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Dr. Annabelle Merieau
LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France

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0 Adaptation
0 Cytotoxicity
0 Epigenetics
0 Pathogens
0 Pseudomonas fluorescens

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Pseudomonas fluorescens
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Journal article
Published: 31 July 2021 in International Journal of Molecular Sciences
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Biofilms are complex structures formed by a community of microbes adhering to a surface and/or to each other through the secretion of an adhesive and protective matrix. The establishment of these structures requires a coordination of action between microorganisms through powerful communication systems such as quorum-sensing. Therefore, auxiliary bacteria capable of interfering with these means of communication could be used to prevent biofilm formation and development. The phytopathogen Rhizobium rhizogenes, which causes hairy root disease and forms large biofilms in hydroponic crops, and the biocontrol agent Rhodococcus erythropolis R138 were used for this study. Changes in biofilm biovolume and structure, as well as interactions between rhizobia and rhodococci, were monitored by confocal laser scanning microscopy with appropriate fluorescent biosensors. We obtained direct visual evidence of an exchange of signals between rhizobia and the jamming of this communication by Rhodococcus within the biofilm. Signaling molecules were characterized as long chain (C14) N-acyl-homoserine lactones. The role of the Qsd quorum-quenching pathway in biofilm alteration was confirmed with an R. erythropolis mutant unable to produce the QsdA lactonase, and by expression of the qsdA gene in a heterologous host, Escherichia coli. Finally, Rhizobium biofilm formation was similarly inhibited by a purified extract of QsdA enzyme.

ACS Style

Yvann Bourigault; Sophie Rodrigues; Alexandre Crépin; Andrea Chane; Laure Taupin; Mathilde Bouteiller; Charly Dupont; Annabelle Merieau; Yoan Konto-Ghiorghi; Amine Boukerb; Marie Turner; Céline Hamon; Alain Dufour; Corinne Barbey; Xavier Latour. Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching. International Journal of Molecular Sciences 2021, 22, 8241 .

AMA Style

Yvann Bourigault, Sophie Rodrigues, Alexandre Crépin, Andrea Chane, Laure Taupin, Mathilde Bouteiller, Charly Dupont, Annabelle Merieau, Yoan Konto-Ghiorghi, Amine Boukerb, Marie Turner, Céline Hamon, Alain Dufour, Corinne Barbey, Xavier Latour. Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching. International Journal of Molecular Sciences. 2021; 22 (15):8241.

Chicago/Turabian Style

Yvann Bourigault; Sophie Rodrigues; Alexandre Crépin; Andrea Chane; Laure Taupin; Mathilde Bouteiller; Charly Dupont; Annabelle Merieau; Yoan Konto-Ghiorghi; Amine Boukerb; Marie Turner; Céline Hamon; Alain Dufour; Corinne Barbey; Xavier Latour. 2021. "Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching." International Journal of Molecular Sciences 22, no. 15: 8241.

Journal article
Published: 30 June 2021 in Agronomy
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Bacterial burn is one of the major diseases affecting pear trees worldwide, with serious impacts on producers and economy. In Morocco, several pear trees (Pyrus communis) have shown leaf burns since 2015. To characterize the causal agent of this disease, we isolated fourteen bacterial strains from different parts of symptomatic pear trees (leaves, shoots, fruits and flowers) that were tested in planta for their pathogenicity on Louise bonne and Williams cultivars. The results showed necrotic lesions with a significant severity range from 47.63 to 57.77% on leaves of the Louise bonne cultivar inoculated with isolate B10, while the other bacterial isolates did not induce any disease symptom. 16S rRNA gene sequencing did not allow robust taxonomic discrimination of the incriminated isolate. Thus, we conducted whole-genome sequencing (WGS) and phylogenetic analyzes based on gyrA, gyrB and cdaA gene sequences, indicating that this isolate belongs to the Bacillus altitudinis species. This taxonomic classification was further confirmed by the Average Nucleotide Identity (ANI) and the in silico DNA-DNA hybridization (isDDH) analyzes compared to sixty-five Bacillus spp. type strains. The genome was mined for genes encoding carbohydrate-active enzymes (CAZymes) known to play a role in the vegetal tissue degradation. 177 candidates with functions that may support the in planta phytopathogenicity results were identified. To the best of our knowledge, this is the first data reporting B. altitudinis as agent of leaf burn in P. communis in Morocco. Our dataset will improve our knowledge on spread and pathogenicity of B. altitudinis genotypes that appears as emergent phytopathogenic agent, unveiling virulence factors and their genomic location (i.e., within genomic islands or the accessory genome) to induce trees disease.

ACS Style

Naima Lemjiber; Khalid Naamani; Annabelle Merieau; Abdelhi Dihazi; Nawal Zhar; Hicham Jediyi; Amine Boukerb. Identification and Genomic Characterization of Pathogenic Bacillus altitudinis from Common Pear Trees in Morocco. Agronomy 2021, 11, 1344 .

AMA Style

Naima Lemjiber, Khalid Naamani, Annabelle Merieau, Abdelhi Dihazi, Nawal Zhar, Hicham Jediyi, Amine Boukerb. Identification and Genomic Characterization of Pathogenic Bacillus altitudinis from Common Pear Trees in Morocco. Agronomy. 2021; 11 (7):1344.

Chicago/Turabian Style

Naima Lemjiber; Khalid Naamani; Annabelle Merieau; Abdelhi Dihazi; Nawal Zhar; Hicham Jediyi; Amine Boukerb. 2021. "Identification and Genomic Characterization of Pathogenic Bacillus altitudinis from Common Pear Trees in Morocco." Agronomy 11, no. 7: 1344.

Review
Published: 24 March 2021 in International Journal of Molecular Sciences
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Flagella-driven motility is an important trait for bacterial colonization and virulence. Flagella rotate and propel bacteria in liquid or semi-liquid media to ensure such bacterial fitness. Bacterial flagella are composed of three parts: a membrane complex, a flexible-hook, and a flagellin filament. The most widely studied models in terms of the flagellar apparatus are E. coli and Salmonella. However, there are many differences between these enteric bacteria and the bacteria of the Pseudomonas genus. Enteric bacteria possess peritrichous flagella, in contrast to Pseudomonads, which possess polar flagella. In addition, flagellar gene expression in Pseudomonas is under a four-tiered regulatory circuit, whereas enteric bacteria express flagellar genes in a three-step manner. Here, we use knowledge of E. coli and Salmonella flagella to describe the general properties of flagella and then focus on the specificities of Pseudomonas flagella. After a description of flagellar structure, which is highly conserved among Gram-negative bacteria, we focus on the steps of flagellar assembly that differ between enteric and polar-flagellated bacteria. In addition, we summarize generalities concerning the fuel used for the production and rotation of the flagellar macromolecular complex. The last part summarizes known regulatory pathways and potential links with the type-six secretion system (T6SS).

ACS Style

Mathilde Bouteiller; Charly Dupont; Yvann Bourigault; Xavier Latour; Corinne Barbey; Yoan Konto-Ghiorghi; Annabelle Merieau. Pseudomonas Flagella: Generalities and Specificities. International Journal of Molecular Sciences 2021, 22, 3337 .

AMA Style

Mathilde Bouteiller, Charly Dupont, Yvann Bourigault, Xavier Latour, Corinne Barbey, Yoan Konto-Ghiorghi, Annabelle Merieau. Pseudomonas Flagella: Generalities and Specificities. International Journal of Molecular Sciences. 2021; 22 (7):3337.

Chicago/Turabian Style

Mathilde Bouteiller; Charly Dupont; Yvann Bourigault; Xavier Latour; Corinne Barbey; Yoan Konto-Ghiorghi; Annabelle Merieau. 2021. "Pseudomonas Flagella: Generalities and Specificities." International Journal of Molecular Sciences 22, no. 7: 3337.

Journal article
Published: 25 April 2020 in Microorganisms
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Type VI secretion systems (T6SSs) are contractile bacterial multiprotein nanomachines that enable the injection of toxic effectors into prey cells. The Pseudomonas fluorescens MFE01 strain has T6SS antibacterial activity and can immobilise competitive bacteria through the T6SS. Hcp1 (hemolysin co-regulated protein 1), a constituent of the T6SS inner tube, is involved in such prey cell inhibition of motility. Paradoxically, disruption of the hcp1 or T6SS contractile tail tssC genes results in the loss of the mucoid and motile phenotypes in MFE01. Here, we focused on the relationship between T6SS and flagella-associated motility. Electron microscopy revealed the absence of flagellar filaments for MFE01Δhcp1 and MFE01ΔtssC mutants. Transcriptomic analysis showed a reduction in the transcription of class IV flagellar genes in these T6SS mutants. However, transcription of fliA, the gene encoding the class IV flagellar sigma factor, was unaffected. Over-expression of fliA restored the motile and mucoid phenotypes in both MFE01Δhcp1+fliA, and MFE01ΔtssC+fliA and a fliA mutant displayed the same phenotypes as MFE01Δhcp1 and MFE01ΔtssC. Moreover, the FliA anti-sigma factor FlgM was not secreted in the T6SS mutants, and flgM over-expression reduced both motility and mucoidy. This study provides arguments to unravel the crosstalk between T6SS and motility.

ACS Style

Mathilde Bouteiller; Mathias Gallique; Yvann Bourigault; Artemis Kosta; Julie Hardouin; Sebastien Massier; Yoan Konto-Ghiorghi; Corinne Barbey; Xavier Latour; Andréa Chane; Marc Feuilloley; Annabelle Merieau. Crosstalk between the Type VI Secretion System and the Expression of Class IV Flagellar Genes in the Pseudomonas fluorescens MFE01 Strain. Microorganisms 2020, 8, 622 .

AMA Style

Mathilde Bouteiller, Mathias Gallique, Yvann Bourigault, Artemis Kosta, Julie Hardouin, Sebastien Massier, Yoan Konto-Ghiorghi, Corinne Barbey, Xavier Latour, Andréa Chane, Marc Feuilloley, Annabelle Merieau. Crosstalk between the Type VI Secretion System and the Expression of Class IV Flagellar Genes in the Pseudomonas fluorescens MFE01 Strain. Microorganisms. 2020; 8 (5):622.

Chicago/Turabian Style

Mathilde Bouteiller; Mathias Gallique; Yvann Bourigault; Artemis Kosta; Julie Hardouin; Sebastien Massier; Yoan Konto-Ghiorghi; Corinne Barbey; Xavier Latour; Andréa Chane; Marc Feuilloley; Annabelle Merieau. 2020. "Crosstalk between the Type VI Secretion System and the Expression of Class IV Flagellar Genes in the Pseudomonas fluorescens MFE01 Strain." Microorganisms 8, no. 5: 622.

Research article
Published: 01 July 2019 in Molecular Plant-Microbe Interactions®
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Confocal laser-scanning microscopy was chosen to observe the colonization and damage caused by the soft rot Pectobacterium atrosepticum and the protection mediated by the biocontrol agent Rhodococcus erythropolis. We developed dual-color reporter strains suited for monitoring quorum-sensing and quorum-quenching activities leading to maceration or biocontrol, respectively. A constitutively expressed cyan or red fluorescent protein served as a cell tag for plant colonization, while an inducible expression reporter system based on the green fluorescent protein gene enabled the simultaneous recording of signaling molecule production, detection, or degradation. The dual-colored pathogen and biocontrol strains were used to coinoculate potato tubers. At cellular quorum, images revealed a strong pectobacterial quorum-sensing activity, especially at the plant cell walls, as well as a concomitant rhodococcal quorum-quenching response, at both the single-cell and microcolony levels. The generated biosensors appear to be promising and complementary tools useful for molecular and cellular studies of bacterial communication and interference.

ACS Style

Andrea Chane; Corinne Barbey; Magalie Robert; Annabelle Merieau; Yoan Konto-Ghiorghi; Amélie Beury-Cirou; Marc Feuilloley; Miroslav Pátek; Virginie Gobert; Xavier Latour. Biocontrol of Soft Rot: Confocal Microscopy Highlights Virulent Pectobacterial Communication and Its Jamming by Rhodococcal Quorum-Quenching. Molecular Plant-Microbe Interactions® 2019, 32, 802 -812.

AMA Style

Andrea Chane, Corinne Barbey, Magalie Robert, Annabelle Merieau, Yoan Konto-Ghiorghi, Amélie Beury-Cirou, Marc Feuilloley, Miroslav Pátek, Virginie Gobert, Xavier Latour. Biocontrol of Soft Rot: Confocal Microscopy Highlights Virulent Pectobacterial Communication and Its Jamming by Rhodococcal Quorum-Quenching. Molecular Plant-Microbe Interactions®. 2019; 32 (7):802-812.

Chicago/Turabian Style

Andrea Chane; Corinne Barbey; Magalie Robert; Annabelle Merieau; Yoan Konto-Ghiorghi; Amélie Beury-Cirou; Marc Feuilloley; Miroslav Pátek; Virginie Gobert; Xavier Latour. 2019. "Biocontrol of Soft Rot: Confocal Microscopy Highlights Virulent Pectobacterial Communication and Its Jamming by Rhodococcal Quorum-Quenching." Molecular Plant-Microbe Interactions® 32, no. 7: 802-812.

Mini review article
Published: 28 July 2017 in Frontiers in Microbiology
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Numerous studies in Gram-negative bacteria have focused on the Type VI Secretion Systems (T6SSs), Quorum Sensing (QS), and social behaviour, such as in biofilms. These interconnected mechanisms are important for bacterial survival; T6SSs allow bacteria to battle other cells, QS is devoted to the perception of bacterial cell density, and biofilm formation is essentially controlled by QS. Here, we review data concerning T6SS dynamics and T6SS–QS cross-talk that suggest the existence of inter-bacterial communication via T6SSs.

ACS Style

Mathias Gallique; Mathilde Bouteiller; Annabelle Merieau. The Type VI Secretion System: A Dynamic System for Bacterial Communication? Frontiers in Microbiology 2017, 8, 1454 .

AMA Style

Mathias Gallique, Mathilde Bouteiller, Annabelle Merieau. The Type VI Secretion System: A Dynamic System for Bacterial Communication? Frontiers in Microbiology. 2017; 8 ():1454.

Chicago/Turabian Style

Mathias Gallique; Mathilde Bouteiller; Annabelle Merieau. 2017. "The Type VI Secretion System: A Dynamic System for Bacterial Communication?" Frontiers in Microbiology 8, no. : 1454.

Journal article
Published: 23 January 2017 in PLOS ONE
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Type VI secretion systems (T6SSs) are widespread in Gram-negative bacteria, including Pseudomonas. These macromolecular machineries inject toxins directly into prokaryotic or eukaryotic prey cells. Hcp proteins are structural components of the extracellular part of this machinery. We recently reported that MFE01, an avirulent strain of Pseudomonas fluorescens, possesses at least two hcp genes, hcp1 and hcp2, encoding proteins playing important roles in interbacterial interactions. Indeed, P. fluorescens MFE01 can immobilise and kill diverse bacteria of various origins through the action of the Hcp1 or Hcp2 proteins of the T6SS. We show here that another Hcp protein, Hcp3, is involved in killing prey cells during co-culture on solid medium. Even after the mutation of hcp1, hcp2, or hcp3, MFE01 impaired biofilm formation by MFP05, a P. fluorescens strain isolated from human skin. These mutations did not reduce P. fluorescens MFE01 biofilm formation, but the three Hcp proteins were required for the completion of biofilm maturation. Moreover, a mutant with a disruption of one of the unique core component genes, MFE01ΔtssC, was unable to produce its own biofilm or inhibit MFP05 biofilm formation. Finally, MFE01 did not produce detectable N-acyl-homoserine lactones for quorum sensing, a phenomenon reported for many other P. fluorescens strains. Our results suggest a role for the T6SS in communication between bacterial cells, in this strain, under biofilm conditions.

ACS Style

Mathias Gallique; Victorien Decoin; Corinne Barbey; Thibaut Rosay; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. Contribution of the Pseudomonas fluorescens MFE01 Type VI Secretion System to Biofilm Formation. PLOS ONE 2017, 12, e0170770 .

AMA Style

Mathias Gallique, Victorien Decoin, Corinne Barbey, Thibaut Rosay, Marc G. J. Feuilloley, Nicole Orange, Annabelle Merieau. Contribution of the Pseudomonas fluorescens MFE01 Type VI Secretion System to Biofilm Formation. PLOS ONE. 2017; 12 (1):e0170770.

Chicago/Turabian Style

Mathias Gallique; Victorien Decoin; Corinne Barbey; Thibaut Rosay; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. 2017. "Contribution of the Pseudomonas fluorescens MFE01 Type VI Secretion System to Biofilm Formation." PLOS ONE 12, no. 1: e0170770.

Journal article
Published: 26 March 2015 in BMC Microbiology
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Pseudomonas fluorescens strain MFE01 secretes in abundance two Hcp proteins (haemolysin co-regulated proteins) Hcp1 and Hcp2, characteristic of a functional type 6 secretion system. Phenotypic studies have shown that MFE01 has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinically relevant bacteria. Mutagenesis of the hcp2 gene abolishes or reduces, depending on the target strain, MFE01 antibacterial activity. Hcp1, encoded by hcp1, may also be involved in bacterial competition. We therefore assessed the contribution of Hcp1 to competition of P. fluorescens MFE01 with other bacteria, by studying MFE01 mutants in various competitive conditions. Mutation of hcp1 had pleiotropic effects on the MFE01 phenotype. It affected mucoidy of the strain and its motility and was associated with the loss of flagella, which were restored by introduction of plasmid expressing hcp1. The hcp1 mutation had no effect on bacterial competition during incubation in solid medium. MFE01 was able to sequester another P. fluorescens strain, MFN1032, under swimming conditions. The hcp2 mutant but not the hcp1 mutant conserved this ability. In competition assays on swarming medium, MFE01 impaired MFN1032 swarming and displayed killing activity. The hcp2 mutant, but not the hcp1 mutant, was able to reduce MFN1032 swarming. The hcp1 and hcp2 mutations each abolished killing activity in these conditions. Our findings implicate type 6 secretion of Hcp1 in mucoidy and motility of MFE01. Our study is the first to establish a link between a type 6 secretion system and flagellin and mucoidy. Hcp1 also appears to contribute to limiting the motility of prey cells to facilitate killing mediated by Hcp2. Inhibition of motility associated with an Hcp protein has never been described. With this work, we illustrate the importance and versatility of type 6 secretion systems in bacterial adaptation and fitness.

ACS Style

Victorien Decoin; Mathias Gallique; Corinne Barbey; Francois Le Mauff; Cecile Duclairoir Poc; Marc G J Feuilloley; Nicole Orange; Annabelle Merieau. A Pseudomonas fluorescens type 6 secretion system is related to mucoidy, motility and bacterial competition. BMC Microbiology 2015, 15, 1 -12.

AMA Style

Victorien Decoin, Mathias Gallique, Corinne Barbey, Francois Le Mauff, Cecile Duclairoir Poc, Marc G J Feuilloley, Nicole Orange, Annabelle Merieau. A Pseudomonas fluorescens type 6 secretion system is related to mucoidy, motility and bacterial competition. BMC Microbiology. 2015; 15 (1):1-12.

Chicago/Turabian Style

Victorien Decoin; Mathias Gallique; Corinne Barbey; Francois Le Mauff; Cecile Duclairoir Poc; Marc G J Feuilloley; Nicole Orange; Annabelle Merieau. 2015. "A Pseudomonas fluorescens type 6 secretion system is related to mucoidy, motility and bacterial competition." BMC Microbiology 15, no. 1: 1-12.

Research article
Published: 14 February 2014 in PLOS ONE
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Protein secretion systems are crucial mediators of bacterial interactions with other organisms. Among them, the type VI secretion system (T6SS) is widespread in Gram-negative bacteria and appears to inject toxins into competitor bacteria and/or eukaryotic cells. Major human pathogens, such as Vibrio cholerae, Burkholderia and Pseudomonas aeruginosa, express T6SSs. Bacteria prevent self-intoxication by their own T6SS toxins by producing immunity proteins, which interact with the cognate toxins. We describe here an environmental P. fluorescens strain, MFE01, displaying an uncommon oversecretion of Hcp (hemolysin-coregulated protein) and VgrG (valine-glycine repeat protein G) into the culture medium. These proteins are characteristic components of a functional T6SS. The aim of this study was to attribute a role to this energy-consuming overexpression of the T6SS. The genome of MFE01 contains at least two hcp genes (hcp1 and hcp2), suggesting that there may be two putative T6SS clusters. Phenotypic studies have shown that MFE01 is avirulent against various eukaryotic cell models (amebas, plant or animal cell models), but has antibacterial activity against a wide range of competitor bacteria, including rhizobacteria and clinical bacteria. Depending on the prey cell, mutagenesis of the hcp2 gene in MFE01 abolishes or reduces this antibacterial killing activity. Moreover, the introduction of T6SS immunity proteins from S. marcescens, which is not killed by MFE01, protects E. coli against MFE01 killing. These findings suggest that the protein encoded by hcp2 is involved in the killing activity of MFE01 mediated by effectors of the T6SS targeting the peptidoglycan of Gram-negative bacteria. Our results indicate that MFE01 can protect potato tubers against Pectobacterium atrosepticum, which causes tuber soft rot. Pseudomonas fluorescens is often described as a major PGPR (plant growth-promoting rhizobacterium), and our results suggest that there may be a connection between the T6SS and the PGPR properties of this bacterium.

ACS Style

Victorien Decoin; Corinne Barbey; Dorian Bergeau; Xavier Latour; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. A Type VI Secretion System Is Involved in Pseudomonas fluorescens Bacterial Competition. PLOS ONE 2014, 9, e89411 .

AMA Style

Victorien Decoin, Corinne Barbey, Dorian Bergeau, Xavier Latour, Marc G. J. Feuilloley, Nicole Orange, Annabelle Merieau. A Type VI Secretion System Is Involved in Pseudomonas fluorescens Bacterial Competition. PLOS ONE. 2014; 9 (2):e89411.

Chicago/Turabian Style

Victorien Decoin; Corinne Barbey; Dorian Bergeau; Xavier Latour; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. 2014. "A Type VI Secretion System Is Involved in Pseudomonas fluorescens Bacterial Competition." PLOS ONE 9, no. 2: e89411.

Journal article
Published: 01 January 2012 in BMC Microbiology
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Pseudomonas fluorescens biovar I MFN1032 is a clinical isolate able to grow at 37°C. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis is independent of biosurfactant production and remains in a gacA mutant. Disruption of the hrpU-like operon (the basal part of type III secretion system from rhizospheric strains) suppresses this activity. We hypothesized that this phenotype could reflect evolution of an ancestral mechanism involved in the survival of this species in its natural niche. In this study, we evaluated the hrpU-like operon's contribution to other virulence mechanisms using a panel of Pseudomonas strains from various sources. We found that MFN1032 inhibited the growth of the amoebae Dictyostelium discoideum and that this inhibition involved the hrpU-like operon and was absent in a gacA mutant. MFN1032 was capable of causing macrophage lysis, if the hrpU-like operon was intact, and this cytotoxicity remained in a gacA mutant. Cell-associated hemolytic activity and macrophage necrosis were found in other P. fluorescens clinical isolates, but not in biocontrol P. fluorescens strains harbouring hrpU-like operon. The growth of Dictyostelium discoideum was inhibited to a different extent by P. fluorescens strains without correlation between this inhibition and hrpU-like operon sequences. In P. fluorescens MFN1032, the basal part of type III secretion system plays a role in D. discoideum growth inhibition and macrophage necrosis. The inhibition of D. discoideum growth is dependent on the GacS/GacA system, while cell-associated hemolytic activity and macrophage lysis are not. Virulence against eukaryotic cells based on the hrpU-like operon may be more than just a stochastic evolution of a conserved system dedicated to survival in competition with natural predators such as amoebae. It may also mean that there are some important modifications of other type III secretion system components, which remain unknown. Cell-associated hemolysis might be a good indicator of the virulence of Pseudomonas fluorescens strain.

ACS Style

Daniel Sperandio; Victorien Decoin; Xavier Latour; Lily Mijouin; Mélanie Hillion; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system. BMC Microbiology 2012, 12, 223 -223.

AMA Style

Daniel Sperandio, Victorien Decoin, Xavier Latour, Lily Mijouin, Mélanie Hillion, Marc G. J. Feuilloley, Nicole Orange, Annabelle Merieau. Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system. BMC Microbiology. 2012; 12 (1):223-223.

Chicago/Turabian Style

Daniel Sperandio; Victorien Decoin; Xavier Latour; Lily Mijouin; Mélanie Hillion; Marc G. J. Feuilloley; Nicole Orange; Annabelle Merieau. 2012. "Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system." BMC Microbiology 12, no. 1: 223-223.

Journal article
Published: 01 February 2011 in Research in Microbiology
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Very few studies have been reported on the cytotoxicity and impact of bacteriocins, and especially enterocins, upon eukaryotic cells. In order to gain more information on the safety of bacteriocins, we focused this study on enterocin S37, a bacteriocin produced by Enterococcus faecalis S37. We observed dose-dependent cytotoxicity toward undifferentiated Caco-2/TC7 cells. Moreover, no significant effect on differentiated monolayer Caco-2/TC7 and no apoptotic features were observed when cells were treated with 10 μg/ml of enterocin S37. The results obtained indicate possible safe use of enterocin S37 in the gastrointestinal tract of animals to prevent pathogen invasion and/or infection.

ACS Style

Yanath Belguesmia; Amar Madi; Daniel Sperandio; Annabelle Merieau; Marc Feuilloley; Hervé Prevost; Djamel Drider; Nathalie Connil. Growing insights into the safety of bacteriocins: the case of enterocin S37. Research in Microbiology 2011, 162, 159 -163.

AMA Style

Yanath Belguesmia, Amar Madi, Daniel Sperandio, Annabelle Merieau, Marc Feuilloley, Hervé Prevost, Djamel Drider, Nathalie Connil. Growing insights into the safety of bacteriocins: the case of enterocin S37. Research in Microbiology. 2011; 162 (2):159-163.

Chicago/Turabian Style

Yanath Belguesmia; Amar Madi; Daniel Sperandio; Annabelle Merieau; Marc Feuilloley; Hervé Prevost; Djamel Drider; Nathalie Connil. 2011. "Growing insights into the safety of bacteriocins: the case of enterocin S37." Research in Microbiology 162, no. 2: 159-163.

Journal article
Published: 01 January 2010 in BMC Microbiology
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MFN1032 is a clinical Pseudomonas fluorescens strain able to grow at 37°C. MFN1032 cells induce necrosis and apoptosis in rat glial cells at this temperature. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides. Under laboratory conditions, this activity is not expressed at 37°C. This activity is tightly regulated and is subject to phase variation.

ACS Style

Daniel Sperandio; Gaelle Rossignol; Josette Guerillon; Nathalie Connil; Nicole Orange; Marc Gj Feuilloley; Annabelle Merieau. Cell-associated hemolysis activity in the clinical strain of Pseudomonas fluorescens MFN1032. BMC Microbiology 2010, 10, 124 -124.

AMA Style

Daniel Sperandio, Gaelle Rossignol, Josette Guerillon, Nathalie Connil, Nicole Orange, Marc Gj Feuilloley, Annabelle Merieau. Cell-associated hemolysis activity in the clinical strain of Pseudomonas fluorescens MFN1032. BMC Microbiology. 2010; 10 (1):124-124.

Chicago/Turabian Style

Daniel Sperandio; Gaelle Rossignol; Josette Guerillon; Nathalie Connil; Nicole Orange; Marc Gj Feuilloley; Annabelle Merieau. 2010. "Cell-associated hemolysis activity in the clinical strain of Pseudomonas fluorescens MFN1032." BMC Microbiology 10, no. 1: 124-124.

Journal article
Published: 30 June 2009 in Research in Microbiology
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Pseudomonas fluorescens is a highly heterogeneous species and includes both avirulent strains and clinical strains involved in nosocomial infections. We previously demonstrated that clinical strain MFN1032 has hemolytic activity involving phospholipase C (PlcC) and biosurfactants (BSs), similar to that of the opportunistic pathogen Pseudomonas aeruginosa. When incubated under specific conditions, MFN1032 forms translucent phenotypic variant colonies defective in hemolysis, but not necessarily in PlcC. We analyzed eight variants of the original strain MFN1032 and found that they clustered into two groups. Mutations of genes encoding the two-component regulatory system GacS/GacA are responsible for phenotypic variation in the first group of variants. These group 1 variants did not produce secondary metabolites and had impaired biofilm formation. The second group was composed of hyperflagellated cells with enhanced biofilm capacity: they did not produce BSs and were thus unable to swarm. Artificial reduction of the intracellular level of c-di-GMP restored the ability to form biofilm to levels shown by the wild type, but production of BSs was still repressed. Phenotypic variation might increase the virulence potential of this strain.

ACS Style

G. Rossignol; D. Sperandio; J. Guerillon; C. Duclairoir Poc; E. Soum-Soutera; N. Orange; M.G.J. Feuilloley; A. Merieau. Phenotypic variation in the Pseudomonas fluorescens clinical strain MFN1032. Research in Microbiology 2009, 160, 337 -344.

AMA Style

G. Rossignol, D. Sperandio, J. Guerillon, C. Duclairoir Poc, E. Soum-Soutera, N. Orange, M.G.J. Feuilloley, A. Merieau. Phenotypic variation in the Pseudomonas fluorescens clinical strain MFN1032. Research in Microbiology. 2009; 160 (5):337-344.

Chicago/Turabian Style

G. Rossignol; D. Sperandio; J. Guerillon; C. Duclairoir Poc; E. Soum-Soutera; N. Orange; M.G.J. Feuilloley; A. Merieau. 2009. "Phenotypic variation in the Pseudomonas fluorescens clinical strain MFN1032." Research in Microbiology 160, no. 5: 337-344.

Journal article
Published: 01 June 2009 in Annals of Microbiology
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In the present study the effect of infection on the resting membrane potential and whole-voltage-activated currents of neurons was determined usingPseudomonas fluorescens and lipopolysaccharide (LPS) extracted from the same species. Electrophysiological studies were performed on cerebellar granule neurons using the whole cell configuration of the patch clamp technique. The resting potential of cells (−63.7±2 mV) was significantly less negative (−46.0±4.7 mV) in cells showing adherent bacteria (106 CFU/ml). In addition, the whole-voltage currents triggered by voltage pulses were markedly reduced in neurons incubated withP. Fluorescens (mean 58%). Treatment with LPS (200 ng/ml) extracted fromP. Fluorescens provoke also a significant depolarisation of the membrane of the granule neurons and a severely alteration of whole-voltage currents. Analysis of the current-voltage relationships of the peak currents revealed the implication of potassium channels in the response of the cells toP. Fluorescens and its LPS. The present report provides the first data on the effect of a living bacterium on the membrane electrical activity of neurons and comforts the recent observations of the high cytotoxic potential ofP. fluorescens.

ACS Style

Sana Mezghani; Olivier Lesouhaitier; Annabelle Merieau; Sylvie Chevalier; Nicole Orange; Marc Feuilloley; Lionel Cazin. Pseudomonas fluorescens alter whole-voltage-activated currents of cultured rat cerebellar granule neurons. Annals of Microbiology 2009, 59, 379 -382.

AMA Style

Sana Mezghani, Olivier Lesouhaitier, Annabelle Merieau, Sylvie Chevalier, Nicole Orange, Marc Feuilloley, Lionel Cazin. Pseudomonas fluorescens alter whole-voltage-activated currents of cultured rat cerebellar granule neurons. Annals of Microbiology. 2009; 59 (2):379-382.

Chicago/Turabian Style

Sana Mezghani; Olivier Lesouhaitier; Annabelle Merieau; Sylvie Chevalier; Nicole Orange; Marc Feuilloley; Lionel Cazin. 2009. "Pseudomonas fluorescens alter whole-voltage-activated currents of cultured rat cerebellar granule neurons." Annals of Microbiology 59, no. 2: 379-382.

Journal article
Published: 01 January 2008 in BMC Microbiology
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Pseudomonas fluorescens is a ubiquitous Gram-negative bacterium frequently encountered in hospitals as a contaminant of injectable material and surfaces. This psychrotrophic bacterium, commonly described as unable to grow at temperatures above 32°C, is now considered non pathogenic. We studied a recently identified clinical strain of P. fluorescens biovar I, MFN1032, which is considered to cause human lung infection and can grow at 37°C in laboratory conditions.

ACS Style

Gaelle Rossignol; Annabelle Merieau; Josette Guerillon; Wilfried Veron; Olivier Lesouhaitier; Marc G J Feuilloley; Nicole Orange. Involvement of a phospholipase C in the hemolytic activity of a clinical strain of Pseudomonas fluorescens. BMC Microbiology 2008, 8, 189 -189.

AMA Style

Gaelle Rossignol, Annabelle Merieau, Josette Guerillon, Wilfried Veron, Olivier Lesouhaitier, Marc G J Feuilloley, Nicole Orange. Involvement of a phospholipase C in the hemolytic activity of a clinical strain of Pseudomonas fluorescens. BMC Microbiology. 2008; 8 (1):189-189.

Chicago/Turabian Style

Gaelle Rossignol; Annabelle Merieau; Josette Guerillon; Wilfried Veron; Olivier Lesouhaitier; Marc G J Feuilloley; Nicole Orange. 2008. "Involvement of a phospholipase C in the hemolytic activity of a clinical strain of Pseudomonas fluorescens." BMC Microbiology 8, no. 1: 189-189.

Journal article
Published: 01 January 2006 in BMC Bioinformatics
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Pseudomonas aeruginosa, an opportunistic pathogen, is often encountered in chronic lung diseases such as cystic fibrosis or chronic obstructive pneumonia, as well as acute settings like mechanical ventilation acquired pneumonia or neutropenic patients. It is a major cause of mortality and morbidity in these diseases. In lungs, P. aeruginosa settles in a biofilm mode of growth with the secretion of exopolysaccharides in which it is encapsulated, enhancing its antibiotic resistance and contributing to the respiratory deficiency of patients. However, bacteria must first multiply to a high density and display a cytotoxic phenotype to avoid the host's defences. A virulence determinant implicated in this step of infection is the type III secretion system (TTSS), allowing toxin injection directly into host cells. At the beginning of the infection, most strains isolated from patients' lungs possess an inducible TTSS allowing toxins injection or secretion upon in vivo or in vitro activation signals. As the infection persists most of the bacteria permanently loose this capacity, although no mutations have been evidenced. We name "non inducible" this phenotype. As suggested by the presence of a positive feedback circuit in the regulatory network controlling TTSS expression, it may be due to an epigenetic switch allowing heritable phenotypic modifications without genotype's mutations. Using the generalised logical method, we designed a minimal model of the TTSS regulatory network that could support the epigenetic hypothesis, and studied its dynamics which helped to define a discriminating experimental scenario sufficient to validate the epigenetic hypothesis. A mathematical framework based on formal methods from computer science allowed a rigorous validation and certification of parameters of this model leading to epigenetic behaviour. Then, we demonstrated that a non inducible strain of P. aeruginosa can stably acquire the capacity to be induced by calcium depletion for the TTSS after a short pulse of a regulatory protein. Finally, the increased cytotoxicity of a strain after this epigenetic switch was demonstrated in vivo in an acute pulmonary infection model. These results may offer new perspectives for therapeutic strategies to prevent lethal infections by P. aeruginosa by reverting the epigenetic inducibility of type III cytotoxicity.

ACS Style

Didier Filopon; Annabelle Mérieau; Gilles Bernot; Jean-Paul Comet; Rozenne Leberre; Benoit Guery; Benoit Polack; Janine Guespin-Michel. Epigenetic acquisition of inducibility of type III cytotoxicity in P. aeruginosa. BMC Bioinformatics 2006, 7, 272 -272.

AMA Style

Didier Filopon, Annabelle Mérieau, Gilles Bernot, Jean-Paul Comet, Rozenne Leberre, Benoit Guery, Benoit Polack, Janine Guespin-Michel. Epigenetic acquisition of inducibility of type III cytotoxicity in P. aeruginosa. BMC Bioinformatics. 2006; 7 (1):272-272.

Chicago/Turabian Style

Didier Filopon; Annabelle Mérieau; Gilles Bernot; Jean-Paul Comet; Rozenne Leberre; Benoit Guery; Benoit Polack; Janine Guespin-Michel. 2006. "Epigenetic acquisition of inducibility of type III cytotoxicity in P. aeruginosa." BMC Bioinformatics 7, no. 1: 272-272.

Comparative study
Published: 31 December 2004 in Systematic and Applied Microbiology
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The major surface protein of the genus Pseudomonas, OprF, is a non-specific porin that plays an important role in maintenance of cell shape, in growth in a low osmolarity environment, and in adhesion to various supports. The objectives of our study were (i) to carry out a comparative analysis of phylogenies obtained from the OprF protein and from the 16S rRNA gene in 41 isolates from various sources (water, soil, milk and the hospital) and (ii) to investigate the physiological characteristics correlated with the phylogeny of OprF. We report here an important incongruence between the phylogenies of the 16S rRNA gene and the OprF protein. Phylogenetic analysis of 16S rRNA genes grouped Pseudomonas fluorescens isolates into one cluster (termed fluorescens r-cluster) whilst the phylogeny of the OprF protein divided Pseudomonas fluorescens isolates into two quite distinct clusters (termed fluorescens 1 o-cluster and fluorescens 2 o-cluster) that may be related to the original habitat of the strain. The fluorescens 1 o-cluster contained the majority of non-rhizospheric soil isolates, while the fluorescens 2 o-cluster contained all our clinical isolates and most of the rhizospheric isolates (which are fixed to the roots). In order to check this correlation, we studied two physiological characteristics: the range of growth temperature and the capacity for non-specific adhesion to polystyrene. The temperature range study for strains did not explain the existence of the two o-clusters but it did confirm the capacity of certain P. fluorescens strains to grow at 37 degrees C. The adhesion capacities of the isolates in the two o-clusters seems to be correlated with ecological niche.

ACS Style

Josselin Bodilis; Raphaël Calbrix; Josette Guerillon; Annabelle Merieau; Barbara Pawlak; Nicole Orange; Sylvie Barray. Phylogenetic Relationships Between Environmental and Clinical Isolates of Pseudomonas fluorescens and Related Species Deduced from 16S rRNA Gene and OprF Protein Sequences. Systematic and Applied Microbiology 2004, 27, 93 -108.

AMA Style

Josselin Bodilis, Raphaël Calbrix, Josette Guerillon, Annabelle Merieau, Barbara Pawlak, Nicole Orange, Sylvie Barray. Phylogenetic Relationships Between Environmental and Clinical Isolates of Pseudomonas fluorescens and Related Species Deduced from 16S rRNA Gene and OprF Protein Sequences. Systematic and Applied Microbiology. 2004; 27 (1):93-108.

Chicago/Turabian Style

Josselin Bodilis; Raphaël Calbrix; Josette Guerillon; Annabelle Merieau; Barbara Pawlak; Nicole Orange; Sylvie Barray. 2004. "Phylogenetic Relationships Between Environmental and Clinical Isolates of Pseudomonas fluorescens and Related Species Deduced from 16S rRNA Gene and OprF Protein Sequences." Systematic and Applied Microbiology 27, no. 1: 93-108.

Journal article
Published: 29 February 2004 in Research in Microbiology
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We had previously shown that the psychrotrophic bacterium Pseudomonas fluorescens can act as a pathogen, inducing apoptosis and necrosis in neurons and glial cells. In the present study, we investigated the influence of the growth temperature of P. fluorescens on its infectious potential. Adherence of P. fluorescens to glial cells was found to be maximal with bacteria grown at a low temperature (8 degrees C). At that temperature the swimming behaviour was markedly reduced. An increase in the growth temperature to 19, 28 or 32 degrees C strongly diminished the binding of bacteria to host cells. Thus, the adhesion phenotype of P. fluorescens appears to be independent of the motility of the bacteria. The apoptotic effect of P. fluorescens, determined by morphological (nuclear condensation) and biochemical (induction of nitric oxide synthase activity) indicators, correlated well with its binding activity on glial cells. In contrast, there was a clear dissociation between maximum binding and maximal necrotic action (measured by the release of lactate dehydrogenase) observed with bacteria grown at 19 degrees C. As suggested by capillary electrophoresis analysis, the differences in apoptotic effects may be related to variations in the molecular structure of LPS originating from bacteria grown at low and high temperatures, whereas the necrotic effect, which was maximal at the optimum temperature for the secretion of exoenzymes, could reflect variations in the metabolic activity of bacteria.

ACS Style

Laurent Picot; Sana Mezghani-Abdelmoula; Sylvie Chevalier; Annabelle Merieau; Olivier Lesouhaitier; Josette Guerillon; Lionel Cazin; Nicole Orange; Marc G.J. Feuilloley. Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature. Research in Microbiology 2004, 155, 39 -46.

AMA Style

Laurent Picot, Sana Mezghani-Abdelmoula, Sylvie Chevalier, Annabelle Merieau, Olivier Lesouhaitier, Josette Guerillon, Lionel Cazin, Nicole Orange, Marc G.J. Feuilloley. Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature. Research in Microbiology. 2004; 155 (1):39-46.

Chicago/Turabian Style

Laurent Picot; Sana Mezghani-Abdelmoula; Sylvie Chevalier; Annabelle Merieau; Olivier Lesouhaitier; Josette Guerillon; Lionel Cazin; Nicole Orange; Marc G.J. Feuilloley. 2004. "Regulation of the cytotoxic effects of Pseudomonas fluorescens by growth temperature." Research in Microbiology 155, no. 1: 39-46.

Journal article
Published: 22 July 2003 in Microbial Pathogenesis
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Pseudomonas fluorescens is an emerging pathogen closely related to Pseudomonas aeruginosa. In the present study, the effect of the lipopolysaccharide (LPS) from P. fluorescens MF37 was investigated using indicators of apoptosis and necrosis and was compared to the effect of the LPS from P. aeruginosa PAO1. Capillary electrophoresis analysis of the LPS from P. fluorescens MF37 revealed the existence of three forms of the endotoxin and the absence of homology with the LPS from P. aeruginosa. In neurons and glial cells the LPS from P. fluorescens induced major morphological changes including a condensation of the cytoplasmic proteins, a leakage of the cytoplasmic content, the formation of blebs on the nuclear membrane and a marked reorganization of the cytoskeleton. In glial cells, the LPS from P. fluorescens provoked the migration of phosphatidylserine at the surface of the cytoplasmic membrane, a sign of apoptosis, but this reaction was associated to an increase in the permeability to propidium iodide characteristic of necrosis. Biochemical studies revealed an important activation of an inducible nitric oxide synthase and a release of lactate dehydrogenase, a stable cytosolic enzyme. These results demonstrate that the LPS from P. fluorescens induces apoptosis and a concomitant and limited necrosis, reveal the unexpected cytotoxicity of this endotoxin and provide the first demonstration of the apoptotic effect of a non-aeruginosa Pseudomonas on nerve cells.

ACS Style

Laurent Picot; Sylvie Chevalier; Sana Mezghani-Abdelmoula; Annabelle Merieau; Olivier Lesouhaitier; Philippe Leroux; Lionel Cazin; Nicole Orange; Marc G J Feuilloley. Cytotoxic effects of the lipopolysaccharide from Pseudomonas fluorescens on neurons and glial cells. Microbial Pathogenesis 2003, 35, 95 -106.

AMA Style

Laurent Picot, Sylvie Chevalier, Sana Mezghani-Abdelmoula, Annabelle Merieau, Olivier Lesouhaitier, Philippe Leroux, Lionel Cazin, Nicole Orange, Marc G J Feuilloley. Cytotoxic effects of the lipopolysaccharide from Pseudomonas fluorescens on neurons and glial cells. Microbial Pathogenesis. 2003; 35 (3):95-106.

Chicago/Turabian Style

Laurent Picot; Sylvie Chevalier; Sana Mezghani-Abdelmoula; Annabelle Merieau; Olivier Lesouhaitier; Philippe Leroux; Lionel Cazin; Nicole Orange; Marc G J Feuilloley. 2003. "Cytotoxic effects of the lipopolysaccharide from Pseudomonas fluorescens on neurons and glial cells." Microbial Pathogenesis 35, no. 3: 95-106.