References of "Thonart, Philippe"
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See detailOptimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by Plackett-Burman design
Jacques, Philippe ULg; Hbid, C.; Destain, Jacqueline ULg et al

in Applied Biochemistry and Biotechnology (1999), 77-9

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the ... [more ▼]

Bacillus subtilis S499 is well-known for its ability to produce two families of surfactant lipopeptides: Iturin A and Surfactin S1. Fermentation optimization for this strain was performed to amplify the surfactant production. Ten active variables were analyzed by two successive Plackett-Burman designs, consisting respectively of 12 and 16 experiments to give an optimized medium. The amount of biosurfactant lipopeptides in the supernatant of a culture carried out in this optimized medium was about five times higher than that obtained in nonoptimized rich medium. The analysis of the surfactant molecules produced in such optimized conditions has revealed the presence of a third family of lipopeptides: the fengycins. The time-dependent production of these three families of molecules in bioreactors showed that surfactin S1 is produced during the exponential phase and iturin A and fengycins during the stationary phase. [less ▲]

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See detailProtection Of Cucumber Against Pythium Root Rot By Fluorescent Pseudomonads: Predominant Role Of Induced Resistance Over Siderophores And Antibiosis
Ongena, MARC ULg; Daayf, F.; Jacques, Philippe ULg et al

in Plant Pathology (1999), 48(1),

Four Pseudomonas strains were evaluated for their intrinsic properties conferring their ability to protect long English cucumber against Pythium aphanidermatum in hydroponic culture. Two of the strains ... [more ▼]

Four Pseudomonas strains were evaluated for their intrinsic properties conferring their ability to protect long English cucumber against Pythium aphanidermatum in hydroponic culture. Two of the strains, BTP1 and its siderophorenegative mutant M3, increased plant yield as compared with the non-inoculated control plants. Strain BTP7 was intermediate in its biocontrol activity while strain ATCC 17400 failed to reduce disease development. The role of pyoverdines could not be confirmed since treatment with either BTP1 or its siderophore-negative mutant M3 provided similar suppression of Pythium disease. In addition, no siderophores were detected in the nutrient solution. BTP1 did not inhibit pathogen growth in vitro on several media, suggesting that antibiosis was not a mechanism of suppression. Quantification of root bacterial populations did not indicate differences among the strains. On the other hand, roots treated with either BTP1 or its sid¹ mutant M3 contained more antifungal phenolics than roots from any other treatments including controls. These results suggest that antifungal compounds induced by inoculation of cucumber roots with the fluorescent Pseudomonas strains BTP1 and M3 participate actively in the protection of cucumber plants against P. aphanidermatum [less ▲]

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See detailCharacterization of acetification enzymes from thermotolerant acetic acid bacteria, Acetobacter pasteurianus VM 136.
Mouanda, P.; Thonart, Philippe ULg; Tanazefti, H. et al

in Mededelingen Faculteit Landbouwkundige en Toegepaste Biologische Wetenschappen Universiteit Gent (1999), 64(5a),

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See detailMicroencapsulation Of Erythromycin And Clarithromycin Using A Spray-Drying Technique
Zgoulli, S.; Grek, V.; Barre, G. et al

in Journal of Microencapsulation (1999), 16(5), 565-71

Previous methods of microencapsulation are unable to process particles smaller than 100 microm without organic solvents or the use of multistep processes. The present study investigates the feasiblity of ... [more ▼]

Previous methods of microencapsulation are unable to process particles smaller than 100 microm without organic solvents or the use of multistep processes. The present study investigates the feasiblity of a one-step spray-drying process to microencapsulate erythromycin and clarithromycin, antibiotics known to have an unpleasant, bitter taste. Mixtures of clarithromycin (5% by weight) or erythromycin (30% by weight) with a biodegradable polymer were prepared and spray-dried under specific conditions of temperature and turbine speed. This process resulted in the microencapsulation of 80% of each drug as determined by high pressure liquid chromatography. Particle size ranged from 1 to 80 microm as determined by electron microscopy. These data show that microencapsulation of macrolides using a spray-drying technique is feasible. Spray-drying microencapsulation might be useful in the formulation of palatable oral suspensions of bitter tasting drugs. [less ▲]

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See detailModification of the Thermoresistance to Spray-Drying of a Cold-Adapted Subtilisin by Genetic Engineering
Bare, G.; Diakiese, A.; Zgoulli, S. et al

in Applied Biochemistry and Biotechnology (1999), 77-79(Spring), 857-65

The thermoresistance of a cold-adapted subtilisin dried by spray-drying was studied. Proteolytic activity of this enzyme was measured before and after spray-drying. Without chemical additives, spray ... [more ▼]

The thermoresistance of a cold-adapted subtilisin dried by spray-drying was studied. Proteolytic activity of this enzyme was measured before and after spray-drying. Without chemical additives, spray-drying yields ranged from 2-13%. The use of arabic gum and lactose in the composition of the enzyme solutions allowed the strengthening of the enzyme structures and increased water mobility in the product. Increase of water mobility led to a shorter residence time of the product in the spray-drier and a net yield increase was obtained (yield higher than 50%). The effect of two selective mutations on the thermoresistance to spray-drying of the cold-adapted subtilisin was also investigated. Mutation T85D (introduction of an additional link with an ion Ca2+ necessary for enzyme activity, by substitution of Asp for Thr 85) had no effect on the thermoresistance of the subtilisin to spray-drying. Mutation H121W (introduction of an additional aromatic link by substitution of Trp for His 121) reduced the drying yield from 66% (not modified subtilisin) to 52%. This higher thermosensitivity could be explained by an increase of the hygroscopic character of the modified subtilisin (mutation H121W). [less ▲]

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See detailA biological pluridisciplinary model to predict municipal landfill life
Steyer, E.; Hiligsmann, Serge ULg; Radu, Jean-Pol ULg et al

in Christensen; Cossu; Stegmann (Eds.) Proceedings Sardinia 99, Seventh International Waste Management and Landfill Symposium (1999)

The degradation processes occurring within landfills are the keys to assessment and control of their environmental impact. This degradation results from different microbial activities interacting all ... [more ▼]

The degradation processes occurring within landfills are the keys to assessment and control of their environmental impact. This degradation results from different microbial activities interacting all along the landfill lifetime and influenced by several non-biological factors. Approaching these complex biological and chemical processes requires a multidisciplinary pattern. Thanks to Walloon Region support, we have developed a pattern or model combining the evolution of different key parameters. Such parameters qualify biogas (composition, production rate), leachate (pH, BOD5, COD, volatile fatty acids, redox potential, nitrogen balance, humic acids...), or solid waste (moisture, settlement, cellulose content...). This paper presents relationships, including our model, between these parameters. Variations of pH, BOD5/COD ratio, sulphate concentration in leachates and settlement measures allows to predict landfill age since completion. Evaluation of cellulose and water content in refuse as well as settlement degree are useful to estimate the time required for complete biological degradation. The mathematical model has also been applied, with success, to the case of Anton Sclayn site. [less ▲]

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See detailLandfill management in Africa
Lardinois, M.; Kapepula, D.; Hiligsmann, Serge ULg et al

in Christensen; Cossu; Stegmann (Eds.) Proceedings Sardinia 99, Seventh International Waste Management and Landfill Symposium (1999)

Landfill management is an important matter to study in order to set up techniques respectful of the environment. Before any suggestions of management solutions, behaviour of landfills has to be ... [more ▼]

Landfill management is an important matter to study in order to set up techniques respectful of the environment. Before any suggestions of management solutions, behaviour of landfills has to be characterised. This is necessary to predict future interactions between a landfill and the neighbourhood, and to estimate the landfill lifetime. Water is one of the most important parameter implied in the biological degradation of refuse, which is a substantial source of pollution. Therefore, this parameter is characterised in terms of quantitative and qualitative data. A relationship between climatic conditions, one of the main source of water, and possible evolution of landfills is propounded. [less ▲]

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See detailL’évaluation biologique des décharges en relation avec les propriétés de perméabilité
Steyer, E.; Ourth, A.; Hiligsmann, Serge ULg et al

Scientific conference (1998, September 25)

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See detailProtection des pommes Jona Gold par Bacillus subtilis GA1 et S499 contre Botrytis cinerea
Toure, Y.; Jacques, Ph.; Thonart, Philippe ULg

Poster (1998, May 08)

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See detailImproving the catabolic functions in desiccation-tolerant soil bacteria in view of their use in bioaugmentation.
Weekers, F.; Jacques, Ph.; Springael, D. et al

Poster (1998, May 08)

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See detailModification of the thermoresistance to spray-drying of a cold-adapted subtilisin by genetic engineering
Bare, G.; Diakiese, A.; Zgoulli, S. et al

Poster (1998, May 08)

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See detailDevelopment of a regenerable filter aid for beverages
Bonacchelli, B.; Zgoulli, S.; Harmegnies, F. et al

Poster (1998, May 08)

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See detailOptimization of biosurfactant lipopeptide production from Bacillus subtilis S499 by plackett-burman design
Jacques, Ph.; Hbid, Ch.; Razafindralambo, Hary ULg et al

Poster (1998, May)

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See detailImproving the catabolic functions in dessication-tolerant soil bacteria in view of their use in bioaugmentation
Weekers, F.; Jacques, Ph.; Springael, D. et al

Poster (1998, May)

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See detailIsolation Of Highly Performant Sulfate Reducers From Sulfate-Rich Environments
Hiligsmann, Serge ULg; Jacques, Philippe ULg; Thonart, Philippe ULg

in Biodegradation (1998), 9(3-4), 285-292

Eleven pure strains of sulfate-reducing bacteria have been isolated from lab-scale bioreactors or disposal sites, all featuring relatively high concentrations of sulfate, and from natural environments in ... [more ▼]

Eleven pure strains of sulfate-reducing bacteria have been isolated from lab-scale bioreactors or disposal sites, all featuring relatively high concentrations of sulfate, and from natural environments in order to produce sulfide from gypsum using hydrogen as energy source. The properties of the eleven strains have been investigated and compared to these of three collection strains i.e. Desulfovibrio desulfuricans and vulgaris and Desulfotomaculum orientis. Particular attention was paid to the absolute and relative sulfide production rate and to the hydrogen sulfide inhibition level. By comparison to the collection strains, a 75 % higher production rate and a hydrogen sulfide inhibition level about twice higher i.e. 25.1 mM have been achieved with strains isolated from sulfate-rich environments. The strain selection, particularly from sulfate-rich environments, should be considered as an optimization factor for the sulfate reduction processes. [less ▲]

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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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