References of "Delvigne, Frank"
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See detailMetabolic variability in bioprocessing : implications of microbial phenotypic heterogeneity
Delvigne, Frank ULg; Zune, Quentin ULg; Lara, Alvaro et al

in Trends in Biotechnology (in press)

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See detailDynamic single-cell analysis of Saccharomyces cerevisiae under process perturbation: comparison of different methods for monitoring the intensity of population heterogeneity
Delvigne, Frank ULg; Baert, Jonathan ULg; Gofflot, Sébastien et al

in Journal of Chemical Technology & Biotechnology (in press)

BACKGROUND: Single cell biology has attracted a lot of attention these past few years and has led to numerous fundamental results pointing out the heterogeneity of clonal cell populations. In this context ... [more ▼]

BACKGROUND: Single cell biology has attracted a lot of attention these past few years and has led to numerous fundamental results pointing out the heterogeneity of clonal cell populations. In this context, microbial phenotypic heterogeneity under bioprocessing conditions needs to be further investigated. In this study, yeast based processes have been investigated by using on-line flow cytometry in combination with a fluorescent transcriptional reporter (GFP) and viability fluorescence tags (propidium iodide, PI). Methods aiming at expressing the dispersion of these fluorescence tags among the yeast populations have been investigated for different bioreactor operating conditions. RESULTS: Yeast viability was determined on the basis of PI uptake. Segregation between PI negative and positive subpopulations could be efficiently quantified on the basis of the mean-to-median ratio or the amplitude of the interquartile range. On the other hand, the same quantification could not be made for the segregation occurring at the level of GFP synthesis. Indeed, when cells were exposed to sub-lethal or mild stresses (such as in scale-down reactors) two GFP subpopulations could be visualized by real-time FC, but quantification by one of the above-mentioned methods was not possible. CONCLUSIONS: Yeast population heterogeneity was observed in representative bioreactor operating conditions. Difficulties for the determination of segregation at the level of GFP synthesis point out the fact that one needs to understand the segregation mechanisms for the applied fluorescent reporters, to judge whether simple mathematical tools may be applied or if more sophisticated computational tools are needed for the quantification of the microbial population segregation. [less ▲]

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See detailFungal biofilm reactor improves the productivity of hydrophobin HFBII
Khalesi, Mohammadreza; Zune, Quentin ULg; Telek, Samuel ULg et al

in Biochemical Engineering Journal (in press)

Production and purification of hydrophobin HFBII has recently been the subject of intensive research, but the yield of production needs to be further improved for a generic use of this molecule at ... [more ▼]

Production and purification of hydrophobin HFBII has recently been the subject of intensive research, but the yield of production needs to be further improved for a generic use of this molecule at industrial scale. In a first step, the influence of different carbon sources on the growth of Trichoderma reesei and the production of HFBII was investigated. The optimum productivity was obtained by using 40 g/L lactose. Carbon starvation and excretion of extracellular enzyme were determined as two main conditions for the production of HFBII. In the second phase, and according to the physiological mechanisms observed during the screening phase, a bioreactor set up has been designed and two modes of cultures have been investigated, i.e. the classical submerged fermentation and a fungal biofilm reactor. In this last set-up, the broth is continuously recirculated on a metal packing exhibiting a high specific surface. In this case, the fungal biomass was mainly attached to the metal packing, leading to a simplification of downstream processing scheme. More importantly, the HFBII concentration increased up to 48.6 ± 6.2 mg/L which was 1.8 times higher in this reactor configuration and faster than the submerged culture. X-ray tomography analysis shows that the biofilm overgrowth occurs when successive cultures are performed on the same packing. However, this phenomenon has no significant influence on the yield of HFBII, suggesting that this process could be operated in continuous mode. Protein hydrolysis during stationary phase was observed by MALDI-TOF analysis according to the removal of the last amino acid from the structure of HFBII after 48 h from the beginning of fermentation in biofilm reactor. Hopefully this modification does not lead to alternation of the main physicochemical properties of HFBII. [less ▲]

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See detailBiofilm fermentation for the production of insect pathogenic fungi
Bawin, Thomas ULg; Francis, Frédéric ULg; Delvigne, Frank ULg

Poster (2016, July 27)

Currently, integrated pest management that aims to reduce the use of synthetic insecticides by considering all appropriate alternative methods, is promoted. In that context, insect pathogenic fungi could ... [more ▼]

Currently, integrated pest management that aims to reduce the use of synthetic insecticides by considering all appropriate alternative methods, is promoted. In that context, insect pathogenic fungi could be developed as biopesticides in two ways: spores but also metabolites that are recognized as virulence factors. Targeting adequate fermentation method is an important requirement to obtain fungal products (i.e. spores, enzymes and metabolites) of biotechnological interest. The 'Microbial Processes and Interactions' laboratory has developed an innovative fermentation technology (referred to as ‘biofilm fermentation’) involving the growth of fungal biomass on inert supports that are immersed in a liquid nutrient medium. Confining fungal biomass on immersed inert structures provides a hybrid production system aiming to keep a solid-state physiology for sporulation and secretion of metabolites while controlling fermentation parameters. This research project proposes to transfer this technology to culture insect pathogenic fungi, such as Metarhizium anisopliae, for the production of spores and insecticidal metabolites. Development stages include the qualitative and quantitative characterization of its impact on insecticidal products as well as scale-up to industrial level. [less ▲]

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See detailImpacts of entomopathogenic fungi on biology and behaviour of the invasive Brown Marmorated Stink Bug (Hemiptera, Pentatomidae)
Fingu Mabola, Junior Corneille ULg; Serteyn, Laurent ULg; Bawin, Thomas ULg et al

Poster (2016, July 25)

Halyomorpha halys St˚al (Hemiptera, Pentatomidae) is an invasive stink bug coming from Eastern Asia. Besides causing important yields losses in orchards, crop and vegetable fields, it overwinters inside ... [more ▼]

Halyomorpha halys St˚al (Hemiptera, Pentatomidae) is an invasive stink bug coming from Eastern Asia. Besides causing important yields losses in orchards, crop and vegetable fields, it overwinters inside houses as agglomerates of dozens. In Europe, this Brown Marmorated Stink Bug (BMSB) was accidentally introduced in Switzerland in 2007 and has been later observed in surrounding countries (France, Italy, Germany). Based on the current US situation, we can reasonably fear that BMSB will have colonized most of Europe countries in less than a decade. If we already discern a few fungus strains that are efficient against BMSB, very little is known about their actual impact on the insect itself. So we investigated the in- fluence of a fungal infection on insect development parameters and behaviour. Olfactometry was settled to investigate the dispersion and aggregation trends, while electropenetography was used to assess the feeding behaviour. Our results will be discussed to present changes according to healthy/fungus-infected status, in relation to potential biological control for that pest. [less ▲]

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See detailOn the α-polarization of bacterial suspensions: SIP measurements on four bacterial strains
Pilawski, Tamara ULg; Tappe, Wolfgang; Zimmermann, Egon et al

Poster (2016, June 06)

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See detailCharacterisation of Phosphate Accumulating Organisms and Techniques for Polyphosphate Detection: A Review
Tarayre, Cédric ULg; Nguyen, Huu-Thanh; Brognaux, Alison ULg et al

in Sensors (2016), 16(797), 1-14

Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are ... [more ▼]

Phosphate minerals have long been used for the production of phosphorus-based chemicals used in many economic sectors. However, these resources are not renewable and the natural phosphate stocks are decreasing. In this context, the research of new phosphate sources has become necessary. Many types of wastes contain non-negligible phosphate concentrations, such as wastewater. In wastewater treatment plants, phosphorus is eliminated by physicochemical and/or biological techniques. In this latter case, a specific microbiota, phosphate accumulating organisms (PAOs), accumulates phosphate as polyphosphate. This molecule can be considered as an alternative phosphate source, and is directly extracted from wastewater generated by human activities. This review focuses on the techniques which can be applied to enrich and try to isolate these PAOs, and to detect the presence of polyphosphate in microbial cells. [less ▲]

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See detailSingle cell analysis of Escherichia coli outer membrane porin composition in response to nutrient depletion
Delepierre, Anissa ULg; Brognaux, Alison ULg; Bauwens, Julien ULg et al

Poster (2016, May 12)

Characterization of outer membrane integrity into isoclonal population of Escherichia coli using fluorescent probe specific to cell viability: propidium iodide (PI) staining; combined to FACS cytometry ... [more ▼]

Characterization of outer membrane integrity into isoclonal population of Escherichia coli using fluorescent probe specific to cell viability: propidium iodide (PI) staining; combined to FACS cytometry and proteomic studies of sorted subpopulations. The results tend to reveal two distincts cellular strategies: Cells positively probed by PI offer a high outer membrane protein (OMP) content, indicating nutrient competence in response to substrate limitative conditions. Unprobed cells, characterized by a low OMPs rate, could suffer from growth arrest and develop stress responses (Crp, Cra, RpoS,RpoN, RpoH-dependent). [less ▲]

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See detailHistopathological effects of Aspergillus clavatus (Ascomycota: Trichocomaceae) on larvae of the southern house mosquito, Culex quinquefasciatus (Diptera: Culicidae)
Bawin, Thomas ULg; Seye, Fawrou; Boukraa, Slimane ULg et al

in Fungal Biology (2016), 120(4), 489-499

Aspergillus clavatus (Ascomycota: Trichocomaceae) was previously found to be an opportunistic pathogen of mosquitoes (Diptera: Culicidae). In the present study, the mechanism leading to its insecticidal ... [more ▼]

Aspergillus clavatus (Ascomycota: Trichocomaceae) was previously found to be an opportunistic pathogen of mosquitoes (Diptera: Culicidae). In the present study, the mechanism leading to its insecticidal activity was investigated regarding histological damages on Culex quinquefasciatus larvae exposed to A. clavatus spores. Multiple concentration assays using spore suspensions (0.5 x 10^8 to 2.5 x 10^8 spores/ml) revealed 17.0% to 74.3% corrected mortalities after 48 h exposure. Heat-deactivated spores induced a lower mortality compared to non-heated spores suggesting that insecticidal effects are actively exerted. Spore-treated and untreated larvae were prepared for light microscopy as well as for scanning and transmission electron microscopy. Spores failed to adhere to the external body surface (except the mouth parts) of these aquatic immature stages but progressively filled the digestive tract where their metabolism seemed to activate. In parallel, the internal tissues of the larvae, i.e. the midgut wall, the skeletal muscles, and the cuticle-secreting epidermis, were progressively destroyed between 8 and 24 h of exposure. These observations suggest that toxins secreted by active germinating spores of A. clavatus in the digestive tract altered the larval tissues, leading to their necrosis and causing larval death. Fungal proliferation and sporulation then occurred during a saprophytic phase. A. clavatus enzymes or toxins responsible for these pathogenic effects need to be identified in further studies before any use of this fungus in mosquito control. [less ▲]

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See detailEnhanced biomass production of a novel Acetobacter strain isolated from Moroccan biotopes using response surface methodology approach
Mounir, Majid ULg; Hamas, Khadija; Tamraoui, Khadija et al

Conference (2016, March 21)

The objective of this work was first the isolation of novel acetic acid bacteria strains from natural Moroccan habitats, and then, the evaluation of their ability to produce microbial starters for vinegar ... [more ▼]

The objective of this work was first the isolation of novel acetic acid bacteria strains from natural Moroccan habitats, and then, the evaluation of their ability to produce microbial starters for vinegar production in large-scale. The isolation was made from figs, dates, cactus, and traditional fruit vinegars. Four strains, selected from a total of 63 isolates were confirmed to be belonged to Acetobacter species according to biochemical tests and molecular study based on 16s rDNA sequence analysis. Acetic acid fermentation tests, performed on date and apple fermented juices by the selected Acetobacter strains, showed high capacity of acidification. The most efficient strain, isolated from cactus vinegar, yielded an acidity of about 42.5 g/L on apple juice. A cell growth optimization was carried out on the most efficient strain using the response surface methodology (RSM). The linear, quadratic and interaction effects of four factors; ethanol, acetic acid, glucose and pH were studied by the application of a central composite design. 30 experiments were designed to predict the maximum concentration of cell biomass. The optimal calculated values of ethanol, acetic acid, glucose and pH allowing the prediction of the maximum biomass production (2.2 g/L) were 28.18 g/L, 10.12 g/L, 15.15 g/L and 5.33, respectively. Subsequently, further batch fermentations were carried out in a 6 L lab-bioreactor using the optimased culture medium. The results were in line with the predict values. It was concluded that the studied strain is well suited to be used as parental strain to prepare a starter for vinegar fruit production. [less ▲]

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See detailProduction of two entomopathogenic Aspergillus species and insecticidal activity against the mosquito Culex quinquefasciatus compared to Metarhizium anisopliae
Bawin, Thomas ULg; Seye, Fawrou; Boukraa, Slimane ULg et al

in Biocontrol Science & Technology (2016), 26(5), 617-629

Entomopathogenic micro-organisms including fungi have become increasingly studied for integrated pest management. The spore productivity and insecticidal activity of two opportunistic insect pathogenic ... [more ▼]

Entomopathogenic micro-organisms including fungi have become increasingly studied for integrated pest management. The spore productivity and insecticidal activity of two opportunistic insect pathogenic Aspergillus species (namely: Aspergillus clavatus Desmazieres and Aspergillus flavus Link (Ascomycota: Eurotiales, Trichocomaceae)) were compared to Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin (Ascomycota: Hypocreales, Clavicipitaceae) for mosquito (Diptera: Culicidae) control. The production of aerial spores on wheat bran and white rice was investigated in solid-, semi-solid-, and liquid-state media supplemented with a nutritive solution. Wheat bran-based media were suitable for spore production and increased the spore yield in solid-state from 3 to 7 fold: A. clavatus produced 48.4 ± 5.2 and 15.7 ± 1.6 x 10^8 spores/g, A. flavus produced 22.3 ± 4.1 and 3.1 ± 2.5 x 10^8 spores/g, and M. anisopliae produced 39.6 ± 6.5 and 13.1 ± 2.6 x 10^8 spores/g of wheat bran or white rice, respectively. A. clavatus, A. flavus and M. anisopliae spores harvested from wheat bran-based solid-state media showed lethal concentrations (LC50) of 1.1, 1.8, and 1.3 x 10^8 spores/ml against Culex quinquefasciatus Say larvae in 72 h. Because A. clavatus and M. anisopliae displayed similar features when cultured under these conditions, our results suggest that insect pathogenic Aspergillus species may be as productive and virulent against mosquito larvae as a well-recognized entomopathogenic fungus. Wheat bran could advantageously be used in large-scale fermentation for a possible cost-effective pest control using these fungi. [less ▲]

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See detailFrom Valeriana officinalis to cancer therapy: the success of a bio-sourced compound
Hamaïdia, Malik ULg; Barez, Pierre-Yves ULg; Carpentier, Alexandre ULg et al

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment (2016), 20

Over the centuries, bio-sourced compounds isolated from plants, insects and microorganisms have been a potent source of drugs for the treatment of human diseases. In this review, we recapitulate the story ... [more ▼]

Over the centuries, bio-sourced compounds isolated from plants, insects and microorganisms have been a potent source of drugs for the treatment of human diseases. In this review, we recapitulate the story of one of these compounds, 2-propylpentanoic acid, derived from the Valeriana officinalis flowering plant and its path to validation as a cancer treatment. [less ▲]

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See detailNew perspectives for the design of sustainable bioprocesses for phosphorus recovery from waste
Tarayre, Cédric ULg; De Clercq, Lies; Charlier, Raphaëlle et al

in Bioresource Technology (2016), 206

Phosphate rock has long been used for the production of phosphorus based chemicals. However, considering the depletion of the reservoirs and the decrease of the quality of phosphate rocks, a potential ... [more ▼]

Phosphate rock has long been used for the production of phosphorus based chemicals. However, considering the depletion of the reservoirs and the decrease of the quality of phosphate rocks, a potential market is now emerging for the recovery of phosphate from waste and its reuse for different applications. Notably, phosphate recovery from wastewater could be included in a circular economy approach. This review focuses on the use of microbial systems for phosphorus accumulation and recovery, by considering the actual range of analytical techniques available for the monitoring of phosphorus accumulating organisms, as well as the actual biochemical and metabolic engineering toolbox available for the optimization of bioprocesses. In this context, knowledge gathered from process, system and synthetic biology could potentially lead to innovative process design. [less ▲]

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See detailFlow cytometry community fingerprinting and amplicon sequencing for the assessment of landfill leachate cellulolytic bioaugmentation
Kinet, Romain ULg; Dzaomuho, Phidias; Baert, Jonathan ULg et al

in Bioresource Technology (2016)

Flow cytometry (FCM) is a high throughput single cell technology that is actually becoming widely used for studying phenotypic and genotypic diversity among microbial communities. This technology is ... [more ▼]

Flow cytometry (FCM) is a high throughput single cell technology that is actually becoming widely used for studying phenotypic and genotypic diversity among microbial communities. This technology is considered in this work for the assessment of a bioaugmentation treatment in order to enhance cellulolytic potential of landfill leachate. The experimental results reveal the relevant increase of leachate cellulolytic potential due to bioaugmentation. Cytometric monitoring of microbial dynamics along these assays is then realized. The Flow FP package is used to establish microbial samples fingerprint from initial 2D cytometry histograms. This procedure allows highlighting microbial communities' variation along the assays. Cytometric and 16S rRNA gene sequencing fingerprinting methods are then compared. The two approaches give same evidence about microbial dynamics throughout digestion assay. There are however a lack of significant correlation between cytometric and amplicon sequencing fingerprint at genus or species level. Same phenotypical profiles of microbiota during assays matched to several 16S rRNA gene sequencing ones. Flow cytometry fingerprinting can thus be considered as a promising routine on-site method suitable for the detection of stability/variation/disturbance of complex microbial communities involved in bioprocesses. [less ▲]

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See detailInfluence of methanol/sorbitol co-feeding rate on pAOX1 induction in a Pichia pastoris Mut+ strain in bioreactor with limited oxygen transfer rate.
Carly, F.; Niu, H.; Delvigne, Frank ULg et al

in Journal of industrial microbiology & biotechnology (2016), 43(4), 517-23

High Pichia pastoris biomass density could be obtained using high co-feeding rate of methanol and sorbitol in a fed-batch or continuous culture, while further higher feeding rate finally leads to oxygen ... [more ▼]

High Pichia pastoris biomass density could be obtained using high co-feeding rate of methanol and sorbitol in a fed-batch or continuous culture, while further higher feeding rate finally leads to oxygen limitation in bioreactor. In the literature, there is lack of report about AOX1 promoter regulation with regard to dissolved oxygen level (DO). Therefore, in this work, chemostat cultures were performed to investigate the cell growth, metabolism and regulation of the AOX1 promoter (pAOX1) regarding co-feeding rate of optimized methanol/sorbitol mixture (methanol fraction 0.60 C-mol/C-mol) using a P. pastoris Mut+/pAOX1-lacZ strain. The oxygen transfer rates (OTR) in bioreactor were kept in the range of typical values of large bioreactor, i.e., 4-8 g/(L h) if DO equals 30 % saturation or 5-10 g/(L h) if DO nears zero. For DO >0, an increase of the carbon fed led to an increase of pAOX1 induction. By contrast, when dissolved oxygen was completely depleted, methanol accumulated, causing a 30 % decrease of pAOX1 induction. However, this decrease is more likely to be lined to methanol accumulation than to low level of dissolved oxygen (<4 % DO). Methanol/sorbitol co-feeding allowed cells to adapt to oxygen transient limitations that often occur at industrial scale with reduced effect on pAOX1 induction. The optimal feeding rate tested here was 6.6 mmol C (DCW h)(-1) at an OTR of 8.28 g O2(L h)(-1) with over fivefold pAOX1 induction (probably directly associated with target protein productivity) compared with previous work. [less ▲]

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