References of "Thonart, Philippe"
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See detailTechniques de séchage des starters lactiques et mécanismes affectant la viabilité cellulaire suite à la lyophilisation
Coulibaly, Ibourahema ULg; Dubois Dauphin, Robin ULg; Danthine, Sabine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2011), 15(2), 287-299

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See detailThe elicitation of a systemic resistance by Pseudomonas putida BTP1 in tomato involves the stimulation of two lipoxygenase isoforms
Mariutto, Martin ULg; Duby, Franceline ULg; Adam, Akram et al

in BMC Plant Biology (2011), 11

Background Some non-pathogenic rhizobacteria called Plant Growth Promoting Rhizobacteria (PGPR) possess the capacity to induce in plant defense mechanisms effective against pathogens. Precedent studies ... [more ▼]

Background Some non-pathogenic rhizobacteria called Plant Growth Promoting Rhizobacteria (PGPR) possess the capacity to induce in plant defense mechanisms effective against pathogens. Precedent studies showed the ability of Pseudomonas putida BTP1 to induce PGPR-mediated resistance, termed ISR (Induced Systemic Resistance), in different plant species. Despite extensive works, molecular defense mechanisms involved in ISR are less well understood that in the case of pathogen induced systemic acquired resistance. Results We analyzed the activities of phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX), key enzymes of the phenylpropanoid and oxylipin pathways respectively, in tomato treated or not with P. putida BTP1. The bacterial treatment did not stimulate PAL activity and linoleate-consuming LOX activities. Linolenate-consuming LOX activity, on the contrary, was significantly stimulated in P. putida BTP1-inoculated plants before and two days after infection by B. cinerea. This stimulation is due to the increase of transcription level of two isoforms of LOX: TomLoxD and TomLoxF, a newly identified LOX gene. We showed that recombinant TomLOXF preferentially consumes linolenic acid and produces 13-derivative of fatty acids. After challenging with B. cinerea, the increase of transcription of these two LOX genes and higher linolenic acid-consuming LOX activity were associated with a more rapid accumulation of free 13-hydroperoxy-octadecatrienoic and 13-hydroxy-octadecatrienoic acids, two antifungal oxylipins, in bacterized plants. Conclusion In addition to the discovery of a new LOX gene in tomato, this work is the first to show differential induction of LOX isozymes and a more rapid accumulation of 13-hydroperoxy-octadecatrienoic and 13-hydroxy-octadecatrienoic acids in rhizobacteria mediated-induced systemic resistance. [less ▲]

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See detailFunctional analysis of hydrogen photoproduction in respiratory-deficient mutants of Chlamydomonas reinhardtii
Lecler, Renaud ULg; Godaux, Damien ULg; Vigeolas, Hélène ULg et al

in International Journal of Hydrogen Energy (2011), 36

In this paper, mitochondrial mutants of Chlamydomonas reinhardtii defective for respiratory complex I (NADH:ubiquinone oxidoreductase), complex III (ubiquinol cytochrome c oxidoreductase) and both ... [more ▼]

In this paper, mitochondrial mutants of Chlamydomonas reinhardtii defective for respiratory complex I (NADH:ubiquinone oxidoreductase), complex III (ubiquinol cytochrome c oxidoreductase) and both complexes I and III were analyzed for H2 photoproduction. Several parameters were followed during the S-deficiency stage and the anaerobic stage leading to H2 photoproduction. At the early aerobic S-deficiency stage, starch and neutral lipids accumulated in all strains but their amount was significantly decreased in mutants compared to wild type. During the H2 photoproduction process, whereas starch content strongly decreased in all strains, neutral lipid amount remained nearly unchanged, suggesting that starch degraded by glycolysis is the preferential substrate for energy production during anaerobiosis. The mutants displayed a decrease in H2 photoproduction correlating to the number of active mitochondrial proton-pumping sites lost in the strains. Our results thus highlight the critical role of oxidative phosphorylation during the first (aerobic) stage of S-starvation when carbon resources are accumulated. [less ▲]

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See detailGenetic determination and localization of multiple bacteriocins produced by Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431
Aguilar Galvez, Ana Consuelo; Dubois Dauphin, Robin ULg; Campos Gutierrez, David Carlos et al

in Food Science and Biotechnology (2011), 20(2), 289-296

Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431 from artisanalproduced Peruvian cheeses showed the presence of 4 putative bacteriocin genes: enterocin A, enterocin B, enterocin P, and ... [more ▼]

Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431 from artisanalproduced Peruvian cheeses showed the presence of 4 putative bacteriocin genes: enterocin A, enterocin B, enterocin P, and mundticin KS. The multiple bacteriocin producer E. faecium CWBI-B1430 presented 1 plasmid of 34.6 kb, whereas E. mundtii CWBI-B1431 contained 1 plasmid of 11.0 kb. The structural gene responsible for mundticin KS production was located on 5.6 and 3.1 kb HindIII plasmid fragments. The reverse transcription-PCR analysis showed the expression of the bacteriocin genes enterocin A, enterocin B, and mundticin KS in E. faecium CWBI-B1430 and the bacteriocin genes enterocin P and mundticin KS in E. mundtii CWBI-B1431. To our knowledge, this is the first report of the expression of mundticin KS in E. faecium and enterocin P in E. mundtii. [less ▲]

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See detailThe influence of growth conditions on enterocin-like production by Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431 isolates from artisanal Peruvian cheeses
Aguilar Galvez, Ana Consuelo ULg; Guillermo Arciniegas, Sandra Denisse; Dubois Dauphin, Robin ULg et al

in Annals of Microbiology (2011), 61

Strains of Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431, isolated from artisanal-produced Peruvian cheeses, offer a broad potential application as food biopreservatives for heat ... [more ▼]

Strains of Enterococcus faecium CWBI-B1430 and Enterococcus mundtii CWBI-B1431, isolated from artisanal-produced Peruvian cheeses, offer a broad potential application as food biopreservatives for heat-processing treatments. The aim of this work was to optimize the production conditions and medium composition for the production of bacteriocin-like substances (BLIS). The kinetics of the BLIS production for both strains is a growth-associated process, and the maximum inhibitory activity for E. faecium CWBI-B1430 and E. mundtii CWBI-B1431 was achieved after 9 and 8 h of fermentation, respectively. Temperature, initial pH, oxygen level, and their interactions all influence BLIS production for both strains; this influence was specific for each strain. The bacteriocin gene expression in a 20.0-L fermentor confirms previous work carried out by fermentation in the flask; the first reports of expression revealed mundticin KS from E. faecium and enterocin P from E. mundtii. Both strains demonstrated antilisteria activity and were multi-producers of enterocin. Furthermore, the study with whey milk as an inexpensive source of fermentable carbohydrates indicated lower BLIS production than that obtained with M17LG broth. The short chain fatty acid (SCFA) analyses offer a new alternative use for both strains, as strains probiotic, for propionic acid production. [less ▲]

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See detailCharacterization of the response of GFP microbial biosensors sensitive to substrate limitation in scale-down bioreactors
Delvigne, Frank ULg; Brognaux, Alison ULg; Gorret, Nathalie et al

in Biochemical Engineering Journal (2011), 55(2), 131-139

The dynamics of microbial stress response in intensive cultivation conditions remains not completely understood. In this work, two green fluorescent protein (GFP) transcriptional reporters have been used ... [more ▼]

The dynamics of microbial stress response in intensive cultivation conditions remains not completely understood. In this work, two green fluorescent protein (GFP) transcriptional reporters have been used as biosensors of the heterogeneities generated in a two-compartment scale-down reactor. The stress promoters have been chosen for their responsiveness to carbon limitation corresponding to the global substrate profiles encountered in intensive fed-batch cultures. From our results, it can be concluded that the exposure of microbial cells to substrates heterogeneities tends to decrease the GFP expression level in fed-batch mode. Fluorescence intensities have been monitored at the single cell level by using flow cytometry. During the course of the fed-batch culture, a drop at the level of the intracellular GFP content has been observed for the two scale-down operating conditions and for the two promoters sensitive to substrate limitation (rpoS and csiE). The fluorescence drop can be attributed to the repression of these promoters but also to the release of GFP to the extracellular medium according to the increase of the fluorescence level of the supernatant. This leakage has been observed for all the operating conditions, i.e. the scale-down reactors and the culture operating in the normal mode, i.e. in a well-mixed bioreactor. Interestingly, GFP leakage is more pronounced in the case of the cultures operated in the normal mode. Indeed, staining by propidium iodide tends to be more elevated for the microbial cells cultured under the normal mode by comparison with those cultured in scale-down conditions, indicating a higher permeability of the membrane. These results suggest that GFP microbial biosensors could be used to detect simultaneously mixing imperfections and their impact on the viability of microorganisms. [less ▲]

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See detailSelection of oleuropein-degrading lactic acid bacteria strains isolated from fermenting Moroccan green olives
Ghabbour, N.; Lamzira, Z.; Thonart, Philippe ULg et al

in Grasas y Aceites (2011), 62(1), 84-89

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See detailPlacenta-Like Structure of the Aphid Endoparasitic Wasp Aphidius ervi: A Strategy of Optimal Resources Acquisition.
Sabri, Ahmed ULg; Hance, Thierry; Leroy, Pascal ULg et al

in PloS one (2011), 6(4), 18847

Aphidius ervi (Hymenoptera: Braconidae) is an entomophagous parasitoid known to be an effective parasitoid of several aphid species of economic importance. A reduction of its production cost during mass ... [more ▼]

Aphidius ervi (Hymenoptera: Braconidae) is an entomophagous parasitoid known to be an effective parasitoid of several aphid species of economic importance. A reduction of its production cost during mass rearing for inundative release is needed to improve its use in biological control of pests. In these contexts, a careful analysis of its entire development phases within its host is needed. This paper shows that this parasitoid has some characteristics in its embryological development rather complex and different from most other reported insects, which can be phylogenetically very close. First, its yolkless egg allows a high fecundity of the female but force them to hatch from the egg shell rapidly to the host hemocoel. An early cellularisation allowing a rapid differentiation of a serosa membrane seems to confirm this hypothesis. The serosa wraps the developing embryo until the first instar larva stage and invades the host tissues by microvilli projections and form a placenta like structure able to divert host resources and allowing nutrition and respiration of embryo. Such interspecific invasion, at the cellular level, recalls mammal's trophoblasts that anchors maternal uterine wall and underlines the high adaptation of A. ervi to develop in the host body. [less ▲]

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See detailComparative study of biological hydrogen production by pure strains and consortia of facultative and strict anaerobic bacteria
Hiligsmann, Serge ULg; Masset, Julien ULg; Hamilton, Christopher ULg et al

in Bioresource Technology (2011), 102

In this paper, a simple and rapid method was developed in order to assess in comparative tests the production of binary biogas mixtures containing CO2 and another gaseous compound such as hydrogen or ... [more ▼]

In this paper, a simple and rapid method was developed in order to assess in comparative tests the production of binary biogas mixtures containing CO2 and another gaseous compound such as hydrogen or methane. This method was validated and experimented for the characterisation of the biochemical hydrogen potential of different pure strains and mixed cultures of hydrogen-producing bacteria (HPB) growing on glucose. The experimental results compared the hydrogen production yield of 19 different pure strains and sludges : facultative and strict anaerobic HPB strains along with anaerobic digester sludges thermally pre-treated or not. Significant yields variations were recorded even between different strains of the same species by i.e. about 20% for three Clostridium butyricum strains. The pure Clostridium butyricum and pasteurianum strains achieved the highest yields i.e. up to 1,36 mol H2/mol glucose compared to the yields achieved by the sludges and the tested Escherichia and Citrobacter strains. [less ▲]

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See detailE.coli prpoS::gfp strain as biosensor of glucose heterogeneity inside industrial bioreactors
Brognaux, Alison ULg; Delvigne, Frank ULg; Thonart, Philippe ULg

Poster (2010, December 08)

• OBJECTIVE: Escherichia coli is a microorganism widely used in the industry for the production of recombinant proteins. The performances obtained at the laboratory level are not reproducible at a large ... [more ▼]

• OBJECTIVE: Escherichia coli is a microorganism widely used in the industry for the production of recombinant proteins. The performances obtained at the laboratory level are not reproducible at a large scale. Actually, the mixing operation is not efficient enough: gradients of glucose and oxygen appear when operating in fed-batch mode (addition of glucose during the culture). These gradients cause adverse impacts on the production of biomass and recombinant protein. The aim of this work is to use the microbial population as biocaptor of the encoutered stress inside heterogeneous industrial bioreactors to better scale-up and regulate these reactors. • MATERIALS AND METHODS: A plasmid carrying a stress promoter followed by the coding sequence of the Green Fluorescent Protein (GFP) is introduced in the bacterial host (in our case, the strain E. coli K12 will be considered as a model organism). When the cell is submitted to given stress condition, GFP synthesis is induced and accumulated into the cytoplasm, leading to the increase of the cell's fluorescence. Flow cytometry detection is used in order to quantify the fluorescence at the single cell level. Obtained results are frequency histograms of fluorescenceintensity in the microbial population • RESULTS: The rpoS gene is a gene of the general stress response, mainly induced at the entrance to stationary phase (during a lack of glucose). The tracking of the GFP fluorescence linked to the activation / repression of the rpoS promoter gives good results. Indeed, there is appearance of a segregation at the level of the GFP content among the microbial population. The intensity of the segregation, as well as its time of appearance during the culture can be related to the bioreactor mixing efficiency. • CONCLUSION: prpoS::gfp strains can be used as biosensors of the heterogeneity of glucose encountered inside industrial reactors. • POTENTIAL APPLICATIONS & KEY BENEFITS: These strains could be used to validate a fed-batch regulation (addition of glucose) at the industrial level. [less ▲]

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See detailInvestigation of anaerobic digestion in a two-stage bioprocess producing hydrogen and methane
Hiligsmann, Serge ULg; Hamilton, Christopher ULg; Beckers, Laurent ULg et al

Conference (2010, November 17)

Hydrogen has received wide attention in the last decades as a clean energy vector. The major advantage of energy generation from hydrogen is the near-zero carbon emissions, since the utilization of ... [more ▼]

Hydrogen has received wide attention in the last decades as a clean energy vector. The major advantage of energy generation from hydrogen is the near-zero carbon emissions, since the utilization of hydrogen, either via combustion or via fuel cells, results in pure water. Recently, there has been increasing interest on the biological production of hydrogen gas from renewable biomass such as carbohydrates from agriculture or agro-food industries. This specific anaerobic digestion is called dark fermentation and is involved in the classic anaerobic digestion producing methane. Indeed, in a two-step process, i.e. when acido- and aceto-genesis are carried out in a different bioreactor than methanogenesis, it is feasible to generate separated biogas flows containing either H2 or CH4 depending on specific operating parameters. This paper deals with the comparison of the first stage performances whether operated in optimum conditions for H2 production with a mixed culture or a pure Clostridium butyricum strain. Hydrogen yields of about 1.75 and 2.3 mol H2/mol glucose were achieved respectively. The metabolites, mainly acetate and butyrate, contained in the spent medium were efficiently converted to methane in a second anaerobic digester with a methane yield of about 170 ml/g COD initially fed in the first stage. [less ▲]

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See detailVinegar Starter Production
Shafiei, Rasoul ULg; Thonart, Philippe ULg

Speech (2010)

Submerged fermentation is used extensively for production of vinegar in industrial manner. One of the main technological gaps in this kind of fermentation is the lack of efficient and cost effective ... [more ▼]

Submerged fermentation is used extensively for production of vinegar in industrial manner. One of the main technological gaps in this kind of fermentation is the lack of efficient and cost effective starter culture. So far, vinegar is one of the fermented beverages produced without selected starter cultures (SSC) inoculation. In this speech, the technical problems are discussed encountered during production of starter production. [less ▲]

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