References of "Bauwens, Julien"
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See detailWood digestion in lower termites: multidisciplinary approaches based on differential feeding
Bauwens, Julien ULg; Brasseur, Catherine ULg; Tarayre, Cédric ULg et al

Poster (2014, December)

Termites digestive tract and hindgut especially still holds many secrets despites hundreds of years of research. The complexity of the symbiotic microbial community and the contrast of physio-chemical ... [more ▼]

Termites digestive tract and hindgut especially still holds many secrets despites hundreds of years of research. The complexity of the symbiotic microbial community and the contrast of physio-chemical environments found in lower termites paunch are potentially the key point to explain the efficiency of ligno-cellulose digestion. Contribution of advancing technologies accelerates the progress of our knowledge in this field. Here, we present multiple approaches combining old and recent techniques used to highlight the effect of ligno-cellulosic compounds on termite gut and the role of populations from the symbiotic microbial community. Termites Reticulitermes flavipes (Kollar) submitted to various artificial diets showed variations in flagellates populations profile and enzymatic activities. Differential protein expression was investigated using 2D-DIGE MALDI-TOF-TOF and 2D-LC-MS/MS using high resolution orbitrap analyzer. Results from both proteomic experiments tend to support each-other and bring complementary points of view. The gel-free analysis resulted in highly contrasted identification of enzymes involved in ligno-cellulose digestion and metabolism. Finally, differential feeding experiments leaded to in vivo selection of different symbiotic communities. These communities were characterized following some metabolism assays and allowed the cultivation of diverse microbial consortia using media closely related to the respective artificial diets. This work provides relevant data on termite and associated microbial community response to alimentary diets. [less ▲]

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See detailIsolation and cultivation of xylanolytic and cellulolytic Sarocladium kiliense and Trichoderma virens from the gut of the termite Reticulitermes santonensis
Tarayre, Cédric ULg; Bauwens, Julien ULg; Brasseur, Catherine ULg et al

in Environmental Science & Pollution Research (2014)

The purpose of this work was the isolation and cultivation of cellulolytic and xylanolytic microorganisms extracted from the gut of the lower termite Reticulitermes santonensis. Microcrystalline cellulose ... [more ▼]

The purpose of this work was the isolation and cultivation of cellulolytic and xylanolytic microorganisms extracted from the gut of the lower termite Reticulitermes santonensis. Microcrystalline cellulose (with and without lignin) and beech wood xylan were used as diets instead of poplar wood in order to select cellulose and hemicellulose-degrading fungi. The strain Sarocladium kiliense (Acremonium kiliense) CTGxxyl was isolated from the termites fed on xylan, while the strain Trichoderma virens CTGxAviL was isolated from the termites fed on cellulose (with and without lignin). Both molds were cultivated in liquid media containing different substrates: agro-residues or purified polymers. S. kiliense produced maximal β-glucosidase, endo-1,4-β-D-glucanase, exo-1,4-β-D-glucanase and endo-1,4-β-D-xylanase activities of 0.103, 3.99, 0.53, and 40.8 IU/ml, respectively. T. virens produced maximal β-xylosidase, endo-1,4-β-D-glucanase, exo-1,4-β-D-glucanase, and endo-1,4-β-D-xylanase activities of 0.38, 1.48, 0.69, and 426 IU/ml. The cellulase and the xylanase of S. kiliense, less common than T. virens, were further investigated. The optimal activity of the xylanase was observed at pH 9–10 at 60 °C. The cellulase showed its maximal activity at pH 10, 70 °C. Zymography identified different xylanases produced by both molds, and some fragment sizes were highlighted: 35, 100, and 170 kDa for S. kiliense and 20, 40, 80, and 170 kDa for T. virens. In both cases, endo-1,4-β-D-xylanase activitieswere confirmed through mass spectrometry. [less ▲]

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See detailDesign of a fungal biofilm reactor for recombinant protein production from Aspergillus oryzae
Zune, Quentin ULg; Delepierre, Anissa ULg; Bauwens, Julien ULg et al

Poster (2014, September 07)

Fungi are microorganisms exhibiting high secretive power of various metabolites and have the ability to perform post-translational modifications during protein synthesis. In the field of fermentation ... [more ▼]

Fungi are microorganisms exhibiting high secretive power of various metabolites and have the ability to perform post-translational modifications during protein synthesis. In the field of fermentation industry, they are ideal hosts for secondary metabolites and recombinant protein production. At the industrial-scale, equipments usually required for solid-state or submerged fermentation of filamentous fungi have demonstrated their limitations in terms of productivity, mass transfers or products recovery (1, 2). Recently, fungal biofilm reactors were designed to combine advantages from submerged and solid-state culture and reveal their usefulness for greater secondary metabolites production relative to submerged culture conditions (3). In our work, we propose the design of a fungal biofilm reactor for a recombinant protein production from an Aspergillus oryzae strain containing a GFP reporter gene system under the control of a promoter specifically induced in solid-state conditions. The fungal biofilm reactor is composed of a metal structured packing, having the function of inert support for biofilm growth, immerged or aspersed by a liquid medium. Whereas recombinant protein production is not significantly different at the flask-scale between submerged and biofilm conditions, productivity is higher in the submerged conditions at the bioreactor-scale. Presence of recombinant proteins entrapped in the biofilm matrix highlights a diffusion constraint and a lower mass transfer in our fungal biofilm reactor. However, persistence of a free liquid biomass of low viscosity and fungal biomass retention on the support are attractive for the implementation of a continuous process in our fungal biofilm reactor. Further studies will consider a 2-D proteomic comparison of the extracellular medium from fungal biofilm reactor and submerged culture conditions in order to better understand proteins secretion and identify over-expressed proteins in biofilm conditions. [less ▲]

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See detailMultidisciplinary approaches and fractionations to study lower termite symbiotic system and ligno-cellulose digestion
Bauwens, Julien ULg; Brasseur, Catherine ULg; Tarayre, Cédric ULg et al

Poster (2014, August)

Wood-feeding termites are a considerable source of enzymes active on ligno-cellulosic compounds. These enzymes are produced by the termite host and some representatives of its symbiotic microbial ... [more ▼]

Wood-feeding termites are a considerable source of enzymes active on ligno-cellulosic compounds. These enzymes are produced by the termite host and some representatives of its symbiotic microbial community, and are of particular interest in regard second generation biofuel. However, the complexity of microbial interactions renders micro-organisms isolation very difficult. Culture-independent methods permitted to gather a large amount of data and to understand a little more the role of each microbial population, particularly the prokaryotes. Proteomics allows working on the final product of gene expression, and corresponds more to the real operation of the digestive system. In order to investigate such a complex system, it is necessary to use multidisciplinary approaches and to fractionate this system. Zymography or affinity chromatography are used in parallel of routine proteomics techniques such as two-dimensional gel electrophoresis associated to MALDI-TOF mass spectrometry and nano-LC ESI-MS/MS. We used an artificial-diet based rearing to induce changes in microbial population balance. We performed preliminary assay to investigate the glycosylated proteome in the hindgut of a lower termite, using Multi-Lectin Affinity Chromatography (M-LAC) and enzymatic activity of harvested fractions was assessed on cellulosic substrates. [less ▲]

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See detailAphid - symbiont interactions : multitrophic "omic" approaches to investigate multitrophic interactions
Bosquée, Emilie ULg; Bauwens, Julien ULg; Mazzucchelli, Gabriel ULg et al

Poster (2014, August)

« Omics » found recent developments due to significant improvement and availability of both separation and identification methods. For proteomics, functional information’s linked to the studied proteins ... [more ▼]

« Omics » found recent developments due to significant improvement and availability of both separation and identification methods. For proteomics, functional information’s linked to the studied proteins was brought when compared to genomic approach. For these reasons, a panel of tools is available to determine the proteome patterns related to differential adaptation of insects to cope with plant defence mechanisms or to transmit virus. The adaptation and metabolic changes of aphids in relation to host plants focusing on the role of the bacterial endosymbionts was investigated. Use of artificial diet including diverse antibiotics but also the comparison of proteomes related to whole aphid and respective purified bacterial symbionts were studied to identify the respective origin and function of proteins constituting the studied proteomes. Diverse methods including 2D-DIGE, liquid chromatography coupled with mass spectrometry and data bank investigations were developed. From the proteome investigation, characterisation of good and bad virus vectors was also performed in different aphid - plant - virus models. Particular proteins of interest were selected. This broad proteomic approach will be discussed as an interesting and reliable tool to study the biologically involved proteins from aphids in response to several environmental changes [less ▲]

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See detailEffect of an anti-termite treatment on hindgut content metaproteome
Bauwens, Julien ULg; Fossépré, Marie; De Pauw, Edwin ULg et al

Conference (2014, July 16)

Introduction Termites are studied for many aspects of their biology. Historically known as pests in regard of human activities, these insects were more recently intensively investigated in the biofuel ... [more ▼]

Introduction Termites are studied for many aspects of their biology. Historically known as pests in regard of human activities, these insects were more recently intensively investigated in the biofuel context. Symbiotic interactions occurring along the termite gut are of particular interest for both of these scopes. In this study we compared hindgut metaproteome of termites fed with an anti-termite treatment and an untreated diet. Material & Methods Termites were fed with Whatman paper for 84 hours. For untreated and treated diet respectively, paper was moisten with water and a sub lethal suspension of tannins associated with boric acid (BAT). Termite hindgut content proteome was extracted and digested. Peptides were analyzed through nano-LC-ESI-MS/MS using an Orbitrap analyzer. Proteins identification was realized by Mascot search in a homemade termite protein sequences database. Non redundant peptides with a score above identity threshold were blasted against NCBI nr database and results of this blast were analyzed using MeGAn 5. Results High resolution mass spectrometry allowed identification of around 1500 and 1000 non redundant peptides respectively for water and ABT treatment. Peptides were parsed following their taxonomic and functional attribution in order to highlight differences in hindgut metabolism such as cellulose digestion or detoxification process. Identification of ubiquitous proteins also revealed differences in symbiotic populations balance. Conclusions Despite the sub lethal concentration for the anti-termite treatment, significant perturbation of hindgut metabolism was observed. Tannins are slightly repulsive for termites compared to boric acid alone, and this has to be taken in account. These results will be completed with biochemical assays, microscopic observations and 2D-DIGE MALDI-TOF/TOF experiment, analyzing potentially synergistic effect between boric acid and tannins. [less ▲]

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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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See detailShort communication - Isolation of amylolytic, xylanolytic, and cellulolytic microorganisms extracted from the gut of the termite Reticulitermes santonensis by means of a micro-aerobic atmosphere
Tarayre, Cédric ULg; Brognaux, Alison ULg; Bauwens, Julien ULg et al

in World Journal of Microbiology & Biotechnology (2013)

The aim of this work was to isolate enzyme-producing microorganisms from the tract of the termite Reticulitermes santonensis. The microorganisms were extracted from the guts and anaerobic (CO2 or CO2/H2 ... [more ▼]

The aim of this work was to isolate enzyme-producing microorganisms from the tract of the termite Reticulitermes santonensis. The microorganisms were extracted from the guts and anaerobic (CO2 or CO2/H2) and micro-aerobic atmospheres were used to stimulate growth. Three different strategies were tried out. First, the sample was spread on Petri dishes containing solid media with carboxymethylcellulose, microcrystalline cellulose or cellobiose. This technique allowed us to isolate two bacteria: Streptomyces sp. strain ABGxAviA1 and Pseudomonas sp. strain ABGxCellA. The second strategy consisted in inoculating a specific liquid medium containing carboxymethylcellulose, microcrystalline cellulose, or cellobiose. The samples were then spread on Petri dishes with the same specific medium containing carboxymethylcellulose, microcrystalline cellulose, or cellobiose. This led to the isolation of the mold Aspergillus sp. strain ABGxAviA2. Finally, the third strategy consisted in heating the first culture and spreading samples on agar plates containing rich medium. This led to the isolation of the bacterium Bacills subtilis strain ABGx. All those steps were achieved in controlled atmospheres. The four enzyme-producing strains which were isolated were obtained by using a micro-aerobic atmosphere. Later, enzymatic assays were performed on the four strains. Streptomyces sp. strain ABGxAviA1 was found to produce only amylase, while Pseudomonas sp. strain ABGxCellA was found to produce β-glucosidase as well. Aspergillus sp. strain ABGxAviA2 showed β-glucosidase, amylase, cellulase, and xylanase activities. Finally, Bacillus subtilis strain ABGx produced xylanase and amylase. [less ▲]

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See detailIsolation and Cultivation of a Xylanolytic Bacillus subtilis Extracted from the Gut of the Termite Reticulitermes santonensis
Tarayre, Cédric ULg; Brognaux, Alison ULg; Brasseur, Catherine ULg et al

in Applied Biochemistry and Biotechnology (2013)

The aim of this work was the isolation of xylanolytic microorganisms from the digestive tract of the termite Reticulitermes santonensis. The reducing sugars released after the hydrolysis of xylans can be ... [more ▼]

The aim of this work was the isolation of xylanolytic microorganisms from the digestive tract of the termite Reticulitermes santonensis. The reducing sugars released after the hydrolysis of xylans can be further fermented to provide bioethanol. A xylanolytic strain of Bacillus subtilis was isolated from the hindgut of the termite and displayed amylase and xylanase activities. The bacterium was grown on media containing agricultural residues: wheat bran, wheat distiller’s grains, and rapeseed oil cake. Wheat bran led to the highest induction of xylanase activity, although the development of the strain was less fast than in the other media. It was possible to reach maximal xylanase activities of 44.3, 33.5, and 29.1 I.U./ml in the media containing wheat bran, wheat distiller’s grains, and rapeseed oil cake, respectively. Mass spectrometry identified a wide range of xylose oligomers, highlighting an endoxylanase activity. The enzyme was stable up to 45 °C and displayed an optimal pH close to 8. [less ▲]

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See detailIsolation and cultivation of cellulolytic and xylanolytic bacteria and molds extracted from the gut of the termite Reticulitermes santonensis (3DV.1.14)
Tarayre, Cédric ULg; Bauwens, Julien ULg; Mattéotti, Christel et al

Poster (2013, June)

Biofuel production can be based on the use of agro-residues, consisting in a complex lignocellulosic structure which is not easily hydrolysable. The digestive tract of the termite Reticulitermes ... [more ▼]

Biofuel production can be based on the use of agro-residues, consisting in a complex lignocellulosic structure which is not easily hydrolysable. The digestive tract of the termite Reticulitermes santonensis contains a diversified microflora able to hydrolyze the wood components. Bacteria, molds and protists form efficient consortia, able to break the lignocellulosic complex by producing enzymes, such as xylanases and cellulases. Our purpose is the isolation of microbial strains from termite guts in order to evaluate their potential for hydrolysis of lignocellulosic materials. Termites were fed using different diets chosen to improve the xylanolytic and cellulolytic microflora: wood, microcristalline cellulose (added with lignin or not), α-cellulose (added with lignin or not) and birchwood xylan. Then, dissections were realized to isolate the potential xylanolytic and cellulolytic strains. This approach led us to isolate and to study several strains of bacteria (Bacillus sp. strain CTGx and Chryseobacterium sp. strain CTGx) and molds (Trichoderma virens strain CTGx and Sarocladium kiliense strain CTGx). These microorganisms were able to hydrolyze starch, xylan, cellulose, carboxymethylcellulose, esculin, β-glucan and Whatman® filter paper. They can produce glucose and xylose monomers and oligomers which can be further fermented to produce bioethanol. [less ▲]

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See detailResearch of New Enzyme Producing Strains in the Gut of the Termite Reticulitermes santonensis
Tarayre, Cédric ULg; Bauwens, Julien ULg; Mattéotti, Christel et al

Poster (2013, June)

Termites contain a complex microflora inside of their guts. Inferior termites contain bacteria, mycetes and protists that interact to degrade vegetable components. These strains act as consortia to break ... [more ▼]

Termites contain a complex microflora inside of their guts. Inferior termites contain bacteria, mycetes and protists that interact to degrade vegetable components. These strains act as consortia to break natural materials by secreting various enzymes. Our aim was the isolation and cultivation of microorganisms in order to produce new enzymes that can be further used in green chemistry. Termites were fed with different diets: pinewood, microcristalline cellulose (added with lignin or not), α-cellulose (added with lignin or not) and birchwood xylan. Then, dissections were realized to isolate interesting strains. All the microorganisms were subjected to enzyme assays. That technique allowed us to isolate and to cultivate various strains of bacteria, molds and protists. Three strains of bacteria, two strains of molds and one strain of protist were isolated and displayed different enzymatic activities. The bacteria Bacillus subtilis strain ABGx, Bacillus sp. strain CTGx and Chryseobacterium sp. strain CTGx displayed amylase, cellulase and xylanase activities. The molds Trichoderma virens strain CTGx and Sarocladium kiliense strain CTGx were also able to produce those enzymes. However, the protist Poterioochromonas sp. was found to produce only amylase. In conlusion, the termite gut is a complex culivation medium that provides a habitat for many microorganisms that show interesting enzymatic activities. [less ▲]

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See detailSymbiont Diversity in Reticulitermes santonensis (Isoptera: Rhinotermitidae): Investigation Strategy Through Proteomics.
Bauwens, Julien ULg; Millet, Catherine ULg; Tarayre, Cédric ULg et al

in Environmental entomology (2013), 42(5), 882-7

The complex microbial community living in the hindgut of lower termites includes prokaryotes, flagellates, yeasts, and filamentous fungi. Many microorganisms are found in the termite gut, but only a few ... [more ▼]

The complex microbial community living in the hindgut of lower termites includes prokaryotes, flagellates, yeasts, and filamentous fungi. Many microorganisms are found in the termite gut, but only a few are thought to be involved in symbiotic association to participate in cellulose digestion. Proteomics provides analyses from both taxonomical and functional perspectives. We aimed to identify symbiont diversity in the gut of Reticulitermes santonensis (Feytaud), via complementary electrospray ionization associated to ion trap tandem mass spectrometry (LC-MS/MS) and two-dimensional gel electrophoresis associated to matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry analysis. One specific challenge to the study of lower termites is the relatively few data available on abundant symbiotic flagellates. Analysis based on LC-MS/MS revealed few protein families showing assignments to eukaryotes and the taxonomic origin of highly represented actins could not be established. Tubulins proved to be the most suitable protein family with which to identify flagellate populations from hindgut samples using LC-MS/MS, compared with other protein families, although this method targeted few prokaryotes in our assay. Similarly, two-dimensional gel electrophoresis associated to matrix-assisted laser desorption-ionization-time-of-flight mass spectrometry did not succeed in identifying flagellate populations, but did permit the identification of most of the prokaryotic components of the symbiotic system. Finally, fungi and yeasts were identified by both methods. Owing to the lack of sequenced genes in flagellates, targeting tubulins for LC-MS/MS could allow fingerprints of flagellate populations to be established. Experimental and technical improvements might increase the efficiency of identification of prokaryotic populations in the near future, based on metaproteomic development. [less ▲]

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