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La biomasse lignocellulosique est au cœur du développement de la bioraffinerie de par l’intérêt de fractionner ses composants avec divers procédés pour la production de biocarburants, de molécules d’intérêt et de matériaux agro-sourcés. L’objectif de cette thèse visait à étudier la transformation des xylanes du son de blé en molécules tensio-actives (esters de pentoses). Cette transformation a été envisagée en deux étapes : une première étape d’hydrolyse du son de blé par des hémicellulases pour la production de xylose et d’arabinose, suivie d’une seconde étape d’acylation de ces glucides par une lipase pour accéder aux esters de pentoses. La thèse s’est principalement focalisée sur l’étude de la transestérification de D- xylose et de L-arabinose (purs ou issus d’un hydrolysat de son de blé) et du laurate de vinyle par la lipase immobilisée N435. L’influence de divers paramètres réactionnels a été étudiée. Des mono- et diesters lauriques de D-xylose et de L-arabinose, dont la structure a été caractérisée, sont produits par la lipase. Les propriétés physico-chimiques de ces esters lauriques de pentoses, originaux et nouvellement décrits, ont été évaluées et ont montré l’intérêt de ces molécules en tant que tensio-actifs. Une approche préliminaire a également été développée pour étudier la synthèse d’esters lauriques de xylo-oligosaccharides par la lipase N435. Nos résultats montrent que cette production a lieu mais qu’elle est moins efficace que dans le cas des monosaccharides. La transestérification catalysée par la lipase N435 reste dans ce cas à optimiser, de même que la purification et la caractérisation de ces esters lauriques de xylo-oligosaccharides. / Lignocellulosic biomass is at the center of biorefinery development. This development is achieved by the fractionation of the main components of lignocellulosic biomass (cellulose and hemicelluloses) in order to produce biofuels, molecules of interest and agromaterials.This PhD thesis had the objective to study the transformation of wheat bran xylanes into pentose based surfactants. A two steps system was studied, a first step of enzymatic hydrolysis of wheat bran with hemicellulases (to produce xylose and arabinose) and a second step of sugar acylation catalyzed by a lipase to produce pentoses based surfactants.The PhD thesis mainly focused on the transesterification of D- xylose and L-arabinose (pure or obtained from wheat bran hydrolysate) by the immobilized lipase N435 with vinyllaurate. Several parameters were studied. Lauryl mono- and diesters of D- xylose and L-arabinose were produced by the lipase and their structures were elucidated. Physico-chemical properties of the original and newly produced pentoses based esters were investigated and shown the surfactant potential of these molecules. A preliminary approach was also developed to study the enzymatic synthesis of lauryl xylo-oligosaccharides esters by the lipase N435. Our results showed that such a production is possible but is less efficient than with monosaccharides. The production by transesterification of xylo-oligosaccharides with the lipase N435 needs to be optimized as well as the purification and the characterization of lauryl xylo-oligosaccharides esters.

Made available in DSpace on 2014-12-17T14:07:23Z (GMT). No. of bitstreams: 1 MauricioRB.pdf: 2052566 bytes, checksum: ecabe62a65c1b9db9e09054f3321c5b1 (MD5) Previous issue date: 2007-03-12 / Sugar esters are substances which possess surfactant, antifungical and bactericidal actions and can be obtained through two renewable sources of raw materials: sugars and vegetable oils. Their excellent biodegradability, allied to lhe fact that they are non toxic, insipid, inodorous, biocompatible, no-ionic, digestible and because they can resist to adverse conditions of temperature, pH and salinity, explain lhe crescent use of these substances in several sections of lhe industry. The objective of this thesis was to synthesize and characterize surfactants and polymers containing sugar branched in their structures, through enzymatic transesterification of vinyl esters and sugars, using alkaline protease from Bacillus subtilis as catalyst, in organic medium (DMF).Three types of sugars were used: L-arabinose, D-glucose and sucrose and two types of vinyl esters: vinyl laurate and vinyl adipate. Aiming to reach high conversions from substrates to products for a possible future large scale industrial production, a serie of variables was optimized, through Design of Experiments (DOE), using Response Surface Methodology (RSM).The investigated variables were: (1) enzyme concentration; (2) molar reason of substrates; (3) water/solvent rale; (4) temperature and (5) time. We obtained six distinct sugar esters: 5-0-lauroyl L-arabinose, 6-0-lauroyl D-glucose, 1'-O-lauroyl sucrose, 5-0-vinyladipoyl L-arabinose, 6-0-vinyladipoyl D-glucose and 1 '-O-vinyladipoyl sucrose, being lhe last three polymerizable. The progress of lhe reaction was monitored by HPLC analysis, through lhe decrease of sugar concentration in comparison to lhe blank. Qualitative analysis by TLC confirmed lhe formation of lhe products. In lhe purification step, two methodologies were adopted: (1) chromatographic column and (2) extraction with hot acetone. The acylation position and lhe chemical structure were determined by 13C-RMN. The polymerization of lhe three vinyl sugar esters was possible, through chemical catalysis, using H2O2 and K2S2O8 as initiators, at 60?C, for 24 hours. IR spectra of lhe monomers and respective polymers were compared revealing lhe disappearance of lhe vinyl group in lhe polymer spectra. The molar weights of lhe polymers were determined by GPC and presented lhe following results: poly (5-0-vinyladipoyl L-arabinose): Mw = 7.2 X 104; PD = 2.48; poly (6-0-vinyladipoyl D-glucose): Mw = 2.7 X 103; PD = 1.75 and poly (1'-O-vinyladipoyl sucrose): Mw = 4.2 X 104; PD = 6.57. The six sugar esters were submitted to superficial tension tests for determination of the critical micelle concentrations (CMC), which varied from 122 to 167 ppm. Finally, a study of applicability of these sugar esters, as lubricants for completion fluids of petroleum wells was' accomplished through comparative analysis of lhe efficiency of these sugar esters, in relation to three commercial lubricants. The products synthesized in this thesis presented equivalent or superior action to lhe tested commercial products / ?steres de a??car s?o compostos que possuem a??o surfactante, antif?ngica e bactericida e podem ser obtidos a partir de duas fontes renov?veis de mat?ria-prima: a??cares e ?leos vegetais. Sua capacidade de se biodegradar, aliada ao fato de serem at?xicos, ins?pidos, inodoros, biocompat?veis, n?o-i?nicos, digest?veis e resistirem a condi??es severas de temperatura, pH e salinidade, explicam o crescente emprego destas subst?ncias em diversos setores da ind?stria. O objetivo desta tese foi sintetizar e caracterizar surfactantes e pol?meros, contendo a??cares ramificados em suas estruturas, atrav?s de transesterifica??o enzim?tica de ?steres vin?licos com a??cares, empregando-se protease alcalina de Bac?llus subtilis como catalisador, em meio org?nico (DMF). Foram empregados tr?s tipos de a??cares: L-arabinose, D-glicose e sacarose e dois tipos de ?steres vin?licos: laurato de vinila e adipato de vinila. Para a obten??o de altas convers?es de substratos em produtos, visando uma futura produ??o em larga escala, uma s?rie de vari?veis foram otimizadas, atrav?s de an?lise estat?stica experimental (DOE), por metodologia de resposta de superf?cie (RSM). As vari?veis investigadas foram: (1) a concentra??o de enzima; (2) a raz?o molar entre substratos; (3) a raz?o ?gua/solvente org?nico; (4) a temperatura e (5) o tempo. Foram obtidos seis ?steres de a??car: 5-0-lauroil L-arabinose, 6-0lauroil D-glicose, 1 '-O-Iauroil sacarose, 5-0-viniladipoil L-arabinose, 6-0viniladipoil D-glicose e 1 '-O-viniladipoil sacarose, sendo os tr?s ?ltimos polimeriz?veis. O progresso da rea??o foi monitorado por an?lise em HPLC, atrav?s do decr?scimo da concentra??o de a??car em rela??o ao branco. An?lises qualitativas, por TLC, confirmaram a forma??o dos produtos. Foram obtidas convers?es superiores a 98% na s?ntese do laurato de sacarose. Na purifica??o, foram adotadas duas metodologias: (1) coluna cromatogr?fica e (2) extra??o com acetona a quente. A posi??o de acila??o e a estrutura qu?mica foram determinadas por 13C-RMN. A polimeriza??o dos tr?s ?steres de a??car foi poss?vel, atrav?s de cat?lise qu?mica, empregando-se H2O2 e K2S2O8 como iniciadores, a 60?C, por 24 horas. Espectros de IR dos pol?meros foram comparados com os seus mon?meros, revelando o desaparecimento do grupo vinil. As massas molares dos pol?meros foram determinadas por GPC. Os pol?meros de a??car obtidos apresentaram as seguintes massas molares: poli (5-0-viniladipoil L-arabinose): Mw = 7,2 X 104; PD = 2,48; poli (6-0-viniladipoil D-glicose): Mw = 2,7 x 103; PD = 1,75 e poli (1 '-O-viniladipoil sacarose): Mw = 4,2 X 104; PD = 6,57. Os seis ?steres de a??car foram submetidos a ensaios de tens?o superficial para a determina??o das concentra??es micelares cr?ticas (CMC), que variaram de 122 a 167 ppm. Por fim, um estudo de aplicabilidade dos ?steres n?o polimeriz?veis, como lubrificantes para fluidos de completa??o de po?os de petr?leo foi realizado, atrav?s de an?lise comparativa da efici?ncia destes, em rela??o a tr?s lubrificantes comerciais. Os produtos sintetizados nesta tese apresentaram desempenho equivalente ou superior aos produtos comerciais testados

Submitted by Caroline Periotto (carol@ufscar.br) on 2016-09-21T12:53:09Z No. of bitstreams: 1 TeseVV.pdf: 2152205 bytes, checksum: cbcb3bfba1aaf9c801ac47859a7bd77a (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-23T18:25:02Z (GMT) No. of bitstreams: 1 TeseVV.pdf: 2152205 bytes, checksum: cbcb3bfba1aaf9c801ac47859a7bd77a (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-23T18:25:10Z (GMT) No. of bitstreams: 1 TeseVV.pdf: 2152205 bytes, checksum: cbcb3bfba1aaf9c801ac47859a7bd77a (MD5) / Made available in DSpace on 2016-09-23T18:25:16Z (GMT). No. of bitstreams: 1 TeseVV.pdf: 2152205 bytes, checksum: cbcb3bfba1aaf9c801ac47859a7bd77a (MD5) Previous issue date: 2016-05-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The use of lipases in large scale processes is limited due to their high cost. The reuse of the catalyst can contribute to make the enzymatic process more attractive. Hydrophobic supports are the mostly used for lipase immobilization, due to the mechanism of interfacial activation in the presence of hydrophobic interface. However, enzyme physically adsorbed to the support does not allow high operational stability. Therefore, in this work was evaluated the immobilization of commercial lipases from Candida antarctica type B (CALB), Thermomyces lanuginosus (LTL) e Pseudomonas fluorescens (LPF) on hybrid supports, that enable the hydrophobic adsorption, followed by covalent linkage between the adsorbed enzyme and the activated support. Silica was activated with trietoxy(octyl)silane (OCTES), (3-aminopropyl)trietoxysilane (APTES) e 3-glycidyloxypropyl)trimetoxysilane (GPTMS), aiming to produce supports with different functionality, as following: silica containing octyl groups (octyl-silica, OS), octyl and aldehyde groups (octyl-silica-glyoxyl and octyl-silicaaldehyde, OSGlx and OSGlu, respectively), and silica containing octyl and epoxy groups (octyl-silica-epoxy, OSEpx). From adsorption assays using the hydrophobic dye Rose of Bengal it was found that the modification of the silica with OCTES significantly increased the hydrophobicity of all the supports. Silica modified with OCTES groups showed to be 4 times more hydrophobic than non-modified silica. The support OSGlu yielded more active CALB biocatalyst, while OS yielded more active biocatalysts prepared with PFL and TLL. All the biocatalysts showed high stability in tert-butanol, specially CALB immobilized on OSGlu (OSGlu-CALB), maintaining 95% of its initial activity after 168 h at 60 ºC. CALB-OSGlu was successfully used in the synthesis of fructose oleate at 55ºC, yielding up to 70% conversion after 9 cycles of 6 hours, while the commercial biocatalyst Novozyme 435 retained around 53%. TLL and PFL were used in the synthesis of fructose oleate at 35ºC in presence of different amounts of water. All biocatalysts showed excellent performance in the ester synthesis when small amount of water (1%, v/v) was added to the organic phase, except for the lipases immobilized on silica modified with octyl and epoxy groups (OSEpx). Small amount of water increased around 5-times the ester productivity compared to reaction without water. Conversions around 70% were achieved at low temperature (35ºC) and short time of reaction (30 min). These results represent an advance in this field from of industrial point of view, where productivity is a relevant parameter for large-scale processes. Finally, porcine pancreatic lipase (PPL) immobilized on OS was used in the synthesis of xylose oleate and xylose caprilate, because it is the most inexpensive lipase commercially available. The results showed to be promising, because conversions around of 70% were achieved after 2 h of reaction at 60 oC. Generally, this work showed that the chemical modification of the silica surface with different active groups allowed the preparation of biocatalysts with different microenvironment, which exhibits an important role in the activity and stability of the immobilized enzymes. Besides, the biocatalysts prepared in this work showed excellent performance and operational stability in syntheses of sugar esters, showing to have potential for industrial application. / O uso de lipases em larga escala é limitado devido ao seu alto custo. O reuso do biocatalisador contribuiria para tornar o processo custo-efetivo. Suportes hidrofóbicos são os mais utilizados na imobilização de lipases, devido ao mecanismo de ativação interfacial na presença de interfaces hidrofóbicas. Entretanto, o fato da enzima ligar-se fisicamente ao suporte não garante maior estabilidade operacional. Portanto, nesse trabalho foi avaliada a imobilização de lipases comerciais de Candida antarctica tipo B (CALB), Thermomyces lanuginosus (LTL) e Pseudomonas fluorescens (LPF) em suportes híbridos, os quais possibilitam adsorção hidrofóbica, seguida de ligação covalente enzima-suporte. Sílica foi funcionalizada com trietoxi(octil)silano (OCTES), (3-aminopropil)trietoxisilano (APTES) e 3-glicidiloxipropil)trimetoxisilano (GPTMS), para produzir suportes com diferentes funcionalidades: sílica contendo grupos octil (octil-silica, OS), sílica contendo grupos octil e aldeídos (octil-sílica-glioxil e octil-sílica-glutaraldeído, OSGlx e OSGlu, respectivamente) e sílica contendo grupos octil e epóxi (octil-sílica-epóxi, OSEpx). A modificação da sílica com OCTES aumentou significativamente a hidrofobicidade de todos os suportes, observado a partir de ensaios de adsorção do corante hidrofóbico Rosa de Bengala. Sílica modificada com grupos OCTES apresentou hidrofobicidade cerca de quatro vezes superior à apresentada pela sílica não modificada. O suporte OSGlu rendeu biocatalisadores mais ativos para CALB, enquanto OS rendeu biocatalisadores mais ativos para LPF and LTL. Todos os biocatalisadores apresentaram boa estabilidade em terc-butanol, especialmente CALB imobilizada em OSGlu (CALB-OSGlu), retendo em torno de 95 % de sua atividade inicial após 168 h a 60 ºC. CALB-OSGlu foi usada com sucesso na síntese de oleato de frutose a 55ºC, mantendo mais de 70% de conversão após nove ciclos de 6 horas, enquanto para o biocatalisador comercial Novozyme 435 a conversão foi de aproximadamente 53%. LTL e LPF foram aplicados na síntese de oleato de frutose a 35ºC na presença de diferentes percentuais de água. Todos os biocatalisadores mostram excelente desempenho na síntese do éster adicionando-se uma pequena quantidade de água (1%, v/v) na fase orgânica, exceto para as enzimas imobilizadas em OSEpx. A presença de água contribuiu para aumentar em até cinco vezes a produtividade do éster em comparação à reação na ausência de água. Uma conversão de aproximadamente 70% foi alcançada à baixa temperatura (35ºC) e curto período de tempo (30 min). Esses resultados representam um avanço nesta área do ponto de vista industrial, onde a produtividade é um parâmetro relevante para processos em larga escala. Por fim, a lipase do pâncreas de porco (LPP) imobilizada em OS foi empregada na síntese de oleato de xilose e caprilato de xilose, devido ao seu menor custo dentre as lipases disponíveis comercialmente. Os resultados foram expressivos, obtendo-se uma conversão de aproximadamente 70% após 2 h de reação à 60ºC. De modo geral, esse trabalho mostrou que a modificação química da superfície da sílica com diferentes grupos ativos permitiu a preparação de biocatalisadores com diferentes microambientes, exercendo papel importante na atividade e estabilidade das lipases imobilizadas. Além disso, os biocatalisadores preparados neste trabalho apresentaram excelente desempenho e estabilidade operacional em reações de síntese de ésteres de açúcares, mostrando ter potencial para aplicação industrial.