC6638100 DOI: 10.1111/mpp.12718] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 06/08/2018] [Accepted: 06/17/2018] [Indexed: 05/26/2023]
Abstract
The Xanthomonas group of phytopathogens causes several economically important diseases in crops. In the bacterial pathogen of rice, Xanthomonas oryzae pv. oryzae (Xoo), it has been proposed that chemotaxis may play a role in the entry and colonization of the pathogen inside the host. However, components of the chemotaxis system, including the chemoreceptors involved, and their role in entry and virulence, are not well defined. In this study, we show that Xoo displays a positive chemotaxis response to components of rice xylem sap-glutamine, xylose and methionine. In order to understand the role of chemotaxis components involved in the promotion of chemotaxis, entry and virulence, we performed detailed deletion mutant analysis. Analysis of mutants defective in chemotaxis components, flagellar biogenesis, expression analysis and assays of virulence-associated functions indicated that chemotaxis-mediated signalling in Xoo is involved in the regulation of several virulence-associated functions, such as motility, attachment and iron homeostasis. The ∆cheY1 mutant of Xoo exhibited a reduced expression of genes involved in motility, adhesins, and iron uptake and metabolism. We show that the expression of Xoo chemotaxis and motility components is induced under in planta conditions and is required for entry, colonization and virulence. Furthermore, deletion analysis of a putative chemoreceptor mcp2 gene revealed that chemoreceptor Mcp2 is involved in the sensing of xylem sap and constituents of xylem exudate, including methionine, serine and histidine, and plays an important role in epiphytic entry and virulence. This is the first report of the role of chemotaxis in the virulence of this important group of phytopathogens.
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Affiliation(s)
- Raj Kumar Verma
- Centre for DNA Fingerprinting and DiagnosticsUppal RoadHyderabad500039India
- Graduate StudiesManipal Academy of Higher EducationMangaluruKarnataka576104India
| | - Biswajit Samal
- Centre for DNA Fingerprinting and DiagnosticsUppal RoadHyderabad500039India
- Graduate StudiesManipal Academy of Higher EducationMangaluruKarnataka576104India
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Berne C, Ellison CK, Agarwal R, Severin GB, Fiebig A, Morton RI, Waters CM, Brun YV. Feedback regulation of Caulobacter crescentus holdfast synthesis by flagellum assembly via the holdfast inhibitor HfiA. Mol Microbiol 2018; 110:219-238. [PMID: 30079982 DOI: 10.1111/mmi.14099] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2018] [Indexed: 12/23/2022]
Abstract
To permanently attach to surfaces, Caulobacter crescentusproduces a strong adhesive, the holdfast. The timing of holdfast synthesis is developmentally regulated by cell cycle cues. When C. crescentusis grown in a complex medium, holdfast synthesis can also be stimulated by surface sensing, in which swarmer cells rapidly synthesize holdfast in direct response to surface contact. In contrast to growth in complex medium, here we show that when cells are grown in a defined medium, surface contact does not trigger holdfast synthesis. Moreover, we show that in a defined medium, flagellum synthesis and regulation of holdfast production are linked. In these conditions, mutants lacking a flagellum attach to surfaces over time more efficiently than either wild-type strains or strains harboring a paralyzed flagellum. Enhanced adhesion in mutants lacking flagellar components is due to premature holdfast synthesis during the cell cycle and is regulated by the holdfast synthesis inhibitor HfiA. hfiA transcription is reduced in flagellar mutants and this reduction is modulated by the diguanylate cyclase developmental regulator PleD. We also show that, in contrast to previous predictions, flagella are not necessarily required for C. crescentus surface sensing in the absence of flow, and that arrest of flagellar rotation does not stimulate holdfast synthesis. Rather, our data support a model in which flagellum assembly feeds back to control holdfast synthesis via HfiA expression in a c-di-GMP-dependent manner under defined nutrient conditions.
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Affiliation(s)
- Cécile Berne
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN, 47405, USA
| | - Courtney K Ellison
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN, 47405, USA
| | - Radhika Agarwal
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN, 47405, USA.,Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Geoffrey B Severin
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Aretha Fiebig
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Robert I Morton
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN, 47405, USA
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Yves V Brun
- Department of Biology, Indiana University, 1001 E. 3rd Street, Bloomington, IN, 47405, USA
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The alternative sigma factor RpoQ regulates colony morphology, biofilm formation and motility in the fish pathogen Aliivibrio salmonicida. BMC Microbiol 2018; 18:116. [PMID: 30208852 PMCID: PMC6134601 DOI: 10.1186/s12866-018-1258-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 09/04/2018] [Indexed: 02/04/2023] Open
Abstract
Background Quorum sensing (QS) is a cell-to cell communication system that bacteria use to synchronize activities as a group. LitR, the master regulator of QS in Aliivibrio salmonicida, was recently shown to regulate activities such as motility, rugosity and biofilm formation in a temperature dependent manner. LitR was also found to be a positive regulator of rpoQ. RpoQ is an alternative sigma factor belonging to the sigma −70 family. Alternative sigma factors direct gene transcription in response to environmental signals. In this work we have studied the role of RpoQ in biofilm formation, colony morphology and motility of A. salmonicida LFI1238. Results The rpoQ gene in A. salmonicida LFI1238 was deleted using allelic exchange. We found that RpoQ is a strong repressor of rugose colony morphology and biofilm formation, and that it controls motility of the bacteria. We also show that overexpression of rpoQ in a ΔlitR mutant of A. salmonicida disrupts the biofilm produced by the ΔlitR mutant and decreases its motility, whereas rpoQ overexpression in the wild-type completely eliminates the motility. Conclusion The present work demonstrates that the RpoQ sigma factor is a novel regulatory component involved in modulating motility, colony morphology and biofilm formation in the fish pathogen A. salmonicida. The findings also confirm that RpoQ functions downstream of the QS master regulator LitR. However further studies are needed to elucidate how LitR and RpoQ work together in controlling phenotypes related to QS in A. salmonicida. Electronic supplementary material The online version of this article (10.1186/s12866-018-1258-9) contains supplementary material, which is available to authorized users.
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Meyer T, Renoud S, Vigouroux A, Miomandre A, Gaillard V, Kerzaon I, Prigent-Combaret C, Comte G, Moréra S, Vial L, Lavire C. Regulation of Hydroxycinnamic Acid Degradation Drives Agrobacterium fabrum Lifestyles. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:814-822. [PMID: 29460677 DOI: 10.1094/mpmi-10-17-0236-r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Regulatory factors are key components for the transition between different lifestyles to ensure rapid and appropriate gene expression upon perceiving environmental cues. Agrobacterium fabrum C58 (formerly called A. tumefaciens C58) has two contrasting lifestyles: it can interact with plants as either a rhizosphere inhabitant (rhizospheric lifestyle) or a pathogen that creates its own ecological niche in a plant tumor via its tumor-inducing plasmid (pathogenic lifestyle). Hydroxycinnamic acids are known to play an important role in the pathogenic lifestyle of Agrobacterium spp. but can be degraded in A. fabrum species. We investigated the molecular and ecological mechanisms involved in the regulation of A. fabrum species-specific genes responsible for hydroxycinnamic acid degradation. We characterized the effectors (feruloyl-CoA and p-coumaroyl-CoA) and the DNA targets of the MarR transcriptional repressor, which we named HcaR, which regulates hydroxycinnamic acid degradation. Using an hcaR-deleted strain, we further revealed that hydroxycinnamic acid degradation interfere with virulence gene expression. The HcaR deletion mutant shows a contrasting competitive colonization ability, being less abundant than the wild-type strain in tumors but more abundant in the rhizosphere. This supports the view that A. fabrum C58 HcaR regulation through ferulic and p-coumaric acid perception is important for the transition between lifestyles.
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Affiliation(s)
- Thibault Meyer
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Sébastien Renoud
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Armelle Vigouroux
- 2 Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France
| | - Aurélie Miomandre
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Vincent Gaillard
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Isabelle Kerzaon
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Claire Prigent-Combaret
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Gilles Comte
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Solange Moréra
- 2 Institute for Integrative Biology of the Cell (I2BC), CNRS CEA Univ. Paris-Sud, Université Paris-Saclay, Avenue de la Terrasse, Gif-sur-Yvette 91198, France
| | - Ludovic Vial
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
| | - Céline Lavire
- 1 Université de Lyon, F-69622, Lyon, France; Université Lyon 1, Villeurbanne, France; CNRS, UMR5557, Ecologie Microbienne, Villeurbanne, France; INRA, UMR1418, Villeurbanne, France; and
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Liu W, Sun Y, Shen R, Dang X, Liu X, Sui F, Li Y, Zhang Z, Alexandre G, Elmerich C, Xie Z. A Chemotaxis-Like Pathway of Azorhizobium caulinodans Controls Flagella-Driven Motility, Which Regulates Biofilm Formation, Exopolysaccharide Biosynthesis, and Competitive Nodulation. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:737-749. [PMID: 29424664 DOI: 10.1094/mpmi-12-17-0290-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The genome of the Azorhizobium caulinodans ORS571 contains a unique chemotaxis gene cluster (che) including five chemotaxis genes: cheA, cheW, cheY1, cheB, and cheR. Analysis of the role of the chemotaxis cluster of A. caulinodans using deletion mutant strains revealed that CheA or the Che signaling pathway controls chemotaxis behavior and flagella-driven motility and plays important roles in formation of biofilms and production of extracellular polysaccharides (EPS). Furthermore, the deletion mutants (ΔcheA and ΔcheA-R) were defective in competitive adsorption and colonization on the root surface of host plants. In addition, a functional CheA or Che pathway promoted competitive nodulation on roots and stems. Interestingly, a nonflagellated mutant, ΔfliM, displayed a phenotype highly similar to that of the ΔcheA or ΔcheA-R mutant strains. These findings suggest that through controlling flagella-driven motility behavior, the chemotaxis signaling pathway in A. caulinodans coordinates biofilm formation, EPS, and competitive colonization and nodulation.
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Affiliation(s)
- Wei Liu
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yu Sun
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Rimin Shen
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
- 2 Shanxi Agricultural University, Taigu, Shanxi, China
| | - Xiaoxiao Dang
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Xiaolin Liu
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Fu Sui
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Yan Li
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Zhenpeng Zhang
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
| | - Gladys Alexandre
- 3 Biochemistry, Cellular and Molecular Biology Department, University of Tennessee, Knoxville, U.S.A.; and
| | | | - Zhihong Xie
- 1 Key Laboratory of Coastal Biology and Bioresource Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China
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Kang X, Zhang W, Cai X, Zhu T, Xue Y, Liu C. Bacillus velezensis CC09: A Potential 'Vaccine' for Controlling Wheat Diseases. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:623-632. [PMID: 29372814 DOI: 10.1094/mpmi-09-17-0227-r] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Biocontrol bacteria that can act like a "vaccine", stimulating plant resistance to pathogenic diseases, are still not fully elucidated. In this study, an endophytic bacterium, Bacillus velezensis CC09, labeled with green fluorescent protein, was tested for its colonization, migration, and expression of genes encoding iturin A synthetase within wheat tissues and organs as well as for protective effects against wheat take-all and spot blotch diseases. The results showed that strain CC09 not only formed biofilm on the root surface but was also widely distributed in almost every tissue, including the epidermis, cortex, and xylem vessels, and even migrated to stems and leaves, resulting in 66.67% disease-control efficacy (DCE) of take-all and 21.64% DCE of spot blotch. Moreover, the gene cluster encoding iturin A synthase under the control of the pitu promoter is expressed in B. velezensis CC09 in wheat tissues, which indicates that iturin A might contribute to the in-vivo antifungal activity and leads to the disease control. All these data suggested that strain CC09 can act like a 'vaccine' in the control of wheat diseases, with a single treatment inoculated on roots through multiple mechanisms.
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Affiliation(s)
- Xingxing Kang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Wanling Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Xunchao Cai
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Tong Zhu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yarong Xue
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Changhong Liu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
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Flores SA, Howell M, Daniel JJ, Piccolo R, Brown PJB. Absence of the Min System Does Not Cause Major Cell Division Defects in Agrobacterium tumefaciens. Front Microbiol 2018; 9:681. [PMID: 29686659 PMCID: PMC5900048 DOI: 10.3389/fmicb.2018.00681] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/22/2018] [Indexed: 12/19/2022] Open
Abstract
In A. tumefaciens, the essential FtsZ protein is located at the growth pole before shifting to the mid-cell right before division. Loss of FtsZ causes a halt in cell separation and lysis of cells. To understand how FtsZ polymerization is regulated to properly localize the FtsZ ring at the mid-cell, we have conducted a systematic characterization of the Min system in A. tumefaciens. Our findings indicate that the Min system is not required for cell survival. Yet, we find that the deletion of either minE or minCDE results in a broad cell size distribution, including an increase in the proportion of short and long cells. We observe that the site of constriction is misplaced in the minE or minCDE deletion strains allowing for short cells to arise from sites of constriction near the cell poles. Remarkably, the short cells are viable and contain DNA. In order to observe chromosome replication and segregation in these strains, YFP-ParB is used as a proxy to track the origin of replication as cells elongate and divide. In the absence of the Min proteins, duplication and segregation of the origin of replication is frequently delayed. Taken together, our data suggest that the Min system contributes to the proper regulation of FtsZ placement and subsequent cell division. Furthermore, the failure to precisely place FtsZ rings at mid-cell in the min mutants impacts other cell cycle features including chromosome segregation.
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Affiliation(s)
- Sue A Flores
- Division of Biological Sciences, University of Missouri, Columbia, MO, United States
| | - Matthew Howell
- Division of Biological Sciences, University of Missouri, Columbia, MO, United States
| | - Jeremy J Daniel
- Division of Biological Sciences, University of Missouri, Columbia, MO, United States
| | - Rebecca Piccolo
- Division of Biological Sciences, University of Missouri, Columbia, MO, United States
| | - Pamela J B Brown
- Division of Biological Sciences, University of Missouri, Columbia, MO, United States
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Bakenhus I, Voget S, Poehlein A, Brinkhoff T, Daniel R, Simon M. Genome sequence of Planktotalea frisia type strain (SH6-1 T), a representative of the Roseobacter group isolated from the North Sea during a phytoplankton bloom. Stand Genomic Sci 2018; 13:7. [PMID: 29682168 PMCID: PMC5896138 DOI: 10.1186/s40793-018-0311-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Accepted: 03/21/2018] [Indexed: 12/15/2022] Open
Abstract
Planktotalea frisia SH6-1T Hahnke et al. (Int J Syst Evol Microbiol 62:1619-24, 2012) is a planktonic marine bacterium isolated during a phytoplankton bloom from the southern North Sea. It belongs to the Roseobacter group within the alphaproteobacterial family Rhodobacteraceae. Here we describe the draft genome sequence and annotation of the type strain SH6-1T. The genome comprises 4,106,736 bp and contains 4128 protein-coding and 38 RNA genes. The draft genome sequence provides evidence for at least three extrachromosomal elements, encodes genes for DMSP utilization, quorum sensing, photoheterotrophy and a type IV secretion system. This indicates not only adaptation to a free-living lifestyle of P. frisia but points also to interactions with prokaryotic or eukaryotic organisms.
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Affiliation(s)
- Insa Bakenhus
- 1Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
| | - Sonja Voget
- 2Institute of Microbiology and Genetics, Genomic and Applied Microbiology and Göttingen Genomics Laboratory, University of Göttingen, Göttingen, Germany
| | - Anja Poehlein
- 2Institute of Microbiology and Genetics, Genomic and Applied Microbiology and Göttingen Genomics Laboratory, University of Göttingen, Göttingen, Germany
| | - Thorsten Brinkhoff
- 1Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
| | - Rolf Daniel
- 2Institute of Microbiology and Genetics, Genomic and Applied Microbiology and Göttingen Genomics Laboratory, University of Göttingen, Göttingen, Germany
| | - Meinhard Simon
- 1Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Oldenburg, Germany
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Martínez-García R, Nadell CD, Hartmann R, Drescher K, Bonachela JA. Cell adhesion and fluid flow jointly initiate genotype spatial distribution in biofilms. PLoS Comput Biol 2018; 14:e1006094. [PMID: 29659578 PMCID: PMC5901778 DOI: 10.1371/journal.pcbi.1006094] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/16/2018] [Indexed: 11/18/2022] Open
Abstract
Biofilms are microbial collectives that occupy a diverse array of surfaces. It is well known that the function and evolution of biofilms are strongly influenced by the spatial arrangement of different strains and species within them, but how spatiotemporal distributions of different genotypes in biofilm populations originate is still underexplored. Here, we study the origins of biofilm genetic structure by combining model development, numerical simulations, and microfluidic experiments using the human pathogen Vibrio cholerae. Using spatial correlation functions to quantify the differences between emergent cell lineage segregation patterns, we find that strong adhesion often, but not always, maximizes the size of clonal cell clusters on flat surfaces. Counterintuitively, our model predicts that, under some conditions, investing in adhesion can reduce rather than increase clonal group size. Our results emphasize that a complex interaction between fluid flow and cell adhesiveness can underlie emergent patterns of biofilm genetic structure. This structure, in turn, has an outsize influence on how biofilm-dwelling populations function and evolve.
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Affiliation(s)
- Ricardo Martínez-García
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Carey D. Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, United States of America
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Raimo Hartmann
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Knut Drescher
- Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
- Department of Physics, Phillips-Universität Marburg, Marburg, Germany
| | - Juan A. Bonachela
- Marine Population Modeling Group, Department of Mathematics and Statistics, University of Strathclyde, Glasgow, Scotland, United Kingdom
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
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Huang Z, Zhou Q, Sun P, Yang J, Guo M. Two Agrobacterium tumefaciens CheW Proteins Are Incorporated into One Chemosensory Pathway with Different Efficiencies. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2018; 31:460-470. [PMID: 29182466 DOI: 10.1094/mpmi-10-17-0255-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Agrobacterium tumefaciens is the agent that causes crown gall tumor disease on more than 140 species of dicotyledonous plants. Chemotaxis of A. tumefaciens toward the wound sites of the host plant is the first step to recognize the host. CheW is a coupling protein that bridges the histidine kinase CheA and the chemoreceptors to form the chemotaxis core signaling complex and plays a crucial role in the assembly and function of the large chemosensory array. Unlike all previously reported chemotaxis systems, A. tumefaciens has only one major che operon but two cheW homologs (atu2075 as cheW1 and atu2617 as cheW2) on unlinked loci. The in-frame deletion of either cheW gene significantly affects A. tumefaciens chemotaxis but does not abolish the chemotaxis, unless both cheW genes were deleted. The effect of cheW2 deletion on the chemotaxis is more severe than that of cheW1 deletion. Either CheW can interact with CheA and couple it to the cell poles. The promoter activity of cheW2 is always higher than that of cheW1 under all of the tested conditions. When two cheW genes were adjusted to the same expression level by using the identical promoter, the difference between the effects of two CheW proteins on the chemotaxis still existed. Therefore, we envision that both the different molecular ratio of two CheW proteins in cell and the different affinities of two CheW proteins with CheA and chemoreceptors result in the efficiency difference of two CheW proteins in functioning in the large chemosensory array.
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Affiliation(s)
- Zhiwei Huang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Qingxuan Zhou
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Pan Sun
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Jing Yang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
| | - Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou City, Jiangsu 225009, P R China
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A cheZ-Like Gene in Azorhizobium caulinodans Is a Key Gene in the Control of Chemotaxis and Colonization of the Host Plant. Appl Environ Microbiol 2018; 84:AEM.01827-17. [PMID: 29150498 DOI: 10.1128/aem.01827-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/01/2017] [Indexed: 02/07/2023] Open
Abstract
Chemotaxis can provide bacteria with competitive advantages for survival in complex environments. The CheZ chemotaxis protein is a phosphatase, affecting the flagellar motor in Escherichia coli by dephosphorylating the response regulator phosphorylated CheY protein (CheY∼P) responsible for clockwise rotation. A cheZ gene has been found in Azorhizobium caulinodans ORS571, in contrast to other rhizobial species studied so far. The CheZ protein in strain ORS571 has a conserved motif similar to that corresponding to the phosphatase active site in E. coli The construction of a cheZ deletion mutant strain and of cheZ mutant strains carrying a mutation in residues of the putative phosphatase active site showed that strain ORS571 participates in chemotaxis and motility, causing a hyperreversal behavior. In addition, the properties of the cheZ deletion mutant revealed that ORS571 CheZ is involved in other physiological processes, since it displayed increased flocculation, biofilm formation, exopolysaccharide (EPS) production, and host root colonization. In particular, it was observed that the expression of several exp genes, involved in EPS synthesis, was upregulated in the cheZ mutant compared to that in the wild type, suggesting that CheZ negatively controls exp gene expression through an unknown mechanism. It is proposed that CheZ influences the Azorhizobium-plant association by negatively regulating early colonization via the regulation of EPS production. This report established that CheZ in A. caulinodans plays roles in chemotaxis and the symbiotic association with the host plant.IMPORTANCE Chemotaxis allows bacteria to swim toward plant roots and is beneficial to the establishment of various plant-microbe associations. The level of CheY phosphorylation (CheY∼P) is central to the chemotaxis signal transduction. The mechanism of the signal termination of CheY∼P remains poorly characterized among Alphaproteobacteria, except for Sinorhizobium meliloti, which does not contain CheZ but which controls CheY∼P dephosphorylation through a phosphate sink mechanism. Azorhizobium caulinodans ORS571, a microsymbiont of Sesbania rostrata, has an orphan cheZ gene besides two cheY genes similar to those in S. meliloti In addition to controlling the chemotaxis response, the CheZ-like protein in strain ORS571 is playing a role by decreasing bacterial adhesion to the host plant, in contrast to the general situation where chemotaxis-associated proteins promote adhesion. In this study, we identified a CheZ-like protein among Alphaproteobacteria functioning in chemotaxis and the A. caulinodans-S. rostrata symbiosis.
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Function and Regulation of Agrobacterium tumefaciens Cell Surface Structures that Promote Attachment. Curr Top Microbiol Immunol 2018; 418:143-184. [PMID: 29998422 DOI: 10.1007/82_2018_96] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Agrobacterium tumefaciens attaches stably to plant host tissues and abiotic surfaces. During pathogenesis, physical attachment to the site of infection is a prerequisite to infection and horizontal gene transfer to the plant. Virulent and avirulent strains may also attach to plant tissue in more benign plant associations, and as with other soil microbes, to soil surfaces in the terrestrial environment. Although most A. tumefaciens virulence functions are encoded on the tumor-inducing plasmid, genes that direct general surface attachment are chromosomally encoded, and thus this process is not obligatorily tied to virulence, but is a more fundamental capacity. Several different cellular structures are known or suspected to contribute to the attachment process. The flagella influence surface attachment primarily via their propulsive activity, but control of their rotation during the transition to the attached state may be quite complex. A. tumefaciens produces several pili, including the Tad-type Ctp pili, and several plasmid-borne conjugal pili encoded by the Ti and At plasmids, as well as the so-called T-pilus, involved in interkingdom horizontal gene transfer. The Ctp pili promote reversible interactions with surfaces, whereas the conjugal and T-pili drive horizontal gene transfer (HGT) interactions with other cells and tissues. The T-pilus is likely to contribute to physical association with plant tissues during DNA transfer to plants. A. tumefaciens can synthesize a variety of polysaccharides including cellulose, curdlan (β-1,3 glucan), β-1,2 glucan (cyclic and linear), succinoglycan, and a localized polysaccharide(s) that is confined to a single cellular pole and is called the unipolar polysaccharide (UPP). Lipopolysaccharides are also in the outer leaflet of the outer membrane. Cellulose and curdlan production can influence attachment under certain conditions. The UPP is required for stable attachment under a range of conditions and on abiotic and biotic surfaces. Other factors that have been reported to play a role in attachment include the elusive protein called rhicadhesin. The process of surface attachment is under extensive regulatory control and can be modulated by environmental conditions, as well as by direct responses to surface contact. Complex transcriptional and post-transcriptional control circuitry underlies much of the production and deployment of these attachment functions.
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Feirer N, Kim D, Xu J, Fernandez N, Waters CM, Fuqua C. The Agrobacterium tumefaciens CheY-like protein ClaR regulates biofilm formation. MICROBIOLOGY-SGM 2017; 163:1680-1691. [PMID: 29068284 DOI: 10.1099/mic.0.000558] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The switch from a motile, planktonic existence to an attached biofilm is a major bacterial lifestyle transition that is often mediated by complex regulatory pathways. In this report, we describe a CheY-like protein required for control of the motile-to-sessile switch in the plant pathogen Agrobacterium tumefaciens. This regulator, which we have designated ClaR, possesses two distinct CheY-like receiver (REC) domains and is involved in the negative regulation of biofilm formation, through production of the unipolar polysaccharide (UPP) adhesin and cellulose. The ClaR REC domains share predicted structural homology with characterized REC domains and contain the majority of active site residues known to be essential for protein phosphorylation. REC1 is missing the conserved aspartate (N72) residue and although present in REC 2 (D193), it is not required for ClaR-dependent regulation suggesting that phosphorylation, which modulates the activity of many CheY-like proteins, appears not to be essential for ClaR activity. We also show that ClaR-dependent negative regulation of attachment is diminished significantly in mutants for PruA and PruR, proteins known to be involved in a pterin-mediated attachment regulation pathway. In A. tumefaciens, pterins are required for control of the intracellular signal cyclic diguanylate monophosphate through the DcpA regulator, but our findings suggest that pterin-dependent ClaR control of attachment can function independently from DcpA, including dampening of c-di-GMP levels. This report of a novel CheY-type biofilm regulator in A. tumefaciens thus also adds significant details to the role of pterin-mediated signalling.
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Affiliation(s)
- Nathan Feirer
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - DohHyun Kim
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jing Xu
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Nico Fernandez
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Christopher M Waters
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
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Absence of the Polar Organizing Protein PopZ Results in Reduced and Asymmetric Cell Division in Agrobacterium tumefaciens. J Bacteriol 2017. [PMID: 28630123 DOI: 10.1128/jb.00101-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Agrobacterium tumefaciens is a rod-shaped bacterium that grows by polar insertion of new peptidoglycan during cell elongation. As the cell cycle progresses, peptidoglycan synthesis at the pole ceases prior to insertion of new peptidoglycan at midcell to enable cell division. The A. tumefaciens homolog of the Caulobacter crescentus polar organelle development protein PopZ has been identified as a growth pole marker and a candidate polar growth-promoting factor. Here, we characterize the function of PopZ in cell growth and division of A. tumefaciens Consistent with previous observations, we observe that PopZ localizes specifically to the growth pole in wild-type cells. Despite the striking localization pattern of PopZ, we find the absence of the protein does not impair polar elongation or cause major changes in the peptidoglycan composition. Instead, we observe an atypical cell length distribution, including minicells, elongated cells, and cells with ectopic poles. Most minicells lack DNA, suggesting a defect in chromosome segregation. Furthermore, the canonical cell division proteins FtsZ and FtsA are misplaced, leading to asymmetric sites of cell constriction. Together, these data suggest that PopZ plays an important role in the regulation of chromosome segregation and cell division.IMPORTANCEA. tumefaciens is a bacterial plant pathogen and a natural genetic engineer. However, very little is known about the spatial and temporal regulation of cell wall biogenesis that leads to polar growth in this bacterium. Understanding the molecular basis of A. tumefaciens growth may allow for the development of innovations to prevent disease or to promote growth during biotechnology applications. Finally, since many closely related plant and animal pathogens exhibit polar growth, discoveries in A. tumefaciens may be broadly applicable for devising antimicrobial strategies.
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Velmourougane K, Prasanna R, Saxena AK. Agriculturally important microbial biofilms: Present status and future prospects. J Basic Microbiol 2017; 57:548-573. [PMID: 28407275 DOI: 10.1002/jobm.201700046] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/17/2017] [Accepted: 03/19/2017] [Indexed: 11/07/2022]
Abstract
Microbial biofilms are a fascinating subject, due to their significant roles in the environment, industry, and health. Advances in biochemical and molecular techniques have helped in enhancing our understanding of biofilm structure and development. In the past, research on biofilms primarily focussed on health and industrial sectors; however, lately, biofilms in agriculture are gaining attention due to their immense potential in crop production, protection, and improvement. Biofilms play an important role in colonization of surfaces - soil, roots, or shoots of plants and enable proliferation in the desired niche, besides enhancing soil fertility. Although reports are available on microbial biofilms in general; scanty information is published on biofilm formation by agriculturally important microorganisms (bacteria, fungi, bacterial-fungal) and their interactions in the ecosystem. Better understanding of agriculturally important bacterial-fungal communities and their interactions can have several implications on climate change, soil quality, plant nutrition, plant protection, bioremediation, etc. Understanding the factors and genes involved in biofilm formation will help to develop more effective strategies for sustainable and environment-friendly agriculture. The present review brings together fundamental aspects of biofilms, in relation to their formation, regulatory mechanisms, genes involved, and their application in different fields, with special emphasis on agriculturally important microbial biofilms.
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Affiliation(s)
| | - Radha Prasanna
- Division of Microbiology, ICAR-Indian Agricultural Research Institute, New Delhi, India
| | - Anil Kumar Saxena
- ICAR-National Bureau of Agriculturally Important Microorganisms (NBAIM), Mau Nath Bhanjan, Uttar Pradesh, India
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70
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Guo M, Huang Z, Yang J. Is there any crosstalk between the chemotaxis and virulence induction signaling in Agrobacterium tumefaciens? Biotechnol Adv 2017; 35:505-511. [PMID: 28342941 DOI: 10.1016/j.biotechadv.2017.03.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 03/17/2017] [Accepted: 03/22/2017] [Indexed: 12/25/2022]
Abstract
Agrobacterium tumefaciens, a soil-born phytopathogenic bacterium, is well known as a nature's engineer due to its ability to genetically transform the host by transferring a DNA fragment (called T-DNA) from its Ti plasmid to host-cell genome. To combat the harsh soil environment and seek the appropriate host, A. tumefaciens can sense and be attracted by a large number of chemical compounds released by wounded host. As a member of α-proteobacterium, A. tumefaciens has a chemotaxis system different from that found in Escherichia coli, since many chemoattractants for A. tumefaciens chemotaxis are virulence (vir) inducers. However, advances in the study of the chemotaxis paradigm, E. coli chemotaxis system, have provided enough information to analyze the A. tumefaciens chemotaxis. At low concentration, chemoattractants elicit A. tumefaciens chemotaxis and attract the species to the wound sites of the host. At high concentration, chemoattractants induce the expression of virulence genes and trigger T-DNA transfer. Recent studies on the VirA and ChvE of the vir-induction system provide some evidences to support the crosstalk between chemotaxis and vir-induction. This review compares the core components of chemotaxis signaling system of A. tumefaciens with those observed in other species, discusses the connection between chemotaxis and vir-induction in A. tumefaciens, and proposes a model depicting the signaling crosstalk between chemotaxis and vir-induction.
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Affiliation(s)
- Minliang Guo
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China.
| | - Zhiwei Huang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Jing Yang
- College of Bioscience and Biotechnology, Yangzhou University, Yangzhou, Jiangsu 225009, China
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71
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Licata NA, Mohari B, Fuqua C, Setayeshgar S. Diffusion of Bacterial Cells in Porous Media. Biophys J 2016; 110:247-57. [PMID: 26745427 DOI: 10.1016/j.bpj.2015.09.035] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 09/22/2015] [Accepted: 09/30/2015] [Indexed: 12/24/2022] Open
Abstract
The chemotaxis signal transduction network regulates the biased random walk of many bacteria in favorable directions and away from harmful ones through modulating the frequency of directional reorientations. In mutants of diverse bacteria lacking the chemotaxis response, migration in classic motility agar, which constitutes a fluid-filled porous medium, is compromised; straight-swimming cells unable to tumble become trapped within the agar matrix. Spontaneous mutations that restore spreading have been previously observed in the enteric bacterium Escherichia coli, and recent work in other bacterial species has isolated and quantified different classes of nonchemotacting mutants exhibiting the same spreading phenotype. We present a theoretical description of bacterial diffusion in a porous medium-the natural habitat for many cell types-which elucidates how diverse modifications of the motility apparatus resulting in a nonzero tumbling frequency allows for unjamming of otherwise straight-swimming cells at internal boundaries and leads to net migration. A unique result of our analysis is increasing diffusive spread with increasing tumbling frequency in the small pore limit, consistent with earlier experimental observations but not captured by previous models. Our theoretical results, combined with a simple model of bacterial diffusion and growth in agar, are compared with our experimental measurements of swim ring expansion as a function of time, demonstrating good quantitative agreement. Our results suggest that the details of the cellular tumbling process may be adapted to enable bacteria to propagate efficiently through complex environments. For engineered, self-propelled microswimmers that navigate via alternating straight runs and changes in direction, these results suggest an optimal reorientation strategy for efficient migration in a porous environment with a given microarchitecture.
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Affiliation(s)
- Nicholas A Licata
- Department of Physics, Indiana University, Bloomington, Indiana; Department of Natural Sciences, University of Michigan-Dearborn, Dearborn, Michigan
| | - Bitan Mohari
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Sima Setayeshgar
- Department of Physics, Indiana University, Bloomington, Indiana.
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Duarte CM, Basile LA, Zalguizuri A, Lepek VC. The transcriptional factor TtsI is involved in a negative regulation of swimming motility in Mesorhizobium loti MAFF303099. FEMS Microbiol Lett 2016; 363:fnw222. [PMID: 27664056 DOI: 10.1093/femsle/fnw222] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 06/13/2016] [Accepted: 09/16/2016] [Indexed: 01/10/2023] Open
Abstract
Mesorhizobium loti MAFF303099 has a functional Type III secretion system (T3SS) that is involved in the determination of competitiveness for legume nodulation. Here we demonstrate that the transcriptional factor TtsI, which positively regulates T3SS genes expression, is involved in a negative regulation of M. loti swimming motility in soft-agar. Conditions that induce T3SS expression affect flagella production. The same conditions also affect promoter activity of M. loti visN gene, a homolog to the positive regulator of flagellar genes that has been described in other rhizobia. Defects in T3SS complex assembly at membranes limited the negative regulation of motility by the expression of TtsI.
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73
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Ng HM, Kin LX, Dashper SG, Slakeski N, Butler CA, Reynolds EC. Bacterial interactions in pathogenic subgingival plaque. Microb Pathog 2016; 94:60-9. [DOI: 10.1016/j.micpath.2015.10.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 10/29/2015] [Accepted: 10/30/2015] [Indexed: 12/18/2022]
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Abstract
During the first step of biofilm formation, initial attachment is dictated by physicochemical and electrostatic interactions between the surface and the bacterial envelope. Depending on the nature of these interactions, attachment can be transient or permanent. To achieve irreversible attachment, bacterial cells have developed a series of surface adhesins promoting specific or nonspecific adhesion under various environmental conditions. This article reviews the recent advances in our understanding of the secretion, assembly, and regulation of the bacterial adhesins during biofilm formation, with a particular emphasis on the fimbrial, nonfimbrial, and discrete polysaccharide adhesins in Gram-negative bacteria.
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Condori S, Atkinson S, Leys N, Wattiez R, Mastroleo F. Construction and phenotypic characterization of M68, an RruI quorum sensing knockout mutant of the photosynthetic alphaproteobacterium Rhodospirillum rubrum. Res Microbiol 2016; 167:380-92. [PMID: 26993754 DOI: 10.1016/j.resmic.2016.02.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 02/19/2016] [Accepted: 02/25/2016] [Indexed: 01/08/2023]
Abstract
Many bacterial species communicate using a complex system known as quorum sensing (QS) in which gene expression is controlled in response to cell density. In this study an N-acylhomoserine lactone (AHL) synthase (Rru_A3396) knockout mutant (M68) of Rhodospirillum rubrum S1H (WT) was constructed and characterized phenotypically under light anaerobic conditions. Results showed that R. rubrum WT produces unsubstituted, 3-OH and 3-oxo-substituted AHLs with acyl chains ranging from 4 to 14 carbons, with 3-OH-C8 being the most abundant. Growth, pigment content and swimming motility were found to be under the control of this LuxI-type QS system. In addition, cultivation in a low shear environment put forward the aggregative phenotype of M68 and linked biofilm formation to QS in R. rubrum S1H. Interestingly, QS-mutant M68 continued to produce decreased levels of 3-OH-C8-HSL, probably due to the presence of an extra HdtS-type AHL synthase.
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Affiliation(s)
- Sandra Condori
- Research Unit for Microbiology, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400 Mol, Belgium; Research Institute for Biosciences, Proteomics and Microbiology Laboratory, University of Mons, Avenue du champ de Mars 6, Mons, Belgium.
| | - Steve Atkinson
- Center for Biomolecular Science, School of Molecular Medical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
| | - Natalie Leys
- Research Unit for Microbiology, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400 Mol, Belgium.
| | - Ruddy Wattiez
- Research Institute for Biosciences, Proteomics and Microbiology Laboratory, University of Mons, Avenue du champ de Mars 6, Mons, Belgium.
| | - Felice Mastroleo
- Research Unit for Microbiology, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, 2400 Mol, Belgium.
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Rapid, high-throughput tracking of bacterial motility in 3D via phase-contrast holographic video microscopy. Biophys J 2016; 108:1248-56. [PMID: 25762336 PMCID: PMC4375448 DOI: 10.1016/j.bpj.2015.01.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 01/02/2015] [Accepted: 01/08/2015] [Indexed: 12/25/2022] Open
Abstract
Tracking fast-swimming bacteria in three dimensions can be extremely challenging with current optical techniques and a microscopic approach that can rapidly acquire volumetric information is required. Here, we introduce phase-contrast holographic video microscopy as a solution for the simultaneous tracking of multiple fast moving cells in three dimensions. This technique uses interference patterns formed between the scattered and the incident field to infer the three-dimensional (3D) position and size of bacteria. Using this optical approach, motility dynamics of multiple bacteria in three dimensions, such as speed and turn angles, can be obtained within minutes. We demonstrated the feasibility of this method by effectively tracking multiple bacteria species, including Escherichia coli, Agrobacterium tumefaciens, and Pseudomonas aeruginosa. In addition, we combined our fast 3D imaging technique with a microfluidic device to present an example of a drug/chemical assay to study effects on bacterial motility.
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Discrete Responses to Limitation for Iron and Manganese in Agrobacterium tumefaciens: Influence on Attachment and Biofilm Formation. J Bacteriol 2015; 198:816-29. [PMID: 26712936 DOI: 10.1128/jb.00668-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 12/13/2015] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED Transition metals such as iron and manganese are crucial trace nutrients for the growth of most bacteria, functioning as catalytic cofactors for many essential enzymes. Dedicated uptake and regulatory systems have evolved to ensure their acquisition for growth, while preventing toxicity. Transcriptomic analysis of the iron- and manganese-responsive regulons of Agrobacterium tumefaciens revealed that there are discrete regulatory networks that respond to changes in iron and manganese levels. Complementing earlier studies, the iron-responsive gene network is quite large and includes many aspects of iron-dependent metabolism and the iron-sparing response. In contrast, the manganese-responsive network is restricted to a limited number of genes, many of which can be linked to transport and utilization of the transition metal. Several of the target genes predicted to drive manganese uptake are required for growth under manganese-limited conditions, and an A. tumefaciens mutant with a manganese transport deficiency is attenuated for plant virulence. Iron and manganese limitation independently inhibit biofilm formation by A. tumefaciens, and several candidate genes that could impact biofilm formation were identified in each regulon. The biofilm-inhibitory effects of iron and manganese do not rely on recognized metal-responsive transcriptional regulators, suggesting alternate mechanisms influencing biofilm formation. However, under low-manganese conditions the dcpA operon is upregulated, encoding a system that controls levels of the cyclic di-GMP second messenger. Mutation of this regulatory pathway dampens the effect of manganese limitation. IMPORTANCE Responses to changes in transition metal levels, such as those of manganese and iron, are important for normal metabolism and growth in bacteria. Our study used global gene expression profiling to understand the response of the plant pathogen Agrobacterium tumefaciens to changes of transition metal availability. Among the properties that are affected by both iron and manganese levels are those required for normal surface attachment and biofilm formation, but the requirement for each of these transition metals is mechanistically independent from the other.
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Chaban B, Hughes HV, Beeby M. The flagellum in bacterial pathogens: For motility and a whole lot more. Semin Cell Dev Biol 2015; 46:91-103. [DOI: 10.1016/j.semcdb.2015.10.032] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 02/05/2023]
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A Cardiolipin-Deficient Mutant of Rhodobacter sphaeroides Has an Altered Cell Shape and Is Impaired in Biofilm Formation. J Bacteriol 2015; 197:3446-55. [PMID: 26283770 DOI: 10.1128/jb.00420-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/13/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Cell shape has been suggested to play an important role in the regulation of bacterial attachment to surfaces and the formation of communities associated with surfaces. We found that a cardiolipin synthase (Δcls) mutant of the rod-shaped bacterium Rhodobacter sphaeroides--in which synthesis of the anionic, highly curved phospholipid cardiolipin (CL) is reduced by 90%--produces ellipsoid-shaped cells that are impaired in biofilm formation. Reducing the concentration of CL did not cause significant defects in R. sphaeroides cell growth, swimming motility, lipopolysaccharide and exopolysaccharide production, surface adhesion protein expression, and membrane permeability. Complementation of the CL-deficient mutant by ectopically expressing CL synthase restored cells to their rod shape and increased biofilm formation. Treating R. sphaeroides cells with a low concentration (10 μg/ml) of the small-molecule MreB inhibitor S-(3,4-dichlorobenzyl)isothiourea produced ellipsoid-shaped cells that had no obvious growth defect yet reduced R. sphaeroides biofilm formation. This study demonstrates that CL plays a role in R. sphaeroides cell shape determination, biofilm formation, and the ability of the bacterium to adapt to its environment. IMPORTANCE Membrane composition plays a fundamental role in the adaptation of many bacteria to environmental stress. In this study, we build a new connection between the anionic phospholipid cardiolipin (CL) and cellular adaptation in Rhodobacter sphaeroides. We demonstrate that CL plays a role in the regulation of R. sphaeroides morphology and is important for the ability of this bacterium to form biofilms. This study correlates CL concentration, cell shape, and biofilm formation and provides the first example of how membrane composition in bacteria alters cell morphology and influences adaptation. This study also provides insight into the potential of phospholipid biosynthesis as a target for new chemical strategies designed to alter or prevent biofilm formation.
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Abstract
Chemotaxis affords motile cells the ability to rapidly respond to environmental challenges by navigating cells to niches favoring growth. Such a property results from the activities of dedicated signal transduction systems on the motility apparatus, such as flagella, type IV pili, and gliding machineries. Once cells have reached a niche with favorable conditions, they often stop moving and aggregate into complex communities termed biofilms. An intermediate and reversible stage that precedes commitment to permanent adhesion often includes transient cell-cell contacts between motile cells. Chemotaxis signaling has been implicated in modulating the transient aggregation of motile cells. Evidence further indicates that chemotaxis-dependent transient cell aggregation events are behavioral responses to changes in metabolic cues that temporarily prohibit permanent attachment by maintaining motility and chemotaxis. This minireview discusses a few examples illustrating the role of chemotaxis signaling in the initiation of cell-cell contacts in bacteria moving via flagella, pili, or gliding.
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81
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Novel pseudotaxis mechanisms improve migration of straight-swimming bacterial mutants through a porous environment. mBio 2015; 6:e00005. [PMID: 25714707 PMCID: PMC4358000 DOI: 10.1128/mbio.00005-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Bacterial locomotion driven by flagella is given directionality by the chemotaxis signal transduction network. In the classic plate assays of migration in porous motility agar, efficient motility is compromised in chemotaxis mutants of diverse bacteria. Nonchemotactic mutants become trapped within the agar matrix. Suppressor mutations that prevent this entanglement but do not restore chemotaxis, a phenomenon designated pseudotaxis, were first reported to arise for Escherichia coli. In this study, novel mechanisms of pseudotaxis have been identified for the plant-pathogenic alphaproteobacterium Agrobacterium tumefaciens. Mutants with chemotaxis mutation suppressor (cms) mutations that impart enhanced migration in motility agar compared to that of their straight-swimming, nonchemotactic parent were isolated. We find that pseudotaxis in A. tumefaciens occurs most commonly via mutations in the D1 domain of the flagellar hook protein, FlgE, but it can also be found less frequently to be due to mutations in the hook length regulator, FliK, or in the motor protein, MotA. Single-cell-tracking studies of cms mutants in bulk medium clearly reveal frequent changes in the direction of swimming, similar to the swimming of strains that are proficient for chemotaxis, but independent of a sensory mechanism. Our results suggest that the tumbling process can be tuned through mutation and evolution to optimize migration through complex, porous environments. Chemotaxis sensory networks control direct bacterial motility by modulating flagellar rotary motion, alternating cellular movement between runs and tumbles. The straight-swimming phenotype of chemotaxis-deficient cells yields nonexpanding colonies in motility agar. Enhanced, chemotaxis-independent spreading, dubbed pseudotaxis, has been observed in Escherichia coli mutants. We have identified novel pseudotaxis mutations in Agrobacterium tumefaciens that alter the flagellar hook structure or motor, leading to randomly occurring reorientations observed in single-cell tracking studies in bulk medium. These directional changes allow the cells to migrate more efficiently than the parent strain through the agar matrix, independently of the chemotaxis process. These findings reveal that tumbling can be tuned for effective navigation in complex porous environments, analogous to the natural habitats for many bacteria, and provide evidence for the strong selective pressure exerted by the external environment on the basal pattern of motility, even in the absence of chemotaxis.
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82
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Karimi A, Karig D, Kumar A, Ardekani AM. Interplay of physical mechanisms and biofilm processes: review of microfluidic methods. LAB ON A CHIP 2015; 15:23-42. [PMID: 25385289 PMCID: PMC4261921 DOI: 10.1039/c4lc01095g] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Bacteria in natural and artificial environments often reside in self-organized, integrated communities known as biofilms. Biofilms are highly structured entities consisting of bacterial cells embedded in a matrix of self-produced extracellular polymeric substances (EPS). The EPS matrix acts like a biological 'glue' enabling microbes to adhere to and colonize a wide range of surfaces. Once integrated into biofilms, bacterial cells can withstand various forms of stress such as antibiotics, hydrodynamic shear and other environmental challenges. Because of this, biofilms of pathogenic bacteria can be a significant health hazard often leading to recurrent infections. Biofilms can also lead to clogging and material degradation; on the other hand they are an integral part of various environmental processes such as carbon sequestration and nitrogen cycles. There are several determinants of biofilm morphology and dynamics, including the genotypic and phenotypic states of constituent cells and various environmental conditions. Here, we present an overview of the role of relevant physical processes in biofilm formation, including propulsion mechanisms, hydrodynamic effects, and transport of quorum sensing signals. We also provide a survey of microfluidic techniques utilized to unravel the associated physical mechanisms. Further, we discuss the future research areas for exploring new ways to extend the scope of the microfluidic approach in biofilm studies.
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Affiliation(s)
- A. Karimi
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - D. Karig
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723
| | - A. Kumar
- Department of Mechanical Engineering, University of Alberta, Edmonton, Canada AB T6G 2G8
| | - A. M. Ardekani
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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83
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Li GJ, Karimi A, Ardekani AM. Effect of solid boundaries on swimming dynamics of microorganisms in a viscoelastic fluid. RHEOLOGICA ACTA 2014; 53:911-926. [PMID: 26855446 PMCID: PMC4743766 DOI: 10.1007/s00397-014-0796-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We numerically study the effect of solid boundaries on the swimming behavior of a motile microorganism in viscoelastic media. Understanding the swimmer-wall hydrodynamic interactions is crucial to elucidate the adhesion of bacterial cells to nearby substrates which is precursor to the formation of the microbial biofilms. The microorganism is simulated using a squirmer model that captures the major swimming mechanisms of potential, extensile, and contractile types of swimmers, while neglecting the biological complexities. A Giesekus constitutive equation is utilized to describe both viscoelasticity and shear-thinning behavior of the background fluid. We found that the viscoelasticity strongly affects the near-wall motion of a squirmer by generating an opposing polymeric torque which impedes the rotation of the swimmer away from the wall. In particular, the time a neutral squirmer spends at the close proximity of the wall is shown to increase with polymer relaxation time and reaches a maximum at Weissenberg number of unity. The shear-thinning effect is found to weaken the solvent stress and therefore, increases the swimmer-wall contact time. For a puller swimmer, the polymer stretching mainly occurs around its lateral sides, leading to reduced elastic resistance against its locomotion. The neutral and puller swimmers eventually escape the wall attraction effect due to a releasing force generated by the Newtonian viscous stress. In contrast, the pusher is found to be perpetually trapped near the wall as a result of the formation of a highly stretched region behind its body. It is shown that the shear-thinning property of the fluid weakens the wall-trapping effect for the pusher squirmer.
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Affiliation(s)
- G. -J. Li
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - A. Karimi
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - A. M. Ardekani
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
- School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA
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84
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Lipopolysaccharide O-chain core region required for cellular cohesion and compaction of in vitro and root biofilms developed by Rhizobium leguminosarum. Appl Environ Microbiol 2014; 81:1013-23. [PMID: 25416773 DOI: 10.1128/aem.03175-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The formation of biofilms is an important survival strategy allowing rhizobia to live on soil particles and plant roots. Within the microcolonies of the biofilm developed by Rhizobium leguminosarum, rhizobial cells interact tightly through lateral and polar connections, forming organized and compact cell aggregates. These microcolonies are embedded in a biofilm matrix, whose main component is the acidic exopolysaccharide (EPS). Our work shows that the O-chain core region of the R. leguminosarum lipopolysaccharide (LPS) (which stretches out of the cell surface) strongly influences bacterial adhesive properties and cell-cell cohesion. Mutants defective in the O chain or O-chain core moiety developed premature microcolonies in which lateral bacterial contacts were greatly reduced. Furthermore, cell-cell interactions within the microcolonies of the LPS mutants were mediated mostly through their poles, resulting in a biofilm with an altered three-dimensional structure and increased thickness. In addition, on the root epidermis and on root hairs, O-antigen core-defective strains showed altered biofilm patterns with the typical microcolony compaction impaired. Taken together, these results indicate that the surface-exposed moiety of the LPS is crucial for proper cell-to-cell interactions and for the formation of robust biofilms on different surfaces.
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85
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Moreira LM, Facincani AP, Ferreira CB, Ferreira RM, Ferro MIT, Gozzo FC, de Oliveira JCF, Ferro JA, Soares MR. Chemotactic signal transduction and phosphate metabolism as adaptive strategies during citrus canker induction by Xanthomonas citri. Funct Integr Genomics 2014; 15:197-210. [PMID: 25403594 DOI: 10.1007/s10142-014-0414-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 11/03/2014] [Accepted: 11/07/2014] [Indexed: 12/11/2022]
Abstract
The genome of Xanthomonas citri subsp. Citri strain 306 pathotype A (Xac) was completely sequenced more than 10 years; to date, few studies involving functional genomics Xac and its host compatible have been developed, specially related to adaptive events that allow the survival of Xac within the plant. Proteomic analysis of Xac showed that the processes of chemotactic signal transduction and phosphate metabolism are key adaptive strategies during the interaction of a pathogenic bacterium with its plant host. The results also indicate the importance of a group of proteins that may not be directly related to the classical virulence factors, but that are likely fundamental to the success of the initial stages of the infection, such as methyl-accepting chemotaxis protein (Mcp) and phosphate specific transport (Pst). Furthermore, the analysis of the mutant of the gene pstB which codifies to an ABC phosphate transporter subunit revealed a complete absence of citrus canker symptoms when inoculated in compatible hosts. We also conducted an in silico analysis which established the possible network of genes regulated by two-component systems PhoPQ and PhoBR (related to phosphate metabolism), and possible transcriptional factor binding site (TFBS) motifs of regulatory proteins PhoB and PhoP, detaching high degree of conservation of PhoB TFBS in 84 genes of Xac genome. This is the first time that chemotaxis signal transduction and phosphate metabolism were therefore indicated to be fundamental to the process of colonization of plant tissue during the induction of disease associated with Xanthomonas genus bacteria.
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Affiliation(s)
- Leandro Marcio Moreira
- Departamento de Ciências Biológicas, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil
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86
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Chlorine stress mediates microbial surface attachment in drinking water systems. Appl Microbiol Biotechnol 2014; 99:2861-9. [DOI: 10.1007/s00253-014-6166-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 10/10/2014] [Accepted: 10/14/2014] [Indexed: 10/24/2022]
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87
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Lee JH, Kim YG, Baek KH, Cho MH, Lee J. The multifaceted roles of the interspecies signalling molecule indole inAgrobacterium tumefaciens. Environ Microbiol 2014; 17:1234-44. [DOI: 10.1111/1462-2920.12560] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 07/02/2014] [Indexed: 12/24/2022]
Affiliation(s)
- Jin-Hyung Lee
- School of Chemical Engineering; Yeungnam University; Gyeongsan 712-749 Korea
| | - Yong-Guy Kim
- School of Chemical Engineering; Yeungnam University; Gyeongsan 712-749 Korea
| | - Kwang-Hyun Baek
- School of Biotechnology; Yeungnam University; Gyeongsan 712-749 Korea
| | - Moo Hwan Cho
- School of Chemical Engineering; Yeungnam University; Gyeongsan 712-749 Korea
| | - Jintae Lee
- School of Chemical Engineering; Yeungnam University; Gyeongsan 712-749 Korea
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88
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Agrobacterium tumefaciens exoR controls acid response genes and impacts exopolysaccharide synthesis, horizontal gene transfer, and virulence gene expression. J Bacteriol 2014; 196:3221-33. [PMID: 24982308 DOI: 10.1128/jb.01751-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues, and subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR, including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role that this regulator plays on gene expression.
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89
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The Ctp type IVb pilus locus of Agrobacterium tumefaciens directs formation of the common pili and contributes to reversible surface attachment. J Bacteriol 2014; 196:2979-88. [PMID: 24914181 DOI: 10.1128/jb.01670-14] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Agrobacterium tumefaciens can adhere to plant tissues and abiotic surfaces and forms biofilms. Cell surface appendages called pili play an important role in adhesion and biofilm formation in diverse bacterial systems. The A. tumefaciens C58 genome sequence revealed the presence of the ctpABCDEFGHI genes (cluster of type IV pili; Atu0216 to Atu0224), homologous to tad-type pilus systems from several bacteria, including Aggregatibacter actinomycetemcomitans and Caulobacter crescentus. These systems fall into the type IVb pilus group, which can function in bacterial adhesion. Transmission electron microscopy of A. tumefaciens revealed the presence of filaments, significantly thinner than flagella and often bundled, associated with cell surfaces and shed into the external milieu. In-frame deletion mutations of all of the ctp genes, with the exception of ctpF, resulted in nonpiliated derivatives. Mutations in ctpA (a pilin homologue), ctpB, and ctpG decreased early attachment and biofilm formation. The adherence of the ctpA mutant could be restored by ectopic expression of the paralogous pilA gene. The ΔctpA ΔpilA double pilin mutant displayed a diminished biovolume and lower biofilm height than the wild type under flowing conditions. Surprisingly, however, the ctpCD, ctpE, ctpF, ctpH, and ctpI mutants formed normal biofilms and showed enhanced reversible attachment. In-frame deletion of the ctpA pilin gene in the ctpCD, ctpE, ctpF, ctpH, and ctpI mutants caused the same attachment-deficient phenotype as the ctpA single mutant. Collectively, these findings indicate that the ctp locus is involved in pilus assembly and that nonpiliated mutants, which retain the CtpA pilin, are proficient in attachment and adherence.
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90
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Heindl JE, Wang Y, Heckel BC, Mohari B, Feirer N, Fuqua C. Mechanisms and regulation of surface interactions and biofilm formation in Agrobacterium. FRONTIERS IN PLANT SCIENCE 2014; 5:176. [PMID: 24834068 PMCID: PMC4018554 DOI: 10.3389/fpls.2014.00176] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 04/12/2014] [Indexed: 05/05/2023]
Abstract
For many pathogenic bacteria surface attachment is a required first step during host interactions. Attachment can proceed to invasion of host tissue or cells or to establishment of a multicellular bacterial community known as a biofilm. The transition from a unicellular, often motile, state to a sessile, multicellular, biofilm-associated state is one of the most important developmental decisions for bacteria. Agrobacterium tumefaciens genetically transforms plant cells by transfer and integration of a segment of plasmid-encoded transferred DNA (T-DNA) into the host genome, and has also been a valuable tool for plant geneticists. A. tumefaciens attaches to and forms a complex biofilm on a variety of biotic and abiotic substrates in vitro. Although rarely studied in situ, it is hypothesized that the biofilm state plays an important functional role in the ecology of this organism. Surface attachment, motility, and cell division are coordinated through a complex regulatory network that imparts an unexpected asymmetry to the A. tumefaciens life cycle. In this review, we describe the mechanisms by which A. tumefaciens associates with surfaces, and regulation of this process. We focus on the transition between flagellar-based motility and surface attachment, and on the composition, production, and secretion of multiple extracellular components that contribute to the biofilm matrix. Biofilm formation by A. tumefaciens is linked with virulence both mechanistically and through shared regulatory molecules. We detail our current understanding of these and other regulatory schemes, as well as the internal and external (environmental) cues mediating development of the biofilm state, including the second messenger cyclic-di-GMP, nutrient levels, and the role of the plant host in influencing attachment and biofilm formation. A. tumefaciens is an important model system contributing to our understanding of developmental transitions, bacterial cell biology, and biofilm formation.
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Affiliation(s)
| | | | | | | | | | - Clay Fuqua
- Department of Biology, Indiana University, BloomingtonIN, USA
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91
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Xie JB, Du Z, Bai L, Tian C, Zhang Y, Xie JY, Wang T, Liu X, Chen X, Cheng Q, Chen S, Li J. Comparative genomic analysis of N2-fixing and non-N2-fixing Paenibacillus spp.: organization, evolution and expression of the nitrogen fixation genes. PLoS Genet 2014; 10:e1004231. [PMID: 24651173 PMCID: PMC3961195 DOI: 10.1371/journal.pgen.1004231] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/26/2014] [Indexed: 11/18/2022] Open
Abstract
We provide here a comparative genome analysis of 31 strains within the genus Paenibacillus including 11 new genomic sequences of N2-fixing strains. The heterogeneity of the 31 genomes (15 N2-fixing and 16 non-N2-fixing Paenibacillus strains) was reflected in the large size of the shell genome, which makes up approximately 65.2% of the genes in pan genome. Large numbers of transposable elements might be related to the heterogeneity. We discovered that a minimal and compact nif cluster comprising nine genes nifB, nifH, nifD, nifK, nifE, nifN, nifX, hesA and nifV encoding Mo-nitrogenase is conserved in the 15 N2-fixing strains. The nif cluster is under control of a σ(70)-depedent promoter and possesses a GlnR/TnrA-binding site in the promoter. Suf system encoding [Fe-S] cluster is highly conserved in N2-fixing and non-N2-fixing strains. Furthermore, we demonstrate that the nif cluster enabled Escherichia coli JM109 to fix nitrogen. Phylogeny of the concatenated NifHDK sequences indicates that Paenibacillus and Frankia are sister groups. Phylogeny of the concatenated 275 single-copy core genes suggests that the ancestral Paenibacillus did not fix nitrogen. The N2-fixing Paenibacillus strains were generated by acquiring the nif cluster via horizontal gene transfer (HGT) from a source related to Frankia. During the history of evolution, the nif cluster was lost, producing some non-N2-fixing strains, and vnf encoding V-nitrogenase or anf encoding Fe-nitrogenase was acquired, causing further diversification of some strains. In addition, some N2-fixing strains have additional nif and nif-like genes which may result from gene duplications. The evolution of nitrogen fixation in Paenibacillus involves a mix of gain, loss, HGT and duplication of nif/anf/vnf genes. This study not only reveals the organization and distribution of nitrogen fixation genes in Paenibacillus, but also provides insight into the complex evolutionary history of nitrogen fixation.
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Affiliation(s)
- Jian-Bo Xie
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Zhenglin Du
- Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, P. R. China
| | - Lanqing Bai
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Changfu Tian
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Yunzhi Zhang
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Jiu-Yan Xie
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Tianshu Wang
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Xiaomeng Liu
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Xi Chen
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
| | - Qi Cheng
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing, P. R. China
- * E-mail: (QC); (SC)
| | - Sanfeng Chen
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
- * E-mail: (QC); (SC)
| | - Jilun Li
- Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing, P. R. China
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92
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Bravo D, Cailleau G, Bindschedler S, Simon A, Job D, Verrecchia E, Junier P. Isolation of oxalotrophic bacteria able to disperse on fungal mycelium. FEMS Microbiol Lett 2013; 348:157-66. [PMID: 24106816 DOI: 10.1111/1574-6968.12287] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/17/2013] [Accepted: 09/17/2013] [Indexed: 11/28/2022] Open
Abstract
A technique based on an inverted Petri dish system was developed for the growth and isolation of soil oxalotrophic bacteria able to disperse on fungal mycelia. The method is related to the 'fungal highways' dispersion theory in which mycelial fungal networks allow active movement of bacteria in soil. Quantification of this phenomenon showed that bacterial dispersal occurs preferentially in upper soil horizons. Eight bacteria and one fungal strain were isolated by this method. The oxalotrophic activity of the isolated bacteria was confirmed through calcium oxalate dissolution in solid selective medium. After separation of the bacteria-fungus couple, partial sequencing of the 16S and the ITS1 and ITS2 sequences of the ribosomal RNA genes were used for the identification of bacteria and the associated fungus. The isolated oxalotrophic bacteria included strains related to Stenotrophomonas, Achromobacter, Lysobacter, Pseudomonas, Agrobacterium, Cohnella, and Variovorax. The recovered fungus corresponded to Trichoderma sp. A test carried out to verify bacterial transport in an unsaturated medium showed that all the isolated bacteria were able to migrate on Trichoderma hyphae or glass fibers to re-colonize an oxalate-rich medium. The results highlight the importance of fungus-driven bacterial dispersal to understand the functional role of oxalotrophic bacteria and fungi in soils.
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Affiliation(s)
- Daniel Bravo
- Laboratory of Microbiology, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
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93
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Malamud F, Homem RA, Conforte VP, Yaryura PM, Castagnaro AP, Marano MR, do Amaral AM, Vojnov AA. Identification and characterization of biofilm formation-defective mutants of Xanthomonas citri subsp. citri. Microbiology (Reading) 2013; 159:1911-1919. [DOI: 10.1099/mic.0.064709-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Florencia Malamud
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Rafael Augusto Homem
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Valeria Paola Conforte
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Pablo Marcelo Yaryura
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
| | - Atilio Pedro Castagnaro
- Estación Experimental Agroindustrial Obispo Colombres, Av. William Cross 3150, Las Talitas, Tucumán, Argentina
| | - María Rosa Marano
- IBR-Depto Microbiología, Facultad de Ciencias, Bioquímicas y Farmacéuticas, U.N.R. Suipacha 531, S2002LRK Rosario, Argentina
| | - Alexandre Morais do Amaral
- Embrapa Recursos Genéticos e Biotecnología and Centro APTA Citros Sylvio Moreira, Instituto Agronômico de Campinas, Cordeiropolis, Sao Pablo, Brazil
| | - Adrián Alberto Vojnov
- Instituto de Ciencia y Tecnología Dr César Milstein, Fundación Pablo Cassará, CONICET, Saladillo 2468, C1440FFX Ciudad de Buenos Aires, Argentina
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94
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Bogino PC, de las Mercedes Oliva M, Sorroche FG, Giordano W. The role of bacterial biofilms and surface components in plant-bacterial associations. Int J Mol Sci 2013; 14:15838-59. [PMID: 23903045 PMCID: PMC3759889 DOI: 10.3390/ijms140815838] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 06/18/2013] [Accepted: 06/28/2013] [Indexed: 01/09/2023] Open
Abstract
The role of bacterial surface components in combination with bacterial functional signals in the process of biofilm formation has been increasingly studied in recent years. Plants support a diverse array of bacteria on or in their roots, transport vessels, stems, and leaves. These plant-associated bacteria have important effects on plant health and productivity. Biofilm formation on plants is associated with symbiotic and pathogenic responses, but how plants regulate such associations is unclear. Certain bacteria in biofilm matrices have been found to induce plant growth and to protect plants from phytopathogens (a process termed biocontrol), whereas others are involved in pathogenesis. In this review, we systematically describe the various components and mechanisms involved in bacterial biofilm formation and attachment to plant surfaces and the relationships of these mechanisms to bacterial activity and survival.
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Affiliation(s)
- Pablo C. Bogino
- Department of Molecular Biology, National University of Río Cuarto, Ruta 36 Km 601, Río Cuarto, Córdoba X5804BYA, Argentina; E-Mails: (P.C.B.); (F.G.S.)
| | - María de las Mercedes Oliva
- Department of Microbiology and Immunology, National University of Río Cuarto, Ruta 36 Km 601, Córdoba X5804BYA, Argentina; E-Mail:
| | - Fernando G. Sorroche
- Department of Molecular Biology, National University of Río Cuarto, Ruta 36 Km 601, Río Cuarto, Córdoba X5804BYA, Argentina; E-Mails: (P.C.B.); (F.G.S.)
| | - Walter Giordano
- Department of Molecular Biology, National University of Río Cuarto, Ruta 36 Km 601, Río Cuarto, Córdoba X5804BYA, Argentina; E-Mails: (P.C.B.); (F.G.S.)
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95
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Xu J, Kim J, Koestler BJ, Choi JH, Waters CM, Fuqua C. Genetic analysis of Agrobacterium tumefaciens unipolar polysaccharide production reveals complex integrated control of the motile-to-sessile switch. Mol Microbiol 2013; 89:929-48. [PMID: 23829710 DOI: 10.1111/mmi.12321] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2013] [Indexed: 01/22/2023]
Abstract
Many bacteria colonize surfaces and transition to a sessile mode of growth. The plant pathogen Agrobacterium tumefaciens produces a unipolar polysaccharide (UPP) adhesin at single cell poles that contact surfaces. Here we report that elevated levels of the intracellular signal cyclic diguanosine monophosphate (c-di-GMP) lead to surface-contact-independent UPP production and a red colony phenotype due to production of UPP and the exopolysaccharide cellulose, when A. tumefaciens is incubated with the polysaccharide stain Congo Red. Transposon mutations with elevated Congo Red staining identified presumptive UPP-negative regulators, mutants for which were hyperadherent, producing UPP irrespective of surface contact. Multiple independent mutations were obtained in visN and visR, activators of flagellar motility in A. tumefaciens, now found to inhibit UPP and cellulose production. Expression analysis in a visR mutant and isolation of suppressor mutations, identified three diguanylate cyclases inhibited by VisR. Null mutations for two of these genes decrease attachment and UPP production, but do not alter cellular c-di-GMP levels. However, analysis of catalytic site mutants revealed their GGDEF motifs are required to increase UPP production and surface attachment. Mutations in a specific presumptive c-di-GMP phosphodiesterase also elevate UPP production and attachment, consistent with c-di-GMP activation of surface-dependent adhesin deployment.
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Affiliation(s)
- Jing Xu
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
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96
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Zan J, Heindl JE, Liu Y, Fuqua C, Hill RT. The CckA-ChpT-CtrA phosphorelay system is regulated by quorum sensing and controls flagellar motility in the marine sponge symbiont Ruegeria sp. KLH11. PLoS One 2013; 8:e66346. [PMID: 23825536 PMCID: PMC3692519 DOI: 10.1371/journal.pone.0066346] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 05/08/2013] [Indexed: 01/12/2023] Open
Abstract
Bacteria respond to their environment via signal transduction pathways, often two-component type systems that function through phosphotransfer to control expression of specific genes. Phosphorelays are derived from two-component systems but are comprised of additional components. The essential cckA-chpT-ctrA phosphorelay in Caulobacter crescentus has been well studied and is important in orchestrating the cell cycle, polar development and flagellar biogenesis. Although cckA, chpT and ctrA homologues are widespread among the Alphaproteobacteria, relatively few is known about their function in the large and ecologically significant Roseobacter clade of the Rhodobacterales. In this study the cckA-chpT-ctrA system of the marine sponge symbiont Ruegeria sp. KLH11 was investigated. Our results reveal that the cckA, chpT and ctrA genes positively control flagellar biosynthesis. In contrast to C. crescentus, the cckA, chpT and ctrA genes in Ruegeria sp. KLH11 are non-essential and do not affect bacterial growth. Gene fusion and transcript analyses provide evidence for ctrA autoregulation and the control of motility-related genes. In KLH11, flagellar motility is controlled by the SsaRI system and acylhomoserine lactone (AHL) quorum sensing. SsaR and long chain AHLs are required for cckA, chpT and ctrA gene expression, providing a regulatory link between flagellar locomotion and population density in KLH11.
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Affiliation(s)
- Jindong Zan
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, United States of America
| | - Jason E. Heindl
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Yue Liu
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, United States of America
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Russell T. Hill
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, Maryland, United States of America
- * E-mail:
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97
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Armitano J, Méjean V, Jourlin-Castelli C. Aerotaxis governs floating biofilm formation inShewanella oneidensis. Environ Microbiol 2013; 15:3108-18. [DOI: 10.1111/1462-2920.12158] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 05/15/2013] [Indexed: 11/30/2022]
Affiliation(s)
- Joshua Armitano
- Laboratoire de Chimie Bactérienne UMR7283; Aix-Marseille Université; CNRS; 13402; Marseille; France
| | - Vincent Méjean
- Laboratoire de Chimie Bactérienne UMR7283; Aix-Marseille Université; CNRS; 13402; Marseille; France
| | - Cécile Jourlin-Castelli
- Laboratoire de Chimie Bactérienne UMR7283; Aix-Marseille Université; CNRS; 13402; Marseille; France
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98
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Coordination of division and development influences complex multicellular behavior in Agrobacterium tumefaciens. PLoS One 2013; 8:e56682. [PMID: 23437210 PMCID: PMC3577659 DOI: 10.1371/journal.pone.0056682] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 01/13/2013] [Indexed: 01/20/2023] Open
Abstract
The α-Proteobacterium Agrobacterium tumefaciens has proteins homologous to known regulators that govern cell division and development in Caulobacter crescentus, many of which are also conserved among diverse α-Proteobacteria. In light of recent work demonstrating similarity between the division cycle of C. crescentus and that of A. tumefaciens, the functional conservation for this presumptive control pathway was examined. In C. crescentus the CtrA response regulator serves as the master regulator of cell cycle progression and cell division. CtrA activity is controlled by an integrated pair of multi-component phosphorelays: PleC/DivJ-DivK and CckA-ChpT-CtrA. Although several of the conserved orthologues appear to be essential in A. tumefaciens, deletions in pleC or divK were isolated and resulted in cell division defects, diminished swimming motility, and a decrease in biofilm formation. A. tumefaciens also has two additional pleC/divJhomologue sensor kinases called pdhS1 and pdhS2, absent in C. crescentus. Deletion of pdhS1 phenocopied the ΔpleC and ΔdivK mutants. Cells lacking pdhS2 morphologically resembled wild-type bacteria, but were decreased in swimming motility and elevated for biofilm formation, suggesting that pdhS2 may serve to regulate the motile to non-motile switch in A. tumefaciens. Genetic analysis suggests that the PleC/DivJ-DivK and CckA-ChpT-CtrA phosphorelays in A. tumefaciens are vertically-integrated, as in C. crescentus. A gain-of-function mutation in CckA (Y674D) was identified as a spontaneous suppressor of the ΔpleC motility phenotype. Thus, although the core architecture of the A. tumefaciens pathway resembles that of C. crescentus there are specific differences including additional regulators, divergent pathway architecture, and distinct target functions.
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99
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Lassak K, Ghosh A, Albers SV. Diversity, assembly and regulation of archaeal type IV pili-like and non-type-IV pili-like surface structures. Res Microbiol 2012; 163:630-44. [PMID: 23146836 DOI: 10.1016/j.resmic.2012.10.024] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/04/2012] [Indexed: 11/25/2022]
Abstract
Archaea have evolved fascinating surface structures allowing rapid adaptation to changing environments. The archaeal surface appendages display such diverse biological roles as motility, adhesion, biofilm formation, exchange of genetic material and species-specific interactions and, in turn, increase fitness of the cells. Intriguingly, despite sharing the same functions with their bacterial counterparts, the assembly mechanism of many archaeal surface structures is rather related to assembly of bacterial type IV pili. This review summarizes our state-of-the-art knowledge about unique structural and biochemical properties of archaeal surface appendages with a particular focus on archaeal type IV pili-like structures. The latter comprise not only widely distributed archaella (formerly known as archaeal flagella), but also different highly specialized archaeal pili, which are often restricted to certain species. Recent findings regarding assembly mechanisms, structural aspects and physiological roles of these type IV pili-like structures will be discussed in detail. Recently, first regulatory proteins involved in transition from both planktonic to sessile lifestyle and in assembly of archaella were identified. To conclude, we provide novel insights into regulatory mechanisms underlying the assembly of archaeal surface structures.
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Affiliation(s)
- Kerstin Lassak
- Max Planck Institute for Terrestrial Microbiology, Molecular Biology of Archaea, Karl-von-Frisch-Strasse 10, 35043 Marburg, Germany
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100
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Xu J, Kim J, Danhorn T, Merritt PM, Fuqua C. Phosphorus limitation increases attachment in Agrobacterium tumefaciens and reveals a conditional functional redundancy in adhesin biosynthesis. Res Microbiol 2012; 163:674-84. [PMID: 23103488 DOI: 10.1016/j.resmic.2012.10.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 10/12/2012] [Indexed: 11/30/2022]
Abstract
Bacterial responses to phosphorus limitation, commonly inorganic phosphate (P(i)), are important survival mechanisms in a variety of environments. The two-component sensor kinase PhoR and its cognate response regulator PhoB are central to the P(i) limitation response of many bacteria and control the large Pho regulon. Limitation for P(i) significantly increased attachment and biofilm formation by the plant pathogen Agrobacterium tumefaciens, and this was driven by PhoB. Surprisingly, it was also found that both phoR and phoB were essential in A. tumefaciens. Expression of a plasmid-borne copy of the low affinity P(i) transporter (pit) from Sinorhizobium meliloti in A. tumefaciens abolished the phoB and phoR essentiality in A. tumefaciens and allowed direct demonstration of the requirement for this regulatory system in the biofilm response. Increased attachment under P(i) limitation required a unipolar polysaccharide (UPP) adhesin. Mutation of a polyisoprenylphosphate hexose-1-phosphate transferase (PHPT) called uppE abolished UPP production and prevented surface attachment under P(i)-replete conditions, but this was rescued under P(i) limitation, and this rescue required phoB. In low P(i) conditions, either uppE or a paralogous gene Atu0102 is functionally redundant, but only uppE functions in UPP synthesis and attachment when P(i) is replete. This conditional functional redundancy illustrates the influence of phosphorus availability on A. tumefaciens surface colonization.
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Affiliation(s)
- Jing Xu
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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