References of "Ongena, MARC"
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See detailImportance of surfactin for plant resistance induction by Bacillus isolates
Cawoy, Hélène ULg; Mariutto, Martin; Jourdan, Emmanuel et al

Conference (2012, June 27)

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See detailCalcium-induced conformational changes of the elicitor and membrane-active fengycin
Nasir, Mehmet Nail ULg; Lins, Laurence ULg; Ongena, Marc ULg et al

Poster (2012, April)

Fengycin is a natural lipopeptide synthetized by Bacillus subtilis strains. It is characterized by strong antifungal and low hemolytic activities. It seems also play a role in the promoting of elicitor ... [more ▼]

Fengycin is a natural lipopeptide synthetized by Bacillus subtilis strains. It is characterized by strong antifungal and low hemolytic activities. It seems also play a role in the promoting of elicitor activities of other compounds. The target of the biological activities of fengycin is supposed to be plasma membrane of sensitive cells. Even though the natural fengycin from has been discovered 25 years ago, nowadays, there is an increase of interest for this compound because of its potent applications. Until 15 years ago, the primary structure of fengycin was a matter of open debate before the publication of the corrected structure obtained by nuclear magnetic resonance and mass spectroscopy techniques. Although the infrared and ultraviolet absorption spectra of the lipopeptide were measured, no detailed analysis of these data was performed probably because of the unconventional sequence of the lipopeptide making these kinds of analyses complicated. In this work, our attempt was to analyze the conformational properties of fengycin as well as the calcium-induced changes using two complementary spectroscopic methods, Fourrier transformed infrared spectroscopy (FTIR) and circular dichroism (CD). In a first step, we have characterized the conformational properties of pure fengycin. The lipopeptide adopts turn conformation in trifluoroethanol, a membrane-mimicking solvent. D-aminoacids seem to be involved in intra molecular hydrogen bonds. In a second step, we have investigated the role played by Ca2+ ions on the possible conformational changes of fengycin. The addition of calcium gives rise to important modifications of the conformation. As fengycin has two glutamate residues, calcium is supposed to bind to their side chains. In conclusion, we have demonstrated that the conformation of fengycin is closely depending of the environment and the presence of calcium ions play an important role on the conformational changes of the lipopeptide. Moreover, spectra obtained both FTIR and CD methods ascertain the presence of turn conformation. [less ▲]

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See detailHow does elicitor and antimicrobial fengycin interact with plasma membranes of sensitive cells ?
Nasir, Mehmet Nail ULg; Eeman, Marc; Lins, Laurence ULg et al

Conference (2012, April)

Fengycin is characterized by its strong antifungal and low hemolytic activities. It has also been recently demonstrated that it has plant elicitor properties and is also able to enhance the elicitors’ ... [more ▼]

Fengycin is characterized by its strong antifungal and low hemolytic activities. It has also been recently demonstrated that it has plant elicitor properties and is also able to enhance the elicitors’ activity of surfactin. The cell target of its biological activities is supposed to be plasma membrane. In spite of these interesting biological activities, fengycin has not been extensively investigated probably because of the difficulties related to its production. In a first time; we have characterized the interfacial properties of fengycin by tensiometry measurements and demonstrated that this surface activity was pH-dependent. In a second time; we have investigated the interactions of the lipopeptide with membrane lipids using model membranes such as Langmuir monolayers and multilammelar vesicles (MLVs). Our results indicate that the lipopeptide was able to penetrate into different lipid monolayers showing a preference for sterol-containing monolayers. In order to better understand the mechanism of the interactions of fengycin with membranes at the molecular level, MLVs with or without fengycin have been analyzed by spectroscopic techniques. We have shown that conformational changes of the lipopeptide occurred in the presence of lipids and they were more significant in the presence of sterol. Moreover, tyrosine residues of the lipopeptide seem to play an important role in these interactions. In conclusion, we have determined that the surface-active behavior as well as the conformation of fengycin depends on its environment. We have also showed that the lipopeptide does not interact with all class of lipids in the same way and presents a preference for sterols. The presence of key groups within peptide cycle has also been supposed for the biological activities of the lipopeptide. [less ▲]

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See detailDesign of a biofilm reactor comprising a metal structured packing for the production of lipopeptides by B. subtilis
Zune, Quentin ULg; Ongena, Marc ULg; Toye, Dominique ULg et al

Poster (2012, February 08)

Abstract : The design of a new single species biofilm bioreactor has been investigated. Bacillus subtilis S499 has been chosen as a model organism for the production of lipopetides. Nevertheless ... [more ▼]

Abstract : The design of a new single species biofilm bioreactor has been investigated. Bacillus subtilis S499 has been chosen as a model organism for the production of lipopetides. Nevertheless, considering the surface active properties for this kind of metabolite, processes based on submerged culture in stirred-tank bioreactor involve the use of important amount of antifoam and therefore downstream processes are tedious. In this work, an original process was developed with an experimental setting leading to the suppression of foam formation during the culture. B. subtilis S499 makes a biofilm on a stainless steel structured packing in the top of a bioreactor, nutrient and oxygen supply being carried out by the media recirculation as liquid film on the packing. Lipopeptides secreted by biofilm are accumulated in the liquid phase under the packing and can reach concentrations as high as 800 mg/l. The colonization of the packing by the biofilm has been monitored by X-ray tomography. [less ▲]

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See detailUnsuspected Control of Siderophore production by N-acetylglucosamine in Streptomycetes
Craig, Matthias ULg; Lambert, Stéphany ULg; Jourdan, Samuel ULg et al

in Environmental Microbiology Reports (2012)

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See detailNewly discovered natural functions for cyclic lipopeptides from rhizobacteria
Ongena, Marc ULg; Henry, G.; Deleu, Magali ULg et al

Conference (2012)

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See detailBacillus subtilis: biocontrol and growth promotion
Ongena, Marc ULg

Conference (2012)

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See detailEffect of environmental factors on the interaction plant-pathogen-Bacillus amyloliquefaciens S499
Pertot, I.; Hosni, T.; Pedrotti, L. et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2012), sous presse

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See detailModulation of the lipopeptide pattern secreted by Bacillus subtilis upon colonization of different plant roots
Ongena, Marc ULg; Cawoy, Hélène ULg; Smargiassi, Maïté et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2012), 78

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See detailCyclic lipopeptide profile of the plant-beneficial endophytic bacterium Bacillus subtilis HC8
Malfanova, N.; Franzil, Laurent ULg; Lugtenberg, B. et al

in Archives of Microbiology (2012)

In a previous study (Malfanova et al. in Microbial Biotech 4:523-532, 2011), we described the isolation and partial characterization of the biocontrol endophytic bacterium B. subtilis HC8. Using thin ... [more ▼]

In a previous study (Malfanova et al. in Microbial Biotech 4:523-532, 2011), we described the isolation and partial characterization of the biocontrol endophytic bacterium B. subtilis HC8. Using thin-layer chromatography, we have detected several bioactive antifungal compounds in the methanolic extract from the acid-precipitated supernatant of HC8. In the present study, we have further analyzed this methanolic extract using liquid chromatography-mass spectrometry. Based on the comparison of retention times and molecular masses with those of known antifungal compounds, we identified three families of lipopeptide antibiotics. These include four iturins A having fatty acyl chain lengths of C14 to C17, eight fengycins A (from C14 to C18 and from C15 to C17 containing a double bond in the acyl chain), four fengycins B (C15 to C18), and five surfactins (C12 to C16). Evaluation of the antifungal activity of the isolated lipopeptides showed that fengycins are the most active ones. To our knowledge, this is the first report of an endophytic Bacillus subtilis producing all three major families of lipopeptide antibiotics containing a very heterogeneous mixture of homologues. The questions remain open which of these lipopeptides (1) are being produced during interaction with the plant and (2) are contributing to the biocontrol activity of HC8. © 2012 The Author(s). [less ▲]

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See detailPAMPs, MAMPs, DAMPs and others: An update on the diversity of plant immunity elicitors [PAMPs, MAMPs, DAMPs et autres: Mise à jour de la diversité des éliciteurs de l'immunité des plantes]
Henry, Guillaume; Thonart, Philippe ULg; Ongena, Marc ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(2), 257-268

Plants possess a broad array of defenses that could be actively expressed in response of pathogenic organisms or parasites but also following beneficial saprophytic microorganisms recognition ... [more ▼]

Plants possess a broad array of defenses that could be actively expressed in response of pathogenic organisms or parasites but also following beneficial saprophytic microorganisms recognition. Specifically, there are compounds derived from these organisms and called elicitors that are perceived by the plant to induce a locally or systemically expressed resistance. The understanding of the physiological and biological basis of these induced immunity mechanisms have greatly advanced over the past years but a deeper investigation of the mechanisms underlying the perception of elicitors is essential to develop novel strategies for pest control. The application of chemical and biological stimulators of plant immune defenses in conventional agriculture is expected to increase within the next years. Because of their organic origin and as they provide means for conferring plant protection in a non-transgenic manner, elicitors of plant immunity have a huge potential as biocontrol products. Through this review, we want to illustrate the diversity of compounds identified as stimulators of the plant immune system and describe the mechanisms by which they could be recognized at the plasma membrane level. [less ▲]

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See detailInteraction network of antimicrobial peptides of Arabidopsis thaliana, based on hith-throughput yeast two-hybrid screening
Damon, Coralie ULg; Dmitrieva, Joelia Borisnova; Muhovski, Yordan et al

in Plant Physiology & Biochemistry (2012)

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See detailImpact of rhizosphere factors on cyclic lipopeptide signature from the plant beneficial strain Bacillus amyloliquefaciens S499
Nihorimbere, Venant; Cawoy, Hélène ULg; Seyer, Alexandre et al

in FEMS Microbiology Ecology (2012), 79

Detailed reference viewed: 28 (4 ULg)