References of "Hbid, Choukri"
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See detailFoaming properties of lipopeptides produced by Bacillus subtilis: effect of lipid and peptide structural attributes
Razafindralambo, Hary ULg; Popineau, Yves; Deleu, Magali ULg et al

in Journal of Agricultural and Food Chemistry (1998), 46(3), 911-916

To study the effect of lipid and peptide structural attributes of Bacillus subtilis lipopeptides on their foaming properties, the formation, stability, and appearance of foams prepared with surfactins ... [more ▼]

To study the effect of lipid and peptide structural attributes of Bacillus subtilis lipopeptides on their foaming properties, the formation, stability, and appearance of foams prepared with surfactins (C13 C15) and iturins A (C14 C17) were characterized. The density and stability of lipopeptide foams depend on both the alkyl chain hydrophobic character and peptide molecular intrinsic properties. A lipidic chain length of 14 carbon atoms provides lipopeptides with the best foaming properties in terms of foam density and liquid stability in foams. Increases in alkyl chain length above 15 carbon atoms result in a drastic decrease of iturin A foam density. With the same alkyl chain, surfactin produces denser foam whereas iturin A exhibits better foaming stability. These results demonstrate the importance of the peptide structural attributes of B. subtilis on their foaming properties. [less ▲]

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See detailSurface-active properties of surfactin iturin A mixtures produced by Bacillus subtilis
Razafindralambo, Hary ULg; Popineau, Yves; Deleu, Magali ULg et al

in Langmuir (1997), 13(23), 6026-6031

Surface-active properties including dynamic adsorption, monolayer stability, micelle forming capacity, and foaming aptitudes of surfactin-C-15/iturin A-C-15 mixtures were studied. Surfactin-C-15 and ... [more ▼]

Surface-active properties including dynamic adsorption, monolayer stability, micelle forming capacity, and foaming aptitudes of surfactin-C-15/iturin A-C-15 mixtures were studied. Surfactin-C-15 and iturin A-C-15 molecules interact in synergism on the most surface-active properties evaluated at 20 degrees C at the air-water interface and in aqueous solution (pH 8.0). The synergism is positive on the adsorption effect, monolayer stability, foam density, and liquid stability in foam, whereas it is negative on the adsorption rate. No synergism occurs an micelle forming capacity, but surfactin-C-15 and iturin A-C-15 form mixed micelles when the solution contains a low proportion of surfactin-C-15.ses the synergistic effect is maximum when surfactin-C-15 and iturin A-C-15 molecules are mixed in a 2:3 ratio. This is attributed to the surfactin/iturin A complex formation resulting from specific interactions among two surfactin-C-15 molecules and three iturin A-C-15 molecules. A model of such a complex formation is proposed. [less ▲]

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See detailFoaming Properties Of Surfactin, A Lipopeptide Biosurfactant From Bacillus Subtilis
Razafindralambo, Hary ULg; Paquot, Michel ULg; Baniel, Alain et al

in Journal of the American Oil Chemists' Society (1996), 73(1), 149-151

Foaming properties of surfactin were investigated and compared to those of sodium dodecyl sulfate (SDS) and bovine serum albumin (BSA). Foams were formed by a bubbling technique. Evolution of the foam ... [more ▼]

Foaming properties of surfactin were investigated and compared to those of sodium dodecyl sulfate (SDS) and bovine serum albumin (BSA). Foams were formed by a bubbling technique. Evolution of the foam volume and the liquid in the foam was monitored with optical and conductimetric methods to characterize foam formation and stability. Excellent foaming properties of surfactin were shown by its higher ability to form and stabilize the foam at a concentration as low as 0.05 mg/mL, in comparison with SDS and BSA. Surfactin produced a foam with intermediate maximum density and stabilized the liquid in foam, as well as BSA. [less ▲]

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See detailInfluence of the production of two lipopeptides, Iturin A and Surfactin S1, on oxygen transfer during Bacillus subtilis fermentation
Hbid, Choukri; Jacques, Philippe; Razafindralambo, Hary ULg et al

in Applied Biochemistry and Biotechnology (1996), 57-8

Bacillus subtilis produces three types of lipopeptides: Iturins, Fengycins, and Surfactins. These amphiphilic molecules influence the volumetric oxygen transfer (K(L)a) like chemical surfactant. K(L)a ... [more ▼]

Bacillus subtilis produces three types of lipopeptides: Iturins, Fengycins, and Surfactins. These amphiphilic molecules influence the volumetric oxygen transfer (K(L)a) like chemical surfactant. K(L)a values were from two- to fivefold lower when both Iturin A and Surfactin S1 were coproduced, and from 0.57- to 0.8-fold lower when only Iturin A was produced. The addition of an oxygen vector (n-Dodecane) during fermentation increased K(L)a values (7.5-fold) and biomass production (twofold), and decreased Iturin A and Surfactin S1 production. However, at high stirring conditions and in the presence of n-Dodecane, Iturin A production was improved. [less ▲]

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See detailInfluence of lipopeptide production on oxygen transfer during fermentation of Bacillus subtilis
Hbid, Choukri; Jacques, Philippe; Razafindralambo, Hary ULg et al

Poster (1995, May 07)

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See detailEtude du comportement du film de surfactine à l'interface air-eau
Razafindralambo, Hary ULg; Paquot, Michel ULg; Hbid, Choukri et al

Poster (1993, May 13)

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See detailPurification Of Antifungal Lipopeptides By Reversed-Phase High-Performance Liquid-Chromatography
Razafindralambo, Hary ULg; Paquot, Michel ULg; Hbid, Choukri et al

in Journal of Chromatography. A (1993), 639(1), 81-85

A rapid procedure for the purification of antifungal lipopeptides from Bacillus subtilis, a potential agent for biocontrol of plant diseases, was tested. It consists of a solid-phase extraction on C18 gel ... [more ▼]

A rapid procedure for the purification of antifungal lipopeptides from Bacillus subtilis, a potential agent for biocontrol of plant diseases, was tested. It consists of a solid-phase extraction on C18 gel followed by reversed-phase chromatography using a biocompatible PepRPC HR 515 column with a pharmacia fast protein liquid chromatographic system. This is a very effective method for isolating and fractionating iturin A and surfactin, two lipopeptides of different nature, co-produced by Bacillus subtilis strain S499. The presence of homologous lipopeptides was easily detected. [less ▲]

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