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See detailIMPLEMENTATION OF A METAL STRUCTURED PACKING IN A FUNGAL BIOFILM REACTOR FOR THE PRODUCTION OF A RECOMBINANT PROTEIN BY ASPERGILLUS ORYZAE
Zune, Quentin ULg; Delepierre, Anissa; Toye, Dominique ULg et al

in Communications in Agricultural and Applied Biological Sciences (2014, February 07)

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See detailCan phytoestrogen-rich plants restore the image of livestock in terms of human health? Do they promise a differentiated quality products chain?
Daems, Frédéric ULg; Jasselette, Christophe; Lognay, Georges ULg et al

Poster (2014, February 07)

In a project named PhytoHealth, the development of analytical methods for studying the impact of phytoestrogens rich diet on the «health value» of animal products is in progress. Despite the ambiguous ... [more ▼]

In a project named PhytoHealth, the development of analytical methods for studying the impact of phytoestrogens rich diet on the «health value» of animal products is in progress. Despite the ambiguous image that have phytoestrogens, some of their metabolites seemed to have potentially beneficial effects to human health. In a first time, a microbial metabolite (equol) was selected and its metabolism in dairy cow is studied. A first method using the UPLC®-MS/MS technology has been validated and has achieved a screening of equol content in milk consumed in Wallonia. Equol was found in all milk samples analyzed and a significant difference between farming methods has been highlighted. A second analytical method to quantify the equol precursors was then developed and a study of forage plants consumed by Belgian dairy cows will be conducted to select the richest fodder varieties. Other methods will be developed to better understand the metabolism in the cow and estimate the impact of enriched milk on human health. An original approach involving the use of minipigs will be considered. In the end, creating of a differentiated quality animal products chain could be interesting for the consumer, but also recoverable for the producer. [less ▲]

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See detailGold nanorods coated with a thermo-responsive poly(ethylene glycol)-b-poly(N-vinylcaprolactam) corona as drug delivery systems for remotely near infrared-triggered release
Liu, Ji ULg; Detrembleur, Christophe ULg; De Pauw, Marie-Claire ULg et al

in Polymer Chemistry (2014), 5(3), 799-813

Poly(ethylene glycol)-b-poly(N-vinylcaprolactam) (PEG-b-PNVCL) copolymers are prepared from a PEG macro-chain transfer agent in DMF at 65 °C via reversible addition-fragmentation chain transfer (RAFT ... [more ▼]

Poly(ethylene glycol)-b-poly(N-vinylcaprolactam) (PEG-b-PNVCL) copolymers are prepared from a PEG macro-chain transfer agent in DMF at 65 °C via reversible addition-fragmentation chain transfer (RAFT) polymerization. The well-defined PEG114-b-PNVCL237 copolymer with a cloud point temperature of 39 °C is used for the formation of a thermo-responsive polymer corona on the surface of gold nanorods (GNRs) via a “grafting-to” approach. Thermo-responsiveness and thermo-dependent optical properties of the as-obtained GNR@PEG-b-PNVCL nanoparticles are studied with dynamic light scattering and UV/vis spectroscopy techniques. Near infrared (NIR)-induced heating of GNR@PEG-b-PNVCL is also explored in aqueous suspension under NIR laser irradiation (802 nm, up to 250 mW). The potential of these GNR@PEG-b-PNVCL nanoparticles to be used as smart drug delivery systems (DDS) is then studied. A hydrophilic drug model, Rhodamine ® B, is used to assess the guest loading capacity, and triggered release behaviours are then evaluated under conventional external heating or internal heating induced by remote NIR irradiation. Cytotoxicity evaluation of the GNR@PEG-b-PNVCL against the fibroblast-like L929 cell line is carried out via the MTS assay in order to confirm the improved biocompatibility of the GNRs after polymer coating. These thermo-responsive GNR@PEG-b-PNVCL nanoparticles are promising DDS that combine the chemotherapeutic and phototherapeutic functions. [less ▲]

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See detailFrom wood charcoals to trees: pitfalls and successes of the taxonomic identification in tropical contexts
Morin-Rivat, Julie ULg; De Weerdt, Joëlle; Hubau, Wannes et al

Poster (2014, February 07)

So as to document the past history of tropical forests, several palaeoenvironmental proxies have been used. For instance, charcoals from soil deposits provide a local signal of the evolution of the ... [more ▼]

So as to document the past history of tropical forests, several palaeoenvironmental proxies have been used. For instance, charcoals from soil deposits provide a local signal of the evolution of the vegetation together with snapshots of human interactions with the environment. As charcoal analyses are rare in tropical contexts, here we aim at presenting the different aspects of charcoal studies through their pitfalls and successes as well as the needs for further research. Charcoal analysis (anthracology) is a discipline initially from archaeobotany that consists in the analysis of pieces of charred wood primarily found in archaeological contexts but also in natural soil layers. Its goal is to identified the species that burnt during the past through the observation of the charred wood structure. Indeed carbonization, as the incomplete combustion of the ligneous material, preserves the wood structure. The identifications obtained through microscopic observations allow assessing past uses of wood and human impacts on the forest landscape. However, issues typically tropical exist: difficulties related to fieldwork accessibility, to sampling, to soil processing so as to collect the charcoals, difficulties related to the taxonomic identification because of the huge number of species and of the limited number of anatomical descriptions. New developments are nonetheless emerging for Central Africa with original anatomical descriptions, identification protocols and visual keys. [less ▲]

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See detailUsing micro-injection technique to assess fungal toxicity in mosquito control
Bawin, Thomas ULg; Boukraa, Slimane; Seye, Fawrou et al

in Communications in Agricultural and Applied Biological Sciences (2014, February 07), 79(1), 181-185

Topical application of insecticidal compounds allows directly exposing these substances on insect tissues and measuring their toxicity while ignoring many factors. However, this technique remains ... [more ▼]

Topical application of insecticidal compounds allows directly exposing these substances on insect tissues and measuring their toxicity while ignoring many factors. However, this technique remains difficult to apply on mosquito larvae considering their aquatic lifestyle. Micro-injection could be used for the direct deposition of toxic compounds in the larvae. Capillaries exhibiting an injection tip with an external diameter of 0.5 mm have been designed from silica tubes. For each treatment, a capillary is mounted on a pump connected to a flow rate regulator. Culex quinquefasciatus larvae were injected with 10^7 spores/ml of entomopathogenic fungi (Aspergillus clavatus, Metarhizium anisopliae, Metarhizium sp.). Mortalities were recorded daily during 72h. The distribution of spores stained with methylene blue and injected into the body of larvae was also observed according to the system described. Results showed that spores were distributed over the whole body. The injection of Aspergillus clavatus, Metarhizium anisopliae and Metarhizium sp spores induced corrected mortalities of 62%, 53% and 57% after 72h, and differed statistically from control groups. Finally, post-mortem emergences of filaments from dead larvae were observed in the case of the three fungal strains confirming spore viability. Injection of inactivated spores (or inert bodies of similar size) could help to reject the hypothesis of a response due to the presence of foreign bodies. [less ▲]

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See detailField bordering flower strips as source of lipids
Paul, Aman ULg; Danthine, Sabine ULg; Stephanie, Heuskin et al

Poster (2014, February 07)

Field bordering flower strips not just only improves the biodiversity but also serves as a source of beneficial compounds. Some of the plants in these strips can be really interesting source of lipids ... [more ▼]

Field bordering flower strips not just only improves the biodiversity but also serves as a source of beneficial compounds. Some of the plants in these strips can be really interesting source of lipids, the oils extracted from their seeds can be important for food, pharmaceutical and cosmetics industries. Six species of plants from flowering strips in Belgium were investigated for their seed oil content. The oil from seeds was extracted by cold extraction technique using chloroform/methanol in 2:1 ratio as solvent. Oil extraction from seeds of Red Clover (Trifolium pratense), Rough Hawkbit (Leontodon hispidus), Cow Parsley (Anthriscus sylvestris), St John’s Wort (Hypericum perforatum), Common Yarrow (Achillea millefollium) and Birdsfoot Trefoil (Lotus corniculatus) plant species was done on wet weight which came out to be 7.89±0.11%, 11.86±0.07%, 14.78±0.31%, 24.20±0.02%, 20.08±0.15% and 7.04±0.12% respectively. The physicochemical properties of the extracted oils were analyzed. Some of these oils can be of great commercial value. [less ▲]

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See detailBiofilms from entomopathogenic fungi in mosquito control
Bawin, Thomas ULg; Boukraa, Slimane; Seye, Fawrou et al

Poster (2014, February 07)

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. As part of an integrated vector control, metabolites secreted by entomopathogenic fungi could be developed as ... [more ▼]

Mosquitoes (Diptera: Culicidae) are zoonotic vectors of medical and veterinary importance. As part of an integrated vector control, metabolites secreted by entomopathogenic fungi could be developed as biopesticides. In this context, filamentous microorganisms growing on a support as biofilm in a liquid medium would offer several advantages in bioreactor regarding performances and metabolites recovery. The production of toxic metabolites by an entomopathogenic fungus Aspergillus flavus in such conditions was assessed. Three initial inoculum levels, i.e. 10^1, 10^3 and 10^6 spores/ml of PYG medium, have been tested in shake flask with or without support. Toxicity tests were performed on Culex quinquefasciatus larvae using dilutions of 1, 2, 4, 6, 8 and 10% of liquid cultures. The results indicated that A. flavus tends to form pellets in submerged culture; the size and the amount of pellets was affected by the initial inoculum level of spores. Under similar conditions, the filaments fixed on a support and didn’t appear in free form in the liquid. Toxicity tests revealed differences between both free and fixed forms. All combined conditions, LC50s ranging up to dilutions of 2.2 and 4.8% were observed within 48 hours. Secretomes could be compared between these culture conditions by proteomic and metabolomic approaches. [less ▲]

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See detailIncrease in Soil Macroporosity managed with Winter Ploughing - a preliminary results
Parvin, Nargish ULg; Chelin, Marie ULg; Hiel, Marie-Pierre ULg et al

Poster (2014, February 07)

Measurement of soil water retention capacity by the conventional pressure plate technique always gives a substantial view of soil porosity distribution. The structural orientation is observed in the ... [more ▼]

Measurement of soil water retention capacity by the conventional pressure plate technique always gives a substantial view of soil porosity distribution. The structural orientation is observed in the beginning (higher water retention at 9.8 to 98 hPa water head pressure indicates greater proportion of macroporosity) of the soil moisture characteristic curve obtained from the water retention measurement. Since, tillage practices generally increase soil porosity, the correlation between soil hydraulics and porosity distribution would expect to be different for different tillage systems. In general, macroporosity increase with the adoption of conservative tillage or no tillage system but the changes can be varied with the seasonal variation. In our study, winter ploughing retains more water at the range of 9.8 to 98 hPa than Strip tillage, No-till residues in and No-till residues out. So, we can conclude that there is certainly increase in macroporosity in ploughing than other conservation practices of reduced tillage and no tillage. [less ▲]

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See detailDevelopment of formulated elicitors to control bioagressors of wheat: which interests?
Le Mire, Géraldine ULg; Deleu, Magali ULg; Ongena, Marc ULg et al

Poster (2014, February 07)

Crop plants are constantly exposed to a wide range of environmental stresses that can cause major productivity loss. Fungicide treatments are the most efficient disease control methods used up to now ... [more ▼]

Crop plants are constantly exposed to a wide range of environmental stresses that can cause major productivity loss. Fungicide treatments are the most efficient disease control methods used up to now. However, the environmental and health issues caused by these chemicals make it urgent to develop safer methods for pathogen control. In the optic of a sustainable agriculture, several biocontrol tools have been developed during the last decades. Elicitors are increasingly subject to research as interesting alternatives to phytosanitary products. Yet, few efficient formulations exist on the market, and no product has been designed specifically to protect wheat crops. This study will thus focus on the the manipulation of host natural defenses through the use of elicitors as a preventive treatment against major wheat diseases such as Septoria tritici, Fusarium graminearum and Fusarium culmorum. [less ▲]

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See detailBiofilter in aquaponics
Delaide, Boris ULg; Lambrechts, Paul Emile ULg; Willaert, Jean-François ULg et al

Poster (2014, February 07)

Aquaponics is a combination of aquaculture (fish farming) and hydroponics (horticulture). In this concept, the fish faeces and excreted ammonia are partially transformed into soluble nutrients which then ... [more ▼]

Aquaponics is a combination of aquaculture (fish farming) and hydroponics (horticulture). In this concept, the fish faeces and excreted ammonia are partially transformed into soluble nutrients which then are available for plants. Wastewater from aquaculture is filtrated by plants and return to the fish tank in a loop cycle. This strongly reduces the use of water and increases the economic efficiency with an additional production of plant, e.g. vegetables. From the hydroponics view, this combination allows important decreases in chemical nutrients use for plant grow. A central part of this system is the biofilter. The microorganisms that colonize it are essential to process the fish waste into soluble nutrients easily assimilated by plants. During this process, nitrifying bacteria convert free ammonia into nitrite and then nitrate. The first objective of this research will concern the identification and isolation of the main microorganism species involved by the dilution plating and metagenomics technics. The optimal conditions to process the fish waste will be determined for such microorganism. The efficiency of nitrite and nitrate production by these micro-organisms will be tested in different conditions (T°, pH, O2, water flow, support, etc..) in vitro at the lab scale and in aquaponics prototypes. [less ▲]

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See detailEstimating daily yield and content of major fatty acids from single milking
Arnould, Valérie ULg; Reding, Romain; Delvaux, Charles et al

Poster (2014, February 07)

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of official milk recording. However, fewer samples lead to a decrease ... [more ▼]

Reducing the frequency of milk recording and the number of recorded samples per test-day could be a solution in order to reduce costs of official milk recording. However, fewer samples lead to a decrease in the accuracy of predicted daily yields. Unfortunately, the current published equations use the milking interval that is often not available and/or reliable in practice. The first objective of this study was to propose models using easily available traits. Therefore the milking interval was replaced by a combination of data easily recorded by milk recording. The second objective of this study was to enlarge the previous investigations to milk fatty acids (FA) in order to propose a practical method for estimating accurate daily milk, fat and major FA yields from single milking. The fit goodness of proposed models was evaluated based on the correlation values between the estimated and observed daily yields in addition to the calculation of the mean square error. Obtained results are promising. Correlation values were comprised between 96.4% and 97.6% when daily yield were estimated from morning milking, and from 96.9% to 98.3% when daily yield were estimated from evening milking. The combination of records related to lactation stage, month of test, milk yield, and fat could replace the milking interval effect. Because of their simplicity, proposed models would be easy to implement. [less ▲]

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See detailA diachronic analysis of the dynamic of two cities: Kisangani and Lubumbashi (Democratic Republic of Congo): How do the extension and/or of the densification of these cities impact the urban internal and peripheral ecosystems?
Andre, Marie ULg; Mahy, Grégory ULg; Lejeune, Philippe ULg et al

Poster (2014, February 07)

The dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how their ... [more ▼]

The dynamics of two cities between two years (2002 and 2010 for Kisangani; 2002 and 2008 for Lubumbashi, both part of the Democratic Republic of Congo) have been examined in order to estimate how their extension and/or of the densification have impacted the urban internal and peripheral ecosystems. This study singularizes itself from the subjective ones by its quantified and objective approach based on landscape ecology. This discipline assumes that the landscape pattern description is important because, according to its central hypothesis called “pattern-process paradigm”, the ecological processes influence landscape structure and vice versa. Composition metrics, which are commonly used in landscape ecology, describe the pattern among other things in quantifying the presence and the number of patches from the various classes within the landscape. For each city two SPOT 5 images were classified with a oriented-object supervised approach; then built area proportion index, a composition landscape metric, has been evaluated in order to 1) identify the extent of each area (urban, suburban, rural) within the urban-rural gradient, 2) quantify the dynamic of the different areas in the urban-rural gradient during the last decade and 3) quantify the effect of a decade of urban and suburban growth on ecosystems. The similarities and differences between these cities, relevance and gaps in the method have then been identified and discussed. [less ▲]

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See detailAnd the winner is ... When =f and pAj=f play hide-and-seek
Winand, Jean ULg

Conference (2014, February 07)

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See detailThree aspects, One concept: Agroecology. Agroecological practices and human interactions for a new approach for science. An example at the Univeristy of Liege.
Hatt, Séverin ULg; Artru, Sidonie ULg; Boeraeve, Fanny et al

Poster (2014, February 07)

Critics are raising about conventional farming and its consequences on biodiversity, human health and society. As alternatives, novel models for agriculture are proposed, and among them Agroecology. Quite ... [more ▼]

Critics are raising about conventional farming and its consequences on biodiversity, human health and society. As alternatives, novel models for agriculture are proposed, and among them Agroecology. Quite often, Agroecology is seen as the application of ecological knowledge to the agricultural production. Indeed, this helps to develop more ecological farming practices favoring biodiversity to provide ecosystem services at multiple scales. Agroecology goes further in considering that the agricultural production is integrated in a food system guided by human interactions. This latter one takes into account socio-economic and political dimensions to develop new production systems. Doing so, it assures food security worldwide while preserving resources for future generations. Facing these ambitious objectives, academics are invited to elaborate a new approach for science in developing participatory and action-oriented approaches as well as multidisciplinarity. AgricultureIsLife is a research platform built up at the University of Liège (ULg). In 2013, 40 researchers (including 18 young researchers) from 16 research units of ULg were working in a multidisciplinary approach. About twenty research topics have been divided in four research axes of which objectives are to develop a more sustainable agriculture. The platform has the ambition to discuss its results to a large comity gathering the actors of the agricultural development. The aim of our work is firstly to present Agrocology as a concept made of three interrelated aspects. To illustrate it, the organization and objectives of the research platform AgricultureIsLife will be discussed in a second part. [less ▲]

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See detailPaints based on renewable materials
Olive, Gilles ULg; Richel, Aurore ULg

in BOOK OF SHORT ABSTRACTS - POSTER PRESENTATIONS 19TH NATIONAL SYMPOSIUM ON APPLIED BIOLOGICAL SCIENCES (2014, February 07)

Paints, at the coating meaning, are known since a long time. Typically, paint is a dispersion of one or more powders (pigments and fillers) in a macromolecular substance ("resin"), called film-forming ... [more ▼]

Paints, at the coating meaning, are known since a long time. Typically, paint is a dispersion of one or more powders (pigments and fillers) in a macromolecular substance ("resin"), called film-forming material, diluted in solvents. Pigments are solid particles, used to give opacity and/or color. Today almost all pigments have a synthetic origin. The fillers are often natural compounds. Unlike pigments, fillers have low opacity and are colorless. These very cheap products achieve the required solid content under satisfactory economic conditions. Resins used in paints have the property of forming a continuous solid (hard or flexible) film under specific conditions. They are often called “resins”. They can be solid or liquid at room temperature. The solvents are used to control the viscosity of the paint in order to facilitate its production and application. The solvents used are volatile compounds. Additives are minor compounds (a few percent), whose function is to either promote or prevent some developments of the product. For example, surfactants improve the homogeneity of the dispersion. Some additives protect the film against mold or ultraviolet radiation, or against the formation of free radicals under the action of sunlight. Since the end of the 18th century most of those paints are petroleum-based. But the near disappearance of the petroleum causes a renewed interest in bio-based preparations. In this communication, we present an overview of bio-based alternatives. [less ▲]

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See detailOld inks: pigments extracted from plants
Despy, Jessica; Wymeersch, Noémie; Bouchat, Isabelle et al

in BOOK OF SHORT ABSTRACTS - POSTER PRESENTATIONS 19TH NATIONAL SYMPOSIUM ON APPLIED BIOLOGICAL SCIENCES (2014, February 07)

Thousands of years ago, natural pigments were discovered and they have been used ever since. Indeed, prehistoric people already used them to paint the walls of the caves in which they were living. A ... [more ▼]

Thousands of years ago, natural pigments were discovered and they have been used ever since. Indeed, prehistoric people already used them to paint the walls of the caves in which they were living. A significant example of this is the Cosquer cave (-19,000 to -27,000 years) located near Marseilles. Pigments and dyes can be classified into two broad categories and five families: natural pigments and dyes and those called artificial. The first one of these five families includes the mineral pigments. Among these we can find the clays (yellow ochre, red ochre, green clay, brown clay) and the stones like lapis lazuli (blue). The second and third families gather the organic dyes and pigments. Those that have vegetal origins like indigo (blue) and madder (red) compose the second family and those that have animal origins like cochineal (red) and kermes dyers (carmine) form the third family. One family includes pigments and dyes stemming from chemical reactions such as verdigris or red lead (family 4) and the other one is made of the miscellaneous inks such as iron-gall type who are vegetal and mineral one (family 5). All these pigments, although they have been used for centuries, have been replaced by synthetic dyes from the oil industry at the end of the 19th century. Indeed, they have the advantage of reproducibility of the properties unlike natural pigments. But the scarcity of oil causes a renewed interest in natural preparations. We report the extraction of pigments from plants. [less ▲]

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See detailBiodiversity and ecosystem services: think functional!
Uyttenbroeck, Roel ULg; Hatt, Séverin ULg; Paul, Aman ULg et al

Poster (2014, February 07)

During the last years, several studies and reviews have considered the relation between biodiversity and ecosystem functioning or the provision of ecosystem services. Many studies found that plant ... [more ▼]

During the last years, several studies and reviews have considered the relation between biodiversity and ecosystem functioning or the provision of ecosystem services. Many studies found that plant functional traits and plant functional diversity (FD) are key drivers in this relation in terrestrial ecosystems. Researchers used different methods to obtain a gradient in plant FD to examine the effect on ecosystem services, going from observational studies of natural communities to synthetic assemblages. Furthermore, different methods exist to quantify plant FD going from simple functional trait richness to indices, distance-based frameworks and the division into FD components. In the AgricultureIsLife project, we set up a field experiment aiming to examine the biodiversity – ecosystem service relation in agricultural context. The experiment consists of perennial wildflower strips with different plant functional diversities in an arable field with conventional crop production. The wildflower strips were sown as synthetic assemblages but are subject to natural succession during the following years. We monitor the evolution of FD from the sowing to the establishment of a typical wildflower strip using Rhao’s quadratic entropy index to quantify FD. In addition, the flower strips will be monitored for four ecosystem services they are expected to provide: pollination, pest control, biodiversity support and provision of valuable compounds. [less ▲]

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See detailLa malédiction de Cassandre. Histoire d'une plateforme distribuée d'analyse qualitative de textes et d'images
Lejeune, Christophe ULg

Scientific conference (2014, February 07)

Le logciel Cassandre fait partie de la plateforme Hypertopic d'annotation collaborative de textes et d'images. Du point de vue de la recherche en informatique, le développement de cette plateforme s ... [more ▼]

Le logciel Cassandre fait partie de la plateforme Hypertopic d'annotation collaborative de textes et d'images. Du point de vue de la recherche en informatique, le développement de cette plateforme s'insère dans le courant du Web socio-sémantique. Du point de vue des sciences humaines, la plateforme fournit des outils de recherche qualitative. Christophe Lejeune fait le récit de son expérience de développement (de 2005 à aujourd'hui). Ce faisant, il illustre des notions abordées dans les séances précédentes, telles que les questions de gestionnaire de versions, les services Web RESTful, les centres de calcul, les nuages, les collaborations inter-universitaires, les communautés Open Source et la relation avec les utilisateurs. [less ▲]

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See detailContribution to the study of alliinase, the active principle of garlic
DETHIER, Bérénice ULg; Ponchaux, Julien; Laloux, Morgan et al

Poster (2014, February 07)

Alliinase is a crucial enzyme in the Allium genus. The conversion of its substrates, cysteine sulfoxides, into volatile thiosulfinates is an important mechanism in the defence of the plant. It also ... [more ▼]

Alliinase is a crucial enzyme in the Allium genus. The conversion of its substrates, cysteine sulfoxides, into volatile thiosulfinates is an important mechanism in the defence of the plant. It also provides the typical pungent flavour of garlic. As a matter of fact, the thiosulfinates decompose in a range of organosulfur compounds (OSC) known for their biological activities (antioxidant, anticancer, anti-diabetes properties, etc.). The environment of the decomposition of the thiosulfinates determines the type and amount of products released. A deeper knowledge of the conditions that form each OSC could help us in the preparation of garlic-based nutraceutics in the perspective of healthier food consumption. This study aims to improve the extraction and purification the enzyme alliinase in order to perform the reaction between the enzyme and its substrates and assess the potentialities of garlic preparations. Three methods have been applied to evaluate the efficiency of the extractions and purifications of the enzyme. A first idea of the purity of the enzyme is given by an electrophoresis separation of each sample on a polyacrylamide gel (SDS-PAGE). The protein content is then measured by UV-vis spectrometry with Lowry-Folin reagent for the coloration and BSA as an external standard. Finally, the specific activity is assessed by an indirect measure of the pyruvate (released as a co-product): the addition of NADH and lactate dehydrogenase turns the pyruvate in lactate, and the disappearance of NADH is measured by UV-vis spectrometry at 340 nm. The extraction of the enzyme from garlic was performed either by PEG 8000 precipitation or by ammonium sulphate precipitation. Two purifications were tested: affinity chromatography (on ConA) and size-exclusion chromatography. The combination of the ammonium sulphate process with the ConA chromatography provided the purest enzyme, with the best activity but a lower yield than the size-exclusion process. Finally the stability of the enzyme has been assessed at 4, -20 and -80 °C, showing that the enzyme could be kept at -80 °C for over 4 months without deterioration, while activity loss was observed at higher temperature. [less ▲]

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