Alain Dufour

Laboratoire de Biotechnologie et Chimie Marines

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Alexis Bazire

Institut Universitaire Européen de la Mer

Sylvie Chevalier

Université de Rouen Normandie

Olivier Lesouhaitier

Normandie Université

Marc Feuilloley

Université de Rouen Normandie

Emeline Bouffartigues

Université de Rouen Normandie

Sophie Rodrigues

Institut Universitaire Européen de la Mer

Nicole Orange

Université de Rouen Normandie

Laure Taupin

Laboratoire de Biotechnologie et Chimie Marines

Pierre Cornélis

Université de Rouen Normandie

Olivier Maillot

Université de Rouen Normandie

Cooperative Institutions

Centre National de la Recherche Scientifique

116

Université de Rouen Normandie

Normandie Université

Université de Bretagne Sud

Laboratoire de Biotechnologie et Chimie Marines

Institut Universitaire Européen de la Mer

Inserm

Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail

Université de Bretagne Occidentale

Ifremer

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Traceable Polyacrylic Acid - An Improved Standard in Water Treatment Formulations

CORROSION (1999)

Kathryn M. Yocom Thomas W. Sanders William M. Hann Anne Blaes Alain Dufour

Polyacrylic acid

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Osmotic stress and phosphate limitation alter production of cell-to-cell signal molecules and rhamnolipid biosurfactant by Pseudomonas aeruginosa

FEMS Microbiology Letters (2005)

Alexis Bazire Alexandra Dheilly Farès Diab Danièle Morin Mohamed Jebbar

In Pseudomonas aeruginosa, rhamnolipid production is controlled by the quorum-sensing system RhlRI, which itself depends on LasRI. These systems use cell-to-cell signal molecules: N-butyryl-l-homoserine lactone (C4-HSL) and N-(3-oxododecanoyl)-l-homoserine lactone (3OC(12)-HSL), respectively. Whereas both HSLs were produced in M63 medium, rhamnolipid synthesis was not achieved. Phosphate limitation reduced the HSL concentrations, while allowing rhamnolipid production. Hyperosmotic shock applied during the exponential growth phase stopped the accumulation of 3OC(12)-HSL, and prevented C4-HSL and rhamnolipid production. These defects result from lower expression of genes involved in C4-HSL and rhamnolipid syntheses. The osmoprotectant glycine betaine partially restored C4-HSL and rhamnolipid production.

Rhamnolipid

Homoserine

Osmotic shock

Betaine

Pseudomonadales

10.1016/j.femsle.2005.09.029

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Citations (55)

Antibiofilm activity in the culture supernatant of a marine Pseudomonas sp. bacterium

Microbiology (2020)

Ibtissem Doghri Florence Brian-Jaisson Marianne Graber Alexis Bazire Alain Dufour

In the marine environment, most solid surfaces are covered by microbial biofilms, mainly composed of bacteria and diatoms. The negative effects of biofilms on materials and equipment are numerous and pose a major problem for industry and human activities. Since marine micro-organisms are an important source of bioactive metabolites, it is possible that they synthesize natural ecofriendly molecules that inhibit the adhesion of organisms. In this work, the antibiofilm potential of marine bacteria was investigated using Flavobacterium sp. II2003 as a target. This strain is potentially a pioneer strain of bacteria that was previously selected from marine biofilms for its strong biofilm-forming ability. The culture supernatants of 86 marine heterotrophic bacteria were tested for their ability to inhibit Flavobacterium sp. II2003 biofilm formation and the Pseudomonas sp. IV2006 strain was identified as producing a strong antibiofilm activity. The Pseudomonas sp. IV2006 culture supernatant (SN IV2006 ) inhibited Flavobacterium sp. II2003 adhesion without killing the bacteria or inhibiting its growth. Moreover, SN IV2006 had no effect on the Flavobacterium sp. II2003 cell surface hydrophilic/hydrophobic and general Lewis acid–base characteristics, but modified the surface properties of glass, making it on the whole more hydrophilic and more alkaline and significantly reducing bacterial cell adhesion. The glass-coating molecules produced by Pseudomonas sp. IV2006 were found to probably be polysaccharides, whereas the antibiofilm molecules contained in SN IV2006 and acting during the 2 h adhesion step on glass and polystyrene surfaces would be proteinaceous. Finally, SN IV2006 exhibited a broad spectrum of antibiofilm activity on other marine bacteria such as Flavobacterium species that are pathogenic for fish, and human pathogens in both the medical environment, such as Staphylococcus aureus and Pseudomonas aeruginosa , and in the food industry, such as Yersinia enterocolitica . Thus, a wide range of applications could be envisaged for the SN IV2006 compounds, both in aquaculture and human health.

Marine bacteriophage

Microbiological culture

10.1099/mic.0.000878

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Citations (7)

Role of Adenosine Nucleotides in the Regulation of a Stress-response Transcription Factor inBacillus subtilis

Journal of Molecular Biology (1996)

Scott Alper Alain Dufour Danielle A. Garsin Leonard Duncan Richard Losick

Transcription

10.1006/jmbi.1996.0390

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Citations (131)

Full Virulence of Pseudomonas aeruginosa Requires OprF

Infection and Immunity (2010)

Laurène Fito-Boncompte Annelise Chapalain Emeline Bouffartigues Hichem Chaker Olivier Lesouhaitier

ABSTRACT OprF is a general outer membrane porin of Pseudomonas aeruginosa , a well-known human opportunistic pathogen associated with severe hospital-acquired sepsis and chronic lung infections of cystic fibrosis patients. A multiphenotypic approach, based on the comparative study of a wild-type strain of P. aeruginosa , its isogenic oprF mutant, and an oprF -complemented strain, showed that OprF is required for P. aeruginosa virulence. The absence of OprF results in impaired adhesion to animal cells, secretion of ExoT and ExoS toxins through the type III secretion system (T3SS), and production of the quorum-sensing-dependent virulence factors pyocyanin, elastase, lectin PA-1L, and exotoxin A. Accordingly, in the oprF mutant, production of the signal molecules N -(3-oxododecanoyl)- l -homoserine lactone and N -butanoyl- l -homoserine lactone was found to be reduced and delayed, respectively. Pseudomonas quinolone signal (PQS) production was decreased, while its precursor, 4-hydroxy-2-heptylquinoline (HHQ), accumulated in the cells. Taken together, these results show the involvement of OprF in P. aeruginosa virulence, at least partly through modulation of the quorum-sensing network. This is the first study showing a link between OprF, PQS synthesis, T3SS, and virulence factor production, providing novel insights into virulence expression.

Pyocyanin

Porin

Virulence factor

Pseudomonadales

10.1128/iai.00850-10

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Citations (153)

Separate mechanisms activate sigma B of Bacillus subtilis in response to environmental and metabolic stresses

Journal of Bacteriology (1995)

Uwe Voelker A Voelker Björn Maul Michael Hecker Alain Dufour

sigma B is a secondary sigma factor that controls the general stress response of Bacillus subtilis. sigma B-dependent transcription is induced by the activation of sigma B itself, a process that involves release of sigma B from an inhibitory complex with its primary regulator, RsbW. sigma B becomes available to RNA polymerase when RsbW forms a complex with an additional regulatory protein (RsbV) and, because of this, fails to bind sigma B. Using Western blot (immunoblot) analyses, reporter gene fusion assays, and measurements of nucleotide pool sizes, we provide evidence for two independent processes that promote the binding of RsbW to RsbV. The first occurs during carbon limitation or entry into stationary phase. Activation of sigma B under these circumstances correlates with a drop in the intracellular levels of ATP and may be a direct consequence of ATP levels on RsbW's binding preference. The second activation process relies on the product of a third regulatory gene, rsbU. RsbU is dispensable for sigma B activation during carbon limitation or stationary phase but is needed for activation of sigma B in response to any of a number of different environmental insults (ethanol treatment, salt or acid shock, etc.). RsbU, or a process dependent on it, alters RsbW binding without regard for intracellular levels of ATP. In at least some instances, the effects of multiple inducing stimuli are additive. The data are consistent with RsbW being a regulator at which distinct signals from separate effectors can be integrated to modulate sigma B activity.

Sigma factor

Sigma

10.1128/jb.177.13.3771-3780.1995

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Citations (207)

The absence of OprF increased biofilm formation through variation of the c- di-GMP level in Pseudomonas aeruginosa

HAL (Le Centre pour la Communication Scientifique Directe) (2017)

Emeline Bouffartigues Joana A. Moscoso Rachel Duchesne Thibaut Rosay Laurène Fito-Boncompte

Introduction Pseudomonas aeruginosa is well known to be a human opportunistic pathogen able to adapt to many environmental conditions. The first cellular structure in contact with the environment is the outer membrane. In Pseudomonas genus, OprF is the major outer membrane protein. It is an aspecific porin allowing the diffusion of several types of small polar molecules. OprF is also a pleiotropic protein involved in other numerous cellular functions, as adhesion on biotic or abiotic surfaces, cell wall resistance and virulence of P. aeruginosa. Through a multiphenotypic study, we show here that the lack of OprF increased biofilm formation through modulation of the c-di-GMP level.

Porin

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Bacteriocin Detection from Whole Bacteria by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

Applied and Environmental Microbiology (2003)

Thomas Hindré Sandrine Didelot J Pennec Dominique Haras Alain Dufour

ABSTRACT Class I bacteriocins (lantibiotics) and class II bacteriocins are antimicrobial peptides secreted by gram-positive bacteria. Using two lantibiotics, lacticin 481 and nisin, and the class II bacteriocin coagulin, we showed that bacteriocins can be detected without any purification from whole producer bacteria grown on plates by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS). When we compared the results of MALDI-TOF-MS performed with samples of whole cells and with samples of crude supernatants of liquid cultures, the former samples led to more efficient bacteriocin detection and required less handling. Nisin and lacticin 481 were both detected from a mixture of their producer strains, but such a mixture can yield additional signals. We used this method to determine the masses of two lacticin 481 variants, which confirmed at the peptide level the effect of mutations in the corresponding structural gene.

Lantibiotics

10.1128/aem.69.2.1051-1058.2003

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Citations (41)

The involvement of the ami operon in Pseudomonas aeruginosa virulence regulation and biofilm formation reveals new functions for the amidase AmiE

HAL (Le Centre pour la Communication Scientifique Directe) (2017)

Thomas Clamens Florie Desriac Thibaut Rosay Alexandre Crépin Alain Dufour

We have previously shown that the C-type Natriuretic Peptide (CNP), a peptide produced by the lung, prevents Pseudomonas aeruginosa biofilm formation. In the present study, we identified AmiC as the bacterial target explaining CNP effects, and we studied the involvement of the aliphatic amidase AmiE in these effects. Comparison of 3D structures of human natriuretic peptide receptors and Pseudomonas proteins revealed that the bacterial protein AmiC shows significant similarity with the human C-type natriuretic peptide receptor (hNPR-C). Recombinant protein AmiC was purified and protein/peptide interactions assessed using MicroScale Thermophoresis. Results showed that both CNP and hNPR-C agonists bind the AmiC protein. The amiC gene belongs to the ami operon. This operon also encodes the aliphatic amidase AmiE which hydrolyses short-chain aliphatic amides to their corresponding organic acids. We investigated AmiE potential alternative functions in P. aeruginosa. We observed that over expression of AmiE protein altered biofilm formation, bacterial motilities and quorum sensing molecules production. Using several infection models, we demonstrated that AmiE overproduction led to a strong decrease in P. aeruginosa virulence both in vitro and in vivo, suggesting that in addition to its carbon-nitrogen metabolic process activities, AmiE would have multiple other functions. We demonstrate that the bacterial protein AmiC is an ortholog of the eukaryotic receptor hNPR-C, acting as a CNP sensor in P. aeruginosa. Our data show that the whole ami operon has new functions in bacteria, allowing to modulate the switch between chronic and acute infection depending on exposition to host factors.

Amidase

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Virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata involves both quorum sensing and a type III secretion system

Environmental Microbiology (2021)

Amandine Morot Sahar El Fekih Adeline Bidault Alizée Le Ferrand Albane Jouault

Environmental Vibrio strains represent a major threat in aquaculture, but the understanding of their virulence mechanisms heavily relies on the transposition of knowledge from human-pathogen vibrios. Here, the genetic bases of the virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata were characterized. We demonstrated that luxO, encoding a major regulator of the quorum sensing system, is crucial for the virulence of this strain, and that its deletion leads to a decrease in swimming motility, biofilm formation, and exopolysaccharide production. Furthermore, the biofilm formation by V. harveyi ORM4 was increased by abalone serum, which required LuxO. The absence of LuxO in V. harveyi ORM4 yielded opposite phenotypes compared with other Vibrio species including V. campbellii (still frequently named V. harveyi). In addition, we report a full type III secretion system (T3SS) gene cluster in the V. harveyi ORM4 genome. LuxO was shown to negatively regulate the promoter activity of exsA, encoding the major regulator of the T3SS genes, and the deletion of exsA abolished the virulence of V. harveyi ORM4. These results unveil virulence mechanisms set up by this environmentally important bacterial pathogen and pave the way for a better molecular understanding of the regulation of its pathogenicity.

Vibrio harveyi

Haliotis

10.1111/1462-2920.15592

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Citations (22)