Dissertationen zum Thema „Cultures microbiennes“
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Postec, Anne. „Diversité de populations microbiennes thermophiles d'une cheminée hydrothermale océanique : cultures d'enrichissement en bioréacteur et isolement d'espèces nouvelles“. Aix-Marseille 1, 2005. http://www.theses.fr/2005AIX11049.
Der volle Inhalt der QuelleBouderka, Feriel. „Exploring the symbiotic lifestyle of Patescibacteria : from a single consortium to phylum-level evolution“. Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL018.
Der volle Inhalt der QuellePatescibacteria is a highly diverse bacterial phylum, including at least 25% of the bacterial diversity. Representatives of this clade can be found in many environments, ranging from freshwater and marine ecosystems to animal microbiomes and sediments. Very few Patescibacteria cultures are available to date. Due to this lack of cultured representatives, they have been extensively studied using metagenomics. These investigations revealed that, overall, they present small genomes with significant gaps in the genes coding for metabolic functions, and thus, they are hypothesized to depend on a host for survival. There is no evidence, however, that all Patescibacteria are actual symbionts. Besides, about half of their genes cannot be functionally annotated by similarity approaches. More cultured representatives are needed to better understand the ecology of this bacterial phylum. Patescibacteria have been recently reported to be a sister group to the free-living phyla Chloroflexota and Dormibacterota. The evolution of the Patescibacteria, particularly their symbiotic lifestyle, and diversification from their free-living sister group, is not fully comprehended. Here, we obtained an enriched culture of a representative of a new genus-level patescibacterium, which is an epibiont of methanol-oxidizing proteobacteria, a type of host never observed before to be associated with this clade. Additionally, using a CRISPR-spacer match, we identified a new potential phage targeting this patescibacterium. Thus, we characterized the first potential three-partite interaction between a patescibacterium, its host, and a phage. Furthermore, we reconstructed the ancestral gene content of the different Patescibacteria classes to decipher the early steps of the evolution of the symbiotic lifestyle in the clade and the basis of their diversification. Our results suggest that the last common ancestor of Patescibacteria was already host-dependent. The subsequent patescibacterial diversification appears driven by a combination of independent and substantial losses of metabolic genes, complemented by the acquisition of novel genes with functions yet to be identified
Birou, Bernard Birou Bernard. „Etude de la chaleur dégagée par des cultures microbiennes dans un fermenteur de laboratoire /“. [S.l.] : [s.n.], 1986. http://library.epfl.ch/theses/?nr=612.
Der volle Inhalt der QuelleLaplace, Jean-Marie. „Cultures microbiennes pures et mixtes : production d'éthanol à partir des pentoses et des héxoses dérivés des lignocelluloses“. Montpellier 2, 1992. http://www.theses.fr/1992MON20155.
Der volle Inhalt der QuelleTang, Xiaoyan. „Biomasse et communautés microbiennes en relation avec la disponibilité du phosphore dans la rhizosphère de cultures associées“. Thesis, Montpellier, SupAgro, 2013. http://www.theses.fr/2013NSAM0043/document.
Der volle Inhalt der QuellePhosphorus (P) is a major nutrient that is often limiting plant growth in agroecosystems but phosphate rocks being a finite resource, there is an urgent need to find alternatives to P fertilizers and to better use soil P resources. In this context, the aim of my thesis was to elucidate the implication of rhizosphere processes determining the availability of soil P in cereal/legume intercropping systems, and ultimately the acquisition of P by these intercrops. We hypothesized that the facilitation of P acquisition in the rhizosphere in such intercrops was the consequence of microbially mediated processes, as evidenced by shifts of microbial biomass carbon (C), nitrogen (N) and P, or of specific microbial groups. Thus, my research strategy focused on root-induced changes of microbial biomass CNP and community in the rhizosphere of intercrops relative to the same crops grown alone. The effects of P or N fertilization and consequent pH changes as related to N2-fixation were also investigated, either in field experiments or in the controlled conditions of rhizobox microcosms. Durum wheat and different grain legume species were grown as sole crops and intercropped on two types of soils with different fertilization histories. In a first field trial in a calcareous, Mediterranean soil with high P availability, we demonstrated that cereal-legumes intercrops could be used to facilitate P cycling through increasing the microbial biomass and altering its CNP stoichiometry in the rhizosphere. In a second field experiment in a long term P fertilizer trial, we evidenced that a cereal-legume intercrop could increase the microbial biomass P at low P availability and modify microbial groups possibly involved in soil P cycling. Finally, we designed a rhizobox experiment in controlled conditions with soils of this long term trial where we manipulated nitrate availability, in order to assess the interactions of the above-mentioned processes with root-induced pH changes in the rhizosphere. When comparing intercrops and sole crops, we obtained significant differences of soil pH, P availability and microbial biomass CNP and community in the rhizosphere. Although such changes concerned phytase-producing bacteria, the causal relationships between the observed effects still need to be established. A better knowledge of such processes shall help designing more P-efficient intercropping systems in the future
Nercessian, Olivier. „Etude de la diversité spécifique et fonctionnelle des communautes microbiennes associées à des sources hydrothermales marines profondes par des approches moléculaires“. Brest, 2003. http://www.theses.fr/2003BRES2005.
Der volle Inhalt der QuelleOur knowledge of the diversity of marine microbial communities has long been restricted to the precious but incomplete informations generated by the culture-based methods. In this study, molecular techniques (PCR, RT-PCR, cloning, sequencing, hybridization) and genetic markers [16S rRNA, genes coding for enzymes specific of diverse metabolic pathways (mcr A, pmo A, dsrAB)] were used to circumvent the limits inherent to cultivation methods ant to get a more realistic view of the specific and functional diversity of the deep-sea hydrothermal vent microbial communities. This research allowed (i) to reveal a wide diversity af archaeal and bacterial 16S rRNA, and to show the existence of variations in the archaeal coomunity composition at the hydrothermal site and hydrothermal field scales, (ii) to discover new microbial lineages whatever the genetic markers used, and to study the phylogenetic diversity and geopgraphic distribution of one of them (iii) to develop and validate 16S rRNA oligonucleotide probes targeting Archaea frequently found in hydrothermal systems, and (iv) to identify the most active Archaea of a microbial community associated with an hydrothermal sample. By the combined use of diverse molecular approaches, this work enlarges our view of the diversity of microbial communities in deep-sea hydrothermal vents
Vallance, Jessica. „Lutte biologique par utilisation de l’oomycète Pythium oligandrum : colonisation de la rhizosphère et influence sur la dynamique des populations microbiennes“. Brest, 2009. http://www.theses.fr/2009BRES2030.
Der volle Inhalt der QuelleBiocontrol efficacy is mainly limited by the variability of the rhizosphere competence of the inoculated microorganisms. This doctoral thesis focused on Pythium oligandrum, an oomycete acknowledged as an antagonistic organism able to protect plants from pathogenic attacks. The aim of this work was to study the colonisation and the persistence of P. Oligandrum after its introduction in the root system of tomato plants grown in soilless culture; and to assess its impact on microbial communities colonizing the rhizosphere and the greenhouse effluents. Three strains of P. Oligandrum were selected on the basis of their ability to produce oospores (resting structures) and production of tryptamine (an auxin like compound) and of oligandrin (a glycoprotein elicitor). Real-time PCR and plate counting demonstrated the persistence of large amounts of the antagonistic oomycete in the rhizosphere throughout the cropping season (April to September). Inter Simple Sequence Repeat (ISSR) analysis showed that, among the three strains inoculated, the one producing the lowest amount of oospores was detected at 90%. Despite its abundance on roots, no traces of P. Oligandrum were detected in the different effluents of the soilless greenhouse. P. Clissotocum (ubiquitous tomato root minor pathogen) colonized the rhizosphere and the effluents only in summer. There was a reduction of P. Dissotocum populations in inoculated root systems. Single-Strand Conformational Polymorphism (SSCP) analysis revealed that the genetic structure of microbial communities (fungi and bacteria) colonizing the rhizosphere and the effluents, evolved throughout the cropping season. This temporal evolution was independent from the inoculation and the persistence of the antagonist P. Oligandrum. Effluents were also colonized by Archaeabacteria but roots, only during the last two months of culture. These populations grew independently from P. Oligandrum. Results previously described, rely on DNA extraction and amplification. This strategy suffers from the inability to investigate active microbial communities. DNA and RNA data obtained by SSCP analysis of three different genetic regions (ITS1, rRNA 28S, mitochondrial RNA large subunit) highlighted the interest of using different primers for having an exhaustive view of the fungal microflora
Cavaille, Laetitia. „Production de Polyhydroxybutyrates à partir d'acides gras volatils en culture ouverte : influence du degré de limitation en phosphore sur les réponses cinétiques et les sélections microbiennes“. Thesis, Toulouse, INSA, 2015. http://www.theses.fr/2015ISAT0049/document.
Der volle Inhalt der QuelleThe production of polyhydroxyalkanoates (PHA) is an attractive alternative for plastics produced from fossil resources. The technical constraints imposed by pure cultures (purified substrate, sterilization ...) involve a high production cost of PHA production, and the production of these bioplastics is hardly competitive. The use of non-axenic cultures would avoid the constraints of pure cultures but requires a selection step of PHA producers. From a microbial inoculum (activated sludge) and AGV (butyric and acetic acid), a strategy for limiting the growth by phosphorus to accumulate PHB was established. From fed-batch and continuous culture, we studied the selection of PHA producers and the production of PHA based on operating parameters (dilution rate) and environmental (degree of phosphorus limitation). The scientific objective was to improve knowledge on the role of phosphorus limitation according to the operating conditions of the process, first about the nature of selected strains, and then about the cellular growth and PHB accumulation. For this, an approach involving identification of microorganisms by pyrosequencing method, a kinetic characterization of selected microorganisms, a process analysis and development of a kinetic modeling were performed. The ultimate goal of the work was the optimization of PHB production processes in non-axenic culture: productivity, yield, final PHB concentration but also reliability and robustness, to define an optimal production strategy of PHA. The performance achieved during the fed-batch cultures are among the best in the literature (70% PHA) in mixed cultures without enrichment step of PHA producers. The results showed the role of phosphorus limitation on the PHB production. Thus, it has been demonstrated the importance of degree of phosphorus limitation to maintain cell growth allowing enrichment in PHA producers explaining the high content of PHA obtained. From microbial selections in chemostat culture, the analysis of macro-kinetic parameters revealed conversion kinetics of the carbon substrate in PHB, catalytic biomass and CO2, dependent on the degree of phosphorus limitation and growth rate. The limits on the degree of plasticity of the intracellular phosphorus (ranging from 3.8% to 0.045%) were identified as a function of the specific growth rate. This intracellular phosphorus content (depending on the growth rate and degree of phosphorus limitation), is the parameter governing carbon conversion. Furthermore, this role of the intracellular phosphorus was observed for all populations selected under phosphorus limitation in this study, demonstrating a universal behavior of these populations face to phosphorus limitation. In parallel, dynamic studies in batch reactor from these selected populations were used to characterize the kinetic parameters of the strains, showing a maximum PHB production rate of 0.6 and 1.2 Cmol/Cmol.h with acetic acid and butyric respectively. These hypotheses made from experimental observations allowed the establishment of a new kinetic model based on the role of intracellular phosphorus on carbon conversion. The comparison of this model with experimental results has strengthened and improved the understanding of the mechanisms of intracellular phosphorus dilution and storage PHB. This model was also used to explore a wide range of environmental conditions and predict microbial behavior of PHA producers and non-producing organisms according to the operating conditions in continuous or batch reactor. From the results observed and the established kinetic model, the performance of PHA production processes of different configurations was discussed: chemostat single or two-stage, fed-batch, chemostat plus batch... The productivities, intracellular PHB content, performances of selection and the reliability of the process are compared
Riah-Anglet, Wassila. „De la structure des communautés microbiennes, à l'expression des activités enzymatiques dans des sols soumis à différentes contraintes agronomiques“. Rouen, 2014. http://www.theses.fr/2014ROUES058.
Der volle Inhalt der QuelleMulti-criteria assessment of agricultural systems involves acquiring knowledge about the soil biological component, especially about the microbial compartment. The soil microorganisms are essential in biogeochemical cycles and are mainly involved in the transformation of organic matter through their enzymatic activities. Many studies emphasize the possibility to describe the structure and the functions of soil microbial communities. However, little information is available to help the understanding of the structural and functional relationships. Indeed, the factors that influence the structure of microbial communities associated with factors regulating the expression of enzymatic activities make it difficult to apprehend the mechanisms governing these relationships. The objective of this study was to describe the relationships between structure and functions of soil microbial communities. This issue is at the interface between fundamental and applied research. The knowledge of these relationships will improve the understanding of the role of microbial communities in the resistance, resilience and the sustainability of soil. This work was carried out on an agricultural experimental site (Yvetot, Haute Normandie). This site allows the assessment of the effect of the introduction of grasslands in crop rotations. The research strategies developed in this study were based on experiments carried out under natural conditions (in situ) and laboratory soil microcosms (controlled conditions). The selected structural and functional descriptive variables of microbial communities demonstrates, the lively interest of combining qualitative and quantitative approaches based on complementary methods (chemical, biochemical and molecular methods) to restrain the biases of each method and reinforce interpretations. In situ experiments are based on two comparative studies, the first one concerned all plots of the experimental site; these plots had different management practices. The second one consisted of the specific analysis of the two most contrasting agricultural systems: the permanent grassland and conventional cropping. These experiments highlighted that the land use at the time of sampling appears to be the major determinant of the structure of soil microbial communities and their potential enzymatic activities. The change in enzymatic activities weighted by the microbial biomass carbon appears to be determined by the cropping history of the plots. The results also show resilience in functional profile resulting from the evolution of the microbial community structure under the introduction of grasslands in crop rotations. Moreover, the specific analysis of the heterotrophic cultivable bacteria isolated from Biolog Ecoplates substrates of the two most contrasting agricultural soils, highlighted the dominance of Bacteroidetes and γ-Proteobacteria and seems to reflect the initial bacterial diversity of the two soils. In parallel with the previous multifactorial approach under natural conditions, soil microcosm experiments were carried out to investigate the response of microbial communities to drastic stress. The duration and severity of the applied stress aimed to modify the structure of soil microbial communities. These stresses have consisted in applying either a heat shock or a fungicide at 1000 times the recommended dose in the permanent grassland and the conventional crop soils. The results of soil microcosm experiments confirm that the drastic stress changes microbial community structure and enzymatic functions in soils. These results emphasize also that the stress response is dependent on the initial microbial community structure and the type of the applied stress. These results confirm the difficulty to assign a specific enzymatic activity to a specific microbial group due to functional redundancy of soil microbial communities. It also raises the importance of experimental conditions and data statistical analysis in the establishment of these relationships. This study showed the importance of biodiversity in particular its role in ecosystem resilience and also underlined the difficulties describing the microbial communities and their functions in soils under different agronomic constraints. The understanding of these relationships is particularly important as the application of this knowledge in agronomy is required
Guyot, Jean-Pierre. „Etude de quelques interactions microbiennes lors de la digestion anaérobie de la matière organique par des cultures mixtes définies ou naturelles“. Aix-Marseille 1, 1990. http://www.theses.fr/1990AIX11317.
Der volle Inhalt der QuelleBen, Harb Salma. „Formuler des consortia microbiens pour piloter les propriétés sensorielles de gels à base de protéines de pois : Mieux comprendre l’effet de la matrice et des communautés microbiennes sur les propriétés sensorielles“. Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLA045.
Der volle Inhalt der QuelleWestern food systems are not sustainable in terms of environmental impacts and health effects. One solution is to revisit consumption patterns by favoring products based on plant proteins. However, one of the barriers to the introduction plant proteins in our diet is their sensory defects which can be obstacles for the acceptability of products by consumers. Fermentation is an ancient process that could be a solution to this sensory issue. In this context, the aim of this PhD thesis is to study the sensory benefits provided by the fermentation of plant protein-based gels using selected microbial consortia. In order to accomplish this, a strategy combining sensory analyzes, microbiology and physicochemistry was implemented. Two types of matrices containing 10% protein and 10% rapeseed oil were studied: the first consists of 100% pea protein and the second consists of a mixture of milk proteins (50%) and pea proteins (50%).Based on knowledge of the matrix and the functional properties of microorganisms, 56 microbial strains were selected. A reasoned strategy of assembly of these strains was put in place, based on the balanced distribution according to their phylogenetic group, but also on the expert knowledge of the desired aromatic functions. In parallel, several gelling processes were studied to structure the gels. In the first step, the fermentation was studied on non-gelled emulsions to allow the selection of specific microbial communities for each matrix. In the second step, the adaptation and functioning potential of the selected ecosystems were studied on gelled emulsions. The growth and abundance of microorganisms in the gels after three and seven days of fermentation were evaluated on a specific growing medium and the aromatic potential of the consortia was mapped by a sensory panel. In the final section of this study, the sensory defects / benefits of fermentation were studied from a sensorial and analytical point of view. The results show a highpotential for implantation of lactic acid bacteria and the majority of eukaryotes (in particular Mucor and Geotrichum) for the mixed emulsion and for the vegetable emulsion. Although strains belonging to the Actinobacteria and Proteobacteria groups are not competitive with endogenous flora (Bacillus), certain species such as Hafnia alvei, Acinetobacter johnsonii and Glutamicibacter arilaitensis, have shown strong growth when inoculated into associations. Specific aromatic notes for each emulsion were generated to mask the green note characteristic of peas. Thus, two consortia were selected on the basis of lactic and fruity notes for the vegetable emulsion (VEGAN), and fruity notes for the mixed emulsion (MEGAN). The adaptation potential of these two consortia depended on the composition and structure of the gel. Thus, the VEGAN consortium seems well suited for vegetable gels and generates roasted / grilled notes, while it generates dairy notes (fresh cream / fresh curd) in the mixed gels. The MEGAN consortium implements itself very well in both types of gels, generating cheesy and fruity notes in the mixed gel, but does not mask the green notes in the vegetable gels. The sensory defects attributed to green notes and bitterness are mainly related to the presence of aldehydes and hydrophobic amino acids respectively, but still need to be deepened. This study validated a proof of concept of formulation of fermented food products and will create opportunities for innovation
Retureau, Emilie. „Reconstitution de communautés microbiennes complexes pour l'inhibition de Listeria monocytogenes à la surface de fromages à pâte pressée non cuite“. Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00719220.
Der volle Inhalt der QuelleAscon, Dolorès. „Caractérisation des activités métaboliques des bactéries lactiques en cultures pures et mixtes par impédancemétrie et chromatographie gazeuse "headspace"“. Compiègne, 1994. http://www.theses.fr/1994COMPD757.
Der volle Inhalt der QuelleLeblanc, Pierrick. „Sélection et mise en oeuvre "optimale" de souches microbiennes en bioréacteur, pour la production d'acide hyaluronique“. Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0228/document.
Der volle Inhalt der QuelleThis work intended to develop a laboratory scaleproduction process ofhyaluronic acid (HA), a biopolymer of health and cosmetic interest, using a naturally AH producing lactic acid bacterium, Streptococcus zooepidemicus. A literature review allowed to identify the following critical points: firstly, the composition of the culture medium (identification of essential nutrients for microbial growth and synthesis of HA), secondly, the oxygenation level (oxygen transfer and associated redox modifications), and finally, in relation with, the production and metabolism abilities of the considered strains. A preliminary step was dedicated to the developmentorthe improvementof analytical techniques in order todispose of appropriate tools for the monitoring of Streptococcus zooepidemicus metabolism. The quantification of the biomass without considering capsular HA fraction as well as detection of hyaluronidase activity have been developed while other chromatographic and enzymatic methods have been more basically applied to and validated with the substrates and metabolites considered. The laboratory scale cultures of collection (ATCC) as well as “environmental” strains were initially used to formulate a workable cultivation broth and to define suitable culture conditionsfor a use at a larger scale to produce HA. Very positive results were obtained with higher production of HA in comparison with literature assays, while critical influencing factors such as the initial glucose concentration or the oxygenation levelin cultures were highlighted. The influence of these factors was thoroughly studied with bioreactor cultures in both batch and fed-batch modes leading to improved cultivation conditions and culture mode. In parallel, another important step consisted in the highly performance improvement of initially low HA producing "environmental" strains via random mutagenesis. Very promising overproducing mutants have therefore been generated, characterized in their kinetic and metabolic capabilities and long-term stored. At last, one of the best and most reliable mutant has been cultivated with the best previously selected medium composition and operating conditions. Both the HA production level, productivity and size observed validated the findings of this process development work, while helping to identify new improvement domains and strategies
Ben, Harb Salma. „Formuler des consortia microbiens pour piloter les propriétés sensorielles de gels à base de protéines de pois : Mieux comprendre l’effet de la matrice et des communautés microbiennes sur les propriétés sensorielles“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLA045/document.
Der volle Inhalt der QuelleWestern food systems are not sustainable in terms of environmental impacts and health effects. One solution is to revisit consumption patterns by favoring products based on plant proteins. However, one of the barriers to the introduction plant proteins in our diet is their sensory defects which can be obstacles for the acceptability of products by consumers. Fermentation is an ancient process that could be a solution to this sensory issue. In this context, the aim of this PhD thesis is to study the sensory benefits provided by the fermentation of plant protein-based gels using selected microbial consortia. In order to accomplish this, a strategy combining sensory analyzes, microbiology and physicochemistry was implemented. Two types of matrices containing 10% protein and 10% rapeseed oil were studied: the first consists of 100% pea protein and the second consists of a mixture of milk proteins (50%) and pea proteins (50%).Based on knowledge of the matrix and the functional properties of microorganisms, 56 microbial strains were selected. A reasoned strategy of assembly of these strains was put in place, based on the balanced distribution according to their phylogenetic group, but also on the expert knowledge of the desired aromatic functions. In parallel, several gelling processes were studied to structure the gels. In the first step, the fermentation was studied on non-gelled emulsions to allow the selection of specific microbial communities for each matrix. In the second step, the adaptation and functioning potential of the selected ecosystems were studied on gelled emulsions. The growth and abundance of microorganisms in the gels after three and seven days of fermentation were evaluated on a specific growing medium and the aromatic potential of the consortia was mapped by a sensory panel. In the final section of this study, the sensory defects / benefits of fermentation were studied from a sensorial and analytical point of view. The results show a highpotential for implantation of lactic acid bacteria and the majority of eukaryotes (in particular Mucor and Geotrichum) for the mixed emulsion and for the vegetable emulsion. Although strains belonging to the Actinobacteria and Proteobacteria groups are not competitive with endogenous flora (Bacillus), certain species such as Hafnia alvei, Acinetobacter johnsonii and Glutamicibacter arilaitensis, have shown strong growth when inoculated into associations. Specific aromatic notes for each emulsion were generated to mask the green note characteristic of peas. Thus, two consortia were selected on the basis of lactic and fruity notes for the vegetable emulsion (VEGAN), and fruity notes for the mixed emulsion (MEGAN). The adaptation potential of these two consortia depended on the composition and structure of the gel. Thus, the VEGAN consortium seems well suited for vegetable gels and generates roasted / grilled notes, while it generates dairy notes (fresh cream / fresh curd) in the mixed gels. The MEGAN consortium implements itself very well in both types of gels, generating cheesy and fruity notes in the mixed gel, but does not mask the green notes in the vegetable gels. The sensory defects attributed to green notes and bitterness are mainly related to the presence of aldehydes and hydrophobic amino acids respectively, but still need to be deepened. This study validated a proof of concept of formulation of fermented food products and will create opportunities for innovation
Maillard, Francois. „Rôle des communautés microbiennes dans la dégradation de la matière organique en forêt dans un contexte d'exportation intense de biomasse“. Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0190.
Der volle Inhalt der QuelleOne of the main usages of wood in Europe is renewable energy supply that implies intensification of forest management to respond to this increasing demand. However, the impact of intense forestry practices on soil microbial communities remains poorly investigated. In the frame of my PhD thesis, I evaluated effects of artificial organic matter removal on functional and taxonomical diversity of soil bacterial and fungal communities in temperate forest, using six experimental sites across France (INRA MOS experimental network). In parallel, I also characterised impact of intensified forest management practices on functional microbial communities in tropical plantation of Eucalyptus trees. This work permitted to identify several sensitive functional indicators of organic matter degradation. Notably, the degradation of chitin – a nitrogen polymer main component of arthropods and fungal cell walls – was revealed to be particularly sensitive to organic matter removal. Genomics and enzymatic approaches were then used to estimate chitinolytic potentials of the different genera of soil fungi. In controlled conditions, we were able to quantify ectomycorrhizal fungus carbon and nitrogen mobilisation and transfer capacities from chitin enriched organic matter to its host during symbiotic interaction. Finally, we evaluated chitinolytic functions of ectomycorrhizal fungi at large scale by combining enzymatic and isotopic approaches. Taken together, the results acquired in the frame of my PhD thesis, illustrate the significant role of ectomycorrhizal fungi in carbon and nitrogen mobilisation from organic matter. We particularly highlight that microbial compartment in soil must be considered in studies of forest management practices
Hellequin, Eve. „Effets des biostimulants sur le fonctionnement biologique de sols d’agrosystèmes : réponses des communautés microbiennes et dynamique de minéralisation du carbone organique“. Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B029.
Der volle Inhalt der QuelleModern agriculture is undergoing important changes toward agroecological practices that rely on biodiversity and ecological processes. In agrosystems, the organic matter is the key of the soil fertility and an important reserve of carbon. Organic fertilization by crop residues is therefore an agricultural practice that improve the organic matter content in soil. Soil microorganisms have an important role in the organic carbon (orgC) dynamic because they are key players of its mineralization and are involved in the nutrients recycling. Thus, the use of agricultural biostimulant (BS) intended to enhance this microbial function is proposed as an alternative solution to improve indirectly plant growth while reducing chemical inputs. This thesis aimed to i) identify the effect of soil biostimulant on heterotrophic microbial communities, the orgC mineralization and the nutrient releases, ii) evaluate its genericity by testing different experimental conditions and iii) identify the environmental filters that control both the microbial communities and the mineralization function. We showed that the orgC dynamic was different according to contrasted physico-chemical and biological characteristics of different soils. We showed that plants can also influence the orgC dynamic by returning litter to the soil and through its root effect on the bacterial and fungal communities. Unlike plants, the amount of orgC provided by the two tested BS was negligible. However, we evaluated the effect of one BS as at least similar or even higher than those of plant on active bacterial and fungal abundances, richness and diversity. Among the two BS tested we showed that one enhanced the orgC mineralization by recruiting indigenous soil bacterial and fungal decomposers and that the other did not affect the orgC mineralization but activated indigenous soil plant-growth-promoting bacteria as well as soil bacterial and fungal decomposers. Furthermore, our study call for new normative methodological and systemic approach by monitoring simultaneously several descriptors for advancing our knowledge on BS action on microbial soil functioning
Saltaji, Sabrina. „Étude de l’apport de flores microbiennes issues du lait cru, purifiées par le procédé Bionatif®, appliquées à une production fromagère“. Electronic Thesis or Diss., La Rochelle, 2020. http://www.theses.fr/2020LAROS033.
Der volle Inhalt der QuelleStarter cultures confer enhanced properties to improve organoleptic, sensory and nutritional attributes upon the cheese matrix. The subject of this PhD project was the patented Bionatif® process. That process purifies raw milk from hygiene and spoilage microflora. Then, it restores a functional Undefined Mixed Starter Culture (UMSC) to the cheesemaker. That unique UMSC is composed of an intra-specific bacterial diversity specific to the terroir where the raw milk is collected.This work fixed two goals: i) to characterize the diversity of the UMSC and study their metabolic potential, ii) to study the expression of the UMSC in soft cheese technology. The UMSC intra-specific diversity study highlighted some bacterial variants of the L. lactis species. UMSC's L. lactis isolates showed superior and diversified metabolic properties through the expression of their sugar metabolism (D-xylose, D-tagatose, etc.). A comparative genome study confirmed this result and could link these metabolic properties to an environmental origin. L. lactis isolates also possess rich CRISPR-Cas clusters. These clusters could confer them a high resistance against bacteriophages. Besides, an antimicrobial potential has been phenotypically observed and then confirmed through genomic studies. In soft cheese technology, the comparison between defined starter cultures designed under laboratory conditions and UMSC from the Bionatif® process demonstrated that the more complex and diversified the bacterial consortium of the UMSC, the better the sensory and rheological properties of the cheese
Maillard, Francois. „Rôle des communautés microbiennes dans la dégradation de la matière organique en forêt dans un contexte d'exportation intense de biomasse“. Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0190/document.
Der volle Inhalt der QuelleOne of the main usages of wood in Europe is renewable energy supply that implies intensification of forest management to respond to this increasing demand. However, the impact of intense forestry practices on soil microbial communities remains poorly investigated. In the frame of my PhD thesis, I evaluated effects of artificial organic matter removal on functional and taxonomical diversity of soil bacterial and fungal communities in temperate forest, using six experimental sites across France (INRA MOS experimental network). In parallel, I also characterised impact of intensified forest management practices on functional microbial communities in tropical plantation of Eucalyptus trees. This work permitted to identify several sensitive functional indicators of organic matter degradation. Notably, the degradation of chitin – a nitrogen polymer main component of arthropods and fungal cell walls – was revealed to be particularly sensitive to organic matter removal. Genomics and enzymatic approaches were then used to estimate chitinolytic potentials of the different genera of soil fungi. In controlled conditions, we were able to quantify ectomycorrhizal fungus carbon and nitrogen mobilisation and transfer capacities from chitin enriched organic matter to its host during symbiotic interaction. Finally, we evaluated chitinolytic functions of ectomycorrhizal fungi at large scale by combining enzymatic and isotopic approaches. Taken together, the results acquired in the frame of my PhD thesis, illustrate the significant role of ectomycorrhizal fungi in carbon and nitrogen mobilisation from organic matter. We particularly highlight that microbial compartment in soil must be considered in studies of forest management practices
Fifani, Barbara. „Développement de stratégies de coculture favorisant l’amensalisme ou la coopération entre les agents de biocontrôle Bacillus velezensis et Trichoderma harzianum“. Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR054.
Der volle Inhalt der QuelleUnderstanding the interaction between microorganisms is essential for the development of new biocontrol products. The fungus Trichoderma harzianum and the bacteria Bacillus velezensis are exploited for their antagonist activity against phytopathogens. Two coculture strategies of these two microorganisms were developed in order to determine the conditions leading to an interaction which increases the biocontrol activity of this couple, defined in terms of the production of lipopeptides by the bacteria. The culture medium essentially varies between these two strategies. The two media differ depending on the availability of nutrients for the microorganisms. In the medium where Bacillus and Trichoderma have all the necessary elements for their growth, the bacteria thrives at the expense of the fungus thanks to its faster growth rate and the production of antifungal lipopeptides. Sequential inoculation of Trichoderma followed by Bacillus solved these problems preventing the coexistence of the two microorganisms. However, in all of these approaches, the presence of Trichoderma did not influence the production of lipopeptides by B. velezensis and consequently its activity in biocontrol. The effect on the production of these NRPs is most noticeable in a minimal medium designed to impose a nutritional dependence between Bacillus and Trichoderma. The bacteria's requirement for a nitrogen source provided by T. harzianum, mainly in the form of peptides and amino acids, allows them to coexist in coculture. The physical presence of the fungus inhibits the production of lipopeptides, but the presence of its supernatant promotes it. The molecular dialogue between the Trichoderma - Bacillus couple needs to be further deciphered in order to exploit it in agricultural applications
Dijamentiuk, Alexis. „Propagation de communautés bactériennes : modelage, stabilisation et sélection pour la biopréservation“. Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0124.
Der volle Inhalt der QuelleRecent discoveries about microbial communities, or microbiota, have revealed considerable biotechnological potential in a variety of fields. They are considered essential to accelerate innovation in food production systems. However, existing processes are not adapted to the cultivation of microbiota. One major barrier to community propagation is competition between microorganisms, which can lead to an undesirable reduction in biodiversity within the culture reactor. This phenomenon can lead to communities that lack the desired functionality. The objective of this thesis was to study the influence of microbiota propagation, under controlled conditions, on their structure and function. During this work, a process of microbial culture excluding microbial competition for the propagation of bacterial communities was developed. The chosen strategy is based on the micro-confinement and spatial segregation of bacteria within a broth structured as an invert emulsion. The effect of the invert emulsion culture on the growth of individual bacteria was studied, then the effect of this system on the dynamics of communities propagated according to a sequential regime, or backslopping, as well as that exerted by a conventional non-emulsified system was investigated. The results showed that the use of an inverse emulsion leads to the generation of new community structures during propagation, and that the use of the classical culture leads to their stabilization. The different behaviors of these two culture systems make them complementary tools for the modeling and the propagation of microbial communities. Finally, the effect of propagation on the functional variability of communities was studied in a biopreservation context. The screening of propagated raw milk microbiota showed that they differed in terms of robustness and reproducibility of anti-Listeria activity, emphasizing the need to take into account the functional variability of communities when selecting communities of interest for microbiota engineering
Fahimi, Noura. „Étude des interactions entre bactéries lactiques œnologiques Œnococcus œni. Analyses cinétiques et modélisation“. Thesis, Toulouse, INPT, 2012. http://www.theses.fr/2012INPT0008/document.
Der volle Inhalt der QuelleIn winemaking, the control of malolactic fermentation (MLF) by OEnococcus oeni is an essential step for this process. Although winemakers have the availability for selected OE.oeni strains, the MLF is not always successful. The physical-chemical conditions (pH, ethanol, and temperature), the composition of wine, and biological factors, all together influence the activity of this bacterium; regarding biological factors, the interactions between microorganisms are essential. Often, after alcoholic fermentation by yeast, indigenous strains of OE.oeni are naturally present in wine, negative interactions can then occur between the indigenous strains and selected strains; therefore, knowledge on these interactions is needed. The goal of the present work was to study the interactions during MLF between five strains of OE.oeni from different origins. Experiments were performed in the modified MRS medium to be in nearly conditions to those of wine (20 °C, pH 3.5, and 10% ethanol). The characterization of the behavior of strains in pure cultures was done under both, micro-aerobic and anaerobic conditions; a large variability was found between the strains in the two conditions: three out of five strains were favored under anaerobic conditions while the two others were better developed in micro-aerobic conditions. The presence of 4 g.L-1 of L-malic acid in the culture medium increased the biomass produced, about two-fold higher than that obtained in medium without L-malic acid. All of the L-malic acid is consumed by the five strains but at different specific rates. A mathematical model allowed to quantifying the relationship between the specific consumption rate of L-malic acid (ν) and the specific growth rate two specific rates for each strain; for a given strain, both rates have similar profiles during the MLF. Interactions in mixed cultures of 10 couples formed by the five strains were then examined in a Membrane Bioreactor (BRM) under anaerobic conditions. Three different interaction types were identified: 1) negative reciprocal interactions of the both strains in mixture culture, 2) interaction that affect negatively the favored strain in pure culture and positively the slowest one, and 3) interaction with positive effect on the fastest strain in pure culture. Comparison of pure and mixed culture showed that the specific activity of strains was affected in mixture culture causing the extension of the lag phase in the case of inhibition and its shortcut in the case of stimulation. Modeling of the consumption of the L-malic acid revealed activation of the consumption of this acid for some couples however, growth is strongly affected. The interactions affecting the course of the MLF are due solely to the effect of excreted extracellular metabolite(s); these metabolites remain to be identified
Garrido-Sanchez, Luis Edmundo. „Conception et mise en œuvre d'un système d'aide a la modélisation de procédés de fermentation utilisant un système expert et des réseaux de neurones“. Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL023N.
Der volle Inhalt der QuelleLebrun, Laurent. „Production d'exopolysaccharides par des cultures microbiennes libres ou immobilisees dans des membranes planes gel d'agar/membrane microporeuse. Mise en evidence des problemes de transfert de matiere par l'etude de la diffusion de macromolecules (dextrane) a travers les structures immobilisatrices“. Paris 6, 1993. http://www.theses.fr/1993PA066590.
Der volle Inhalt der QuelleBoukhdoud, Nathalie. „Réponses des communautés microbiennes associées à l'olivier à des pratiques agricoles conventionnelles et de conservation : influence des variantes climatiques de la France et du Liban et selon la distance à la mer“. Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4316.
Der volle Inhalt der QuelleOlive grove soils are subjected to harsh environmental pressures such as Mediterranean constraints and intensive agriculture practices. They require a great attention in the context of climate change. In coastal areas, osmotic and thermal stresses are intensified. Under these conditions of intensified pressure, significant changes in soil quality may occur and these changes can be mitigated by ‘sustainable’ farming practices. Thus, this thesis project aimed at evaluating, under coastal constraints, the impact of conventional and conservation practices on microbial activities involved in C and N cycles, and soil chemical characteristics. Depending on the distance from the sea, we evaluated i) functions of microbial communities of olive rhizosphere and phyllosphere, ii) the effect of tillage, Fabaceae co-culture, natural grass, OMW in Lebanon and France, iii) microbial responses to water stress under different practices. This work focused on microbial activities involved in the transformation of organic matter, whose quality was studied by solid state NMR 13C. Therefore, this work reported a ‘coastal print’ on microbial functioning and a likely reduction of CO2 emissions through the application of conservation practices. Therefore, it is necessary to develop, under olive tree culture intensification, practices ensuring stability of ecological functions supported by soils / microorganisms / plants relationships
Fyferling, Mathias. „Transfert d'oxygène en condition de culture microbienne intensive“. Toulouse, INSA, 2007. http://eprint.insa-toulouse.fr/archive/00000172/.
Der volle Inhalt der QuelleThis work aims to quantify and model oxygen transfer in microbial cultures with an objective of intensification of bioprocess performances. Labworks in bioreactors are achieved in mineral media, free from biological reaction, then in fed-batch cultures of Escherichia coli, Saccharomyces cerevisiae and Aspergillus niger. The fieldwork is original because of the high oxygen consumptions rates (0,6 g. L-1. H-1) and the high dissipated power (35 kW. M-3) used. The oxygen transfer coefficient is determined from continuous and dynamic methods, using several unstructured models, to take into account the profile of the dispersed gaseous flow, the gas entrained from the surface, and hold-up. Among the observations, in biological media, (i) values of the oxygen transfer coefficient KT are 5 to 10 times higher than values from the literature on oxygen transfer, (ii) compared with the initial medium prior to inoculation, KT and KL (the oxygen transfer conductance) are 4 to 6 times smaller. Effects of microbial activity on oxygen transfer are characterised and quantified according to enhancements factors related to chemical modifications of the medium, oxygen consumption, and physical presence of cells. Limits of mass transfer models in intensive microbial cultures are discussed and new areas of investigation are proposed
Vallaeys, Tatiana. „Isolement d'une communauté microbienne dégradant l'acide 2,4-dichlorophénoxyacétique à partir d'un sol de Dijon : caractérisations cinétique et génétique des souches impliquées“. Lille 1, 1992. http://www.theses.fr/1992LIL10080.
Der volle Inhalt der QuelleOueslati, Nadia. „Conception et optimisation d'un procédé extrapolable de purification d'acides hyaluroniques produits par culture microbienne“. Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0191/document.
Der volle Inhalt der QuelleHyaluronic acid (HA) is a biopolymer with mechanical and biological properties interesting the health and cosmetic areas. The industrial HA production is realized by implementation of streptococcus strains (group C or D). At the end of the production phase, a part of HA is free in a complex culture medium while the other remains associated to the cells in a capsule. The two main difficulties of the purification of HA lie, firstly, on the complexity of the production medium and, secondly, on the high requirements of the European Pharmacopoeia for such an application. The aim of this thesis was to provide an appropriate sequence of separation processes and a set of operating conditions for HA purification from a complex production medium which complies with the Pharmacopea. Initially, two original analytical methods for quantifying and evaluating the size of HA in complex environments have been developed in order to evaluate the performance criteria of the separation processes. Then, the HA extraction from the capsule, the elimination of cells, the purification and drying of HA were using classical separation processes and studied. The HA extraction by SDS or TCA showed that the HA bound to cells corresponds to 7 % of HA production. As a consequence, it was concluded that this step was not necessary. The cell separations from the culture medium by tangential microfiltration was unsuitable because of an excessive retention of HA (even at pore diameters higher than 0.22 µm) and a too fast membrane clogging. Good performances were observed with dead-end filtration using Celite. Then, the purification of HA by diafiltration (DF) with ultrafiltration membranes was considered. The operating conditions (PTM, feed rate, HA concentration and cutoff) allowing to maximize the permeate flow rate and the HA retention were selected from design of experiments methodology. The performances of purification by diafiltration (DF) in these conditions (yield, purity and productivity) were monitored. A method for predicting the performances according to the complex medium composition, based on the conventional mass balance equations and the DF permeate flow rate, was then proposed. This was done in order to facilitate the arrangement of the purification steps. In DF, the requirement of the pharmacopoeia in term of overall purity was obtained (> 95 %) but the proteins and nucleic acids levels were still above the threshold. This is why the adsorption of these molecules on activated carbon was studied as a function of temperature, ionic strength, pH and the type of activated carbon. The isotherm equations that better fitted the experimental data were selected and used combined to the equations of DF performances in order to find an appropriate chaining. Finally, the AH lyophilization and precipitation in organic solvent were compared. Both drying methods present less than 20 % moisture and preserve the properties of the molecule
Hugues, Patrick d'. „Biolixiviation d'une pyrite cobaltifère : optimisation des conditions de culture et bilans gazeux“. Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11062.
Der volle Inhalt der QuelleAbdelgafour, Djamila. „Epuration biologique des effluents a forte charge“. Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0045.
Der volle Inhalt der QuelleBlanc, Philippe. „Contribution à l'étude de la production d'acide propionique par voie microbienne : modélisation-effets des fortes concentrations cellulaires“. Toulouse, INSA, 1986. http://www.theses.fr/1986ISAT0047.
Der volle Inhalt der QuelleTallon, Richard. „Caractérisation biochimique et moléculaire de la production d'exopolysaccharides (EPS) et étude de la capacité d'adhésion de souches de Lactobacillus plantarum potentiellement probiotiques“. Bordeaux 2, 2004. http://www.theses.fr/2004BOR21157.
Der volle Inhalt der QuelleIsolation of Lb. Plantarum EPS-producing strains is of technological and probiotic interest. Considering its EPS production, a first strain, named EP56, was studied for its physiological, biochemical and genetic aspects. We also investigated the EPS production biodiversity among several Lb. Plantarum strains. Their thickening capacities during soymilk fermentation and adhesion abilities on several biological matrices were also determined. It appeared that EPS nature influences the texture of the end fermented product whereas these polymers were not involved in adhesion on mucin and human GI-tract cell lines. Extraction of the cell-surface components showed that proteinous material was implicated in adhesion
Cros, Camille. „Régulations microbiennes et rhizosphériques des cycles du carbone et de l'azote dans les systèmes de culture conventionnels et innovants“. Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC005/document.
Der volle Inhalt der QuelleThe presence of plants accelerates the decomposition of soil organic matter (SOM) through the supply of energy-rich compounds (rhizodeposits and litter) stimulating microorganisms; a phenomenon called rhizosphere priming effect (RPE). An increase of photosynthesis, supplying soil with rhizodeposited energy, could increase the RPE and soil nutrients offer. Recently, the SYMPHONY model coupling photosynthesis and soil microbial activities suggested an adjustment of the soil nutrient offer (delta mineralization-immobilization) to plant demand. However, the key role of photosynthesis in this offer-demand adjustment needs to be investigated experimentally.The general objective of the thesis is to study the role of interactions between photosynthesis and soil microbial activities in the regulation of carbon (C) and nitrogen (N) fluxes of ecosystems. Three ecosystem types were studied: grassland, wheat monoculture and a new cropping system (NSC) where wheat and perennial grassland species were intercropped. We hypothesize that perennial species, through a continuous photosynthetic activity supplying microorganisms with energy over the year, are essential for offer-demand adjustment.Many technical challenges were overcame to build an experimental platform of 40 mesocosms under natural light and temperature. This platform allows to couple 13C labeling of plants, continuous CO2-exchange measurements, RPE, plant production, soil C storage, N mineralization-immobilization turnover and N leaching.This experimental platform allowed us to determine the contribution of RPE to C fluxes of ecosystems including net ecosystem production (NEP), gross primary production (GPP) and ecosystem respiration (ER) expressed in g C m-2 24h-1. We found positive linear relationships between (1) RPE and GPP and (2) RPE and aboveground biomass (AGB) (g C m-2). Using these relationships, the RPE can be predicted with the following equations: (...).We show an adjustment of soil N-offer to plant N-demand across seasons: a high photosynthetic activity (spring) is linked to high RPE and delta mineralization-immobilization of N whereas a low photosynthetic activity (autumn) is linked to low RPE and delta mineralization-immobilization of N. This adjustment was observed in grassland and NSC but not in wheat monoculture. Consistently, N leaching was high in wheat monoculture while it was almost null in grassland and NSC. After two years of establishment of the three ecosystems, the total aboveground production of the NSC was equivalent to the grassland, each being about twice as high as the wheat monoculture. These results confirm the importance of perennial species in the offer-demand adjustment of N.Our findings underline the importance of plant activities and rhizosphere processes in the regulation of ecosystems C N cycles. Using the proxies of rhizosphere processes (RPE, offer-demand adjustment) provided in the thesis, further studies could investigate these regulations in situ and at the global scale. The presence of photosynthetic and rhizospheric activities over the year are essential for offer-demand adjustment of nutrients leading to high primary production, closing nutrient cycles and SOM storage. These findings offer the opportunity to build new cropping systems such as the wheat-perennial species studied, with high agro-environmental performances
Delavat, François. „Composition et fonctionnement d'une communauté microbienne au sein d'un drainage minier acide : approches culturales et fonctionnelles“. Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00797981.
Der volle Inhalt der QuellePierra, Mélanie. „Couplage de la fermentation sombre et de l’électrolyse microbienne pour la production d’hydrogène : formation et maintenance du biofilm électro-actif“. Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20150/document.
Der volle Inhalt der QuelleNowadays, alternative and sustainable solutions are proposed to avoid the use of fossil fuel. Hydrogen, which constitutes a promising energy vector, is essentially produced by fossil fuel reforming (95%). Environmentally friendly production systems have to be studied. Two main families of technologies are explored to produce hydrogen: 1) by thermochemical and electrochemical decomposition of water and 2) from different biomass sources. Among those last ones, microbial electrolysis cells (MEC) allow to produce hydrogen by electrolysis of organic matter. A MEC consists in a classical cathode, which provides hydrogen production by electrochemical reduction of water, associated to a bio-anode that oxidizes organic substrates into carbon dioxide. This process is only possible because of the anodic development of an electroactive microbial biofilm which constitutes an electrocatalyst. In comparison to classical water electrolysis process, a MEC requires 5 to 10 times less electrical energy and therefore reduces the energetic cost of produced hydrogen. Furthermore, classical process of dark fermentation in mixed cultures converts sugars (saccharose, glucose) to hydrogen with a limited yield of 2-3 moles of hydrogen per mole of hexose because of the coproduction of organic acids (mainly acetic and butyric acids). Fed with acetate, a MEC can produce up-to 3 moles of hydrogen per mole of acetate. Therefore, the association of these two processes could permit to produce 8 to 9 moles of hydrogen per mole of hexose, which represents a major step toward the theoretical limit of 12 moles of hydrogen per mole of hexose.Therefore, this work aims at analyzing the relationship between microbial community structures and compositions and the associated macroscopic functions (biofilm electroactive properties, hydrogen production potential) in electroactive biofilms and in dark fermentation in conditions allowing the coupling of the two processes. The originality of this study is to work in saline conditions (30-35 gNaCl/L), which favors the charges transfer in the MEC electrolyte.First of all, feasibility of dark fermentation in saline conditions (3-75 gNaCl/L) has been shown. This was linked to an inhibition of produced hydrogen consumption and the predominance of a new Vibrionaceae species at salt concentrations higher than 58 gNaCl/L. Secondly, electroactive biofilm growth in conditions compatibles to dark fermentation (pH 5.5-7 and fed with different organic acids) allowed to select dominant microbial species in anodic biofilms that present promising electroactive properties (Geoalkalibacter subterraneus and Desulfuromonas acetoxidans) with maximum current densities up to 8.5 A/m². In parallel, the microbial selection occurring during iron-reducing enrichment method used to select species from a natural inoculum source and based on their capacity to transfer electrons to iron oxydes (Fe(III)) has been studied. A decrease of electroactive performances of the biofilm linked to the divergence of microbial selection led to a limitation of the number of iron-enrichment steps. However, enrichment on Fe(III) presents an efficient alternative to pre-select electroactive species with an increase of coulombic efficiency from 30±4% to 99±8% in comparison with a biofilm obtained with a non-acclimated inoculum. Finally, the addition of exogenous bacteria from a dark fermenter on the electroactive biofilm revealed a decrease of electroactivity with a decrease of maximum current density produced. This diminution could be explained by a lower substrate transfer due to an apparent thickening of the biofilm. Nevertheless, the stability of microbial composition and of bacterial quantity on the anode suggests that a production of exopolymers (EPS) occurred
Pommier, Sébastien. „Dynamique de populations microbiennes en culture mixte : étude expérimentale en bioréacteur à membranes et modélisation du phénomène killer chez Saccharomyces cerevisiae“. Toulouse, INPT, 2003. http://www.theses.fr/2003INPT007G.
Der volle Inhalt der QuelleBes, Méline. „Etude des communautés microbiennes d'un système hydrothermal serpentinisé, la baie de Prony en Nouvelle-Calédonie : approches culturales et moléculaires“. Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4000.
Der volle Inhalt der QuelleSerpentinization is an alteration process of ultramafic rocks resulting in hydrogen- and methane-rich alkaline hot fluids formation. Serpentinization can provide energy and matter to support chemosynthetic microbial communities but also creates extreme living conditions in terms of pH and limited availability of electron acceptors. This work consisted in the study of the microbial communities of the coastal serpentinized hydrothermal system of the Bay of Prony in New Caledonia. It allowed to determine the taxonomic composition, diversity and structure of prokaryotic communities. The "stable core" of indigenous communities identified by molecular methods (DGGE, SSCP, Sanger sequencing of clone libraries) consisted of Methanosarcinales, Thaumarchaeota, Chloroflexi, Alpha-, Gamma-, Delta, Beta-proteobacteria and Firmicutes. These communities are fueled by redox reactions involving hydrogen, methane and sulfur compounds. The low archaeal diversity is mainly composed of Methanosarcinales who are potential primary producers using or producing methane. High throughput sequencing of the bacterial and archaeal 16S rDNA highlighted numerous rare taxa. Some potentially play a role in the biogeochemical cycles of Prony. The fermentative Acetoanaerobium pronyense ST07-YE sp. nov., belonging to Firmicutes, was isolated and characterized by cultivation approach. This bacterium capable of acetate and other substrates production may play an important role in this ecosystem, especially in the maintenance methanogens
Mrad, Fida. „Décomposition de résidus de culture et de matériaux biosourcés : impact sur les communautés microbiennes des sols agricoles et les fonctions associées“. Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR109/document.
Der volle Inhalt der QuelleWaste management is a major problem worldwide. In agriculture, the return of crop residues to the soil is a common practice and represents an interesting opportunity to maintain soil fertility and / or to store carbon. The decomposition of plant materials in soils is influenced by several factors (such as microbial composition, plant material’s nature and quality), and soil microorganisms are its main actors. Moreover, other ways of valorization of non-harvested plant materials are possible, such as their transformation for non-food applications. In the building industry, the interest in using biobased materials (for thermal insulation) is growing and encouraged by the public authorities in construction or renovation projects. However, to our knowledge, the issue of management of these materials end-of-life is not yet addressed, after deconstructing the buildings. In order to better understand different crop residues (wheat straw, rapeseed straw and sunflower stems) decomposition in agricultural soils, we have combined different biochemical / physicochemical characterizations such as biochemical fractionation, thermogravimetric analysis and infrared spectroscopy, with microbial dynamics monitoring (abundance, diversity, function), supplemented by carbon and nitrogen mineralization measures during 3 months incubation in microcosms. Crop residues mineralization is mainly governed by initially different microbiodiversities (derived from permanent grassland or conventional cropping system), and to a lesser extent by their biochemical quality. However, microbial dynamics are influenced by both, types of soils and nature of inputs. As for the sunflower stem coproducts (pith and bark), C mineralization is mainly dictated by their initial quality. Concerning the manufacturing process of a sunflower pith biobased material, it seems to favor its mineralization in soil. The return of this type of material to soil could thus constitute an interesting means of managing its end-of-life
Calbrix, Raphaël. „Impact des intrants organiques et des conduites culturales sur la biomasse microbienne et la diversité des bactéries telluriques“. Rouen, 2005. http://www.theses.fr/2005ROUES028.
Der volle Inhalt der QuelleThe aim of this work is to analyse the effects of four different organic products (turkey manure, compost of turkey manure and ligneous wastes, sewage sludge and compost of sewage sludge) on soil microbial communities in function of agricultural managements, during a 24 months kinetic. The microbial communities were characterised in a quantitative point of view (enumeration of heterotrophic cultivable bacteria, assay of soil total, microbial carbon assay) and in a qualitative one by potential metabolic fingerprinting (Biolog) and genetic structure of soil bacterial communities (T-RFLP 16S rDNA). A transitory impact specific to the different organic products was shown. The impact of organic products on microbial biomass and on bacterial community structure seemed to depend on their rate of lignin (Van Soest) and of mineralisable carbon. The influence of the tillage and the vegetation was revealed by the evolution of bacterial community structure during the 24 months of the experiments
Alain, Karine. „Approches culturales et moléculaires des assemblages microbiens associés aux polychètes hydrothermaux de la famille Alvinellidae“. Brest, 2003. http://www.theses.fr/2003BRES2027.
Der volle Inhalt der QuelleRenault, David. „Caractérisation des écosystèmes microbiens colonisant les biofiltres, les solutions nutritives et les racines de Lycopersicon esculentum en culture hors-sol“. Brest, 2007. http://www.theses.fr/2007BRES2032.
Der volle Inhalt der QuelleThis work was carried out to investigate the consequences of bacterial inoculation of biofilters in tomato soilless culture. The study carries on microbial populations colonizing i) biofilters, ii) nutrient solutions before and after filtration and iii) rhizosphere of plants. Several strains of Pseudomonas and Bacillus, selected in vitro for several suppressive activities, were inoculated into biofilters (P- and B-filters). Their microbial ecosystems were compared with those of a control filter (C-filter). Each filter has a functional (BiologGN2) and a structural (SSCP-PCR) specific profile. The C-filter contained 70% of Proteobacteria whereas P- and B-filters were significantly colonized by Firmicutes. The metabolism of nutrient-solutions was progressively shifted towards degradation of specific amino acids and carboxylic acids. P- and B- filters change more the molecular structure of nutrient solutions than C-filter and they reduce their phylotypic diversity. When solutions were filtered on C-fllter, the proportion of Proteobacteria increased whereas the uncultured candidate phyla rose in P- and B-filters. The rhizosphere microflora of tomato plants was relatively stable (qPCR) during the whole cultural season. Roots colonizing-bacterial communities had relatively few phyla in common for te 2 cultural conditions (bacteria-amended filter and control filter); mots were mainly colonized by Actinobacteria et Bacteroidetes. The involvement of a suppressive microflora in this process is suggested
Senouci, Samira. „Concentration des Enterovirus à partir des eaux et évaluation de la contamination microbienne du milieu hydrique au Maroc“. Nancy 1, 2000. http://www.theses.fr/2000NAN12016.
Der volle Inhalt der QuellePascault, Noémie. „Réponse des communautés microbiennes du sol à l'apport de résidus de culture : influence des pratiques agricoles et lien avec le fonctionnement biologique du sol“. Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00582567.
Der volle Inhalt der QuelleAmiri, Khouira Boukhoudmi. „Étude génétique de populations naturelles du Baculovirus de polyédroses nucléaires du Lépidoptère-Noctuidae Spodoptera littoralis (Boisduval)“. Montpellier 2, 1987. http://www.theses.fr/1987MON20027.
Der volle Inhalt der QuelleRezgui, Cyrine. „Etude du potentiel d'introduction de la culture du pois d'hiver dans les successions culturales en Normandie : conséquences sur les communautés microbiennes du sol et les flux d'azote Impacts of the winter pea crop (instead of rapeseed) on soil microbial communities, nitrogen balance and wheat yield Quantification et analyse des exsudats racinaires de pois, de blé et de colza : mise au point d’une méthodologie de collecte des exsudats racinaires N rhizodeposition quantification and root exudates characterization of pea (Pisum Sativum L.), rapeseed (Brassica napus L.) and wheat (Triticum aestivum L.) under controlled conditions Linking soil microbial community to C and N dynamics during crop residues decomposition“. Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR047.
Der volle Inhalt der QuelleThe agroecological transition targets triple agronomic, ecological, and societal performance of farms. Some new agricultural practices had emerged to develop a new cropping system to respond to these constraints. Legumes constitute an interesting alternative. Indeed, legumes are advantageous for soils due to their symbiotic relationship with nitrogen-fixing bacteria. The presence of compatible rhizobia combined to nitrogen-limited conditions promotes symbiosis which is the most efficient way for legumes to acquire more nitrogen. Compared with non-nodulated plants, symbiosis provides a competitive advantage by increasing soil nitrogen pool. However, some grain legumes, notably winter pea, are rarely studied, especially in the Normandy region where no reference has been published for this crop. The objective of this study is to compare two crop successions for a period of two years (winter pea-wheat and rapeseed-wheat), in order to assess the effect of replacing rapeseed by winter pea at the head of the rotation .We evaluated the effect of these two crops (winter pea vs rapeseed) on the biological state of the soil and nitrogen fluxes at different spatio-temporal scales. The results showed a significant spatio-temporal effect on the response of soil microbial communities and highlighted the importance of the pedoclimatic context in determining the abundance and activity of soil microbial communities. A positive effect of winter pea has been demonstrated on the availability of mineral nitrogen during the crop cycle and for following crops (wheat and barley). The supply of nitrogen to the soil is linked to the rhizodeposition of nitrogen via plants roots and the degradation of crop residues after harvest. Our results showed that winter pea exhibited the greatest amount of nitrogen rhizodeposition. However, rhizodeposition did not have a significant impact on rhizospheric microbial communities. Contrary to these observations, the degradation of crop residues significantly modified the composition of bacterial communities linked to their initial biochemical composition. Crop succession including winter pea enriched the soil with mineral nitrogen but simulation with STICS software revealed a nitrogen leaching around of 23 kg N. ha-1 during the cropping cycle. These findings underline the importance of adapting an adequate crop management system, including winter pea, to limit nitrogen losses. The results showed also that wheat yields after winter pea without the use of nitrogen fertilizers were equivalent to those obtained after rapeseed. However, rapeseed required significant nitrogen fertilization. Including winter pea in crop rotation in Normandy region may be a key to enhance productivity, to respond to the challenges of agroecological transition, regional protein autonomy, and to reduce environmental and economic costs, by reducing notably, the costs of fertilizers production and uses
Urien, Charlotte. „Diversité des espèces de levures dans des levains naturels français produits à partir de farine issue de l'Agriculture Biologique : une étude pilote pour analyser les pratiques boulangères et les patterns des communautés microbiennes“. Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112007/document.
Der volle Inhalt der QuelleMicroorganisms are essential for the maintenance and functioning of the ecosystems. In some food products, microbial community, mainly composed by yeasts and lacid actic bacteria which ferment sugars, positively affects organoleptic qualities and shelf life of the product. It is the case of bread sourdough. This PhD aimed at describing yeast diversity patterns of organic French bread sourdoughs and conserving a part of this diversity. Using cultural-Based and non-Cultural based analyses of yeast diversity, we highlighted a unique specific diversity of each sourdough. We also shown the predominance of Kazachstania genus and a convergence of sourdoughs’ yeasts isolates for the ability to consume raffinose and sucrose. Although density and species composition varied between sourdoughs, no spatial pattern was highlighted. Bread-Making practices and their effects on microbial communities’ diversity were also analyzed. Two bread-Making practice typologies (quite « intensive » and quite « extensive »), affecting dominant yeast species were also revealed
Gardin, Bouhioui Hélène. „Biodégradation du 2, 4, 6-trichlorophénol, en culture continue, par des populations microbiennes mixtes anaérobies et aérobies, co-immobilisées en billes de gel (-carraghénane/gélatine)“. Compiègne, 1997. http://www.theses.fr/1997COMP1009.
Der volle Inhalt der QuelleChartrel, Valentine. „Fonctionnalisation d’une matrice végétale à base de pois protéagineux (Pisum sativum) par voie microbienne“. Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASB029.
Der volle Inhalt der QuelleROQUETTE transforms and valorizes peas (Pisum sativum) to produce proteins, fibers and starches. During this process, various secondary fractions are generated, including the pea soluble, designated LAB 4960 after atomization. This fiber-rich co-product is unfit for human consumption in its current form as it can cause digestive disorders, caused by the high content of α-GOS, α-galactooligosaccharides formed from 1 to 3 galactose units linked by α-(1-6) bonds. Among the α-GOS are raffinose, stachyose and verbascose which are not digested by humans, but fermented by the intestinal microbiota. The aim of this thesis project is therefore to reduce the α-GOS content of LAB 4960 by microbial fermentation in order to improve its digestibility. To achieve this objective, a twofold strategy has been implemented. In a first part, a microbial collection that is very diverse in terms of species and ori-gins (plant vs. animal) was built up from pea seeds with the characteri-zation of the microbial diversity of peas from different terroirs and from the private collections of the INRAE Laboratory and the ROQUETTE Company. In a second part, the constituted collection was tested for its ability to hydrolyze the α-GOS from LAB 4960. The screening of the strains was split into three steps, involving different selection criteria. Step 1 allowed the selection of strains capable of growing on LAB 4960 agar under two conditions of oxygenation (aerobic and anaerobic) and pH (acidic and neutral). Step 2 allowed the identification of sugars by Thin-layer chromatography after 72 hours of culture on the liquid LAB 4960. The strains that reduced the α-GOS were selected in step 3 for the quantification of sugars by High performance liquid chromatog-raphy coupled to mass spectrometry. In the first part, the metagenetic study of pea surface diversity according to different terroirs after soak-ing, showed a strong dominance of bacterial species belonging to Proteobacteria (57%) and Firmicutes (28%) and fungal species be-longing to Ascomycota (89%) and Basidiomycota (11%). The structure of the epiphytic community associated with the pea seed was strong-ly influenced by its origin (storage cooperatives and countries). From the pea seed soaking juice, 102 strains were isolated and assigned to 52 species. The 52 pea strains representative of each identified spe-cies were added to the 157 strains representative of 82 microbial species in the internal collections. Screening of the collection showed that 89% of the strains tested were capable of growing on LAB 4960 agar. About 20% of the strains degraded only sucrose. The occurrence of sugars as melibiose, manninotriose and manninotetraose, known to be the product of defructosylation, suggested that 19% of the strains hydrolyzed α-GOS by a β-fructosyltransferase of which 4% came from peas. Finally, 4% of the strains hydrolyzed α-GOS by an α-galactosidase, of which 1% came from peas. Among the 23% strains hydrolyzing α-GOS, two strains stood out for their strong hydrolytic activity: Candida pseudoglaebosa CBS 6715T and Serratia liquefa-ciens GBM09. A study on minimum medium, LAB 4960 medium and in a bioreactor on LAB 4960 of different concentrations showed that, under optimal growth conditions, the GBM09 bacterium is capable of hydrolyzing the α-GOS in increasing order of degree of polymeriza-tion at neutral pH and at 20°C whereas the yeast CBS 6715T hydro-lyzes all the α-GOS simultaneously at acid pH and at 28°C.These preliminary trials have made it possible to validate a proof of con-cept for a fermented functional food and hold out promise of their development on an industrial scale, paving the way for many innova-tions
Carlotti, Arnaud. „Interaction "Candida kefir LY496 - levures autochtones" au cours de la production de biomasse de levure à partir de lactosérums bruts : sélection et optimisation d'une culture mixte“. Lyon 1, 1990. http://www.theses.fr/1990LYO10175.
Der volle Inhalt der QuellePerron, Béatrice. „Impact de la nutrition azotée sur l'activité microbienne du milieu de culture et sur la qualité de la tomate et du concombre biologiques de serre“. Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/31390.
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