English: Semiochemicals informative molecules used in insect-insect or plant-insect interactions have been widely considered within various integrated pest management (IPM) strategies. In the present thesis, two sesquiterpenoids, E-β-farnesene and E-β-caryophyllene, were formulated for their related properties as aphid enemy attractants. E-β-farnesene, the alarm pheromone of many aphid species, was also identified as a kairomone by attracting and inducing oviposition of aphid predators (Episyrphus balteatus De Geer (Diptera: Syrphidae)) and by attracting aphid parasitoids (Aphidius ervi Haliday (Hymenoptera: Braconidae)). E-β-caryophyllene was identified as a potential component of the aggregation pheromone of the Asian ladybird, Harmonia axyridis Pallas, another aphid predator. The two products were purified from essential oils of Matricaria chamomilla L. (Asteraceae) and Nepeta cataria L. (Lamiaceae) for E-β-farnesene and E-β-caryophyllene, respectively. Natural and biodegradable slow-release formulations were then investigated in order to deliver these molecules on crop fields for a long period of time as biological control devices. Due to their sensitivity to oxidation, both sesquiterpenes needed to be protected from oxygen degradation. For this purpose, alginate hydrophilic matrix with low oxygen permeability was used as polymer for the formulations: the main objective was to deliver semiochemical substances in the air in a controlled way. Consequently, a careful selection of alginates was realised. Formulated beads showed different structural and encapsulation properties depending on various formulation factors. Alginate formulations were characterized by texturometry and by confocal microscopy in order to observe the distribution of semiochemicals in alginate network. The last step of alginate bead characterisation consisted in studying release rate of semiochemicals in laboratory-controlled conditions by optimised trapping and validated Fast-GC procedures. Finally, the efficiency of formulations as aphid predator (Syrphidae) and parasitoids (A. ervi) attractants was demonstrated by field trapping and olfactometry experiments. Français: Les sémiochimiques molécules véhiculant des informations au sein des interactions insecte-insecte ou plante-insecte ont été largement utilisés dans de nombreuses stratégies de lutte intégrée. La présente thèse de doctorat décrit la formulation de deux sesquiterpènes, le E-β-farnésène et le E-β-caryophyllène, pour leurs propriétés relatées dans la littérature en tant quattractants des ennemis des pucerons. En effet, le E-β-farnésène, la phéromone dalarme de nombreuses espèces de pucerons, a également été identifié comme kairomone en attirant des parasitoïdes (Aphidius ervi Haliday (Hymenoptera: Braconidae)) et des prédateurs de pucerons (Episyrphus balteatus De Geer (Diptera: Syrphidae)) et en induisant un comportement doviposition chez ces derniers. Le E-β-caryophyllène a récemment été identifié comme un composé probable de la phéromone dagrégation des coccinelles asiatiques, Harmonia axyridis Pallas, également prédatrices de pucerons. Les deux produits ont été purifiés au départ des huiles essentielles de Matricaria chamomilla L. (Asteraceae) et de Nepeta cataria L. (Lamiaceae) respectivement dans le cas du E-β-farnésène et du E-β-caryophyllène. Des formulations biodégradables et dorigine naturelle ont ensuite été développées comme outil de contrôle biologique afin de libérer les deux composés de façon progressive. En raison de leur sensibilité à loxydation, ces deux sesquiterpènes devaient être protégés de loxygène. A cette fin, de lalginate matrice hydrophile offrant une faible perméabilité à loxygène a été utilisé comme polymère de formulation : le principal objectif était de délivrer les substances sémiochimiques dans lair dune façon contrôlée. En conséquence, lalginate a été sélectionné de façon minutieuse. Les billes formulées ont montrés des propriétés structurelles et dencapsulation différentes en fonction de nombreux facteurs intervenant lors de la formulation. Les formulations ont été caractérisées par texturométrie et par microscopie confocale de façon à observer la distribution des sémiochimiques au sein du réseau dalginate. La dernière étape de caractérisation des billes a consisté en létude du taux de libération des sémiochimiques dans des conditions contrôlées de laboratoire après avoir optimisé la technique de piégeage des volatils et validé la procédure danalyse par GC rapide. Finalement, lefficacité dattraction des formulations envers les prédateurs et les parasitoïdes de pucerons a été démontrée par des expériences de piégeage sur cultures et des essais dolfactométrie.

This study aims to investigate the possibility of using calcium-alginate as a coagulant in low turbidity waters. Jar tests were initially performed with synthetically prepared turbid waters to investigate the effect of alginate and calcium concentrations, alginate&rsquo / s molecular weight, rapid mixing time and speed (schedule), initial pH and alkalinity of synthetic water on turbidity removal efficiency of calcium-alginate system step by step. Alum as a coagulant was then used in jar tests conducted with synthetic water to compare with calcium-alginate in terms of its turbidity removal efficiency and produced sludge properties. Finally, raw water acquired from water treatment plant was tested for treatability by using calcium-alginate based on previously determined optimum parameters via jar tests. Experiments of calcium-alginate system with synthetic water showed that calcium was a key parameter in coagulation and high molecular weight alginate performed better in turbidity removal. Significant improvements in turbidity removal were observed when mixing schedules were rearranged / especially in case of increasing rapid mixing time following calcium dosing. Calcium-alginate system neither was notably affected by pH or alkalinity nor did significantly change the pH or alkalinity of the medium. Alum worked well in turbidity removal with additional adjustments of pH and alkalinity, however / alum produced higher quantities of sludge than calcium-alginate system. &ldquo / Raw water&ldquo / experiments with calcium-alginate did not result in desired level of turbidity removals due to the excessively different characteristics of this water compared to the synthetically prepared turbid water.

Coagulation and flocculation processes are important parts of water and wastewater treatment. Coagulation or destabilization of colloidal suspensions results in aggregation of colloidal particles by physical and chemical processes. Flocculation results in the formation of larger and settleable structures by bridging. Alginate, a polysaccharide obtained from marine brown algae, produces a gel structure when mixed with calcium ions, which is expected to be a potential coagulant in water treatment. This study aims to determine the use of calcium alginate as a potential coagulant during water treatment and determine its capabilities and deficiencies in coagulation processes. The study was conducted on turbid water samples prepared in the laboratory and those taken from the inlet of Ankara ivedik Water Treatment Plant (IWTP) by running typical jar tests. The main experimental variables were initial alginate and calcium doses, initial turbidity of water samples and the order with which the two chemicals are dosed. The main criteria investigated to check the success of the system was the final turbidity values and the turbidity removal capacity of calcium- alginate. Experiments were conducted on three different laboratory &ndash / prepared turbid water samples and on the raw water taken from the inlet point of Ankara ivedik Drinking Water Treatment Plant (IWTP). These were prepared as high (150 NTU) medium (80 NTU) and low (10 NTU) turbidity samples. The calcium concentrations tested varied between 30 and 200 mg/L and alginate concentrations tested varied between 0.04 to 40 mg/L. Depending on the initial turbidity and initial calcium concentration of water sample the results depict that calcium alginate could be used as an effective coagulant for high (150 NTU) and medium (80 NTU) turbidity water sample especially at the calcium doses of 120 and 160 mg/L for low alginate concentration doses like 0.4 mg/L. The final turbidity met both the requirements of Drinking Water Standards applied in Turkey and Europe. Generally, the higher the initial turbidity was, the higher the turbidity removal efficiency achieved, even with very low alginic acid concentration. As the initial turbidity decreased, initial concentration of calcium required for the effective coagulation processes decreased. However, for low (10 NTU) turbidity water samples the system did not work properlyHowever, for low turbidity water samples, the turbidity removal efficiency decreased, and it was difficult to meet the limits.

Au laboratoire, une méthode originale d'encapsulation par transacylation entre l'alginate de propylène-glycol (PGA) et une protéine a été mise au point. Cette méthode est basée sur la création de liaisons amides entre les fonctions amines libres de la protéine et les groupes esters du PGA dans une phase aqueuse émulsionnée (E/H) après alcalinisation. Les microparticules obtenues, stables, biocompatibles et biodégradables, sont potentiellement intéressantes pour la délivrance de substances actives en thérapeutique ou en cosmétique.Le premier objectif de ce travail est d'étudier l'influence des propriétés physicochimiques des deux biopolymères (protéine et PGA) et de leurs solutions, ainsi que l'effet des paramètres de préparation sur la réaction de transacylation et sur les propriétés des microparticules obtenues. Pour cela, la sérumalbumine humaine (HSA) a servi de protéine modèle et les microparticules ont été préparées dans différentes conditions physicochimiques puis caractérisées. Différents liens ont été établis entre les propriétés physicochimiques des solutions initiales des deux polymères et les propriétés fonctionnelles des microparticules obtenues.Le deuxième objectif est de remplacer le PGA, seul polysaccharide utilisable jusqu'à présent pour la microencapsulation par transacylation, par d'autres polysaccharides naturels, dans la préparation de microparticules. Etant donné ses propriétés intrinsèques limitantes, le remplacement du PGA par d'autres esters polysaccharidiques parait avantageux dans le domaine d'application des microparticules.Dans ce travail, le PGA a été remplacé par une série d'esters semi-synthétiques d'alginate puis par d'autres polysaccharides estérifiés naturels (pectines) ou semi-synthétiques (esters polypectiques et esters de l'acide hyaluronique). Les conditions optimales pour l'utilisation de chaque ester ont été alors déterminées. / In our laboratory, an original method of microencapsulation was developed, based on the use of a transacylation reaction, creating covalent bonds between proteins and propylene glycol alginate (PGA). The covalent bonds are created after alkalization of the aqueous phase of a W/O emulsion, without using bifunctional crosslinking reagent.The resulting microparticles, which are stable, biocompatible and biodegradable, have potential applications for the delivery of active compounds for therapeutics or cosmetics.The first aim of this work is to study the influence of the physicochemical properties of the two polymers (protein and PGA) and of their solutions, as well as the effect of the preparation parameters on the transacylation reaction and on microparticle characteristics. For this purpose, human serum albumin (HSA) was picked as a model protein and microparticles were prepared using several physicochemical conditions then characterized. Several relationships were established between the physicochemical properties of the initial solutions of the two polymers and the functional properties of the resulting microparticles.The second purpose is to replace the PGA, only polysaccharide used for microencapsulation by transacylation so far, by other natural polysaccharides in the preparation of microparticles. Given its limiting intrinsic properties, the replacement of PGA by other polysaccharidic esters seems advantageous in the field of microparticle applications.In this work, the PGA was successfully replaced by a series of semisynthetic alginate esters, and then by other polysaccharidic esters, either natural esters (pectin) or semisynthetic esters (polypectate esters and hyaluronate esters). The optimal conditions for the use of each ester were then determined.

La nisine est un peptide antimicrobien produit par la souche de Lactococus lactis subsp. lactis, autorisée pour des applications alimentaires par le comité d'experts sur les additifs alimentaires et les aliments de l'Organisation des Nations Unies pour l’Alimentation et l'Agriculture et de l’Organisation Mondiale de la Santé (FAO / OMS). La nisine peut être appliquée, par exemple, pour la conservation des aliments, la biopréservation, le contrôle de la flore de fermentation, et potentiellement comme agent antimicrobien clinique. Le piégeage de bactéries capables de produire de la nisine dans des billes d'alginate de calcium est ainsi une voie prometteuse pour immobiliser des cellules actives et prolonger la durée de conservation des aliments. Le travail de thèse visait à concevoir des emballages actifs en biopolymère renfermant des bactéries lactiques bioprotectrices (LAB) pour contrôler la croissance de micro-organismes indésirables dans les aliments, en particulier L. monocytogenes. La stabilité mécanique et chimique des billes d'alginate a d’abord été améliorée, et l'efficacité d'encapsulation a été accrue. Des capsules « alginate / pectine (A / P) » ont été préparés comme premières microsphères, par une technique d'extrusion. La production de nisine par Lactococcus lactis subsp. lactis encapsulé dans différents états physiologiques (phase exponentielle, phase stationnaire) a été étudiée. Les résultats ont montré que les billes composites (A/P) avaient de meilleurs propriétés que celles formulées avec de l'alginate ou de la pectine pure. L’association de l'alginate et de la pectine induit un effet synergique qui a amélioré les propriétés mécaniques des microbilles. La deuxième partie du travail a concerné la mise au point de microcapsules à cœur liquides avec une membrane d'hydrogel d'alginate et d'un noyau de gomme de xanthane. Les résultats ont montré que ces microcapsules contenant L. lactis encapsulé durant la phase exponentielle dans une matrice d’alginate et un noyau nutritif de gomme xanthane ont donné les meilleurs résultats et présentent une activité anti-listeria intéressante. Ces microbilles ont enfin été appliquées pour la conservation des aliments et en particulier dans des emballages alimentaires actifs. Des films (HPMC, amidon) ont été élaborés en piégeant des perles d'«alginate actifs/gomme xanthane» enrichies en L. lactis dans des films d’emballage et appliqués pour la conservation des aliments / Nisin is an antimicrobial peptide produced by strains of Lactococus lactis subsp. lactis, recognized as safe for food applications by the Joint Food and Agriculture Organization/World Health Organization (FAO/WHO). Nisin could be applied, for shelf-life extension, biopreservation, control of fermentation flora, and potentially as clinical antimicrobials. Entrapment of bacteria able to produce nisin in calcium alginate beads is promising way for cells immobilization in active films to extend food shelf-life. The present PhD work aimed to design biopolymeric active packaging entrapping bioprotective lactic acid bacteria (LAB) and control undesirable microorganisms growth in foods, particularly L. monocytogenes. First, the mechanical and chemical stability of the alginate beads were improved, and consequently the effectiveness of encapsulation was increased. Alginate/pectin (A/P) biopolymers were prepared, as first microspheres design, by extrusion technique to encapsulate nisin-producing Lactococcus lactis subsp. lactis in different physiological state (exponential phase, stationary phase). Results showed that A/P composite beads were more efficient to increase beads properties than those formulated with pure alginate or pectin. Association of alginate and pectin induced a synergistic effect which improved microbeads mechanical properties. As a second microspheres design, aqueous-core microcapsules were prepared with an alginate hydrogel membrane and a xanthan gum core. Results showed that microcapsules with L.lactis in exponential state encapsulated in alginate membrane and aqueous-core based on xanthan gum with nutrients gave the best results and exhibit interesting antilisterial activity. These microparticles were applied in food preservation and particularly in active food packaging. A novel bioactive films (HPMC, starch) was developed and tested, entrapping active beads of alginate/xanthan gum core-shell microcapsules and alginate/pectin hydrogel enriched with L.lactis

Ce travail a eu pour objectif la conception de nouveau matériaux à base de polysaccharide pour la libération contrôlée de principes actifs et pour d'éventuelles applications environnementales. Pour cela, des gels ont été préparés par réticulation du carboxymethylepullulane CMP et du pullulane interpénétré par l’alginate avec le sodium trimétaphosphate STMP. Les hydrogels obtenus ont été caractérisés et leurs propriétés physico-chimiques et rhéologiques ont été investiguées. La séquestration de principes actifs modèles dans les hydrogels a été réalisée par regonflement des gels dans une solution de bleu de méthylène BM ou par dispersion de la 3- aminopyridine 3AP à l’intérieur des gels. L'’influence des différents paramètres comme la nature du gel, le taux d’agent réticulant et le pH sur la libération des principes actifs a permis de conclure sur la performance des gels comme matrice à libération contrôlée. D'autre part, ces hydrogels de morphologies différentes se sont révélés être des adsorbants prometteurs, les tests sur le BM servant dans ce cas comme polluant modèle ont montré des capacités d'adsorption plus de 1000 mg/g pour les gels à base de CMP et de 500 mg/g pour les gels Pullulane/alginate. Les capacités d'adsorption étaient sensibles à la quantité du STMP, au degré de substitution du CMP et aux variations du pH. Les résultats expérimentaux étaient bien modélisés par une équation cinétique de pseudo-second ordre et l'isotherme de Freundlich décrivait d'une manière satisfaisante le phénomène. / This work has aimed at the design of new polysaccharide-based materials for the controlled release of active ingredients and for possible environmental applications. For this, gels were prepared by crosslinking the carboxymethylpullulan CMP and the pullulan interpenetrated by the alginate with the sodium trimetaphosphate STMP. The hydrogels obtained were characterized and their physicochemical and rheological properties were investigated. The sequestration of model active ingredient in the hydrogels was carried out by re-inflation gels in a solution of BM or dispersion of 3AP within the gels. The influence of the various parameters such as the nature of the gel, the level of crosslinking agent and the pH on the release of the active ingredients made it possible to conclude on the performance of the gels as a controlled-release matrix. On the other hand, these hydrogels of different morphologies have proved to be promising adsorbents, the tests on the BM used in this case as a model pollutant showed an adsorption capacity of more than 1000 mg / g for CMP-based gels and 500 mg / g for Pullulane / alginate gels. Absorption capacities were sensitive to the amount of SMTP, the degree of CMP substitution, and pH changes. The experimental results were well modeled by a pseudo-second order kinetic equation and the Freundlich isotherm satisfactorily described the phenomenon.

La construction en terre crue constitue une alternative écologique aux bétons de ciment. Afin de promouvoir son usage, la présente étude s’intéresse à la mise au point de bétons de terre coulables permettant une mise en œuvre analogue à celle des bétons usuels. Dans cette optique, il est nécessaire de conférer au matériau une solidification à court terme (24 h) sans attendre son séchage, afin de permettre un débanchage rapide. La voie explorée pour répondre à cette problématique s’inspire de la technique du Gelcasting utilisée dans le domaine des céramiques techniques. Celle-ci s’appuie sur la gélification de polymères préalablement introduits dans une barbotine céramique pour induire une transition liquide-solide rapide et homogène. Une étude bibliographique complétée par des essais préliminaires a mené à la sélection de l’alginate, un polymère biosourcé non toxique et gélifiant à température ambiante sous l’action de cations multivalents tels que le calcium. Ce polymère s’est révélé très prometteur. Il a permis la réalisation d’éprouvettes de mortier démoulables 24 h après coulage et présentant une résistance en compression de l’ordre de 0,1 MPa, théoriquement suffisante à un mur de 3 m de haut pour tenir sous son propre poids. Une preuve de concept à l’échelle du béton a par ailleurs pu être réalisée sous la forme d’un muret de 40 cm de haut coulé et vibré à partir d’une consistance fluide puis décoffrable en 24 h. Les performances mécaniques et hygrothermiques du matériau sec ont été validées, et la présence du polymère gélifié pourrait améliorer la résistance à l’érosion. De premiers essais ont montré que le procédé pouvait être adaptable à des terres moins calcaires que celle utilisée tout au long de l’étude. / Developing raw earthen construction is nowadays a major environmental issue, due to its low embodied energy compared to Portland cement. A solution would be to use a similar process as cement-based concrete, by casting into formworks. Nevertheless, this is limited by technical difficulties, owing to the fact that earth is not a hydraulic binder. In that perspective, this work focuses on inducing a liquid-solid transition to an earth suspension without waiting for drying, similar to cement-based materials. The approach explored to meet this challenge is inspired by the technique of Gelcasting used in the field of technical ceramics. This relies on the gelation of polymers previously introduced into a ceramic slurry to induce a rapid and homogeneous liquid-solid transition. A bibliographic study supplemented by preliminary tests led to the selection of alginate, a biosourced polymer that is non-toxic. Its gelation is allowed at ambient temperature, via addition of multivalent cations such as calcium ions. This polymer proved to be very promising. It made it possible to produce mortar specimens which could be unmoulded 24 hours after casting. A wet compressive strength close to 0.1 MPa could be reached, theoretically sufficient for a wall of 3 meters high to stand under its own weight. A proof of concept at the concrete scale was then realized as a low wall of 40 cm high casted and vibrated and then unmoulded in 24 hours. Mechanical and hygrothermal performances of the dry material were validated, and the presence of the gelled polymer could improve the resistance to erosion. Initial trials showed that the process could be adapted to low calcareous soils.

Existing commercially available microcarriers are very efficient at encouraging cell attachment and proliferation. However, recovery of the cells is problematic as it requires the use of proteolytic enzymes which are damaging to critical cell adhesion proteins. From this perspective, temperature responsive polymers appear to be a valid option. The current innovative study is to produce and engineer microcarriers in terms of particle size, surface coating and properties, as well as thermo-responsiveness for cell release. All these benefits are based on particle production by membrane emulsification to provide a highly controlled particle size. The polymer of choice is poly N-isopropylacrylamide (pNIPAM) because of the sharpness of its phase transition, biocompatibility and transition temperature close to the physiological value. These characteristics make pNIPAM a very attractive material for Tissue Engineering applications. Cells are cultured on the hydrophobic surface at 37??C and can be readily detached without using proteolytic enzymes from the surface by lowering the temperature to room temperature. The Dispersion Cell (MicroPore Technologies Ltd, UK) was successfully employed for the production of W/O emulsions. The generated monomer droplets were additionally solidified by applying a free radical polymerisation to manufacture solid pNIPAM microspheres. Additionally, calcium alginate particles were also generated and further functionalised with amine terminated pNIPAM to form temperature responsive core-shell particles by simply taking advantage of the electrostatic interactions between the carboxyl groups of the alginate and amino groups of the modified pNIPAM. Controlled particle production was achieved by varying process parameters and changing the recipe formulation (e.g. monomer concentration, surfactant concentration, pore size and inter-pore spacing, injection rate, shear stress applied at the membrane s surface). The manufactured particles were then analysed in terms of particle size and size distribution, chemical composition, surface analysis, shrinkage ratio and thermo-responsiveness and further sterilised and used for cell culture and release experiments. Swiss Albino 3T3 fibroblastic cells (ATCC, USA) were utilised to show proof-of-concept for this technology. Cell attachment and proliferation were assessed and successfully demonstrated qualitatively and quantitatively. pNIPAM solid particles, uncoated and with different protein coatings were shown to allow a limited degree of cell attachment and proliferation compared to a commercially available microcarrier. On a different approach, uncoated core-shell structures demonstrated improved capabilities for cell attachment and proliferation, similar to commercially available microcarriers. Having in mind the potential of temperature responsive polymers and the aim of this innovative study, cell detachment from the generated microcarriers was evaluated and compared to a commercially available temperature responsive surface. Necessary time for detachment was recorded and detached cells were recovered and reseeded onto tissue culture plastic surfaces in order to evaluate the replating and reattachment capabilities of the recovered cells. Successful cell detachment was achieved when using the core-shell structures as cell microcarriers, but the necessary time of detachment was of an order higher than that for the commercial temperature responsive surface.

In this paper a novel stimuli responsive hydrogel material, methacrylated sodium alginate beta-cyclodextrin (Alg-MA-β-CD), was used in combination with a microfluidic device to create microspheres. Currently there is no reliable method for fabricating homogeneous stimuli-responsive microspheres, in-house microfluidic devices are not reliable in manufacture quality or long-term use. Alginate hydrogels have many attractive characteristics for bioengineering applications and are commonly used to mimic the features and properties of the extracellular matrix (ECM). Human mesenchymal stem cells (hMSCs) are of top interest to tissue engineers. hMSCs are widely available and can be harvested and cultured directly out of human bone marrow. hMSCs have the ability to differentiate into osteoblasts, adipocytes, chondrocytes, muscle cells, and stromal fibroblasts depending on mechanical signals transmitted through surrounding ECM. The biomechanical properties of alginate based stimuli-responsive hydrogels can be tuned to match those of different types of tissues. When trying to transport and control the differentiation of hMSCs into generating new tissues or regenerating damaged tissues, it is highly beneficial to encapsulate the cells inside a microsphere made from these hydrogels. The proposed research objectives are: 1) To optimize fabrication techniques and create functional microfluidic devices; 2) Analyze the effects of flow parameters on microsphere production; and 3) Encapsulate viable hMSCs inside multi-stimuli responsive alginate microspheres using the fabricated microfluidic devices (MFDs). In this study, photolithography microfabrication methods were used to create flow-focusing style MFDs. The hydrogel materials were characterized via rheological methods. Syringe pumps controlled flow rates of fluids through the devices. Active droplets formation was monitored through a camera attached to an inverted microscope, where images were analyzed. Microsphere production was analyzed optically and characterized. Alg-MA-β-CD polymer solutions containing hMSCs were encapsulated, and a live/dead florescence assay was preformed to verify cell viability. Using a modified fabrication process it was possible to manufacture Alg-MA-β-CD microspheres and encapsulate and maintain viable hMSCs inside.

Le tétrachloroéthène (PCE) et les éthènes chlorés qui lui sont apparentés ont été abondamment utilisés pour plusieurs applications en industrie dès le début du 20e siècle. Ils sont cependant comptés parmi les polluants les plus communs des sols et de l’eau et beaucoup d’efforts sont déployés afin de les éliminer. Nous croyons que la conversion des éthènes chlorés en éthènes par des microorganismes est une solution prometteuse. Le premier aspect du projet visait donc à établir les conditions pour lesquelles un consortium enrichi en Dehalococcoides ethenogenes permettrait la conversion complète de PCE en éthène. Les expériences réalisées nous ont permis de souligner le rôle de l’acide lactique ajouté aux cultures comme source de carbone et source indirecte d’électrons pour la déhalorespiration. Nous avons également pu établir l’effet de la concentration initiale de biomasse dans les cultures sur le profil de déhalogénation du PCE. Le deuxième aspect du projet visait à développer un protocole d’encapsulation du consortium dans une matrice polymérique afin de profiter des nombreux avantages potentiels de l’encapsulation. Nous avons testé trois montages d’encapsulation différents : atomisation avec jet d’air, atomisation avec vibrations ultrasoniques et « drop-wise ». Le dernier montage prévoyait l’encapsulation des cultures dans des billes d’alginate enrobées de chitosane gélifié par du lignosulfonate. C’est le seul montage qui nous a permis d’encapsuler le consortium de façon efficace sans effet significatifs négatifs sur son activité de déchlorination. Aussi, la comparaison des profils de déhalogénation du PCE de cellules encapsulées et cellules libres a montré une plus faible accumulation de TCE, 1,2-DCE et VC dans les échantillons de cellules encapsulée et, par conséquent, une conversion plus rapide et plus complète du PCE en éthène. Finalement, nous avons observé une tendance favorable à l’idée que les microorganismes encapsulés bénéficient d’un effet de protection contre de faibles concentrations d’oxygène. / Tetrachloroethylene (PCE) and other chlorinated ethenes have been used for industrial purposes since the beginnning of 20th century. However, they are now considered common pollutants of soil and water. A lot of efforts are directed toward elimination of these compounds and we believe degradation of these chlorinated ethenes by microorganisms is the best solution. The first step of this project was to establish a complete conversion of PCE to its non-toxic product ethylene using an enriched consortium of Dehalococcoides ethenogenes. Our results show the importance of lactic acid as a carbon source and indirect source of electrons in a reaction known as dehalorespiration. We have been able to establish the effect of initial biomass on the biodegradation profile of PCE. The second step of the project was to obtain a working protocol for encapsulation of the consortium in a polymeric matrix. Such immobilization procedure would then allows numerous possible advantages as shown in the literature. We tested three encapsulation setups: air atomization, ultrasonic atomization and drop-wise technique. In the last setup, we successfully encapsulated the bacterial consortium into particles made of an alginate core surrounded by a chitosan layer. Thus the drop-wise technique allowed encapsulation of the consortium without negative effects on its dechlorination activity. In addition, the dechlorination profiles of encapsulated cells showed a lower accumulation of chlorinated intermediates TCE, 1,2-DCE and VC which yield a more rapid and complete conversion of PCE to ethylene. Finally, our results support the idea that encapsulated microorganisms may benefit from a protective effect when oxygen is present in the medium.