References of "Francis, Frédéric"
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See detailDiversité et abondance entomologique en cultures maraîchères à Libreville et à Owendo (Gabon)
Bayendi-Loudit, Sandrine ULg; Poligui, René Noël ULg; Ndoutoume Ndong, Auguste et al

Conference (2014, April 02)

In order to improve knowledge of the diversity and abundances of the entomofauna occurring within market gardenings in Gabon, this study was conducted in three localities in Libreville and Owendo, from ... [more ▼]

In order to improve knowledge of the diversity and abundances of the entomofauna occurring within market gardenings in Gabon, this study was conducted in three localities in Libreville and Owendo, from July1st to August 31st, 2012. Insect collections from yellow traps and visual observations were performed weekly within plots in which grow Amaranth (Amaranthus sp., Amaranthaceae), red sorrel (Hibiscus sabdariffa L, Malavaceae), Tomato (Lycopersicon esculentum Mill, Solanaceae) and Cabbage (Brassica oleracea L, Brassicaceae). A total of 7119 insects were assessed and taxonomically classified in 8 distinct orders comprising 81 families. The study highlighted some entomologic families with agronomic interest. The main pests were represented by Aphididae (31,0%), Cecidomyiidae (5,1%), Chrysomelidae (4,0%) and Thripidae (2,0%), the useful insects (pollinators and predators) by Dolichopodidae (5,4%), Andrenidae (2,6%) Coccinellidae (1,7%), Syrphidae (0,6%), Braconidae (0,5%) and Hemerobiidae (0,1%) and the associated insects were Psychodidae (7,4%), Muscidae (5,9%), Formicidae (4,4%) and Anthomyiidae (4,2%). Entomological diversity is discussed according to the local conditions and potential for sustainable pest control encountered. [less ▲]

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See detailFirst evidence of a volatile sex pheromone in the invasive Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae)
Fassotte, Bérénice ULg; Fischer, Christophe ULg; Durieux, Delphine ULg et al

Conference (2014, April 02)

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are ... [more ▼]

Data about sex pheromones, or any semiochemicals that play a role in Coccinellid mating, remain limited. Since years, various studies and behavioral observations have hypothesized that such molecules are involved in sexual communication of ladybeetles. In this study, we collected volatile organic compounds released by virgin females of the multicolored Asian ladybeetle, Harmonia axyridis (Pallas), which were either allowed or not allowed to feed on aphids. In the presence of aphids, virgin females exhibited “calling behavior”, which has been associated with the emission of a sex pheromone in several Coleoptera species. Bioassays showed that these females released a blend of volatile compounds that is involved in the attraction of males. Gas Chromatography-Mass Spectrometry analyses highlighted specific volatile cues emanating from females, whereas males did not produce these compounds. Five components were identified: (–)-β-caryophyllene, β elemene, methyl-eugenol, α humulene, and α bulnesene. All compounds were produced after virgin females were fed aphids, and their quantity increased across the experimental period. The results confirm that female H. axyridis produce a volatile sex pheromone. Therefore, this study provides important biological information that could promote the development of efficient pest control management methods to manipulate the movements of this invasive ladybeetle, and to reduce its negative impacts on biodiversity. [less ▲]

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See detailA pheromone-based formulation against phytophagous pests
Fassotte, Bérénice ULg; Vandereycken, Axel ULg; Heuskin, Stéphanie ULg et al

Poster (2014, April 02)

Innovative integrated pest management methods are needed to overcome market withdrawal of synthetic pesticides. Therefore, the identification of environment-friendly bio-products carrying direct or ... [more ▼]

Innovative integrated pest management methods are needed to overcome market withdrawal of synthetic pesticides. Therefore, the identification of environment-friendly bio-products carrying direct or indirect biocide activity is one promising alternative option. Our researches focus on the identification of appropriate formulations releasing volatile organic compounds that are attractive for natural enemies of insect pests. However, the elaboration of slow-release devices that ensure stable and controlled release of active volatile compounds is quite challenging. Here, we developed a formulation based on E-β-farnesene and (–)-β-caryophyllene, these two semiochemicals having strong attractive potential on aphid natural enemies including ladybeetles and hoverflies. Both compounds were encapsulated together in alginate gel beads. The blend efficiency is currently being evaluated through laboratory and field assays. [less ▲]

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See detailWildflower strips: a help for crop protection ?
Hatt, Séverin ULg; Uyttenbroeck, Roel ULg; Bodson, Bernard ULg et al

Poster (2014, March 05)

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See detailWildflower strips: a help for crop protection ?
Hatt, Séverin ULg; Uyttenbroeck, Roel ULg; Bodson, Bernard ULg et al

Conference (2014, March 05)

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See detailImpacts of earthworms on soil components and dynamics. A review
Lemtiri, Aboulkacem ULg; Colinet, Gilles ULg; Alabi, Taofic ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18

Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil ... [more ▼]

Earthworm populations are important decomposers contributing to aggregate formation and nutrient cycling processes involving nitrogen cycles, phosphorus and carbon. They are known to influence soil fertility by participating to important processes in soil such as soil structure regulation and organic matter dynamics. Earthworms also modify the microbial communities through digestion, stimulation and dispersion in casts. Consequently, changes in the activities of earthworm communities, as a result of soil management practices, can also be used as indicators of soil fertility and quality. It is therefore important to understand how earthworm communities affect soil dynamics. This review adresses the current state of knowledge on earthworm’s impacts on soil structure and soil organic matter (carbon, nitrogen, and phosphorus) dynamics, with special emphasis on the effects of land management practices on earthworm communities. [less ▲]

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See detailEffects of Eisenia fetida on metal uptake of heavy metals from polluted soils by Vicia faba and Zea Mays
Lemtiri, Aboulkacem ULg; Liénard, Amandine ULg; Francis, Frédéric ULg et al

Poster (2014, February 26)

Earthworms are known to increase availability of heavy metals in soils and also play an important role in maintaining the structure and quality of soil. The introduction of earthworms into soils ... [more ▼]

Earthworms are known to increase availability of heavy metals in soils and also play an important role in maintaining the structure and quality of soil. The introduction of earthworms into soils contaminated with metals has been suggested as an aid for phytoremediation processes. In Belgium (Wallonia), a century of industrial metallurgic activities produced significant heavy metal soil pollution. A large q u a n t i t y o f s m e l t e r w a s t e c r e a t e d a g r a d i e n t o f zi n c, lead and cadmium c o n c e n t r a t i o n . The objectives of our study were to evaluate : (i) the potential toxicity of heavy metal elements on the epigeic earthworms Eisenia fetida and on two plants Zea mays and Vicia faba and (ii) to determine the effects of the earthworms on the growth and contaminants phytoextraction process. The combination of behavioural factor measurements (survival, growth, reproduction of earthworms), physico-chemical parameters such as metal absorption, bioaccumulation by earthworms, soil physico-chemical changes, and plant responses (root and shoot elongation, dried biomass,…) provided a valuable indication of pollutant bioavailability and ecotoxicity. After 56-days exposure, the results suggest that adult earthworms have a strong tolerance for heavy metals exposure, but the responses depend on metal elements. Earthworms modify the bioavailable heavy metals in root and shoot in the contaminated soils and their activities alter shoot and root biomass of V. faba and Z. mays. The presence of earthworms led to a change in physico-chemical caracteristics in contaminated soils. These results show that the ecological context for phytoremediation should be broadened by considering earthwom – plant – soil interactions as they influence both plant health and absorption of heavy metals. [less ▲]

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See detailScale-down effect on the extracellular proteome of Escherichia coli: correlation with membrane permeability and modulation according substrate heterogeneities
Brognaux, Alison ULg; Francis, Frédéric ULg; Twizere, Jean-Claude ULg et al

in Bioprocess and Biosystems Engineering (2014)

Protein leakage is induced in well-mixed fed-batch bioreactor by comparison with cultures carried out in scale-down conditions. This effect is attributed to a progressive increase of cell membrane ... [more ▼]

Protein leakage is induced in well-mixed fed-batch bioreactor by comparison with cultures carried out in scale-down conditions. This effect is attributed to a progressive increase of cell membrane permeability and the synthesis of several outer-membrane components allowing to cope with substrate limitation commonly found in high-cell density culture. A comparative analysis of protein leakage has thus been performed in well-mixed bioreactors and in scale-down devices. The extracellular proteome of E.coli has been investigated by 2D-gel electrophoresis and identified by subsequent MALDI-TOF analysis. On 110 picked spots, 67 proteins have been identified and the sub-localisation and the molecular function of these proteins have been determined. A majority of the extracellular proteome was composed of outer-membrane and periplasmic proteins (64%) confirming the fact that leakage is involved in high-cell density cultures. About 50% of this extracellular proteome was composed of transport and binding proteins. Furthermore, the more abundant spots on the gel corresponded to porin proteins and periplasmic transporters. In particular, the OmpC porin was found to be very abundant. Moreover, the scale-down effect on this extracellular proteome has been investigated by 2D-DIGE analysis (2-Dimensional Differential in-Gel Electrophoresis) and significant differences have been observed by comparison with culture carried out in well-mixed systems. Indeed, since substrate limitation signal is alleviated in this kind of apparatus, cell permeability was lowered as shown by flow cytometry. In scale-down conditions, protein leakage was thus less abundant. [less ▲]

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See detailScale-down effect on the extracellular proteome of Escherichia coli: correlation with membrane permeability and modulation according substrate heterogeneities
Brognaux, Alison ULg; Francis, Frédéric ULg; Twizere, Jean-Claude ULg et al

in Bioprocess and Biosystems Engineering (2014)

Protein leakage is induced in well-mixed fed-batch bioreactor by comparison with cultures carried out in scale-down conditions. This effect is attributed to a progressive increase of cell membrane ... [more ▼]

Protein leakage is induced in well-mixed fed-batch bioreactor by comparison with cultures carried out in scale-down conditions. This effect is attributed to a progressive increase of cell membrane permeability and the synthesis of several outer-membrane components allowing to cope with substrate limitation commonly found in high-cell density culture. A comparative analysis of protein leakage has thus been performed in well-mixed bioreactors and in scale-down devices. The extracellular proteome of E.coli has been investigated by 2D-gel electrophoresis and identified by subsequent MALDI-TOF analysis. On 110 picked spots, 67 proteins have been identified and the sub-localisation and the molecular function of these proteins have been determined. A majority of the extracellular proteome was composed of outer-membrane and periplasmic proteins (64%) confirming the fact that leakage is involved in high-cell density cultures. About 50% of this extracellular proteome was composed of transport and binding proteins. Furthermore, the more abundant spots on the gel corresponded to porin proteins and periplasmic transporters. In particular, the OmpC porin was found to be very abundant. Moreover, the scale-down effect on this extracellular proteome has been investigated by 2D-DIGE analysis (2-Dimensional Differential in-Gel Electrophoresis) and significant differences have been observed by comparison with culture carried out in well-mixed systems. Indeed, since substrate limitation signal is alleviated in this kind of apparatus, cell permeability was lowered as shown by flow cytometry. In scale-down conditions, protein leakage was thus less abundant. [less ▲]

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See detailPhysico-chemical properties and aroma profile of Acacia Honey produced in Romania
Madas, Mariana-Niculina ULg; Francis, Frédéric ULg; Marghitas, L.A. et al

in Communications in Agricultural and Applied Biological Sciences (2014, February 07), 79(1), 133-135

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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 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 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 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 detailNew alternatives to chemical pesticides: deciphering the action mechanisms of lipid based plant elicitors via complementary biophysical and biological approaches.
Nasir, Mehmet Nail ULg; Polo Lozano, Damien ULg; Luzuriaga Loaiza, Walter ULg et al

Poster (2014, February)

Nowadays, many health and environmental problems are caused by the use of chemical pesticides. In this context, an increasing demand for alternative products such as biopesticides has been observed. Among ... [more ▼]

Nowadays, many health and environmental problems are caused by the use of chemical pesticides. In this context, an increasing demand for alternative products such as biopesticides has been observed. Among biopesticides, elicitor molecules which are able to trigger immune defense responses in plants are one of the most promising options. Although numerous elicitors have been discovered, the mechanisms involved in the perception, by plants, of only a few molecules have been identified. These elicitors usually interact with proteic receptors but we have recently shown that they may also act on the lipid phase of the plasma membrane. This project first aims to improve our understanding of the molecular mechanisms involved in the recognition of specific lipid based elicitors (LBE). On that basis, the FIELD project will contribute to the design and the development of innovative compounds derived natural LBE. A multi-disciplinary approach, based on chemistry, bio-physics, bio-chemistry, and phytopathology will be followed by a consortium of different research groups from Gembloux Agro-Bio Tech in close collaboration with teams from foreign institutions. [less ▲]

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See detailCombination of Genomic and Proteomic Approaches to Characterize the Symbiotic Population of the Banana Aphid (Hemiptera: Aphididae)
De Clerck, Caroline ULg; Tsuchida, Tsutomu; Massart, Sébastien ULg et al

in Environmental Entomology (2014)

Aphids are known to live in symbiosis with speciÞc bacteria called endosymbionts that have positive or negative impacts on their hosts. In this study, six banana aphid (Pentalonia nigronervosa Coquerel ... [more ▼]

Aphids are known to live in symbiosis with speciÞc bacteria called endosymbionts that have positive or negative impacts on their hosts. In this study, six banana aphid (Pentalonia nigronervosa Coquerel) strains from various geographical origins (Gabon, Madagascar, and Burundi) were screened to determine their symbiotic content, using complementary genomic (16S rDNA sequencing and speciÞc polymerase chain reaction) and proteomic (two-dimensional difference gel electrophoresis coupled with protein identiÞcation by matrix assisted laser desorption-ionization time-of-ßight mass spectrometry) approaches. Despite the geographical heterogeneity, the combined methods allowed us to identify the same two symbionts in the six aphids strains tested: Buchnera aphidicola and Wolbachia. Although B. aphidicola is found in almost all aphid species, the systematic presence of Wolbachia in banana aphids is particularly interesting, as this bacterium usually has a low prevalence in aphid species. Phylogenetic analyses showed that the Wolbachia sp. strain found in P. nigronervosa was very similar to the strain present in aphids of the genus Cinara, known to have developed a strong and long-term symbiotic association with Wolbachia. The high level of asexual reproduction in P. nigronervosa could be linked to the presence of Wolbachia, but its prevalence also suggests that this symbiotic bacterium could play a more essential role in its aphid host. [less ▲]

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See detailTechnologie de production de masse d’insectes - INSECTECH
Richard, Gaetan ULg; Hance, Thierry; Fauconnier, Marie-Laure ULg et al

Report (2014)

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See detailIsolation of an amylolytic chrysophyte, Poterioochromonas sp. from the digestive tract of the termite R. santonensis
Tarayre, Cédric ULg; Bauwens, Julien ULg; Brasseur, Catherine ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2014), 18(1),

The aim of this work was the isolation and cultivation of amylolytic protists living in the digestive tract of the termite Reticulitermes santonensis (Feytaud). A chrysophyte identified as ... [more ▼]

The aim of this work was the isolation and cultivation of amylolytic protists living in the digestive tract of the termite Reticulitermes santonensis (Feytaud). A chrysophyte identified as Poterioochromonas sp. was isolated in a special medium containing rice grains as a source of carbon and nitrogen. Then, the protist was grown in a medium containing starch as a carbon source, tryptone, and a phosphate buffer at different pH values (5, 6 and 7). Yeast extract was added or not. Ciprofloxacin was used to avoid the bacterial development. Other antibiotics were also tested but showed an inhibitive effect on the growth of Poterioochromonas sp. Yeast extract allowed reaching 1.9 (pH 5), 2.3 (pH 6) and 2.2 (pH 7) times higher final cell concentrations, and 2.8 (pH 5), 2.8 (pH 6) and 2.2 (pH 7) times higher biomass yields. The starch concentration did not decrease in the medium until 3 and 4 days of culture, with and without yeast extract, respectively. Eight days of culture were necessary for hydrolyzing the starch completely, with and without yeast extract. Maltose and maltotriose were detected in the culture media and were hydrolyzed progressively. Maximal maltose concentrations were 0.68, 0.66 and 0.51 g.l-1 in the medium containing yeast extract. Maltotriose concentrations were only 0.17, 0.14 and 0.12 g.l-1. Other glucose oligomers were also detected but in lower quantities. It was determined that the protist developed a weak amylase activity, particularly at a weakly acidic pH (5-6). Such a pH also allowed a better growth of the protist. A maximal amylase activity of 112 nkat.l-1 was measured with yeast extract at pH 5. No other enzymatic activity (protease, cellulase or xylanase) was detected except amylase. The degradation products of starch which were obtained by enzymatic hydrolysis allow the identification of α-amylase, amyloglucosidase and possibly β-amylase activities. [less ▲]

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