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See detailContribution to the study of physicochemical and functional properties of hemicelluloses and xylooligosaccharides (XOS) extracted from rapeseed meal
Mertens, Cécile ULg; Paquot, Michel ULg; Destain, Jacqueline ULg et al

Poster (2012, February 08)

Rapeseed meal is one of the main industrial co-products from agriculture in Belgium, with more than 30 000 T produced each year. Beside its agricultural and energetic applications, new paths of ... [more ▼]

Rapeseed meal is one of the main industrial co-products from agriculture in Belgium, with more than 30 000 T produced each year. Beside its agricultural and energetic applications, new paths of valorization are being developed in order to add value to the rapeseed meal, usually by extraction of interesting molecules. In this thesis project, the aimed molecules are hemicelluloses, which are obtained via a global fractionation method that is being developed and optimized, constituting the first part of this project. Indeed, while rapeseed meals are globally already well exploited (mainly for their feed value), rapeseed hemicelluloses have not yet been studied for food application. Yet, hemicelluloses can be used as food additives (thickener, stabilizer, etc) mainly in bakery products. The literature being incomplete regarding the chemical structure of rapeseed hemicelluloses, one of the objectives of this project is to study their physicochemical properties, in regard with their technofunctional properties. Rapeseed hemicelluloses can also be used as raw material to produce an emergent type of prebiotic: xylooligosaccharides (XOS). These molecules can be introduced as well in the food supplement sector. Their production will be achieved by enzymatic hydrolysis, for a polymerization degree between two and five. Thus, the production and the physicochemical and technofunctional characterization of rapeseed XOS constitute the last objective of this project. This thesis is part of the SYNBIOFOR project, which aim is to create new symbiotic ingredients. [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 detailMicroorganisms from aphid honeydew attract natural enemies and tending ants
Verheggen, François ULg; Leroy, Pascal; Fischer, Christophe ULg et al

Conference (2012, February)

Aphids are some of the most serious pests of cultivated crops worldwide, causing major yield and economic losses. Previous works have demonstrated ants and natural enemies (including ladybeetles and ... [more ▼]

Aphids are some of the most serious pests of cultivated crops worldwide, causing major yield and economic losses. Previous works have demonstrated ants and natural enemies (including ladybeetles and hoverflies) to be able to use aphid volatile chemicals to locate aphid colonies. Here, we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which produces kairomones used by the aphidophagous hoverfly Episyrphus balteatus and the Asian Ladybeetle Harmonia axyridis during their search for prey colonies. Some specific semiochemicals produced by S. sciuri were identified as attractants and ovipositional stimulants. Similarly, we have shown scouts of the aphid tending ant species, Lasius niger, to orientate their foraging behaviour toward an Aphis fabae infested plant and we have demonstrated that the odours released by this aphid honeydew were attractive for ant scouts. Again, bacteria were involved in the production of these honeydew semiochemicals. Interestingly, ant scouts were also able to discriminate honeydew odour from A. fabae (usually attended by L. niger) and A. pisum (unattendedby L. niger). Comparison of the volatile and bacteria composition of both aphid species honeydew were attended. [less ▲]

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See detailEffect of Additives on Freeze-Drying and Storage of Yarrowia lipolytica Lipase.
Darvishi, Farshad; Destain, Jacqueline ULg; Nahvi, Iraj et al

in Applied Biochemistry and Biotechnology (2012)

The extracellular lipase of Yarrowia lipolytica presents numerous potentialities for biotechnological applications. This work describes the development and storage of powders obtained from supernatants ... [more ▼]

The extracellular lipase of Yarrowia lipolytica presents numerous potentialities for biotechnological applications. This work describes the development and storage of powders obtained from supernatants containing Y. lipolytica lipase by freeze-drying as downstream process that is important in obtaining a stable lipase powder with high enzymatic activity. Lipase was produced by Y. lipolytica U6 mutant strain in 20-L bioreactor. Non-concentrated cell-free culture supernatant samples were supplemented with different concentrations (0.5-1 %) of maltodextrin and glycerol as additives to freeze-drying. Effects of additives, temperature, pH, and storage time on lipase powders were determined. After addition of additives, freeze-drying yield increased 3.5-fold compared to supernatant without additive. Maltodextrin with 0.5 % concentration gave the best protection of lipase during dehydration treatment and its freeze-drying yield (77 %) is better than other formulations. Lipase powders were stored at 4 and 25 degrees C for 46 weeks without loss of lipase activity. A common impediment to the production of commercial enzyme is their low-stability aqueous solutions. The present study shows that freeze-dried lipase powders of Y. lipolytica have good stability for storage and various applications. [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

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See detailPhysical and physiological impacts of different foam control strategies during a process involving hydrophobic substrate for the lipase production by Yarrowia lipolytica
Kar, Tambi ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg et al

in Bioprocess and Biosystems Engineering (2012), 35(4), 483-492

The potentialities for the intensification of the process of lipase production by the yeast Yarrowia lipolytica on a renewable hydrophobic substrate (methyloleate) have been investigated. The key factor ... [more ▼]

The potentialities for the intensification of the process of lipase production by the yeast Yarrowia lipolytica on a renewable hydrophobic substrate (methyloleate) have been investigated. The key factor governing the lipase yield is the intensification of the oxygen transfer rate, considering the fact that Y. lipolytica is a strict aerobe. However, considering the nature of the substrate and the capacity for protein excretion and biosurfactant production of Y. lipolytica, intensification of oxygen transfer rate is accompanied by an excessive formation of foam. Two different foam control strategies have thus been implemented: a classical chemical foam control strategy (CFM) and a mechanical foam control (MFM) based on the Stirring As Foam Disruption (SAFD) principle. The second strategy allows foam control without any modifications of the physico-chemical properties of the broth. However, the MFM system design induced the formation of a persistent foam layer in the bioreactor. This phenomenon has led to the segregation of microbial cells between the foam phase and the liquid phase in the case of the bioreactors operated with MFM control, and induced a reduction at the level of the lipase yield. More interestingly, flow cytometry experiments have shown that residence time of microbial cells in the foam phase tends to induce a dimorphic transition which could potentially explain the reduction of lipase excretion. [less ▲]

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See detailMicrosale interactions between earthworms and microorganisms, a review
Zirbes, Lara ULg; Thonart, Philippe ULg; Haubruge, Eric ULg

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 125-131

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See detailPotentiality of using microbial biosensors for the detection of substrate heterogeneities and the assessment of microbial viability in industrial bioreactors: a complete set of experiments in chemostat and scale-down reactors, and elaboration of a mini scale-down platform
Brognaux, Alison ULg; Neubauer, Peter; Twizere, Jean-Claude ULg et al

in Communications in Agricultural and Applied Biological Sciences (2012), 77(1), 3-7

Substrate limitation responsive biosensors have been used in order to detect spatial substrate heterogeneities, , inside industrial bioreactors (whole-cell biosensor). Three green fluorescent protein (GFP ... [more ▼]

Substrate limitation responsive biosensors have been used in order to detect spatial substrate heterogeneities, , inside industrial bioreactors (whole-cell biosensor). Three green fluorescent protein (GFP) transcriptional reporters have been chosen in E.coli, i.e. uspA::gfp, csiE::gfp and yciG::gfp. The promoter uspA is induced in response to a variety of stresses whereas the two other promoters, csiE and yciG, are supposed to be more specific in front of a substrate limitation. The responsiveness of these biosensors has been assessed in chemostat reactor. Secondly, the same biosensors have been tested in well-mixed laboratory reactors and in scale-down reactors able to reproduce industrial conditions. Finally, a mini scale-down platform has been proposed as a high throughput tool to investigate rapidly the usefulness of a given microbial biosensor. Local heterogeneities in mini-bioreactor have caused a decrease of GFP expression, as in scale-down reactor. The presence of GFP in supernatants was noticed and this leakage seems to be correlated with the membrane permeability. [less ▲]

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See detailIsolation and identification of a new Bacillus strain for amylase production
Bakri, Y.; Ammouneh, H.; El-Khouri, S. et al

in Research in Biotechnology (2012), 3(6), 51-58

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See detailScaphandre La science rencontre l'art: L'art
Haubruge, Eric ULg; Bay, Daniel ULg; Semal, Jean et al

in Haubruge, Eric; Bay, Daniel; Semal, Jean (Eds.) Scaphandre La science rencontre l'art (2012)

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See detailEffect of humic substances on in vitro rooting and acclimatization of Alder (Alnus glutinosa (L.) Gaertn).
Tahiri, Abdelghani ULg; Destain, Jacqueline ULg; Druart, Philippe et al

Poster (2012)

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Present every where in the nature; they are taking part in basic ... [more ▼]

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Present every where in the nature; they are taking part in basic functionalities in any ecosystems involving soils, sediments, waterand landfills. They are heterogeneous and complex carbon macromolecules. Our study aims to compare the effect of HS on in vitro rooting and acclimatization of the Alder species (Alnus glutinosa (L.) Gaertn) as tree growing on river banks or wasted areas. [less ▲]

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See detailPreliminary results on growing tree roots in vitro in presence of humic substances
Tahiri, Abdelghani ULg; Destain, Jacqueline ULg; Druart, Philippe et al

Poster (2012)

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Present everywhere in the nature; they are taking part in basic ... [more ▼]

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Present everywhere in the nature; they are taking part in basic functionalities in any ecosystems involving soils, sediments, water and landfills. They are heterogeneous and complex carbon macromolecules. Our study aims to determine the main biological properties of HS on plant growth in relation to their physicochemical properties. [less ▲]

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See detailLes entérocoques : avantages et inconvénients en biotechnologie (synthèse bibliographique)
Aguilar Galvez, A.; Dubois Dauphin, Robin ULg; Destain, Jacqueline ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2012), 16(1), 67-76

Detailed reference viewed: 21 (6 ULg)
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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)

Detailed reference viewed: 17 (1 ULg)