Showing results 61 to 80 of 86
  Foaming properties of a natural cyclic lipoheptapeptide belonging to a special class of amphiphilic moleculesRazafindralambo, Hary  ; Paquot, Michel ; et alin Food Hydrocolloids (1997), 11(1), 59-62 The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus ... [more ▼] The foaming properties of surfactin, a natural cyclic lipoheptapeptide from Bacillus subtilis, were investigated in comparison and in association with those of bovine serum albumin (BSA). An apparatus combining bubbling, optical and conductimetric methods was used to study continuously foam formation and stability in terms of the quantity and density of foam. The increase in surfactin concentration from 0.05 to 0.2 mg/ml had little effect on its foaming capacity, measured by the bubbling time to produce the required foam volume, but improved the foam maximum density significantly. Surfactin produced foam with higher maximum density and stability, and forms more regular and smaller bubbles than BSA. In addition, a synergistic effect was observed on the stability of liquid in foam prepared with a mixture of 50:50 surfactin/BSA. The liquid half-life of BSA foam was enhanced up to 40% when surfactin was added to the solution. [less ▲] Detailed reference viewed: 34 (25 ULg)Surface-active properties of surfactin iturin A mixtures produced by Bacillus subtilisRazafindralambo, Hary ; ; Deleu, Magali et alin 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 ▲] Detailed reference viewed: 63 (44 ULg)Contribution à l'étude des propriétés tensioactives de lipopeptides de Bacillus subtilisRazafindralambo, Hary Doctoral thesis (1996) Detailed reference viewed: 27 (5 ULg)Foaming properties of a natural cyclic lipoheptapeptide belonging to a special class of amphiphilic moleculesRazafindralambo, Hary ; Paquot, Michel ; et alPoster (1996, April 24) Detailed reference viewed: 4 (0 ULg)Foaming Properties Of Surfactin, A Lipopeptide Biosurfactant From Bacillus SubtilisRazafindralambo, Hary ; Paquot, Michel ; et alin Journal of the American Oil Chemists' Society [=JAOCS] (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 ▲] Detailed reference viewed: 64 (23 ULg)Influence of the production of two lipopeptides, Iturin A and Surfactin S1, on oxygen transfer during Bacillus subtilis fermentation; ; Razafindralambo, Hary et alin 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 ▲] Detailed reference viewed: 39 (21 ULg)Oxygen transfert during Bacillus subtilis fermentation. Influence of lipopeptide production, and an oxygen vector; ; et al in Archives of Physiology & Biochemistry (1995), 103 Detailed reference viewed: 10 (1 ULg)Influence of lipopeptide production on oxygen transfer during fermentation of Bacillus subtilis; ; Razafindralambo, Hary et alPoster (1995, May 07) Detailed reference viewed: 6 (1 ULg)Oxygen transfert during Bacillus subtilis fermentation. Influence of lipopeptide production, and an oxygen vector.; ; et al Poster (1995, May) Detailed reference viewed: 6 (0 ULg)Wheat gluten film in relation with breadmaking properties; Blecker, Christophe ; Razafindralambo, Hary et alPoster (1995, April) Detailed reference viewed: 13 (7 ULg)Coproduction of fengycin and iturin, surfactn or mycosubtilin lipopeptides from Bacillus subtilis; ; Razafindralambo, Hary et alin Archives of Physiology & Biochemistry (1995), 103 Detailed reference viewed: 10 (2 ULg)Two forms of lipase from Mucor miehei exhibit a different behavior at the air-water interface.Blecker, Christophe ; Razafindralambo, Hary ; Paquot, Michel et alin Colloids and Surfaces B : Biointerfaces (1995), (3), 271-279 Detailed reference viewed: 14 (7 ULg)Application Of The Quasi-Static Mode Of The Drop Volume Technique To The Determination Of Fundamental Surfactant PropertiesRazafindralambo, Hary ; Blecker, Christophe ; et alin Journal of Colloid and Interface Science (1995), 174(2), 373-377 The quasi-static mode of the drop volume technique has been applied for determining the equilibrium surface tension-concentration (σe-c) curves of ionic (SDS, CTAB) zwitterionic (CHAPS), and nonionic ... [more ▼] The quasi-static mode of the drop volume technique has been applied for determining the equilibrium surface tension-concentration (σe-c) curves of ionic (SDS, CTAB) zwitterionic (CHAPS), and nonionic (Triton X-100) surfactants. The experimental values have been fitted in two parts by the best polynomial and straight-line equations. Determination coefficients (R2) higher than 0.98 were achieved for all σe-c curves. The critical micelle concentration (CMC) and surface tension at the CMC have been calculated at the intersection point of the two fitted curves. The results conform with those found in the literature. The polynomial equation derivative at the CMC was used in the Gibbs equation to calculate the maximum surface excess concentration and the corresponding molecular area. The space required per molecule under saturation conditions is in agreement with the surfactant structures. A comparison with the Wilhelmy-plate method was also made. It is concluded that the quasi-static drop volume method provides accurate results and presents many practical advantages. [less ▲] Detailed reference viewed: 54 (44 ULg)Oxygen transfert during Bacillus subtilis fermentation. Influence of lipopeptide production and an oxygen vector.; ; et al in Archives Internationales de Physiologie et de Biochimie (1995), 103(B44), Detailed reference viewed: 11 (6 ULg)Surface properties of the milk fat globule membrane: competition between casein and membrane material; Razafindralambo, Hary ; et alin Food macromolecules and colloids (1995) Detailed reference viewed: 4 (0 ULg)surface properties of the milk fat globule membrane: competition between casein and membrane material; Razafindralambo, Hary ; et alin Food macromolecules and colloids adited by E-Dickinson and and D. Lorient, The royal Society of chemistry (1995) Detailed reference viewed: 5 (1 ULg)Propriétés de surface, adsorption aux interfaces et films monomoléculairesRazafindralambo, Hary Scientific conference (1994, May) Detailed reference viewed: 16 (3 ULg)Bacillus subtilis as a biopesticide : biochemical and technological aspectsThonart, Philippe ; ; Destain, Jacqueline et alin Progress in biotechnology (1994), 9 Detailed reference viewed: 22 (4 ULg)Quantitative and qualitative study of the production of broad-spectrum antifungal lipopeptides from Bacillus subtilis S499.; ; et al in Progress in biotechnology (1994), 9 Detailed reference viewed: 41 (1 ULg)Improvement Of Enzymatic-Synthesis Yields Of Flavor Acetates - The Example Of The Isoamyl AcetateRazafindralambo, Hary ; Blecker, Christophe ; Lognay, Georges et alin Biotechnology Letters (1994), 16(3), 247-250 Isoamyl acetate synthesis was chosen as a model to improve flavour acetate yields by optimising the enzymatic reaction. Alcohol:acid molar ratio, temperature, water content and amount of enzyme effects ... [more ▼] Isoamyl acetate synthesis was chosen as a model to improve flavour acetate yields by optimising the enzymatic reaction. Alcohol:acid molar ratio, temperature, water content and amount of enzyme effects were analyzed. The optimum values were respectively 4, 45 degrees C, 0,1% (w/v) and 0,5 g. In these conditions, the synthesis yield reached 80% after 24 h of reaction and was found 15 times greater than those already reported in the literature. [less ▲] Detailed reference viewed: 74 (41 ULg) |
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