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Contreras-Moreno FJ, Moraleda-Muñoz A, Marcos-Torres FJ, Cuéllar V, Soto MJ, Pérez J, Muñoz-Dorado J. Siderophores and competition for iron govern myxobacterial predation dynamics. ISME J 2024:wrae077. [PMID: 38696719 DOI: 10.1093/ismejo/wrae077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Revised: 04/23/2024] [Accepted: 04/29/2024] [Indexed: 05/04/2024]
Abstract
Bacterial predators are decisive organisms that shape microbial ecosystems. In this study, we investigated the role of iron and siderophores during the predatory interaction between two rhizosphere bacteria: Myxococcus xanthus, an epibiotic predator, and Sinorhizobium meliloti, a bacterium that establishes nitrogen-fixing symbiosis with legumes. The results show that iron enhances the motility of the predator and facilitates its predatory capability, and that intoxication by iron is not used by the predator to prey, although oxidative stress increases in both bacteria during predation. However, competition for iron plays an important role in the outcome of predatory interactions. Using combinations of predator and prey mutants (non-producers and overproducers of siderophores), we have investigated the importance of competition for iron in predation. The results demonstrate that the competitor that, via the production of siderophores, obtains sufficient iron for growth and depletes metal availability for the opponent will prevail in the interaction. Consequently, iron fluctuations in soils may modify the composition of microbial communities by altering the activity of myxobacterial predators. In addition, siderophore overproduction during predation can alter soil properties, affecting the productivity and sustainability of agricultural operations.
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Affiliation(s)
| | - Aurelio Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | | | - Virginia Cuéllar
- Departamento de Biotecnología y Protección Ambiental, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - María José Soto
- Departamento de Biotecnología y Protección Ambiental, Estación Experimental del Zaidín, CSIC, Granada, Spain
| | - Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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Carvia-Hermoso C, Cuéllar V, Bernabéu-Roda LM, van Dillewijn P, Soto MJ. Sinorhizobium meliloti GR4 Produces Chromosomal- and pSymA-Encoded Type IVc Pili That Influence the Interaction with Alfalfa Plants. Plants (Basel) 2024; 13:628. [PMID: 38475474 DOI: 10.3390/plants13050628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 02/09/2024] [Accepted: 02/23/2024] [Indexed: 03/14/2024]
Abstract
Type IVc Pili (T4cP), also known as Tad or Flp pili, are long thin microbial filaments that are made up of small-sized pilins. These appendages serve different functions in bacteria, including attachment, biofilm formation, surface sensing, motility, and host colonization. Despite their relevant role in diverse microbial lifestyles, knowledge about T4cP in bacteria that establish symbiosis with legumes, collectively referred to as rhizobia, is still limited. Sinorhizobium meliloti contains two clusters of T4cP-related genes: flp-1 and flp-2, which are located on the chromosome and the pSymA megaplasmid, respectively. Bundle-forming pili associated with flp-1 are involved in the competitive nodulation of alfalfa plants, but the role of flp-2 remains elusive. In this work, we have performed a comprehensive bioinformatic analysis of T4cP genes in the highly competitive S. meliloti GR4 strain and investigated the role of its flp clusters in pilus biogenesis, motility, and in the interaction with alfalfa. Single and double flp-cluster mutants were constructed on the wild-type genetic background as well as in a flagellaless derivative strain. Our data demonstrate that both chromosomal and pSymA flp clusters are functional in pili biogenesis and contribute to surface translocation and nodule formation efficiency in GR4. In this strain, the presence of flp-1 in the absence of flp-2 reduces the competitiveness for nodule occupation.
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Affiliation(s)
- Cristina Carvia-Hermoso
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Virginia Cuéllar
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Lydia M Bernabéu-Roda
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - Pieter van Dillewijn
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
| | - María J Soto
- Department of Biotechnology and Environmental Protection, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
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Fuentes-Romero F, Alías-Villegas C, Navarro-Gómez P, Acosta-Jurado S, Bernabéu-Roda LM, Cuéllar V, Soto MJ, Vinardell JM. Methods for Studying Swimming and Surface Motilities in Rhizobia. Methods Mol Biol 2024; 2751:205-217. [PMID: 38265718 DOI: 10.1007/978-1-0716-3617-6_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Rhizobia are soil proteobacteria able to establish a nitrogen-fixing interaction with legumes. In this interaction, rhizobia must colonize legume roots, infect them, and become hosted inside new organs formed by the plants and called nodules. Rhizobial motility, not being essential for symbiosis, might affect the degree of success of the interaction with legumes. Because of this, the study of rhizobial motility (either swimming or surface motility) might be of interest for research teams working on rhizobial symbiotic performance. In this chapter, we describe the protocols we use in our laboratories for studying the different types of motilities exhibited by Sinorhizobium fredii and Sinorhizobium meliloti, as well as for analyzing the presence of flagella in these bacteria. All these protocols might be used (or adapted) for studying bacterial motility in rhizobia.
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Affiliation(s)
| | - Cynthia Alías-Villegas
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Consejo Superior de Investigaciones Científicas and Junta de Andalucía, Seville, Spain
| | - Pilar Navarro-Gómez
- Department of Microbiology, Faculty of Biology, University of Seville, Seville, Spain
| | - Sebastián Acosta-Jurado
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide, Consejo Superior de Investigaciones Científicas and Junta de Andalucía, Seville, Spain
| | - Lydia M Bernabéu-Roda
- Department ofBiotechnology and EnvironmentalProtection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Virginia Cuéllar
- Department ofBiotechnology and EnvironmentalProtection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - María J Soto
- Department ofBiotechnology and EnvironmentalProtection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - José M Vinardell
- Department of Microbiology, Faculty of Biology, University of Seville, Seville, Spain.
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Brito-Santana P, Duque-Pedraza JJ, Bernabéu-Roda LM, Carvia-Hermoso C, Cuéllar V, Fuentes-Romero F, Acosta-Jurado S, Vinardell JM, Soto MJ. Sinorhizobium meliloti DnaJ Is Required for Surface Motility, Stress Tolerance, and for Efficient Nodulation and Symbiotic Nitrogen Fixation. Int J Mol Sci 2023; 24:ijms24065848. [PMID: 36982921 PMCID: PMC10055731 DOI: 10.3390/ijms24065848] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/14/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023] Open
Abstract
Bacterial surface motility is a complex microbial trait that contributes to host colonization. However, the knowledge about regulatory mechanisms that control surface translocation in rhizobia and their role in the establishment of symbiosis with legumes is still limited. Recently, 2-tridecanone (2-TDC) was identified as an infochemical in bacteria that hampers microbial colonization of plants. In the alfalfa symbiont Sinorhizobium meliloti, 2-TDC promotes a mode of surface motility that is mostly independent of flagella. To understand the mechanism of action of 2-TDC in S. meliloti and unveil genes putatively involved in plant colonization, Tn5 transposants derived from a flagellaless strain that were impaired in 2-TDC-induced surface spreading were isolated and genetically characterized. In one of the mutants, the gene coding for the chaperone DnaJ was inactivated. Characterization of this transposant and newly obtained flagella-minus and flagella-plus dnaJ deletion mutants revealed that DnaJ is essential for surface translocation, while it plays a minor role in swimming motility. DnaJ loss-of-function reduces salt and oxidative stress tolerance in S. meliloti and hinders the establishment of efficient symbiosis by affecting nodule formation efficiency, cellular infection, and nitrogen fixation. Intriguingly, the lack of DnaJ causes more severe defects in a flagellaless background. This work highlights the role of DnaJ in the free-living and symbiotic lifestyles of S. meliloti.
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Affiliation(s)
- Paula Brito-Santana
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
| | - Julián J Duque-Pedraza
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
| | - Lydia M Bernabéu-Roda
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
| | - Cristina Carvia-Hermoso
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
| | - Virginia Cuéllar
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
| | - Francisco Fuentes-Romero
- Facultad de Biología, Departamento de Microbiología, Universidad de Sevilla, 41012 Sevilla, Spain
| | - Sebastián Acosta-Jurado
- Centro Andaluz de Biología del Desarrollo, CSIC, Junta de Andalucía, Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, 41013 Seville, Spain
| | - José-María Vinardell
- Facultad de Biología, Departamento de Microbiología, Universidad de Sevilla, 41012 Sevilla, Spain
| | - María J Soto
- Estación Experimental del Zaidín, CSIC, Department of Biotechnology and Environmental Protection, 18008 Granada, Spain
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Alías-Villegas C, Fuentes-Romero F, Cuéllar V, Navarro-Gómez P, Soto MJ, Vinardell JM, Acosta-Jurado S. Surface Motility Regulation of Sinorhizobium fredii HH103 by Plant Flavonoids and the NodD1, TtsI, NolR, and MucR1 Symbiotic Bacterial Regulators. Int J Mol Sci 2022; 23:7698. [PMID: 35887044 PMCID: PMC9316994 DOI: 10.3390/ijms23147698] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/08/2022] [Accepted: 07/11/2022] [Indexed: 02/04/2023] Open
Abstract
Bacteria can spread on surfaces to colonize new environments and access more resources. Rhizobia, a group of α- and β-Proteobacteria, establish nitrogen-fixing symbioses with legumes that rely on a complex signal interchange between the partners. Flavonoids exuded by plant roots and the bacterial transcriptional activator NodD control the transcription of different rhizobial genes (the so-called nod regulon) and, together with additional bacterial regulatory proteins (such as TtsI, MucR or NolR), influence the production of different rhizobial molecular signals. In Sinorhizobium fredii HH103, flavonoids and NodD have a negative effect on exopolysaccharide production and biofilm production. Since biofilm formation and motility are often inversely regulated, we have analysed whether flavonoids may influence the translocation of S. fredii HH103 on surfaces. We show that the presence of nod gene-inducing flavonoids does not affect swimming but promotes a mode of surface translocation, which involves both flagella-dependent and -independent mechanisms. This surface motility is regulated in a flavonoid-NodD1-TtsI-dependent manner, relies on the assembly of the symbiotic type 3 secretion system (T3SS), and involves the participation of additional modulators of the nod regulon (NolR and MucR1). To our knowledge, this is the first evidence indicating the participation of T3SS in surface motility in a plant-interacting bacterium. Interestingly, flavonoids acting as nod-gene inducers also participate in the inverse regulation of surface motility and biofilm formation, which could contribute to a more efficient plant colonisation.
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Affiliation(s)
- Cynthia Alías-Villegas
- Centro Andaluz de Biología del Desarrollo, CSIC/Junta de Andalucía, Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, 41013 Seville, Spain;
| | - Francisco Fuentes-Romero
- Facultad de Biología, Departamento de Microbiología, Universidad de Sevilla, 41012 Sevilla, Spain; (F.F.-R.); (P.N.-G.)
| | - Virginia Cuéllar
- Estación Experimental del Zaidín, CSIC, Departamento de Biotecnología y Protección Ambiental, 18008 Granada, Spain; (V.C.); (M.J.S.)
| | - Pilar Navarro-Gómez
- Facultad de Biología, Departamento de Microbiología, Universidad de Sevilla, 41012 Sevilla, Spain; (F.F.-R.); (P.N.-G.)
| | - María J. Soto
- Estación Experimental del Zaidín, CSIC, Departamento de Biotecnología y Protección Ambiental, 18008 Granada, Spain; (V.C.); (M.J.S.)
| | - José-María Vinardell
- Facultad de Biología, Departamento de Microbiología, Universidad de Sevilla, 41012 Sevilla, Spain; (F.F.-R.); (P.N.-G.)
| | - Sebastián Acosta-Jurado
- Centro Andaluz de Biología del Desarrollo, CSIC/Junta de Andalucía, Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, 41013 Seville, Spain;
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Crespo-Rivas JC, Navarro-Gómez P, Alias-Villegas C, Shi J, Zhen T, Niu Y, Cuéllar V, Moreno J, Cubo T, Vinardell JM, Ruiz-Sainz JE, Acosta-Jurado S, Soto MJ. Sinorhizobium fredii HH103 RirA Is Required for Oxidative Stress Resistance and Efficient Symbiosis with Soybean. Int J Mol Sci 2019; 20:E787. [PMID: 30759803 PMCID: PMC6386902 DOI: 10.3390/ijms20030787] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 11/28/2022] Open
Abstract
Members of Rhizobiaceae contain a homologue of the iron-responsive regulatory protein RirA. In different bacteria, RirA acts as a repressor of iron uptake systems under iron-replete conditions and contributes to ameliorate cell damage during oxidative stress. In Rhizobium leguminosarum and Sinorhizobium meliloti, mutations in rirA do not impair symbiotic nitrogen fixation. In this study, a rirA mutant of broad host range S. fredii HH103 has been constructed (SVQ780) and its free-living and symbiotic phenotypes evaluated. No production of siderophores could be detected in either the wild-type or SVQ780. The rirA mutant exhibited a growth advantage under iron-deficient conditions and hypersensitivity to hydrogen peroxide in iron-rich medium. Transcription of rirA in HH103 is subject to autoregulation and inactivation of the gene upregulates fbpA, a gene putatively involved in iron transport. The S. fredii rirA mutant was able to nodulate soybean plants, but symbiotic nitrogen fixation was impaired. Nodules induced by the mutant were poorly infected compared to those induced by the wild-type. Genetic complementation reversed the mutant's hypersensitivity to H₂O₂, expression of fbpA, and symbiotic deficiency in soybean plants. This is the first report that demonstrates a role for RirA in the Rhizobium-legume symbiosis.
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Affiliation(s)
- Juan Carlos Crespo-Rivas
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - Pilar Navarro-Gómez
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - Cynthia Alias-Villegas
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - Jie Shi
- Daqing Branch of Heilongjiang Academy of Sciences, Daqing 163000, China.
| | - Tao Zhen
- Institute of Microbiology, Heilongjiang Academy of Sciences, Harbin 150001, China.
| | - Yanbo Niu
- Institute of Microbiology, Heilongjiang Academy of Sciences, Harbin 150001, China.
| | - Virginia Cuéllar
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, c/ Profesor Albareda 1, 18008 Granada, Spain.
| | - Javier Moreno
- Departamento de Biología Celular, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - Teresa Cubo
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - José María Vinardell
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - José Enrique Ruiz-Sainz
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - Sebastián Acosta-Jurado
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, 41012 Sevilla, Spain.
| | - María José Soto
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, c/ Profesor Albareda 1, 18008 Granada, Spain.
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López-Lara IM, Nogales J, Pech-Canul Á, Calatrava-Morales N, Bernabéu-Roda LM, Durán P, Cuéllar V, Olivares J, Alvarez L, Palenzuela-Bretones D, Romero M, Heeb S, Cámara M, Geiger O, Soto MJ. 2-Tridecanone impacts surface-associated bacterial behaviours and hinders plant-bacteria interactions. Environ Microbiol 2018; 20:2049-2065. [PMID: 29488306 DOI: 10.1111/1462-2920.14083] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 11/30/2022]
Abstract
Surface motility and biofilm formation are behaviours which enable bacteria to infect their hosts and are controlled by different chemical signals. In the plant symbiotic alpha-proteobacterium Sinorhizobium meliloti, the lack of long-chain fatty acyl-coenzyme A synthetase activity (FadD) leads to increased surface motility, defects in biofilm development and impaired root colonization. In this study, analyses of lipid extracts and volatiles revealed that a fadD mutant accumulates 2-tridecanone (2-TDC), a methylketone (MK) known as a natural insecticide. Application of pure 2-TDC to the wild-type strain phenocopies the free-living and symbiotic behaviours of the fadD mutant. Structural features of the MK determine its ability to promote S. meliloti surface translocation, which is mainly mediated by a flagella-independent motility. Transcriptomic analyses showed that 2-TDC induces differential expression of iron uptake, redox and stress-related genes. Interestingly, this MK also influences surface motility and impairs biofilm formation in plant and animal pathogenic bacteria. Moreover, 2-TDC not only hampers alfalfa nodulation but also the development of tomato bacterial speck disease. This work assigns a new role to 2-TDC as an infochemical that affects important bacterial traits and hampers plant-bacteria interactions by interfering with microbial colonization of plant tissues.
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Affiliation(s)
- Isabel M López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, C.P. 62210, Mexico
| | - Joaquina Nogales
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - Ángel Pech-Canul
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, C.P. 62210, Mexico
| | - Nieves Calatrava-Morales
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - Lydia M Bernabéu-Roda
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - Paloma Durán
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - Virginia Cuéllar
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - José Olivares
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
| | - Laura Alvarez
- Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Cuernavaca, C.P. 62209, Mexico
| | - Diana Palenzuela-Bretones
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham University Park, Nottingham, NG7 2RD, UK
| | - Manuel Romero
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham University Park, Nottingham, NG7 2RD, UK
| | - Stephan Heeb
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham University Park, Nottingham, NG7 2RD, UK
| | - Miguel Cámara
- Centre for Biomolecular Sciences, School of Life Sciences, University of Nottingham University Park, Nottingham, NG7 2RD, UK
| | - Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, C.P. 62210, Mexico
| | - María J Soto
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, 18008, Spain
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Bernabéu-Roda L, Calatrava-Morales N, Cuéllar V, Soto MJ. Characterization of surface motility in Sinorhizobium meliloti: regulation and role in symbiosis. Symbiosis 2015. [DOI: 10.1007/s13199-015-0340-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Nogales J, Domínguez-Ferreras A, Amaya-Gómez CV, van Dillewijn P, Cuéllar V, Sanjuán J, Olivares J, Soto MJ. Transcriptome profiling of a Sinorhizobium meliloti fadD mutant reveals the role of rhizobactin 1021 biosynthesis and regulation genes in the control of swarming. BMC Genomics 2010; 11:157. [PMID: 20210991 PMCID: PMC2848241 DOI: 10.1186/1471-2164-11-157] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 03/08/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Swarming is a multicellular phenomenom characterized by the coordinated and rapid movement of bacteria across semisolid surfaces. In Sinorhizobium meliloti this type of motility has been described in a fadD mutant. To gain insights into the mechanisms underlying the process of swarming in rhizobia, we compared the transcriptome of a S. meliloti fadD mutant grown under swarming inducing conditions (semisolid medium) to those of cells grown under non-swarming conditions (broth and solid medium). RESULTS More than a thousand genes were identified as differentially expressed in response to growth on agar surfaces including genes for several metabolic activities, iron uptake, chemotaxis, motility and stress-related genes. Under swarming-specific conditions, the most remarkable response was the up-regulation of iron-related genes. We demonstrate that the pSymA plasmid and specifically genes required for the biosynthesis of the siderophore rhizobactin 1021 are essential for swarming of a S. meliloti wild-type strain but not in a fadD mutant. Moreover, high iron conditions inhibit swarming of the wild-type strain but not in mutants lacking either the iron limitation response regulator RirA or FadD. CONCLUSIONS The present work represents the first transcriptomic study of rhizobium growth on surfaces including swarming inducing conditions. The results have revealed major changes in the physiology of S. meliloti cells grown on a surface relative to liquid cultures. Moreover, analysis of genes responding to swarming inducing conditions led to the demonstration that iron and genes involved in rhizobactin 1021 synthesis play a role in the surface motility shown by S. meliloti which can be circumvented in a fadD mutant. This work opens a way to the identification of new traits and regulatory networks involved in swarming by rhizobia.
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Affiliation(s)
- Joaquina Nogales
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Profesor Albareda, 1, 18008 Granada, Spain
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