References of "Deleu, Magali"
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See detailFengycin penetration into a DPPC monlayer: a study using the Langmuir trough technique with the Brewster angle microscopy
Deleu, Magali ULg

in International symposium on surface and colloid chemistry for the life sciences (2003)

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See detailInteraction Of Surfactin With Membranes: A Computational Approach
Deleu, Magali ULg; Bouffioux, O.; Razafindralambo, Hary ULg et al

in Langmuir (2003), 19(8),

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See detailThe Macrolide Antibiotic Azithromycin Interacts With Lipids And Affects Membrane Organization And Fluidity: Studies On Langmuir-Blodgett Monolayers, Liposomes And J774 Macrophages
Tyteca, D.; Schanck, A.; Dufrene, Yf. et al

in Journal of Membrane Biology (2003), 192(3), 203-215

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See detailInsecticide activity of surfactins and iturins from a biopesticide Bacillus subtilis Cohn (S499 strain)
Assié, Lazar; Deleu, Magali ULg; Arnaud, Ludovic et al

in Mededelingen van de Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen (Rijksuniversiteit te Gent) (2002), 67(3), 647-655

Surfactin C14, surfactin C15, and iturin C15 are lipopeptides purified from Bacillus subtilis (S499 strain). They were incorporated into the artificial diet of the fruit fly Drosophila melanogaster to ... [more ▼]

Surfactin C14, surfactin C15, and iturin C15 are lipopeptides purified from Bacillus subtilis (S499 strain). They were incorporated into the artificial diet of the fruit fly Drosophila melanogaster to assess their potential insecticidal activities. Surfactins with long fatty acid chains (C14 and C15) had an insecticidal effect on the fruit fly, D. melanogaster. On the contrary, iturin was not toxic to D. melanogaster. At 100 ppm, surfactin C14 and C15 caused 85.4 and 92.6% adult mortality, respectively, after a one-day exposure. F1 progeny fly emergence inhibition by C14 and C15 were 79.8 and 91.3%, respectively. To check whether the biocide activity of lipopeptides was due to their surface-active properties, detergent Triton X100, SDS, CTAB, and Tween 80 were tested. No adult mortality was recorded with the detergents but Triton X100 and SDS showed F1 progeny emergence inhibition similar to that of surfactins. We showed that there was a dose-response activity with surfactin C15 [less ▲]

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See detailSurface tension measurements on micellar systems.
Deleu, Magali ULg; Paquot, Michel ULg; Blecker, Christophe ULg

in Encyclopedia of Surface and Colloid Science. (2002)

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See detailDifferent techniques to study the conformation of surfactins at interfaces
Deleu, Magali ULg; Gallet, Xavier; Brasseur, Robert et al

Poster (2001)

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See detailImaging Mixed Lipid Monolayers By Dynamic Atomic Force Microscopy
Deleu, Magali ULg; Nott, Katherine ULg; Brasseur, Robert ULg et al

in Biochimica et Biophysica Acta-Biomembranes (2001), 1513(1),

Phase imaging with tapping mode atomic force microscopy (AFM) and force modulation microscopy were used to probe the mechanical properties of phase-separated lipid monolayers made of a mixture (0.25:0.75 ... [more ▼]

Phase imaging with tapping mode atomic force microscopy (AFM) and force modulation microscopy were used to probe the mechanical properties of phase-separated lipid monolayers made of a mixture (0.25:0.75) of the surface-active lipopeptide surfactin and of dipalmitoylphosphatidylcholine (DPPC). The π–A isotherms and the result of a molecular modeling study revealed a loose, 2-D liquid-like organization for the surfactin molecules and a closely packed, 2-D solid-like organization for DPPC molecules. This difference in molecular organization was responsible for a significant contrast in height, tapping mode phase and force modulation amplitude images. Phase imaging at light tapping, i.e., with a ratio of the set-point tapping amplitude with respect to the free amplitude Asp/A0≈0.9, showed larger phase shifts on the solid-like DPPC domains attributed to larger Young’s modulus. However, contrast inversion was observed for Asp/A0<0.7, suggesting that at moderate and hard tapping the image contrast was dominated by the probe–sample contact area. Surprisingly, force modulation amplitude images showed larger stiffness for the liquid-like surfactin domains, suggesting that the contrast was dominated by contact area effects rather than by Young’s modulus. These data emphasize the complex nature of the contrast mechanisms of dynamic AFM images recorded on mixed lipid monolayers. [less ▲]

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See detailSurfactin and iturin A effects on Bacillus subtilis surface hydrophobicity.
Ahimou, F.; Jacques, P.; Deleu, Magali ULg

in Enzyme & Microbial Technology (2000), 27(10), 749-754

The synthesis of extracellular molecules such as biosurfactants should have major consequences on bacterial adhesion. These molecules may be adsorbed on surfaces and modify their hydrophobicities. Certain ... [more ▼]

The synthesis of extracellular molecules such as biosurfactants should have major consequences on bacterial adhesion. These molecules may be adsorbed on surfaces and modify their hydrophobicities. Certain strains of Bacillus subtilis synthesize the lipopeptides, which exhibit antibiotic and surface active properties. In this study the high-performance liquid chromatography (HPLC) analysis of the culture supernatants of the seven B. subtilis strains, showed that the lipopeptide profile varied greatly according to the strain. Among the three lipopeptide types, only iturin A was produced by all B. subtilis strains. Bacterial hydrophobicity, evaluated by the water contact angle measurements and the hydrophobic interaction chromatography, varied according to the strain. Two strains (ATCC 15476 and ATCC 15811) showing extreme behaviors in term of hydrophobicity were selected to study surfactin and iturin A effects on bacterial hydrophobicity. The two lipopeptides modified the B. subtilis surface hydrophobicity. Their effects varied according to the bacterial surface hydrophobic character, the lipopeptide type and the concentration. Lipopeptide adsorption increased the hydrophobicity of the hydrophilic strain but decreased that of the hydrophobic. Comparison of lipopeptide effects on B. subtilis surface hydrophobicity showed that surfactin was more effective than iturin A for the two strains tested. [less ▲]

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See detailConformational analysis of surfactins at interfaces
Deleu, Magali ULg; Gallet, Xavier; Dufrêne, Yves et al

Poster (2000)

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See detailSurfactin and iturin A effects on Bacillus subtilis surface hydrophobicity
Ahimou, F.; Deleu, Magali ULg; Jacques, Ph. et al

Poster (1999, July)

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See detailThe structure of two fengycins from Bacillus subtilis S499.
Schneider, J.; Taraz, K.; Budzikiewicz, H. et al

in Zeitschrift für Naturforschung. C, Journal of Biosciences (1999), 54(11), 859-66

The structures of the two fengycins, lipopeptides from Bacillus subtilis, were elucidated by spectroscopic methods and chemical degradation. They show a close structural relationship to the plipastatins ... [more ▼]

The structures of the two fengycins, lipopeptides from Bacillus subtilis, were elucidated by spectroscopic methods and chemical degradation. They show a close structural relationship to the plipastatins from Bacillus cereus differing only in the stereochemistry of the Tyr residues. [less ▲]

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See detailSurfactin and iturinA effect on Bacillus subtilis surface hydrophobicity
Deleu, Magali ULg

in European Congress on Biotechnology (1999)

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See detailNanometer scale organization of mixed surfactin/phosphatidylcholine monolayers
Deleu, Magali ULg; Paquot, Michel ULg; Jacques, P. et al

in Biophysical Journal (1999), 77(4), 2304-2310

Mixed monolayers of the surface-active lipopeptide surfactin-C-15 and of dipalmitoyl phosphatidylcholine (DPPC) were deposited on mica and their nanometer scale organization was investigated using atomic ... [more ▼]

Mixed monolayers of the surface-active lipopeptide surfactin-C-15 and of dipalmitoyl phosphatidylcholine (DPPC) were deposited on mica and their nanometer scale organization was investigated using atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). AFM topographic images revealed phase separation for mixed monolayers prepared at 0.1, 0.25, and 0.5 surfactin molar ratios. This was in agreement with the monolayer properties at the air-water interface indicating a tendency of the two compounds to form bidimensional domains in the mixed systems. The step height measured between the surfactin and the DPPC domains was 1.2 +/- 0.1 nm, pointing to a difference in molecular orientation: while DPPC had a vertical orientation, the large peptide ring of surfactin was lying on the mica surface. The N/C atom concentration ratios obtained by XPS for pure monolayers were compatible with two distinct geometric models: a random layer for surfactin and for DPPC, a layer of vertically-oriented molecules in which the polar headgroups are in contact with mica. XPS data for mixed systems were accounted for by a combination of the two pure monolayers, considering respective surface coverages that were in excellent agreement with those measured by AFM. These results illustrate the complementarity of AFM and XPS to directly probe the molecular organization of multicomponent monolayers. [less ▲]

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See detailComputer Simulation Of Surfactin Conformation At A Hydrophobic/Hydrophilic Interface
Gallet, X.; Deleu, Magali ULg; Razafindralambo, Hary ULg et al

in Langmuir (1999), 15(7), 2409-13

Using a molecular modeling method, different conformations of surfactin at a hydrophobic/hydrophilic interface are established. Two conformations of the peptide ring (S1 and S2) provided by NMR ... [more ▼]

Using a molecular modeling method, different conformations of surfactin at a hydrophobic/hydrophilic interface are established. Two conformations of the peptide ring (S1 and S2) provided by NMR experiments built with three different aliphatic chains in folded or extended configurations were studied. For the structures including the S2 peptide ring conformation, the theoretical interfacial molecular area corresponds to the experimental limiting area A0 value obtained with a Langmuir film balance. The peptide ring is positioned in the plane of the interface with the two acidic chains close to each other and protruding in the aqueous phase, and the β-hydroxy fatty acid chain, folded to interact mainly with the Leu2 side chain and also with the Val4 side chain. This design has the largest calculated molecular area and would correspond to the most stable amphipathic structure representing the surfactin experimental behavior in weak compression. [less ▲]

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