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See detailMetagenomic analysis targeted on the 16S ribosomal DNA to study the quality of meat : a example with raw minced beef meat
Delhalle, Laurent ULg; Taminiau, Bernard ULg; Nezer, Carine et al

Poster (2013, July 01)

Introduction: Steak tartare is a popular meat dish in Belgium and some other European countries. This meat preparations due to their raw nature, is highly sensitive to bacterial spoilage. A better ... [more ▼]

Introduction: Steak tartare is a popular meat dish in Belgium and some other European countries. This meat preparations due to their raw nature, is highly sensitive to bacterial spoilage. A better understanding of the bacterial content of this product will thus be insightful to control the risk of spoilage. Metagenomics targeted on the 16S ribosomal DNA has appeared as a powerful tool to study bacterial composition of food samples. The aim of this study is to identify the bacterial population sof steak tartare from different origin along their shelf life. Material and methods: A total of 59 samples were analysed from seven butcheries, six restaurants, six sandwich bars, 8 supermarkets without intern butcheries and 8 supermarkets with intern butcheries. Samples where directly analysed the day of receipt (day 0) and at the end their shelf life after storage at 4°C (day 2), except for six restaurants and sandwich bars who were analysed only at day 0. Classical microbiological analyses were performed in order to determine psychotrophic aerobic colony counts using modified ISO 4833 method. Metagenomic analysis targeting the 16S rDNA was performed using the Roche GS junior. Raw sequences were treated by bioinformatics in order to obtain identification and proportion of bacteria in food sample. Results: Remarkable differences appear between the origins of steaks tartare. The bacterial concentration is between 3 and 7 log CFU/g depending of the origin and the day of analysis. The samples from the butcheries are mainly composed of Lactobacillus populations and to a lesser extend of environmental contaminants like Xanthomonas campestris. On the opposite, the samples from some of the restaurants are contaminated with an estimated level of 6 to 7 log CFU/g of Brochotrix thersmosphacta, Leuconostocaceae like Leuconostoc carnosum or an uncultured Weissella sp., or, with a lesser extend, with some contaminants like Pseudomonas sp. or Psychrobacter sp. These last samples were characterized with some spoilage characteristics (slime, off odor) that can thus be put in relation with the identified bacterial populations. The samples from sandwich bars were characterized by a lower level of bacterial population (3-4 log CFU/g), but with a greater diversity in the microflora along with a higher number of environmental contaminants that are not usually found in meat products. The products at the end of the shelf life have a higher bacterial concentration but with a lower diversity with spoiled bacteria as Brochotrix thermosphacta. Significance: Compared to culture based methods on selective media and previous independent culture techniques, metagenomic analysis combined with the enumeration of psychrotrophic flora gives more valuable information, and its use should be considered as a technique for quality control or for accurately determining the shelf life and the quality of the meat. [less ▲]

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See detailThe Metagenomic in the Service of the Food Microbiology.
Taminiau, Bernard ULg; Nezer, Carine; Poullet, Jean-Baptiste et al

Poster (2012, July 23)

Introduction: Food products represent great biotopes for bacteria. The optimisation of foodstuffs conservation, mattering so economically as from the point of view of the public health, pass by a better ... [more ▼]

Introduction: Food products represent great biotopes for bacteria. The optimisation of foodstuffs conservation, mattering so economically as from the point of view of the public health, pass by a better understanding of those biotopes and their spoilage. Microbiologists had already tried to resolve this problem throughout several approaches. Studies based on classical microbiology cultures were completed by strategies centred on approaches independent from the microbiological culture. Purpose: The current techniques of new generation sequencing give a new dimension to the microbial ecology, through the metagenomic analysis of individuals' large number, within a mixed microbial population. Our aim is to demonstrate that this methodology can be successfully applied to the study of foodstuffs microbial flora, and can be adapted to the specific requirements of food microbiology. Methods: This study was carried out on pork's minced meat and white sausage, with shelf-life tests in various conditions of preservation (temperature and packaging). The rDNA 16S was extracted from the original products and samples in the best-before date and, after standardization, hypervariable regions V5 were sequenced. Results: A total about 130.000 sequences were obtained and a metagenomic analysis succeeded in the taxonomic classification to the genus level for 80 % of this population. The subsequent analysis of microbial populations shows that the majority microbial populations at the expiration date are the same ones which are generally observed during microbiological analysis of these meat products. However, the population subdominants and especially several populations of not cultivable germs were able to be identified. These groups of bacteria, more difficult to obtain by the other methods, must be studied because they participate in the spoilage process of food products. Significance: The sensibility of this technology makes possible the analysis of foodstuffs presenting a very low microbial rate and, thus, allows the identification of the microbial contaminants before they grow the levels detected by cultural methods. [less ▲]

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See detailLa métagénomique au service de la microbiologie alimentaire : étude de l’évolution des populations microbiennes lors du vieillissement de deux matrices alimentaires
Taminiau, Bernard ULg; Nezer, Carine; Poullet, Jean-Baptiste et al

Conference (2011, November 17)

La viande et les préparations à base de viande représentent des biotopes de choix pour les bactéries. L’optimisation de la conservation de ces denrées, importante tant du point de vue économique que de ... [more ▼]

La viande et les préparations à base de viande représentent des biotopes de choix pour les bactéries. L’optimisation de la conservation de ces denrées, importante tant du point de vue économique que de santé publique passe par une meilleure connaissance de ces biotopes et des processus de détérioration de leurs qualités. Les microbiologistes ont depuis longtemps abordé ce problème en utilisant différentes approches. Ainsi, les études basées sur les méthodes de culture ont été complétées par des stratégies axées sur des approches indépendantes de la culture microbiologique. Les techniques actuelles de séquençage de nouvelle génération ont permis de donner une nouvelle dimension à l’écologie microbienne à travers l’analyse métagénomique d’un grand nombre d’individus au sein d’une population microbienne mixte. Notre propos est de démontrer que cette méthodologie peut être appliquée avec succès à l’étude des flores microbiennes des denrées alimentaires et pourra être adaptée, à court terme, aux exigences spécifiques de la microbiologie alimentaire. Dans cette étude, un produit de viande crue et une préparation de viande cuite, la viande hachée de porc et le boudin blanc, ont subi un test de vieillissement dans différentes conditions de conservation (Température et packaging). L’ADN ribosomal 16S a été extrait des produits originaux et des échantillons à la date limite de consommation et, après normalisation, les régions hypervariables V5 et V6 de l’ADN 16S ont été séquencées. Un total d’environ 130.000 séquences ont été obtenues et une analyse métagénomique a abouti à la classification taxonomique au genre pour 80% de cette population. L’analyse subséquente des populations microbiennes montre que les populations microbiennes majoritaires à la date limite de conservation sont bien celles qui sont généralement observées lors d’analyse microbiologiques de ces produits de viande. Toutefois, les populations sous-dominantes et surtout plusieurs populations de germes non cultivables ont pu être identifiée. Ces groupes de bactéries, plus difficile à obtenir par d’autres méthodes (culture-dépendante et indépendante confondues), doivent être étudiées car elles participent aux processus de détériorations de ces matrices alimentaires. Enfin, la sensibilité de cette technologie rend possible l’analyse des denrées alimentaires présentant un taux microbien très faible et permet donc l’identification des contaminants microbiens avant leur développement. [less ▲]

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See detailMetal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply.
Barabasz, Anna; Krämer, Ute; Hanikenne, Marc ULg et al

in Journal of Experimental Botany (2010), 61(11), 3057-67

Engineering enhanced transport of zinc to the aerial parts of plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression of the AhHMA4 gene encoding a metal pump of ... [more ▼]

Engineering enhanced transport of zinc to the aerial parts of plants is a major goal in bio-fortification. In Arabidopsis halleri, high constitutive expression of the AhHMA4 gene encoding a metal pump of the P(1B)-ATPase family is necessary for both Zn hyperaccumulation and the full extent of Zn and Cd hypertolerance that are characteristic of this species. In this study, an AhHMA4 cDNA was introduced into N. tabacum var. Xanthi for expression under the control of its endogenous A. halleri promoter known to confer high and cell-type specific expression levels in both A. halleri and the non-hyperaccumulator A. thaliana. The transgene was expressed at similar levels in both roots and shoots upon long-term exposure to low Zn, control, and increased Zn concentrations. A down-regulation of AhHMA4 transcript levels was detected with 10 muM Zn resupply to tobacco plants cultivated in low Zn concentrations. In general, a transcriptional regulation of AhHMA4 in tobacco contrasted with the constitutively high expression previously observed in A. halleri. Differences in root/shoot partitioning of Zn and Cd between transgenic lines and the wild type were strongly dependent on metal concentrations in the hydroponic medium. Under low Zn conditions, an increased Zn accumulation in the upper leaves in the AhHMA4-expressing lines was detected. Moreover, transgenic plants exposed to cadmium accumulated less metal than the wild type. Both modifications of zinc and cadmium accumulation are noteworthy outcomes from the biofortification perspective and healthy food production. Expression of AhHMA4 may be useful in crops grown on soils poor in Zn. [less ▲]

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See detailMetal biogeochemistry in the Tinto-Odiel rivers (Southern Spain) and in the Gulf of Cadiz: a synthesis of the results of TOROS project
Elbaz-Poulichet, Françoise; Braungardt, Chantal; Achterberg, Eric et al

in Continental Shelf Research (2001), 21(18-19), 1961-1973

TOROS (Tinto-Odiel-River-Ocean Study) has been studying the biogeochemical processes which control metals and nutrients cycling in the mixing zone of the Tinto and Odiel rivers (SW Spain) and has ... [more ▼]

TOROS (Tinto-Odiel-River-Ocean Study) has been studying the biogeochemical processes which control metals and nutrients cycling in the mixing zone of the Tinto and Odiel rivers (SW Spain) and has established the fate of metals in the Gulf of Cadiz in relation to hydrodynamics and biological activity. The Tinto and Odiel rivers are small, with a combined mean discharge of 18 m(3)/s. They drain the largest sulphide mineralisation in the world. Predominantly, Zn-Cu-Pb mineralisation has been worked since 2500 yr BC. The estuarine zone includes both an extensive area of salt marsh and an intensively industrialised urban area. As a consequence of pyrite oxidation, the Tinto and Odiel rivers are strongly acidic (pH < 3) with extremely high and variable metal concentrations. Transition metals are poorly removed from the water column in the mixing zone. Moreover, drainage from large phosphogypsum waste deposits contributes to As, Hg, U and phosphate contamination of the estuary. The collapse of the tailing reservoir at los Frailes in 1998 had not impacted the chemistry of the coastal waters up to 6 months later. A large plume of metal-rich waters due to the Tinto arid Odiel discharges occurs along the coast of the Gulf of Cadiz. This plume affects seasonally the Atlantic inflow through the Strait of Gibraltar. The dispersion of the metal discharges has been simulated by injection of a tracer in the 3-D hydrodynamical model. Both model and field study clearly show the inflow of metal contaminated Spanish Shelf Water through the Strait of Gibraltar. (C) 2001 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailMetal catalysts suppported on texture-tailored carbon xerogels
Job, Nathalie ULg; Léonard, Angélique ULg; Colomer, Jean-François et al

in Studies in Surface Science and Catalysis (2006), 162

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See detailMetal Enhanced Fluorescence: effect of surface coating
Lismont, Marjorie ULg; François, Alexandre; Dreesen, Laurent ULg et al

in SPIE proceeding (2014, February)

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific ... [more ▼]

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific irradiation, toxic reactive oxygen species (ROS) to kill cancer cells. However, the amount of ROS generated is limited by both the fluorescence lifetime of the photosensitizer and its concentration around the cancer cells. Metal Enhanced Fluorescence (MEF), a phenomenon arising when a fluorophore is in closed proximity to a metallic structure such as metallic films or nanostructures, is seen as a way to solve these problems by reducing the fluorescence lifetime and increasing the fluorescence emission of the fluorophore. Protoporphyrin IX (PpIX) is a commonly used photosensitizer to treat skin cancers, which presents an intense absorption band around 400 nm while emitting around 630 nm. Because silver nanoparticles (Ag NPs) exhibit a strong Localized Surface Plasmon Resonance (LSPR) around 400 nm, MEF of the PpIX is expected when immobilized onto Ag NPs. Here, we investigate the relevant parameters influencing the coupling effects between the LSPR in Ag NPs and PpIX attached onto the Ag NPs surface when the Ag NPs are dispersed in solution or electrostatically bound to a glass slide. In particular, we study the distance-dependent of MEF by applying multiple layers of polyelectrolyte to progressively increase the distance between Ag NPs and PpIX, covalently bond to the last polyelectrolyte layer as well as exploring the use of Ag NPs of different sizes ranging from 40 to 100 nm. [less ▲]

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See detailMetal enolates in polymer science and technology
Lecomte, Philippe ULg; Jérôme, Robert ULg

in Zabicky, Jacob (Ed.) The Chemistry of Metal Enolates (2009)

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See detailMetal flows in, out and through the Belgian coastal waters
Baeyens, Willy; Gillain, Gérard; Djenidi, Salim ULg et al

in Van Grieken, R.; Wollast, R. (Eds.) Progress in Belgian Oceanographic Research (1985)

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See detailMetal fluxes through the Strait of Gibraltar: the influence of the Tinto and Odiel rivers (SW Spain)
Elbaz-Poulichet, F.; Morley, N. H.; Beckers, Jean-Marie ULg et al

in Marine Chemistry (2001), 73(3-4), 193-213

A large set of new data concerning dissolved metal concentrations has been acquired in the Gulf of Cadiz and in the Strait of Gibraltar from 1996 to 1999. These data, associated with models (hydrodynamic ... [more ▼]

A large set of new data concerning dissolved metal concentrations has been acquired in the Gulf of Cadiz and in the Strait of Gibraltar from 1996 to 1999. These data, associated with models (hydrodynamic, tracer advection-dispersion and mixing), have been used to assess the influence of rivers draining the South Iberian Pyrite Belt on the Gulf of Cadiz and on the Atlantic inflow in the Strait of Gibraltar. Metal concentrations in surface waters from the Gulf of Cadiz are maximal near the mouth of the Tinto/Odiel rivers with values exceeding 50 nmol/kg (Mn), 5 nmol/kg (Ni), 30 nmol/kg (Cu), 100 nmol/kg (Zn), 0.9 nmol/kg (Cd) and 45 nmol/kg (As). From the Tinto/Odiel river, a plume of contamination follows the coast in the direction of the Strait of Gibraltar. The computation of a tracer advection-dispersion model confirms that the coastal currents carry the metals discharged from the Tinto and Odiel to the Strait of Gibraltar. From temperature-salinity and metal-salinity plots, four water masses can be recognised in the Gulf of Cadiz and in the Strait of Gibraltar: North Atlantic Surface Water (NASW), North Atlantic Central Water (NACW) and metal-enriched Spanish Shelf Waters from the Gulf of Cadiz (SSW). The Mediterranean Outflow Water (MOW) is also clearly seen at depths greater than 300 m. The chemical characteristics of these various water masses have been used in a mixing model to evaluate their relative contribution to the Atlantic inflow through the Strait of Gibraltar. These contributions are seasonally variable. in June 1997, the contribution was: 80 +/- 20%, 5 +/- 5% and 15 +/- 10% for NASW, NACW and SSW, respectively. In September, the SSW contribution was apparently negligible. Finally, these relative contributions allow the evaluation of the metal fluxes in the Strait of Gibraltar. The presence of SSW in the Strait increases the metal flux to the Mediterranean Sea by a factor of 2.3 (Cu), 2.4 (Cd), 3 (Zn) and 7 (Mn). It does not modify significantly As and Ni fluxes. (C) 2001 Published by Elsevier Science B.V. [less ▲]

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See detailMetal Forming Analysis via Eulerian-Lagrangian FEM with Adaptive Mesh
Hogge, Michel ULg; Ponthot, Jean-Philippe ULg

in Latin American Research Review (1991), 21

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See detailMetal Forming Processes Optimization Using Inverse Problems
KLEINERMANN, J. P.; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

in Proceedings of the Fifth National Belgian Congress on Theoretical and Applied Mechanics (2000)

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See detailMetal Forming Processes Optimization Using Inverse Problems
KLEINERMANN, J. P.; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

in Proceedings of ECCOMAS 2000/COMPLAS VI, European Congress on Computational Methods in Applied Sciences and Engineering (2000)

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See detailMetal homeostasis in hyperaccumulating plants and algae
Hanikenne, Marc ULg

Scientific conference (2011, February 04)

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See detailMetal homeostasis in plants: what can we learn from zinc hyperaccumulators?
Hanikenne, Marc ULg

Conference (2013, February 26)

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See detailMetal hyperaccumulation and hypertolerance: a model for plant evolutionary genomics
Hanikenne, Marc ULg; Nouet, Cécile ULg

in Current Opinion in Plant Biology (2011), 14

In the course of evolution, plants adapted to major variations in metal availability in soils and therefore represent an important source of natural diversity of metal homeostasis networks. Thus, research ... [more ▼]

In the course of evolution, plants adapted to major variations in metal availability in soils and therefore represent an important source of natural diversity of metal homeostasis networks. Thus, research on plant metal homeostasis can provide insights into the functioning, regulation and adaptations of biological networks. Here, we describe major breakthroughs in our understanding of the genetic and molecular basis of metal hyperaccumulation and associated hypertolerance, a naturally selected complex trait which represents an extreme adaptation of the metal homeostasis network. Investigations in this field reveal further the molecular alterations underlying the evolution of natural phenotypic diversity and provide a highly relevant framework for comparative genomics. [less ▲]

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See detailMetal hyperaccumulation in Arabidopsis halleri: How is Zinc accumulating in the leaves?
Hanikenne, Marc ULg

Scientific conference (2008, June 23)

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See detailMetal hyperaccumulation in Arabidopsis halleri: How is Zinc accumulating in the leaves?
Hanikenne, Marc ULg

Scientific conference (2010, September 17)

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