References of "Thonart, Philippe"
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See detailImpact of different plant secondary metabolites addition: saponin, tannic acid, salicin and aloin on glucose anaerobic co-digestion
Mambanzulua Ngoma, Philippe; Hiligsmann, Serge ULg; Sumbu Zola, Eric et al

in Journal of Fermentation Technology (in press)

Vegetal waste and some wastewater of agro-food industries contain plant secondary metabolites (PSMs). It was showed in nutritional researches that these substances such as saponins and tannins reduced the ... [more ▼]

Vegetal waste and some wastewater of agro-food industries contain plant secondary metabolites (PSMs). It was showed in nutritional researches that these substances such as saponins and tannins reduced the methane production in the rumen. To our knowledge no study was done in the waste treatment domain to evaluate the inhibitory effect of the principal glycosidic metabolites from the wastewater or vegetal waste on their own methane-producing anaerobic digestion. Therefore in this paper BMP tests were carried out at 30°C with four commercial PSMs (CPSMs) in mixture with glucose monohydrate (Gl) used as control sample. These CPSMs were saponin from Quilaja Saponaria Molina Pract (Sap), tannic acid (Tan), salicin (Sal) and aloin from Curacao Aloe (Alo) representing respectively saponins, tannins, alcoholic glycosides and anthraquinones sources. Acidogenesis and acetogenesis were recorded for all the mixtures of Gl and CPSMs; however their conversion rates decreased with the increase of the concentrations of CPSMs. By contrast, the methanogenesis was inhibited at concentrations of CPSMs above 0.3 g/l. The inhibition degree for aromatic compounds on the anaerobic biodegradation of Gl seemed directly to depend on the numbers of benzene rings in the medium and the synergism. Thus, the highest inhibition of the biogas production from Gl was recorded for Alo, followed by Sap, Tan and Sal. However, the highest inhibition of the methane production from Gl was recorded with Sap, Alo, Tan and Sal. It was supposed that the toxicity potentials of these PSMs on the own biomethanization would be in following decreasing order: Sap or Alo, Tan and Sal. Therefore, the concentration of PSMs alone or in mixture in a digester should be bellow 0.3 g/l. for a better methanization . [less ▲]

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See detailBACTERIA MAY CONTRIBUTE TO DISTANT SPECIES RECOGNITION IN ANT-APHID MUTUALISTIC RELATIONSHIPS
Fischer, Christophe ULg; Detrain, Claire; Thonart, Philippe ULg et al

in Insect Science (in press)

Mutualistic interactions between ant and aphid species have been the subject of considerable historical and contemporary investigations, the primary benefits being cleaning and protection for the aphids ... [more ▼]

Mutualistic interactions between ant and aphid species have been the subject of considerable historical and contemporary investigations, the primary benefits being cleaning and protection for the aphids and carbohydrate-rich honeydew for the ants. Questions remained, however, as to the volatile semiochemical factor influencing this relationship. A recent study highlighted the role of bacterial honeydew volatile compounds in ant attraction. Here, ant’s ability to distantly discriminate two aphid species was investigated based on bacterial honeydew semiochemicals emissions using a two-way olfactometer. Both the mutualistic black bean aphid (Aphis fabae L.) and the non-myrmecophilous pea aphid (Acyrthosiphon pisum Harris) were found to be attractive for the black garden ant (Lasius niger L.). The level of attraction was similar in both assays (control versus one of the aphid species). However, when given a choice between these two aphid species, ants showed a significant preference for Aphis fabae. Honeydew volatiles, mostly from bacterial origins, are known to be a key element in ant attraction. Using the same olfactometry protocol, the relative attractiveness of volatiles emitted by honeydews collected from each aphid species and by bacteria isolated from each honeydew was in investigated. Again, ants significantly preferred volatiles released by Aphis fabae honeydew and bacteria. This information suggests that microbial honeydew volatiles enable ants to distantly discriminate aphid species. These results emphasize the importance of investigating the presence and potential effects of microbes in insect symbioses. [less ▲]

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See detailScalable temperature induced stress for the large-scale production of functionalized Bifidobacteria
Nguyen, Huu Thanh ULg; Razafindralambo, Hary; Richel, Aurore ULg et al

in Journal of Industrial Microbiology & Biotechnology (in press)

The application of sub-lethal stresses is known to be an efficient strategy to enhance survival of probiotic bacteria during drying processes. In this context, we previously showed that the application of ... [more ▼]

The application of sub-lethal stresses is known to be an efficient strategy to enhance survival of probiotic bacteria during drying processes. In this context, we previously showed that the application of heat stress upon the entry into stationary phase increased significantly the viability of Bifidobacterium bifidum. However, this heat shock has been considered only in small scale bioreactor and no information is available for a possible scaling-up strategy. Five different operating scales (0.2 L, 2 L, 20 L, 200 L and 2000 L) have thus been tested and the results showed that the viability of B. bifidum increases from 3.15 to 6.57 folds, depending on the scale considered. Our observations pointed out the fact that the heat stress procedure is scalable according to the main outcome, i.e. increases in cell viability, but other factors have to be taken into account. Among these factors, dissolved carbon dioxide seems to play a significant role since it explain the differences observed between the test performed at lab-scale and in industrial conditions. [less ▲]

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See detailPhysiological and bio-functional properties of gum arabic: a notable interest for certain human diseases
Eloundou Mballa, Pierre; Goffin, Dorothée ULg; Destain, Jacqueline ULg et al

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

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See detailSimultaneous production of acetic and gluconic acids by a thermotolerant Acetobacter strain during acetous fermentation in a bioreactor
Mounir, Majid ULg; shafiei, rasoul; Zarmehrkhorshid, Raziyeh et al

in Journal of Bioscience & Bioengineering (2016), 121(2), 166-171

The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to ... [more ▼]

The activity of bacterial strains significantly influences the quality and the taste of vinegar. Previous studies of acetic acid bacteria have primarily focused on the ability of bacterial strains to produce high amounts of acetic acid. However, few studies have examined the production of gluconic acid during acetous fermentation at high temperatures. The production of vinegar at high temperatures by two strains of acetic acid bacteria isolated from apple and cactus fruits, namely AF01 and CV01, respectively, was evaluated in this study. The simultaneous production of gluconic and acetic acids was also examined in this study. Biochemical and molecular identification based on a 16s rDNA sequence analysis confirmed that these strains can be classified as Acetobacter pasteurianus. To assess the ability of the isolated strains to grow and produce acetic acid and gluconic acid at high temperatures, a semi-continuous fermentation was performed in a 20-L bioreactor. The two strains abundantly grew at a high temperature (41°C). At the end of the fermentation, the AF01 and CV01 strains yielded acetic acid concentrations of 7.64% (w/v) and 10.08% (w/v), respectively. Interestingly, CV01 was able to simultaneously produce acetic and gluconic acids during acetic fermentation, whereas AF01 mainly produced acetic acid. In addition, CV01 was less sensitive to ethanol depletion during semi-continuous fermentation. Finally, the enzymatic study showed that the two strains exhibited high ADH and ALDH enzyme activity at 38°C compared with the mesophilic reference strain LMG 1632, which was significantly susceptible to thermal inactivation. [less ▲]

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See detailChange in ATP-binding cassette B1/19, glutamine synthetase and alcohol dehydrogenase gene expression during root elongation in Betula pendula Roth and Alnus glutinosa L. Gaertn in response to leachate and leonardite humic substances
Tahiri, Abdelghani ULg; Delporte, Fabienne ULg; Muhovski, Yordan et al

in Plant Physiology & Biochemistry (2016), 98

Humic substances (HS) are complex and heterogeneous compounds of humified organic matter resulting from the chemical and microbiological decomposition of organic residues. HS have a positive effect on ... [more ▼]

Humic substances (HS) are complex and heterogeneous compounds of humified organic matter resulting from the chemical and microbiological decomposition of organic residues. HS have a positive effect on plant growth and development by improving soil structure and fertility. They have long been recognized as plant growth-promoting substances, particularly with regard to influencing nutrient uptake, root growth and architecture. The biochemical and molecular mechanisms through which HS influence plant physiology are not well understood. This study evaluated the bioactivity of landfill leachate and leonardite HS on alder (Alnus glutinosa L. Gaertn) and birch (Betula pendula Roth) during root elongation in vitro. Changes in root development were studied in relation to auxin, carbon and nitrogen metabolisms, as well as to the stress adaptive response. The cDNA fragments of putative genes encoding two ATP-binding cassette (ABC) transporters (ABCB1 and ABCB19) belonging to the B subfamily of plant ABC auxin transporters were cloned and sequenced. Molecular data indicate that HS and their humic acid (HA) fractions induce root growth by influencing polar auxin transport (PAT), as illustrated by the modulation of the ABCB transporter transcript levels (ABCB1 and ABCB19). There were also changes in alcohol dehydrogenase (ADH) and glutamine synthetase (GS) gene transcript levels in response to HS exposure. These findings confirmed that humic matter affects plant growth and development through various metabolic pathways, including hormonal, carbon and nitrogen metabolisms and stress response or signalization. [less ▲]

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See detailElectrical resistivity tomography to monitor enhanced biodegradation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale
Masy, Thibaut ULg; Caterina, David; Tromme, Oliver et al

in Journal of Contaminant Hydrology (2016), 184

Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of ... [more ▼]

Petroleum hydrocarbons (HC) represent the most widespread contaminants and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on the environment affected and is still difficult to predict a priori. In order to overcome these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was to isolate an electrical signal linked to an enhanced bacterial activity with ERT, in an aged HC-contaminated clayey loam soil. To achieve this, a pilot tank was built to mimic field conditions. Compared to a first insufficient biostimulation phase, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the center of the contaminated zone, where pollutants were less bioavailable. In the meantime, lithological heterogeneities and microbial activities (growth and biosurfactant production) were successively discriminated by ERT images. In the future, this cost-effective technique should be more and more transferred to the field in order to monitor biodegradation processes and assist in selecting the most appropriate remediation technique. [less ▲]

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See detailPhysical, functional and structural characterization of the cell wall fractions from baker's yeast Saccharomyces cerevisiae
Borchani, C.; Fonteyn, F.; Jamin, G. et al

in Food Chemistry (2016), 194

The yeast cell wall of Saccharomyces cerevisiae is an important source of β-D-glucan, a glucose homopolymer with many functional, nutritional and human health benefits. In the present study, the yeast ... [more ▼]

The yeast cell wall of Saccharomyces cerevisiae is an important source of β-D-glucan, a glucose homopolymer with many functional, nutritional and human health benefits. In the present study, the yeast cell wall fractionation process involving enzymatic treatments (savinase and lipolase enzymes) affected most of the physical and functional characteristics of extracted fractions. Thus, the fractionation process showed that β-D-glucan fraction F4 had significantly higher swelling power and fat binding capacity compared to other fractions (F1, F2 and F3). It also exhibited a viscosity of 652.12 mPa s and a high degree of brightness of extracted β-D-glucan fraction. Moreover, the fractionation process seemed to have an effect on structural and thermal properties of extracted fractions. Overall, results showed that yeast β-D-glucan had good potential for use as a prebiotic ingredient in food, as well as medicinal and pharmaceutical products. © 2015, Elsevier Ltd. All rights reserved. [less ▲]

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See detailOpportunités pour la valorisation des végétaux riches en anthocyanes comme sources de colorants alimentaires (synthèse bibliographique)
Beye, Cheikh ULg; Tounkara, Lat Souk; Seck, Mamadou Amadou et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2015), 19(4), 392-401

Introduction. Très répandues dans le règne végétal, les anthocyanes sont le sujet d’un grand nombre d’études qui abordent en général les aspects concernant leur instabilité vis-à-vis des conditions dans ... [more ▼]

Introduction. Très répandues dans le règne végétal, les anthocyanes sont le sujet d’un grand nombre d’études qui abordent en général les aspects concernant leur instabilité vis-à-vis des conditions dans lesquelles elles sont employées ou l’effet bénéfique de leur consommation sur la santé. Littérature. Ces aspects sont particulièrement importants lorsqu’on envisage de les extraire en vue de leur utilisation comme colorant alimentaire naturel. Dans cette revue bibliographique, les propriétés des anthocyanes susceptibles d’être altérées lors de leur transformation ont été étudiées. Par la suite, un état des lieux sur les méthodes de fabrication de colorants à base d’anthocyanes a été fait afin de dégager des perspectives pour l’exploitation des matières végétales qui en contiennent de grandes quantités. Conclusions. Les fruits et légumes utilisables pour la fabrication de colorants alimentaires sont nombreux et variés. Les différences au niveau du contenu ont une influence sur la stabilité de la couleur des extraits, mais les progrès récents en matière de formulation ouvrent des perspectives pour la valorisation des végétaux riches en anthocyanes. [less ▲]

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See detailFungal biofilm reactor improves the quality of a fusion protein GLA::GFP produced by Aspergillus oryzae
Zune, Quentin ULg; Delepierre, Anissa ULg; Bauwens, Julien ULg et al

Poster (2015, October)

Fungal biofilm is known to promote the excretion of secondary metabolites, in accordance with solid-state related physiological mechanisms. In this work, the potentialities of fungal biofilm will be ... [more ▼]

Fungal biofilm is known to promote the excretion of secondary metabolites, in accordance with solid-state related physiological mechanisms. In this work, the potentialities of fungal biofilm will be investigated in the context of the production of a Gla::GFP fusion protein by Aspergillus oryzae. Since the production of this protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, biofilm mode of culture is expected to enhance the global productivity. However, we found that the glaB promoter is also activated in submerged bioreactor and the fusion protein production is higher in this mode of culture. This result is related to the high shear stress leading to biomass autolysis and leakage of intracellular fusion protein into the extracellular medium. Moreover, 2D-gel electrophoresis highlights preservation of the fusion protein integrity produced in biofilm conditions whereas proteolysis strongly affects fusion protein recovery in the submerged cultures performed at high stirring rate. Fungal biofilm reactor design was then further investigated and the scale-up potentialities were evaluated. Indeed, the specific design investigated in this work involves the use of metal structured packing exhibiting a high specific area and that can be easily expanded to large-scale bioprocessing conditions. [less ▲]

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See detailDegradation of p-nitrophenol and bacteria with TiO2 xerogels sensitized in situ with tetra(4-carboxyphenyl)porphyrins
Tasseroul, Ludivine ULg; Lambert, Stéphanie ULg; Eskenazi, David et al

Poster (2015, September 10)

Heterogeneous photocatalysis is widely studied for environmental applications as oxidative processes can completely destroy organic pollutants such as alkanes, pesticides, dyes, etc. and microorganisms ... [more ▼]

Heterogeneous photocatalysis is widely studied for environmental applications as oxidative processes can completely destroy organic pollutants such as alkanes, pesticides, dyes, etc. and microorganisms. The most used photocatalyst is the commercial TiO2 Degussa P25, which is composed of 80% anatase and 20% rutile and which is active when TiO2 is exposed to UV light ( < 380 nm). Recently, several studies have been performed to extend the light absorption range of TiO2 towards the visible range. In this study, TiO2-based materials doped with porphyrins, a widely used dye for the photosensibilization of TiO2, have been prepared using a sol-gel process. To stabilize the TiO2-dye interactions, free metal tetra(4-carboxyphenyl)porphyrin and nickel tetra(4-carboxyphenyl)porphyrin were introduced in situ into the TiO2 matrix during the sol-gel process rather than by grafting. Samples were thoroughly characterized by TEM, X-ray diffraction, FT-IR, DR-UV/Vis and their texture has been examined by nitrogen adsorption–desorption at 77 K. The photocatalytic activity for the degradation of p-nitrophenol and Escherichia coli and Lactobacillus rhamnosus bacteria cells in aqueous medium, under halogen lamp light have been evaluated in relation with the physico-chemical modifications induced by the doping. The low temperature vacuum drying protocol (150°C) used in the present study enabled to obtain porphyrin doped TiO2 xerogels with a high specific surface area, and containing nanoparticles composed of amorphous- and anatase-TiO2. Diffuse reflectance spectroscopy attest the presence of TCPPH2 and TCPPNi within the TiO2 matrix. In a first step, the photoactivity of the xerogels is tested for p-nitrophenol degradation. Results show that crystallinity and nature and concentration of porphyrin introduced in situ have major impact on the degradation performances. In a second step, the best xerogel for p-nitrophenol degradation has been used to degrade bacteria. This xerogel degrades E. coli and L. rhamnosus bacteria cells in less than 48 and 24 h respectively. The photocatalytic degradation of a pollutant is thus correlated to the degradation of bacteria since a xerogel doped with the TCPPNi degrades both p-nitrophenol, E. coli and L. rhamnosus. [less ▲]

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See detailERT to monitor the bioremediation of hydrocarbons with Rhodococcus erythropolis T902.1 at a pilot scale
Masy, Thibaut ULg; Caterina, David; Tromme, Olivier et al

Conference (2015, June 30)

Petroleum hydrocarbons (HC) represent the most widespread contaminants in the world and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the ... [more ▼]

Petroleum hydrocarbons (HC) represent the most widespread contaminants in the world and in-situ bioremediation remains a competitive treatment in terms of cost and environmental concerns. However, the efficiency of such a technique (by biostimulation or bioaugmentation) strongly depends on numerous environmental characteristics (heterogeneities of the subsurface structure, soil moisture, oxygen and pollutants bioavailability, microbial niches…) and is still difficult to predict a priori. In order to lower these uncertainties, Electrical Resistivity Tomography (ERT) appears as a valuable non-invasive tool to detect soil heterogeneities and to monitor biodegradation. The main objective of this study was thus to isolate with ERT an electrical signature corresponding to an enhanced biodegrading activity, in an aged HC-contaminated clay loam soil. To achieve it, a pilot tank with metric dimensions (3.6 × 0.9 × 0.6 m) and a recirculating system (which is quite unique for this type of purpose) was built to mimic field conditions and to control the evolution of the bio-physico-chemical parameters (microbial concentration in soil and groundwater, temperature, pH, pO2, redox potential, bulk and fluid conductivities, water flow, hydrocarbon content) through time and space. Five panels of electrodes were placed at different locations in the tank to detect lithological heterogeneities and to monitor the bulk resistivity variations with time-lapse ERT. Compared to a first insufficient biostimulation phase with H2O2 and KNO3, bioaugmentation with Rhodococcus erythropolis T902.1 led to a HC depletion of almost 80% (6900 to 1600 ppm) in 3 months in the center of the contaminated clay, where pollutants were less bioavailable. Furthermore, lithological heterogeneities (clay, sand, gravels) and microbial activities (growth, degradation and biosurfactant production) were successfully discriminated by ERT images obtained during both remediation phases. In the future, this cost-effective technique should be transferred to the field in order to either (i) detect and forecast biodegradation processes before choosing an appropriate remediation technique, or (ii) monitor the efficiency of this biodegradation during an in-situ bioremediation. [less ▲]

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See detailIn vitro model to study the biological properties of humic fractions from landfill leachate and leonardite during root elongation of Alnus glutinosa L. Gaertn and Betula pendula Roth.
Tahiri, Abdelghani ULg; Destain, Jacqueline ULg; Thonart, Philippe ULg et al

in Plant Cell, Tissue & Organ Culture (2015), 122(3), 739-749

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Our study aims to determine the main biological properties of HS ... [more ▼]

Humic substances (HS) are organic compounds resulting from the physical, chemical and microbiological transformations of organic residues. Our study aims to determine the main biological properties of HS comparing landfill leachate (LHS) source to a stable formulation extracted from leonardite (HHS), and using an in vitro system of root development from shoot and leaf explants of silver birch (Betula pendula Roth) and black alder (Alnus glutinosa L. Gaertn). Results showed that both explants of both species rooted closely to 100% when cultivated in absence of HS. The incorporation of HS or their fractions into the culture medium affect root growth, mainly lateral roots formation and primary root length. Applied at low concentration (10 ppm) HS stimulated especially primary root growth. But at high concentration (100 ppm), LHS inhibited root formation of alder, while birch was more tolerant. The application of 100 ppm of HHS, did not affect alder root growth but increased root growth in birch. Humic acids fractions (HA) were favorable and improved root growth while, fulvic acids (FA) and other molecules (OM) decreased significantly root growth, especially those extracted LHS. The root inhibition expressed at high LHS concentration may be due to the presence of different toxic molecules and root growth inhibitors in OM and FA fractions and that some of them remained in the OM fraction from leonardite. [less ▲]

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See detailMicrobial diversity and function during different bioremediation strategies of diesel-polluted soil
Masy, Thibaut ULg; Hiligsmann, Serge ULg; Thonart, Philippe ULg et al

Poster (2015, June 16)

In numerous hydrocarbon-polluted sites, oxygen and pollutant bioavailability constitutes the main limiting factors for biodegradation because of the strong adsorption of hydrocarbons on organic soil ... [more ▼]

In numerous hydrocarbon-polluted sites, oxygen and pollutant bioavailability constitutes the main limiting factors for biodegradation because of the strong adsorption of hydrocarbons on organic soil particles (clay and peat). Therefore, several strategies such as biostimulation (with air/H2O2 and/or nutrients) or bioaugmentation are used, but often without understanding the endogenous microflora degrading capacity. This lack of differentiation between indigenous and added microorganisms could lead to poor predictability of the biodegradation efficiency. In addition, anaerobic degradation remains less applied in industrial settings for such compounds (especially for saturated hydrocarbons) as this process remains slow. In this context, the main objective of our study was to understand how the bacterial community evolves, in terms of species and degrading gene diversities, during the application of three different bioremediation strategies in a heavily diesel-polluted clay soil: (i) anaerobic natural attenuation, (ii) bioventing and (iii) bioaugmentation with Rhodococcus erythropolis T902.1. In addition to the supply of new degrading genes, bioaugmentation with this biosurfactant-producing strain should facilitate the bioassimilation of desorbed hydrocarbons by the whole degrading microflora. This hypothesis is strengthened by previous results obtained during several microcosm- and pilot-scale experiments. Aerobic and anaerobic microcosms were set up with three different soil samples coming from the same polluted site. Initially, their global organic content was identical but their hydrocarbon and peat concentrations were different, which led to differential oxygen consumption. Soils were sampled every 10 days to extract the DNA to measure changes in bacterial populations (with RISA analysis and 16S rRNA gene sequencing) and function (with qPCR and sequencing of degrading genes). Further analyses of the hydrocarbon content by GC-MS and of the genetic diversity by MiSeq metagenomic analysis provided detailed chemical and functional microbial data related to compound degradation and relative gene increases. Initial results showed significant differences in the microbial community structure. Moreover, Rhodococci seem to be maintained in the soil after inoculation. [less ▲]

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See detailComparative biochemical analysis after steam pretreatment of lignocellulosic agricultural waste biomass from Williams Cavendish banana plant (Triploid Musa AAA group)
Kamdem, Irenée ULg; Jacquet, Nicolas ULg; Tiappi Deumaga, Mathias Florian ULg et al

in Waste Management & Research : The Journal of the International Solid Wastes & Public Cleansing Association (2015)

The accessibility of fermentable substrates to enzymes is a limiting factor for the efficient bioconversion of agricultural wastes in the context of sustainable development. This paper presents the ... [more ▼]

The accessibility of fermentable substrates to enzymes is a limiting factor for the efficient bioconversion of agricultural wastes in the context of sustainable development. This paper presents the results of a biochemical analysis performed on Williams Cavendish Lignocellulosic Biomass (WCLB) after steam cracking (SC) and steam explosion (SE) pretreatments. Solid (S) and liquid (L) fractions (Fs) obtained from SC pretreatment performed at 180°C (SLFSC180) and 210°C (SLFSC210) generated, after diluted acid hydrolysis, the highest proportions of neutral sugar (NS) contents, specifically 52.82±3.51 and 49.78±1.39 %w/w WCLB’s dry matter (DM), respectively. The highest proportions of glucose were found in SFSC210 (53.56±1.33 %w/w DM) and SFSC180 (44.47±0.00 %w/w DM), while the lowest was found in unpretreated WCLB (22.70±0.71 %w/w DM). Total NS content assessed in each LF immediately after SC and SE pretreatments was less than 2 %w/w of the LF’s DM, thus revealing minor acid autohydrolysis consequently leading to minor NS production during the steam pretreatment. WCLB subjected to SC at 210°C (SC210) generated up to 2.7-fold bioaccessible glucan and xylan. SC and SE pretreatments showed potential for the deconstruction of WCLB (delignification, depolymerisation, decrystallization and deacetylation), enhancing its enzymatic hydrolysis. The concentrations of enzymatic inhibitors such as 2-furfuraldehyde and 5-(hydroxymethyl)furfural from LFSC210 were the highest (41 and 21 µg mL-1, respectively). This study shows that steam pretreatments in general and SC210 in particular are required for efficient bioconversion of WCLB. Yet, biotransformation through biochemical processes (e.g., anaerobic digestion) must be performed to assess the efficiency of these pretreatments. [less ▲]

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See detailMultiple analyses of microbial communities applied to the gut of the wood-feeding termite Reticulitermes flavipes fed on artificial diets
Tarayre, Cédric ULg; Bauwens, Julien ULg; Mattéotti, Christel et al

in Symbiosis (2015)

The purpose of this work was the observation of the differences between the microbial communities living in the gut of the termite Reticulitermes flavipes fed on different diets. The termites were fed on ... [more ▼]

The purpose of this work was the observation of the differences between the microbial communities living in the gut of the termite Reticulitermes flavipes fed on different diets. The termites were fed on poplar wood (original diet) and artificial diets consisting of crystalline cellulose (with and without lignin), α-cellulose (with and without lignin) and xylan. The termites were then dissected and the protist communities were analyzed through microscopy, leading to the conclusion that protist species are strongly influenced by diets. BIOLOG ECO Microplates® were used to assess the metabolic properties of the different types of consortia, highlighting strong differences on the basis of principal component analysis and calculation of similarity rates. The microorganisms were cultivated in liquid media corresponding to the artificial diets before being characterized through a metagenetic analysis of gut microbiota (16S ribosomal DNA). This analysis identified several phyla: Acidobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Fibrobacteres, Firmicutes, Nitrospirae, OP9, Planctomycetes, Proteobacteria, Spirochaetes, TM6, Tenericutes, Verrucomicrobia and WS3. The OTUs were also determined and confirmed the abundance of Proteobacteria, Bacteroidetes, Firmicutes and Verrucomicrobia. It was possible to isolate several strains from the liquid media, and one bacterium and several fungi were found to produce interesting enzymatic activities. The bacterium Chryseobacterium sp. XAvLW produced α-amylase, β-glucosidase, endo-1,4-β-D-glucanase, endo-1,4-β-D-xylanase and filter paper-cellulase, while the fungi Sarocladium kiliense CTGxxyl and Trichoderma virens CTGxAviL generated the same activities added with endo-1,3-β-D-glucanase. [less ▲]

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See detailEffect of iron nanoparticles synthesized by a sol-gel process on Rhodococcus erythropolis T902.1 for biphenyl degradation
Wannoussa, Wissal ULg; Masy, Thibaut ULg; Lambert, Stéphanie ULg et al

in Journal of Water Resource and Protection (2015), 7

Nanoparticles (NPS) are considered as a new generation of compounds to improve environmental remediation and biological processes. The aim of this study is to investigate the effect of iron NPS ... [more ▼]

Nanoparticles (NPS) are considered as a new generation of compounds to improve environmental remediation and biological processes. The aim of this study is to investigate the effect of iron NPS encapsulated in porous silica (SiO2) on the biphenyl biodegradation by Rhodococcus erythropolis T902.1 (RT902.1). The iron NPS (major iron oxide FexOy form) were dispersed in the porosity of a SiO2 support synthesized by sol-gel process. These Fe/SiO2 NPS offer a stimulating effect on the biodegradation rate of biphenyl, an organic pollutant that is very stable and water-insoluble. This positive impact of NPS on the microbial biodegradation was found to be dependent on the NPS concentration ranging from 10−6 M to 10−4 M. After 18 days of incubation the cultures containing NPS at a concentration of 10−4 M of iron improved RT902.1 growth and degraded 35% more biphenyl than those without NPS (positive control) or with the sole SiO2 particles. Though the microorganism could not interact directly with the insoluble iron NPS, the results show that about 10% and 35% of the initial 10−4 M iron NPS encapsulated in the SiO2 matrix would be incorporated inside or adsorbed on the cell surface respectively and 35% would be released in the supernatant. These results suggest that RT902.1 would produce siderophore-like molecules to attract iron from the porous silica matrix. [less ▲]

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See detailBacteria may enhance species association in an ant-aphid mutualistic relationship
Fischer, Christophe ULg; Lognay, Georges ULg; Detrain, Claire et al

in Chemoecology (2015)

The mutualistic relationships between certain ant and aphid species are well known, the primary benefits being protection for the aphids and carbohydrate-rich honeydew for the ants. Questions remain ... [more ▼]

The mutualistic relationships between certain ant and aphid species are well known, the primary benefits being protection for the aphids and carbohydrate-rich honeydew for the ants. Questions remain, however, as to the exact semiochemical factors that establish and maintain such relationships. In this study we used a series of treatments and associated controls placed at the end of a two-way olfactometer to determine the degree of attractiveness of a complete plant-aphid-honeydew system as well as individual components of that system. Both the olfactometer branch selected by the black garden ant (Lasius niger), and the linear speed with which ants moved through the device, were measured. Study results showed that ants were attracted not just to the complete plant system and the honeydew itself, but also to the microbial flora in the absence of plant or honeydew, and specifically to a bacterium from the black bean aphid (Aphis fabae) honeydew, Staphylococcus xylosus. This bacterium produces a blend of semiochemicals that attract the ant scouts. This information suggests the presence of a naturally-occurring, reliable biotic cue for detection of potential aphid partners. This would have to be confirmed in natural conditions by further field experiments. Rather than being opportunistic species that coincidentally colonize a sugar-rich environment, microorganisms living in aphid honeydew may be able to alter emissions of volatile organic compounds (VOCs), thus significantly mediating partner attraction. A bacterial involvement in this mutualistic relationship could alter the manner in which these and similar relationships are viewed and evaluated. Future studies into mutualism stability and function among macroscopic partners will likely need to transition from a two-partner perspective to a multiple-partner perspective, and consider the microbial component, with the potential for one or more taxa making significant contributions to the relationship [less ▲]

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See detailManufacturing of Kivuguto milk and stability in storage under refrigeration
Karenzi, Eugène; Fauconnier, Marie-Laure ULg; Destain, Jacqueline ULg et al

in European Scientific Journal (2015), 11(3), 1-16

The kivugutomilk was processed in a 20 liters bioreactor with three bacteria previously selected in kivuguto traditional milk. The work aimed to study the association of three bacteria previously selected ... [more ▼]

The kivugutomilk was processed in a 20 liters bioreactor with three bacteria previously selected in kivuguto traditional milk. The work aimed to study the association of three bacteria previously selected in traditional kivuguto in order to reproduce it in a controlled fermentation, and thereafter to understand its stability during storage under refrigeration. Postacidification, viability, proteolysis, flavor compounds as well as rheological characteristics were monitored for 36 days. The ph decreases from 4.54 to 4.45 and the titratable acidity grew from 73°d to 79°d. The final biomass after storage was 0.60 108 cfu.g-1 which is far higher than the recommended 106 cells.g-1before consumption. The proteolysis was at a range of 3.0 to 7.0 mg.l-1of lysine equivalent, which is too low so that it can’t produce bitter peptides. The evolution of flavor compounds in storage showed that no change found with 3-methylbutan-1-ol, acetic acid and furan-2(5h)-one, whilst pentan-1-ol and furanmethan-2-ol increased slightly upon 24 days’ storage. The complex viscosity decreased from 4 - 5.3 pas before storage to 2.9 - 4.0 pas corresponding respectively to the ratio g''/g' of about 0.3-0.4 with a very low variation. These data allowed the production and the good preservation of kivuguto milk at 4°c on 36 days. [less ▲]

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