References of "Thonart, Philippe"
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See detailInvestigation of nanoparticles as potential activators for the optimization of PAH biodegradation
Masy, Thibaut ULg; Wannoussa, Wissal ULg; Lambert, Stéphanie ULg et al

Poster (2012, April 10)

These last decades, through the industrial development and its imperfect waste management, the contamination by hydrocarbons in water and soils has led to a progressive deterioration of environmental ... [more ▼]

These last decades, through the industrial development and its imperfect waste management, the contamination by hydrocarbons in water and soils has led to a progressive deterioration of environmental quality, which is more and more considered nowadays. Amongst all the existing cleaning-up techniques, the bioremediation appears as the best compromise between treatment costs and effectiveness. However, this bioprocess remains time-consuming, especially for persistent pollutants as PAHs (Polycyclic Aromatic Hydrocarbons). A first way to improve the biodegradation consists in adding a consortium of efficient microorganisms in the polluted area (bioaugmentation). A further way to improve the bioremediation rate is based on the use of nutrients to assist the microbial metabolism (biostimulation). Our project gathers these two methods, specifically for the PAH biodegradation of polluted soils. Firstly, different suitable strains from our lab will be compared together in terms of PAH-degrading rate, in order to select the best microorganisms. As all these strains were selected from a long-term oil-polluted dried soil, they should be able to compete against the endogenous microflora, even if they are injected in the soil in a powdered starter. Secondly, trace elements in the nanoparticulate form, with concentrations of about 10-5M, will be added to catalyze the bacterial metabolism. First results already showed a sharp increase (2 to 3 fold) in the biodegradation kinetics, which is promising for the further scaling-up stages. In addition, this PhD project attempts to understand the mechanism of interaction between bacteria and nanoparticulate catalysts. [less ▲]

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See detailTHE RESPONSE OF ACETOBACTER SENEGALENSIS TO STRESSORS: A STUDY TOWARDS IMPROVEMENT OF VINEGAR STARTER PRODUCTION
Shafiei, Rasoul ULg; Thonart, Philippe ULg

in Acetic Acid Bacteria (2012, April)

Acetic acid bacteria encounter various harsh conditions during acetic acid fermentation. Ethanol as the main substrate and acetic acid as the major product at low pH can influence deeply on the cellular ... [more ▼]

Acetic acid bacteria encounter various harsh conditions during acetic acid fermentation. Ethanol as the main substrate and acetic acid as the major product at low pH can influence deeply on the cellular functions of acetic acid bacteria. In previous studies in CWBI, Acetobacter senegalensis was used for production of dried vinegar starters; however the impact of stressors (ethanol and acetic acid) on A. senegalensis remained unclear. In this study, different techniques such as flow cytometry, culturability on solid medium and 2-DiGE were used comparatively to investigate the effect of carbon sources of inoculum media on the tolerance of A. senegalensis to stressors. Analysis of respiration system by flow cytometric methods showed that the presence of 2% (v/v) acetic acid in inoculum medium, in one hand, causes 80% of cells to continue to do respiration after a sudden exposure to 1- 3% (v/v) acetic acid in stress media while 89.7% of cells grown in glucose appeared as dead cells after an abrupt exposure to 3%(v/v) of acetic acid. On the other hand, 59.2% and 49.33% of cells grown in the presence of 2% (v/v) of acetic acid could maintain their entire membrane integrity after exposure to 1% and 3% (v/v) of acetic acid, respectively. Inoculum medium contained 5% (v/v) of ethanol as a carbon source enabled about 90% of cells to keep their growing capacities after a sudden exposure to 3% acetic acid. In contrast, just 40% of cells grown in glucose as a carbon source maintained their culturability on solid medium after exposure to 1% acetic acid. A similar profile of culturability was observed for the cells grown in 5% (v/v) ethanol or 2% (v/v) of acetic acid. A proteomic approach (2-DiGE) was used to analyze proteins expressed in the presence of different carbon sources. Differentially expressed proteins were mainly associated with energy metabolism, carbohydrate metabolisms, folding, sorting and degradation processes. The relative abundance of proteins was extensively different for cell grown in glucose compared with protein contents of cells grown in ethanol or acetic acid. In conclusion, production of a cost effective vinegar starter needs a qualified biomass which tolerates ethanol and acetic acid. Tolerance of A. senegalensis to acetic acid depends to a great extent on the composition of the medium which cells grow in. In spite of low adaption to acetic acid for cell grown in glucose, using ethanol or acetic acid in inoculum media renders a physiological state in A. senegelensis which enables it to cope with higher concentration of acetic acid readily, this biomass has a potential to be used as a starter [less ▲]

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See detailUse of microbial biosensors to detect substrate heterogeneities at the single cell level and assess microbial viability: Validation of a mini-bioreactor platform
Brognaux, Alison ULg; Neubauer, Peter; Twizere, Jean-Claude ULg et al

Conference (2012, March 15)

The basic principle adopted in our studies is to use substrate limitation responsive biosensors in order to detect spatial glucose heterogeneities inside industrial bioreactors (whole-cell biosensor ... [more ▼]

The basic principle adopted in our studies is to use substrate limitation responsive biosensors in order to detect spatial glucose heterogeneities inside industrial bioreactors (whole-cell biosensor). Indeed, such heterogeneities cause a lowering of the biomass yield and an increase of by-products concentration. In this work, we have used these biosensors for the elaboration of a mini-bioreactor platform that can be used as a scale-down tool. Three green fluorescent protein (GFP) transcriptional reporters have been chosen in Escherichia coli, i.e. uspA::gfp, csiE::gfp and yciG::gfp. Our previous studies have shown that these kinds of promoters are induced in response of substrate limitation and exhibit a strong fluorescence attenuation when cultivated in heterogeneous bioreactors. This sensitivity to substrate limitation has been confirmed in the case of the csiE and yciG biosensors. A mini scale-down platform has been proposed as a high throughput tool to investigate rapidly the usefulness of a given microbial biosensor. This platform is composed of shake flask able to operate in fed-batch mode either by using the slow release or the intermittent feeding principle. The first system is based on a commercial package (Enbase) based on the enzymatic release of glucose in the medium. The Enbase system allows the generation of a very smooth glucose profile without any perturbations. For comparison purpose, we have also used an intermittent feeding that induces strong fluctuation at the level of the glucose and the dissolved oxygen concentration. Local heterogeneities have thus been reproduced at the level of these mini-bioreactors and these one have caused a decrease of GFP expression, as in conventional scale-down reactor. The presence of GFP in supernatants has also been noticed and seems to be correlated with the substrate limitation signal for the three cultivation systems considered in this work (i.e., chemostat, conventional and mini-bioreactors) and with the membrane permeability. [less ▲]

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See detailImpact of Protective Compounds on the Viability, Physiological State and Lipid Degradation of FreezeDried Pseudomonas Fluorescens BTP1 during Storage
Mputu Kanyinda, Jean-Noël ULg; Pierart, C.; Weekers, F. et al

in International Journal of Biotechnology and Biochemistry (2012), 8(4), 17-26

The drying of bacteria remains a major alternative in order to keep them long term. After centrifugation, the bacterial pellet of Pseudomonas fluorescensBTP1 was divided in two fractions one with ... [more ▼]

The drying of bacteria remains a major alternative in order to keep them long term. After centrifugation, the bacterial pellet of Pseudomonas fluorescensBTP1 was divided in two fractions one with protecting compounds (2% glycerol or 5% maltodextrine) and one without and freeze-dried. After freeze drying, powders were sealed in aluminium bag under vacuum and stored at 4 or 20°C. The parameters such as viability, the conductivity and the ratio of polyunsaturated fatty acids/saturated fatty acids were used to investigate the viability of freeze-dried powders during storage. For example cell concentration of powder with glycerol (PG) at CFU/g before storage is 4.109 and after 7 month 2.108 at 4°C and 3,5.107 at 20°C). The ratio of polyunsaturated fatty acids/saturated fatty acids decrease in function of time (e.g. at 4°C the ratios of C18:3 and C18:2 by C16:0 decreases respectively of 0,013 to 0,001 and 0,05 to 0,03 after 60 days of storage). In the present study, flow cytometric analysis was applied to evaluate the state in which the cells are at the end of storage time. We compared the survival results of bacteria obtained by plate count with the flow cytometric analysis results. [less ▲]

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See detailUtilisation d'une composition comme attractant d'auxiliaires
Leroy, Pascal; Sabri, Ahmed; Heuskin, Stéphanie ULg et al

Patent (2012)

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See detailBiofuel by-product for poultry diets
Hissette, Mathias ULg; Destain, Jacqueline ULg; Thewis, André ULg et al

Poster (2012, February 28)

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See detailImpact of glycerol and storage temperature on gluatathione concentration and physiological state of Pseudomonas fluorescens BTP1 freeze-dried
Mputu Kanyinda, Jean-Noël ULg; Pierart, C.; Delvigne, Frank ULg et al

Poster (2012, February 15)

Pseudomonas fluorescens is commonly used as bio-fungicides in agriculture. For this use it requires formulations as either liquid or powder. Formulations have two advantages, storage and transport. Freeze ... [more ▼]

Pseudomonas fluorescens is commonly used as bio-fungicides in agriculture. For this use it requires formulations as either liquid or powder. Formulations have two advantages, storage and transport. Freeze-drying is a commonly used method to preserve bacteria. However, freeze-drying damages the cells, which results in loss of viability. Protective compounds are used to reduce loss of viability during process (freeze-drying and storage). In our study we used flow cytometry analysis to assess the physiological state in which cells are at the end of freeze-drying and Glutathione (GSH) was measured before and during storage. [less ▲]

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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 detailFermentative hydrogen production from glucose and starch using pure strains and artificial co-cultures ofClostridium spp.
Masset, Julien; Calusinska, Magdalena ULg; Hamilton, Christopher et al

in Biotechnology for biofuels (2012), 5(35), 1-15

ABSTRACT: BACKGROUND: Pure bacterial strains give better yields when producing H2 than mixed, natural communities. However the main drawback with the pure cultures is the need to perform the fermentations ... [more ▼]

ABSTRACT: BACKGROUND: Pure bacterial strains give better yields when producing H2 than mixed, natural communities. However the main drawback with the pure cultures is the need to perform the fermentations under sterile conditions. Therefore, H2 production using artificial co-cultures, composed of well characterized strains, is one of the directions currently undertaken in the field of biohydrogen research. RESULTS: Four pure Clostridium cultures, including C. butyricum CWBI1009, C. pasteurianum DSM525, C. beijerinckii DSM1820 and C. felsineum DSM749, and three different co-cultures composed of (1) C. pasteurianum and C. felsineum, (2) C. butyricum and C. felsineum, (3) C. butyricum and C. pasteurianum, were grown in 20 L batch bioreactors. In the first part of the study a strategy composed of three-culture sequences was developed to determine the optimal pH for H2 production (sequence 1); and the H2-producing potential of each pure strain and co-culture, during glucose (sequence 2) and starch (sequence 3) fermentations at the optimal pH. The best H2 yields were obtained for starch fermentations, and the highest yield of 2.91 mol H2/ mol hexose was reported for C. butyricum. By contrast, the biogas production rates were higher for glucose fermentations and the highest value of 1.5 L biogas/ h was observed for the co-culture (1). In general co-cultures produced H2 at higher rates than the pure Clostridium cultures, without negatively affecting the H2 yields. Interestingly, all the Clostridium strains and co-cultures were shown to utilize lactate (present in a starch-containing medium), and C. beijerinckii was able to re-consume formate producing additional H2. In the second part of the study the co-culture (3) was used to produce H2 during 13 days of glucose fermentation in a sequencing batch reactor (SBR). In addition, the species dynamics, as monitored by qPCR (quantitative real-time PCR), showed a stable coexistence of C. pasteurianum and C. butyricum during this fermentation. CONCLUSIONS: The four pure Clostridium strains and the artificial co-cultures tested in this study were shown to efficiently produce H2 using glucose and starch as carbon sources. The artificial co-cultures produced H2 at higher rates than the pure strains, while the H2 yields were only slightly affected. [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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