Les stocks de glycérol à travers le monde augmentent, étant une matière première secondaire, ce produit chimique doit être valorisé. La co-production d'énergie électrique ou d'hydrogène et de produits chimiques à valeur ajoutée à partir du glycérol peut être réalisée dans des réacteurs électrochimiques. L'oxydation de glycérol est une réaction complexe qui peut conduire à un grand nombre de produits chimiques et d'intermédiaires utiles pour l'industrie. Le développement de catalyseurs spécifiques pour orienter les chemins réactionnels de l'électrooxydation du glycérol vers les produits désirés est un objectif très important. Des nanoparticules non supportées de palladium à distribution de taille et de forme contrôlées ont été synthétisées par une voie colloïdale et caractérisées par microscopie électronique et des méthodes électrochimiques afin d'obtenir une corrélation entre la structure de surface et la réponse électrochimique. Ces électrolyseurs modèles ont été modifiés par dépôt d'adatomes de bismuth. Et leur activité et sélectivité vis-à-vis de l'électrooxydation du glycérol ont été respectivement évaluées par voltammétrie cyclique et spectroscopie infrarouge in situ. Des matériaux plus proches d'applications industrielles à base de palladium et d'éléments du groupe p (Bi, Sn) ont ensuite été aussi synthétisés et évalués vis-à-vis de l'électrooxydation du glycérol. Les résultats obtenus montrent clairement l'influence de la composition, de l'orientation de surface et de la nature de catalyseur sur l'activité et la sélectivité dans la réaction de l'électrooxydation du glycérol. / The worldwide glycerol stocks are increasing; this chemical could be used as a secondary primary raw material. Electric energy or hydrogen and added-value-chemical cogeneration can be performed in electrochemical reactors. Glycerol oxidation is made up of complex pathway reactions that can produce a large number of useful products and valuable fine intermediates.The development of specific catalysts for electrooxidation of glycerol to obtain desired products is a very important goal.Unsupported palladium nanoparticles with controlled size and shape distribution were synthesized by a colloidal method and characterized by electron microscopy and electrochemical methods to obtain a correlation between the surface structure and the electrochemical response. These model electrocatalists have been modified by adatoms of bismuth. And their activity and selectivity towards the electrooxidation of glycerol were respectively evaluated by cyclic voltammetry and in situ infrared spectroscopy. Other materials for industrial applications based on palladium and p elements (Bi, Sn) were also synthesized and evaluated towards the electrooxidation of glycerol.The results clearly show the influence of the composition, surface orientation and the nature of the catalyst on activity and selectivity in the reaction of electrooxidation of glycerol.

Les trois familles catalytiques à base de perovskites contenant du Ni: massives [[LnFe1-x-yNiyMxO3-δ] (Ln=La, Pr; B=Co, Mn, Ru), sur support [mLnNi0.9Ru0.1О3/nMg-γ-Al2O3] (Ln = La, Pr) et structuré [mLaNi0.9Ru0.1О3/nMg-γ-Al2O3/mousses structurées] ont été synthétisés, caractérisés et testés dans les réactions de vaporeformage de l'éthanol et de glycérol. Les effets de la composition chimique et de la méthode de synthèse sur les propriétés structurelles et texturales, ainsi que sur la réductibilité des échantillons initiaux ont été évalués. L'utilisation préférentielle de Pr, Ni et Ru dans la composition de catalyseur a été démontrée pour toutes les familles. Le rôle essentiel de la modification du support γ-Al2O3 avec ≥ 10%mass de Mg introduit par imprégnation humide pour le catalyseur supporté a également été prouvé. Des catalyseurs de la composition optimale fournissant une activité élevée dans le vaporeformage de l'éthanol et du glycérol à T = 650 °C ont été trouvés: le meilleur catalyseur massif à base du précurseur PrFe0.6Ni0.3Ru0.1O3 fournit une activité élevée pendant au moins 7 h, grâce à la facilité de leur réduction et les propriétés d'oxydoréduction de l'oxyde de praséodyme formé. Les catalyseurs sur support 10-20% PrNi0.9Ru0.1O3/10-15%Mg-γ-Al2O3 fournissent le meilleur rendement en hydrogène (~ 90%) et la stabilité pendant ~ 20 heures. Le catalyseur structuré optimisé à base de la plaquette Ni-Al métallique fournit le rendement stable en hydrogène 80-87% dans l’oxy-vaporeformage d'éthanol dans les mélanges concentrés (concentration d'éthanol de 30%) dans un réacteur pilote pendant 40 heures. Les résultats obtenus rendent ces systèmes catalytiques structurés très prometteurs à utiliser dans les générateurs électrochimiques à base de piles à combustible avec l'utilisation de ressources renouvelables peu coûteuses comme bio-huile. / The three catalytic families based on Ni-containing perovskites: massive [LnFe1-x-yNiyMxO3-δ] (Ln=La, Pr; B=Co, Mn, Ru), supported [mLnNi0.9Ru0.1О3/nMg-γ-Al2O3] (Ln = La, Pr) and structured [mLaNi0.9Ru0.1О3/nMg-γ-Al2O3/structured foams] were synthesized, characterized and tested in the reactions of the ethanol and glycerol steam reforming. The effects of the chemical composition and synthesis method on the structural and textural properties, as well as on reducibility of initial samples were evaluated. The preferred use of Pr, Ni and Ru in the catalyst composition was shown for all families. The essential role of the effective γ-Al2O3 support modification with the ≥10 % wt. of Mg introduced by wetness impregnation for the supported catalyst was also proved. Catalysts of the optimal composition providing a high activity in steam reforming of both ethanol and glycerol at T= 650 °С were found: the best massive catalyst based on the PrFe0.6Ni0.3Ru0.1O3 precursor provides high activity for at least 7 hours, which is explained by the ease of their reduction and the oxidation-reduction properties of the praseodymium oxide formed. Supported 10-20% PrNi0.9Ru0.1O3/10-15%Mg-γ-Al2O3 provide the greatest yield of hydrogen (~ 90%) and stability for ~ 20 hours. Structured catalyst based on the metal Ni-Al platelet provides the yield of hydrogen 80-87% in oxy-steam and steam reforming of ethanol in the concentrated mixtures (ethanol concentration of 30%) in a pilot reactor for 40 hours. The results obtained make these structured catalytic systems very promising to use in electrochemical generators based on fuel cells with the use of inexpensive renewable resource – bio-oil.

L’électro-fermentation est un nouveau levier permettant le contrôle des procédés fermentaires à travers l'utilisation d'électrodes au potentiel contrôlé. Parmi de nombreux substrats fermentaires, le glycérol est une source de carbone largement utilisée issue de l’industrie du biodiesel, et permettant la production de molécules à valeur ajoutée comme le 1,3-propanediol. L'objectif de cette thèse est d'évaluer le potentiel de l’électro-fermentation du glycérol comme moyen de mieux maîtriser les spectres de produits fermentaires dans les procédés mettant en œuvre des cultures mixtes.La thèse étudie dans un premier temps la fermentation du glycérol en cultures mixtes afin de caractériser les principales voies métaboliques d'intérêt en réponse au paramètre environnemental le plus influent pour la fermentation du glycérol (pH). L'effet de l'introduction d'électrodes colonisées par des bactéries électro-actives, capables d'échanger des électrons avec l'électrode et d’autres microorganismes, est ensuite étudié. Ce travail est réalisé en cultures mixtes dans l'objectif d'améliorer le procédé de fermentation en termes de spécificité des métabolites formés et de leur rendement de production. Enfin, un système modèle composé d’une souche fermentaire et une souche électro-active a ensuite été conçu afin de mieux comprendre les mécanismes mis en jeu lors de l’électro-fermentation. Cette thèse ouvre de nouvelles possibilités quant à la régulation des balances redox lors de fermentation. L’électro-fermentation ainsi que l’utilisation de bactéries électro-actives ont le potentiel de devenir de puissants outils permettant d’améliorer les rendements et spécificité de production du 1,3-propanediol et d’autres molécules à valeur ajoutée. / Electro-fermentation is a novel tool allowing to control classic fermentation through the use of polarized electrodes. Among all possible fermentation substrates, glycerol is a widely used by-product from the biodiesel industry that can be converted in value-added chemicals such as 1,3-propanediol. This PhD thesis aims at evaluating the potential of glycerol electro-fermentation for the improvement of product specificity in mixed-culture fermentation.As a first step, classic fermentation of glycerol by mixed bacterial consortia was studied in order to characterize the main metabolic pathways according to the main influencing environmental parameter (pH). Then, the addition in fermentation broth of electrodes and electro-active bacteria, able to exchange electrons either with an electrode or other microorganisms has been investigated. This work was carried out in mixed-culture glycerol fermentation in order to optimize products selectivity and yields towards 1,3-propanediol. Finally, a model co-culture constituted of one fermentative and one electro-active species was used to elucidate part of the mechanisms underlying electro-fermentation. This thesis opens a whole new range of possibility regarding the regulation of redox balances in fermentation. Hence electro-fermentation and the use of electro-active bacteria could become efficient tools for improving specificity and yield of 1,3-propanediol and other value-added products in fermentation.

Trypanosoma brucei est un parasite protozoaire responsable de la trypanosomiase humaine africaine. Il présente un cycle de vie complexe alternant entre des hôtes mammifères et un vecteur insecte, la mouche tsé-tsé. Au cours de ce cycle, il rencontre des environnements radicalement distincts auxquels il s’adapte en régulant son métabolisme. Nous avons étudié le métabolisme intermédiaire et énergétique de la forme procyclique évoluant dans le tractus digestif de l’insecte vecteur. Dans cet environnement dépourvu de glucose, la néoglucogenèse est cruciale pour la croissance et la survie des parasites car elle permet la synthèse d’hexoses phosphates et en particulier du glucose 6-phosphate qui alimente plusieurs voies de biosynthèse essentielles. Nos travaux confirment ce flux néoglucogénique alimenté par la proline mais aussi par le glycérol. Nous montrons que le glycérol est une source de carbone efficacement métabolisée et préférentiellement utilisée par la forme procyclique à défaut de la proline et même du glucose pour alimenter son métabolisme intermédiaire. Cette situation qu in’a jamais été décrite auparavant met en évidence la répression du glycérol sur le métabolisme du glucose. Nous montrons également que l’enzyme fructose 1,6-biphosphatase(FBPase), spécifique de la néoglucogenèse, n’est pas essentielle à la survie du parasite en conditions dépourvues de glucose indiquant qu’il existe une alternative à cette enzyme.Toutefois, FBPase joue un rôle important dans la virulence de T. brucei dans l’insecte.De plus, nous avons mis en évidence une autre stratégie d’adaptation de T. brucei basée sur des réarrangements génomiques qui peuvent mener à la synthèse de gènes chimères. / Trypanosoma brucei is a protozoan parasite responsible for human African trypanosomiasis. His complex life cycle alternates between mammalian hosts and the insect vector, the tsetsefly. During this cycle, the parasite encounters dissimilar environments and adapts to the sechanging conditions by regulating his metabolism. We have studied intermediate and energetic metabolism of the procyclic form living in the midgut of the insect vector. In this glucose-depleted environment, gluconeogenesis is crucial for growth and viability of the parasites. Indeed, it allows the synthesis of hexoses phosphates and in particular glucose 6-phosphate which feeds several essential biosynthetic pathways. Our work has confirmed the existence of a gluconeogenic flux fed by proline and glycerol. We have shown that glycerol is an efficiently metabolized carbon source and is preferentially used by the procyclic form rather than proline or even glucose. This situation never described before highlights glycerol repression on glucose metabolism. We have also showed that the enzyme fructose 1,6-biphosphatase (FBPase), specific of the gluconeogenesis, is not essential for the viability ofthe parasite in glucose-depleted conditions, suggesting that there is an alternative to this enzyme. However, FBPase plays an important role for virulence of T. brucei in the insect. Moreover, we have showed another adaptation strategy developed by T. brucei which is basedo n genomic rearrangements leading to the synthesis of chimeric genes.

Ce travail s'inscrit dans la démarche générale de compréhension et d'amélioration des propriétés mécaniques des matériaux thermoplastiques amylacés, en proposant une nouvelle démarche originale de modification structurale de l'amidon thermoplastique s’appuyant sur la combinaison de deux techniques: la réticulation de l'amidon sous faisceau d’électrons et l'orientation macromoléculaire issue du procédé de transformation par extrusion. La première partie du manuscrit est consacrée aux propriétés thermomécaniques de l’amidon plastifié et propose notamment une mise à jour de la courbe maitresse contrainte-allongement mettant en évidence le phénomène d’antiplastification mais aussi de surplastification grâce notamment à l’étude des propriétés à Tg équivalentes. L’évolution des températures de transition β (Tβ) des matériaux a pu être reliée aux différentes étapes de la plastification et des analyses ATG ont mises en évidence les phénomènes de sorption et désorption du plastifiant. Les mécanismes d’endommagement de l’amidon plastifié ont également été explorés à l’aide de la technologie de vidéotraction. Le second chapitre du document est consacré à l’étude de la réticulation de l’amidon thermoplastique à l’état solide sous faisceau d’électrons. De nombreux facteurs ont été étudiés comme la dose absorbée, la teneur en eau, la teneur en plastifiant, le type et la teneur en réactif introduit, ainsi que l’impact du taux de réticulation sur le mécanisme de rétrogradation. Le troisième et dernier chapitre traite du mécanisme d’orientation moléculaire particulier de l’amidon thermoplastique, et de son impact sur les propriétés mécaniques. Le couplage de l’orientation et de l’irradiation sous faisceau d’électrons a également été appréhendé. / This work is part of the general approach aiming to understand and improving the mechanical properties of thermoplastics starch materials by proposing a new and original approach to the structural modification of thermoplastic starch through the combination of two techniques: radiation crosslinking and macromolecular orientation. The first part of the thesis focuses on the thermo-mechanical properties of plasticized starch and proposes an update to the master Stress-strain curve highlighting “antiplasticization” and “overplasticization” phenomena thanks to the study of properties at equivalent Tg. The evolution of materials β transition temperature (Tβ) could also be linked to the different plasticization stages and TGA results highlighted the sorption and desorption phenomenon of the plasticizer. The damage and fracture mechanisms of plasticized starch were also explored with videotraction technology. The second chapter of the document is devoted to the study of crosslinking of thermoplastic starch at solid state under an electron beam radiation. Many factors were explored like the absorbed dose, water content, plasticizer content, nature and amount of crosslinking agents introduced, and their impact on curing mechanisms and retrogradation of the plasticized starch. The third and final chapter deals with the specific mechanism of molecular orientation of the thermoplastic starch and its impact on mechanical properties. The coupling of orientation and irradiation under an electron beam was also investigated.

Le travail présenté dans cette thèse porte sur la synthèse et les caractérisations thermiques et rhéologiques d’un nouveau type de nanofluide : le système Cu2O/Glycérol. La caractérisation est faite en fonction de la taille des particules mises en suspension, de la température et de la fraction volumique solide. Ce travail a nécessité la synthèse des nanoparticules et des nanofluides par la méthode de décomposition thermique des précuseurs organométalliques, qui présente un bon rendement en quantité de nanoparticules (17%). Et le montage d’un dispositif de caractérisation thermique utilisant la méthode 3ω. Finalement, nous avons passé à la caractérisation rhéologique et thermique de ces échantillons. Les résultats obtenus avec ce nouveau système sont intéressants, car l’augmentation de la conductivité thermique atteint des valeurs importantes : 120% et 35% respectivement pour des fractions volumiques aussi faibles que 0,625% et 0,078% de nanoparticules de 7 nm de diamètre, sans influence notable sur la viscosité du fluide hôte, permettant une bonne amélioration du bilan énergétique total. Nous avons observé que la concentration et la taille (surface) des nanoparticules sont des paramètres clefs du comportement de la conductivité thermique effective du nanofluide Cu2O/Glycérol. Nos mesures nous ont permis de déduire la prédominance des modifications de la surface des nanoparticules (par fonctionnalisation ou par réaction chimique secondaire) sur le mouvement brownien dans les transferts thermiques nanoparticules/ fluide hôte. / The work presented in this thesis involves the synthesis and thermal and rheological characterization of a new type of nanofluid : the Cu2O/glycerol system. The characterization was carried out as a function of the size of the particles in suspension, the temperature and the volume fraction of nanoparticles. The nanoparticles and nanofluids were synthesised by the thermal decomposition method, providing a good yield of nanoparticles (17%). Apparatus for thermal measurements using the 3ω method was constructed, and rheological and thermal characterization was carried out. Significant increases in thermal conductivity were observed : 120% and 35% for volume fractions as low as 0.625% and 0.078%, respectively, of 7-nm-diameter nanoparticles, without noticeable effect on the viscosity of the host fluid, leading to a considerable improvement in the energy content.We found that the concentration and surface area of the nanoparticles are key parameters influencing the behaviour of the effective thermal conductivity of the nanofluid. Surface modification of the nanoparticles by functionalization or secondary chemical reactions has a profound effect on the Brownian motion in the heat transfer between nanoparticles and fluid host.

To mitigate the problems of depleting and soaring price of fossil fuels, the production and use of renewable energy have been vigorously promoted. In Europe, the role of biologically-derived fuels and in particular biodiesel is gradually increasing in prominent. Rapeseed biodiesel is the most widely produced in Europe. As a consequence, enormous amount of by-products from production processes are being generated. Current strategies for managing these by-products (mainly rapeseed meal and crude glycerol) seem not to be economically sustainable. More efficient utilisation could add more value to the production chain which in turn would raise the competitiveness of biodiesel compared to petro-diesel. The aim of the project reported in this thesis was to study the feasibility of producing a value added product, polyhydroxybutyrate (PHB), from by-products generated from rapeseed biodiesel production processes as well as to investigate the effects of methanol, a major impurity in crude glycerol, on growth of Cupriavidus necator, a PHB-producing micro-organism.The preliminary study of C. necator growth in crude glycerol based media revealed that optimum concentration of crude glycerol was in a range 15-25 g/L. It was also found that slight changes in the carbon to nitrogen ratio of the feedstock did not significantly affect the growth while methanol at concentrations beyond 10 g/L did. A model based on a saturation equation was developed and used to successfully predict the inhibition of growth by methanol. From the developed model, mechanisms of the inhibition were proposed. The model could also be used to predict satisfactorily growth or productivity rates in other systems containing short-chain alcohols. The growth in solutions derived from rapeseed meal (designated as hydrolysate) via solid-state fermentation by Aspergillus oryzae followed by hydrolysis of the fermented solids was also studied. The biomass production was found to increase as a function of initial free amino nitrogen (FAN) concentration presented in the hydrolysate. However, at higher initial FAN concentrations, a lower conversion of nitrogen to biomass was observed. PHB production was studied using a feedstock which was a mixture of the hydrolysate and crude glycerol. Total biomass concentration reached 28.8 g/L at 120 h with 86% PHB content. PHB productivity and PHB yield on glycerol were 0.21 g/L•h and 0.32 g/g respectively. These results were comparable with those obtained when pure glycerol and synthetic crude glycerol were used, suggesting that, technically, the use of the generic rapeseed- and crude glycerol-based feedstock to produce PHB is feasible.Overall, the feasibility of producing PHB from rapeseed biodiesel by-products has been demonstrated. The satisfactory result leads to the more important outlook that the generic feedstock derived from rapeseed biodiesel by-products has the potential to be used to produce a wide range of products depending on the micro-organism used. Further development of this process to improve nutrient production efficiency as well as product yields and subsequent integration of the process into the biodiesel production process could well be an important contribution in the development of a sustainable biodiesel industry.

Zinc oxide (ZnO) is a versatile environmentally benign II-VI direct wide band gap semiconductor with several technologically plausible applications such as transparent conducting oxide in flat panel and flexible displays. Hence, ZnO thin films have to be processed below the glass transition temperatures of polymeric substrates used in flexible displays. ZnO thin films were synthesized via aqueous polymeric precursor process by different metallic salt routes using ethylene glycol, glycerol, citric acid, and ethylene diamine tetraacetic acid (EDTA) as chelating agents. ZnO thin films, derived from ethylene glycol based polymeric precursor, exhibit flower-like morphology whereas thin films derived of other precursors illustrate crack free nanocrystalline films. ZnO thin films on sapphire substrates show an increase in preferential orientation along the (002) plane with increase in annealing temperature. The polymeric precursors have also been used in fabricating maskless patterned ZnO thin films in a single step using the commercial Maskless Mesoscale Materials Deposition system.

Orientador: Ranulfo Monte Alegre / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T15:45:23Z (GMT). No. of bitstreams: 1 Coelho_RenatoSano_M.pdf: 1626359 bytes, checksum: 9f1206c0b5868e3fac4cf8ccec536403 (MD5) Previous issue date: 2011 / Resumo: O interesse a respeito do ácido kójico tem crescido fortemente nos últimos anos desde a descoberta de suas propriedades de inibição de tirosinase, que permitem seu uso no tratamento de hiperpigmentação dermatológica, inibição de escurecimento enzimático de frutas e vegetais, produção de antiinflamatórios e analgésicos, produção de polímeros, dentre outras aplicações. Dado o potencial econômico do ácido kójico, são necessários processos mais eficazes para sua síntese reduzindo custos de produção e tornando-o mais atrativo à aplicação industrial. Este trabalho visou estudar o processo de produção fermentativa do ácido kójico, determinando parâmetros que auxiliarão no desenvolvimento de tecnologias competitivas de produção. Além disso, propõe a utilização de matérias-primas de baixo custo e grande disponibilidade no mercado brasileiro como glicerol e água de maceração de milho. A espécie selecionada para o estudo foi Aspergillus flavus NRRL 626, que apresentou maior velocidade de crescimento, esporulação e produção de ácido kójico. As melhores fontes de carbono foram a glicose e o glicerol e as melhores fontes de nitrogênio foram o extrato de levedura e a água de maceração de milho. A otimização por planejamentos experimentais utilizando glicose como fonte de carbono e água de maceração de milho como fonte de nitrogênio possibilitou produtividade de até 0,12 g ¿ L-1 ¿ h-1 e concentração final de 48 g ¿ L-1 após 22 dias. A otimização de meio de cultivo com glicerol como fonte de carbono e água de maceração de milho apresentou produtividade de 0,13 g ¿ L-1 ¿ h-1 e concentração final de 48 g ¿ L-1 após 20 dias de fermentação. O glicerol bruto da produção de biodiesel causou forte inibição da produção de ácido kójico e forma obtidos até 18 g ¿ L-1 após 22 dias de fermentação. Ensaios em fermentador de bancada apresentaram problemas de formação de espuma devido às características do meio de cultura e de aderência da biomassa às paredes do fermentador. Os processos de cristalização com anti-solvente e clarificação com carvão ativado mostraram-se adequados à recuperação e purificação do ácido kójico / Abstract: There has been a growing interest on kojic acid since the discovery of its tyrosinase inhibiton properties, which make it useful for many different applications like dermal hyperpigmentation treatment, inhibition of fruits and vegetables enzymatic browning, antiinflamatory and analgesic drugs production, polymer productions, among others. The economical potential of kojic acid motivates researchers to develop more efficient and economical ways of producing it and therefore increase its commercial attractiveness. The present work focused on the study of the kojic acid fermentative production process in order to determine parameters that could help the development of more competitive production technologies. It also proposes the use of low cost raw materials with large availability in Brazil, since as glycerol and corn steep liquor. The selected species for the study was the Aspergillus flavus NRRL 626, which showed the highest growth rate, sporulation and kojic acid production. The selection of substrates pointed that glucose e glycerol were the best carbon sources and yeast extract and corn steep liquor were the best nitrogen sources for kojic acid production. Culture medium optimized through experimental designs with glucose as carbon source and corn steep liquor as nitrogen source allowed a productivity of 0,12 g kojic acid ¿ L-1 ¿ h-1 and a final concentration of 48 g ¿ L-1 after 22 days. The optimized medium containing glycerol as carbon source obtained maximum productivity of 0,13 g ¿ L-1 ¿ h-1 and 48 g kojic acid ¿ L-1 after 20 days of fermentation. Crude glycerol from biodiesel strongly inhibited koijc acid production and its use as carbon source reached the maximum concentration of 18 g kojic acid ¿ L-1 after 22 days of fermentation. Cultivation in a 5 L batch fermentor using glycerol and corn steep liquor showed excessive foam formation e wall adherence. Anti-solvent crystallization and active carbon clarification were successful techniques for recovery and purification of kojic acid produced / Mestrado / Engenharia de Alimentos / Mestre em Engenharia de Alimentos

Orientador: Ranulfo Monte Alegre / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-24T06:43:41Z (GMT). No. of bitstreams: 1 Moraes_LuanaPereirade_D.pdf: 2084726 bytes, checksum: 11e04e791877c99a08c60405caa33111 (MD5) Previous issue date: 2014 / Resumo: O ácido y-poliglutâmico, também conhecido como y-PGA, é um polímero largamente estudado com capacidade de produzir polímeros e monômeros de ácido glutâmico quando hidrolisado. Por ser solúvel em água, biodegradável e atóxico, o y-PGA é aplicado em indústrias alimentícias, cosméticas e medicina. Com o objetivo de estudar a produção de y-PGA e sua hidrólise, foram avaliadas diferentes cepas de Bacillus spp e condições experimentais, além disso, meios de cultivos sem a presença do ácido glutâmico a partir de subprodutos industriais, como glicerol e melaço. O estudo iniciou com a escolha do meio de cultivo e aplicação de substratos alternativos e baixo custo. Foram determinadas as possíveis espécies do Bacillus produtoras de y-PGA, analisou-se os componentes do meio fermentativo e as condições de cultivo que interferem na produção de y-PGA através do planejamento experimental e aplicou-se um delineamento composto central rotacional (DCCR) para otimização das condições de cultivo. Por fim, avaliou-se o consumo de y-PGA e a hidrólise de y-PGA pela enzima presente no meio de cultivo. O micro-organismo Bacillus velezensis NRRL B-23189 foi o selecionado para a produção de y-PGA. A produção de y-PGA em meio de cultivo sem ácido glutâmico contendo glicerol (100 g/L) foi otimizado, obtendo-se o ponto ótimo em meio cuja composição foi de sulfato de amônio, 8 g/L, ácido cítrico, 20 g/L, temperatura de 27 °C, agitação de 200 rpm, pHinicial 6,5 em cultivo submerso conduzido por agitador orbital. Nas condições otimizadas a produção de y-PGA sem utilização do ácido glutâmico foi de 4,17 g/L. Ao substituir o glicerol por melaço, obteve-se uma produção de 4,82 g/L do y-PGA em meio contendo melaço, 200 g/L, sulfato de amônio, 8 g/L, ácido cítrico, 12,5 g/L , temperatura de 27 °C, agitação de 200 rpm, pHinicial 6,5 em cultivo submerso conduzido por agitador orbital. A avaliação das condições de cultivo em biorreator com capacidade de 5 L, agitação de 500 rpm, taxa de aeração de 2 VVM, 27 °C e as mesmas condições otimizadas, mostrou um aumento na produção do y-PGA quando o subproduto de glicerol foi utilizado, a produção de y-PGA foi de 28 g/L. Um aumento na produção de ?-PGA para 6,69 g/L foi determinado quando utilizou melaço. O Bacillus velezensis NRRL B-23189 utiliza o y-PGA como fonte de carbono quando outras fontes não estão no meio fermentativo. Para isto o microorganismo libera uma enzima no meio de cultura responsável pela hidrólise do y-PGA / Abstract: The poly(y-glutamic acid), also known as y-PGA, is a polymer that much research has been done on this metabolite and it produces glutamic acid polymers and monomers when hydrolyzed. y-PGA is a water-soluble, biodegradable and non toxic biopolymer with applications in medicine, food, cosmetic industries. This work aims to study the process of y-PGA production and hydrolysis. Bacillus strains and experimental conditions had been determined, as well as different culture conditions without glutamic acid as alternative industrial substrates by-products (glycerol and molasses). Firstly, culture media and alternative and cheap substrates were selected and Bacillus strains was evaluated. A fractional central composite design was utilized to evaluate the effects of fermentative compounds and culture conditions on y-PGA production. The optimization of culture conditions was determined using central composite design (CCD). Finally, consumption and enzymatic hydrolysis of y-PGA in culture media was studied. The Bacillus velezensis NRRL B-23189 strain was selected. The culture media without glutamic acid with 100 g/L of glycerol was optimized. The CCD showed the best y-PGA production in culture media with ammonium sulphate, 8 g/L, citric acid, 20 g/L, the temperature of 27 °C, the agitation of 200 rpm, the initial pH 6,5 in shaker. Under optimized conditions, the production of y-PGA was 4,17 g/L. The production of y-PGA was 4,82 g/L when the molasses, 200 g/L, was supplemented with ammonium sulphate, 8 g/L, citric acid, 12,5 g/L, temperature of 27 °C, agitation of 200 rpm, initial pH 6,5 in shaker. Experimental conditions of 5 L in stirred bioreactor with stirring rates of 500 rpm, aeration rate of 2 VVM, the temperature of 27 °C and same optimal conditions, showed higher y-PGA production than when used glycerol in culture media, 28 g/L. When it was used molasses the y-PGA production was 6,69 g/L. The Bacillus velezensis NRRL B-23189 uses y-PGA as only carbon source or when the carbon at the medium was not sufficient. Thus, the microrganism produces the enzyme that hydrolyses y-PGA / Doutorado / Engenharia de Alimentos / Doutora em Engenharia de Alimentos