Les ressources de carbone primaires doivent être progressivement remplacées par des ressources renouvelables plus complexes comme les matières lignocellulosiques, pour produire des biocarburants ou des synthons (bioraffineries de 2ième génération). Cette évolution nécessite de modifications importantes à différentes étapes du procédé, au niveau de la fermentation elle-même ou dans les étapes ultérieures nécessaire pour l'obtention du produit cible. Dans ce travail, nous avons étudié un procédé de production de succinate à partir du xylose. La fermentation a été réalisée en utilisant une souche d' Escherichia coli modifiée par ingénierie métabolique. La purification du succinate a été réalisée par nanofiltration. Des travaux précédents ont permis, par ingénierie métabolique, de mettre au point une souche E. coli KJ122 permettant de produire du succinate par fermentation anaérobie de glucose dans un milieu contenant des sels minéraux. Cette souche ne permet cependant pas une fermentation performante lorsque le xylose est utilisé comme substrat. Afin de lever cette limitation, E. coli KJ122 a été modifiée. Le transporteur ABC codant pour les gènes xylFGH a été inactivé par une technique de suppression de gènes. La souche ainsi obtenue, baptisée KJ12201 (E. coli KJ122 ?xylFGH) a permis d'atteindre des vitesses de croissances rapides, des consommations de xylose et une production de succinate améliorées par rapport à la souche parente. Après modification génétique, E. coli KJ12201-14T permet de produire en mode une concentration élevée de succinate de 84 g/L, la concentration d'acétate accumulée étant de 11 g/L, à partir d'un milieu de composition adaptée (AM1) contenant 10% de xylose. En fermentation fed-batch, E. coli KJ12201-14T permet de produire du succinate à une concentration de 84 g/L, avec un rendement de 0.85 g/g et une productivité de 2 g/L/h. Ces résultats démontrent les potentialités de cette souche pour produire du succinate à partir de xylose ou d'hydrolysats riches en xylose issus de matières lignocellulosiques. La nanofiltration a ensuite été considérée afin de purifier le succinate obtenu par fermentation. Les expériences ont été réalisées avec une membrane NF45 et des milieux de fermentation synthétiques contenant le succinate et différentes impuretés, sels minéraux, glucose ou autres sels d'acides organiques, acétate en particulier. L'influence des conditions opératoires (pH, pression) sur les performances de la NF a été évaluée. Les mécanismes gouvernant le transfert des espèces à travers la membrane ont été étudiés afin d'expliquer la variation des rétentions en fonction de la composition du milieu. En solution simple, les résultats ont montré que la rétention du succinate augmente avec la pression appliquée et avec le pH et diminue lorsque la concentration augmente. Pour des concentrations faibles, de l'ordre de 0.1M, les rétentions du succinate et de l'acétate en mélange sont différentes et identiques à celles en solution simples. Une bonne purification du succinate est ainsi possible. Au contraire, pour des concentrations plus élevées en succinate, la rétention diminue par suite de l'écrantage des effets de charge. Les rétentions étant trop proches, la séparation acétate/succinate devient impossible. Considérant les mécanismes ainsi mis évidence, une méthodologie a été proposée afin de réaliser la purification du succinate obtenu par fermentation. La séparation acétate/succinate est effectuée en deux étapes. Une diafiltration du jus de fermentation, préalablement dilué, est d'abord réalisée en utilisant la membrane NF45. Le rétentat purifié est ensuite concentré, en utilisant une membrane d'osmose inverse. Grace à ce procédé, il est possible d'augmenter la pureté du succinate de 85 à plus de 99.5% avec un rendement global supérieur à 92%. L'intérêt de la nanofiltration pour purifier le succinate produit par fermentation est ainsi démontrée. / Current trend is to move from primary carbohydrate resources to more complex ones like lignocellulosic materials as a bio-renewable feedstock, to produce biofuels or chemical building blocks. This evolution requires significant modifications at different stages in the bioprocess engineering, including fermentation and downstream processes. In this work, the succinate production by a newly metabolically engineered Escherichia coli from xylose, and its purification from fermentative broth by nanofiltration were studied. Escherichia coli KJ122 strain was previously engineered to produce high titers and yields of succinate in mineral salts medium containing glucose under simple-batch anaerobic conditions. However, this strain does not efficiently utilize xylose due to catabolic repression. To improve the xylose uptake and its utilization of E. coli KJ122, xylFGH genes were inactivated by the gene deletion technique. The mutant strain named KJ12201 (E. coli KJ122 ?xylFGH) exhibited high abilities in fast growth, xylose consumption and succinate production compared to those of the parental strains. After performing metabolic evolution, E. coli KJ12201-14T efficiently consumed 10% xylose to produce a high succinate concentration at 84 g/L with an accumulated acetate concentration at 11 g/L in mineral salts medium (AM1) under batch fermentation. During fed-batch fermentation, E. coli KJ12201-14T produced succinate at a concentration, yield, and overall productivity of 84 g/L, 0.85 g/g, and 1.0 g/L/h, respectively. These results demonstrated that E. coli KJ12201 would be a potential strain for the economic bio-based succinate production from xylose and other xylose-rich hydrolysates derived from lignocellulosic materials. The succinate purification from fermentation broth by nanofiltration (NF) was also investigated. The experiment was carried out with a NF45 membrane and various synthetic fermentation broths containing succinate salt and different impurities such as inorganic salts, glucose, and other organic acid salts including acetate. The influence of the operating conditions (pH, pressure) as well as the broth composition on the NF performances was evaluated. The mechanisms governing the transfer of the solutes through the membrane were studied in order to explain the different solute retentions observed according to the fermentation broth composition. In single-solute solutions, the succinate retention increases with increasing pressure and feed pH and decreases with increasing feed concentration. For instance, at a low salts concentration at 0.1 M, it was observed that the retentions of succinate and acetate in the mixture are identical to those in single solutions. Thus, a good purification of succinate can be obtained. On the contrary, with higher succinate concentrations, the retention was decreased due to the screening effect. Retentions of those solutes were then too close to achieve a separation. Based on abovementioned mechanisms observed, a methodology was proposed to perform the succinate purification from fermentation broth. The succinate/acetate separation was carried out in two steps. A diafiltration of the diluted fermentation broth was initially performed, and the concentration step followed. With this process, it was possible to increase the succinate purity from 85% to more than 99.5% while maintaining a total yield higher than 92%. From this work, it was shown that NF could be effectively used for the succinate purification from fermentation broth.

Mitochondria are essential organelles for most eukaryotic cells, containing intricate networks of numerous proteins. These include, among others, complexes I-IV of the electron transport chain. Being at the crossroads of the tricarboxylic acid cycle and the respiratory chain, mitochondrial complex II plays a key role in cellular metabolism. The protein complex, also known as succinate dehydrogenase, is capable of not only succinate oxidation and electron transfer but also contributes to the production of reactive oxygen species. Mitochondrial complex II consists of four subunits, SDHA-D, and four dedicated protein assembly factors SDHAF1-4 that participate in complex II biogenesis. Mutations and epigenetic modulations of genes coding for succinate dehydrogenase subunits or assembly factors are associated with pathological conditions such as neurodegenerative diseases, or may result in tumor formation. However, inborn complex-II-linked mitochondrial pathologies are rather understudied, compared to diseases with causative errors of other mitochondrial complexes, presumably due to the fact that none of complex II subunits is encoded in the mitochondrial genome. Recent studies have shown that impairment of mitochondrial complex II function or assembly leads to accumulation of alternative assembly forms...

This project investigates the moisture barrier properties of bio-based polymers and ways of improving them. The first section addresses the effect of crystallinity on the water permeability of poly(lactic acid) (PLA). The second section investigates PLA/talc composites and PLA/ montmorillonite nanocomposites. The third section is focused on a new polymer, polybutylene succinate (PBS), and its nanocomposites with montmorillonite. In the first section, the water vapour transmission rates (WVTR) through samples of polylactic acid of different crystallinities have been measured. Three different grades of commercial PLA were used with different ratios of L-lactide and D-lactide to give a range of crystallinities from 0 to 50%. Sheets of PLA were prepared by melt compounding followed by compression moulding and annealing at different temperatures and for different times to give the range of crystallinities required. Crystallinity was measured by differential scanning calorimetry (DSC) and the morphology of the samples was observed under crossed polars in a transmitted light microscope. Water vapour transmission rates through the films were measured at 38°C and at a relative humidity of 90%. It was found that the measured values of WVTR decreased linearly with increasing crystallinity of the PLA from 0 to 50%. The results are discussed in terms of the effect of crystallinity on solubility and shown to fit the tortuous path model. The model was also successfully used to explain published data on water permeability of polyethylene terephthalate. In the second section, a series of PLA/talc composites and PLA/ montmorillonite nanocomposites were prepared by melt compounding followed by compression moulding. The morphologies of the composites were investigated using transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD) and it was found that the fillers were well dispersed in the polymer matrix. The average aspect ratio of the compounded talc was found to be 8, and that of the nanoclay was found to be 50. Water vapour transmission rates (WVTR) through the films were measured at 38°C and at a relative humidity of 90%. It was found that the measured values of WVTR decreased with increasing filler content and the results gave good agreement with predictions from the Nielsen tortuous path model. In the third section, PBS/ montmorillonite nanocomposites were prepared by melt compounding followed by compression moulding. The melting and crystallisation behaviour of the pure PBS samples were investigated using differential scanning calorimetry (DSC) and cross polarised optical microscopy. A slight decrease of the degree of crystallinity was found in PBS containing 5% nanoclay. The morphology of the composites was investigated using transmission electron microscopy (TEM) and wide-angle X-ray diffraction (WAXD) and it was confirmed that that composite structures were intercalated. Water vapour transmission rates (WVTR) through the PBS sheets were measured using a MOCON Permatran-W®398. The measured values of WVTR decreased with increasing nanoclay content. However, the experimental values were all higher than the values predicted by the Nielsen tortuosity model. This result shows that in the case of PBS, which is a highly crystalline polymer, the nanoclay is not as well dispersed and is not as effective in reducing water vapour permeability as in the case of PLA.

The prototype uncoupling protein 1 (UCP1) mediates proton leak-dependent thermogenesis in mammals, but the physiological functions of the novel UCP2-5 are unclear. Nematodes only express one uncoupling protein that is most similar to UCP4 in the human brain, which is believed to be the most evolutionarily conserved of the uncoupling proteins. Consistent with reported UCP functions in mammals, we observed that ceUCP4-null nematodes had decreased metabolic rates and increased adiposity compared to wild type. Surprisingly, these phenotypes corresponded to decreased succinate-mediated mitochondrial respiration without apparent changes in mitochondrial uncoupling. ceUCP4-null mitochondria exhibited normal electron transport chain functions, but had a decreased capacity for succinate import. Supporting the functional importance of ceUCP4-dependent complex II regulation in vivo, ceUCP4 deficiency was demonstrated to result in a selectively lethal response to genetic and pharmacological inhibition of Complex I. Similarly, ceUCP4-deficiency significantly prolonged lifespan in the short-lived mev-1 mutant that generates deleterious complex II-derived reactive oxidants. These results define a new physiological function for the ancestral ceUCP4 in the regulation of complex II-mediated oxidative phosphorylation through an unexpected effect on mitochondrial succinate transport. The data described in this dissertation also describe a novel mechanism by which uncoupling proteins mediate mitochondrial bioenergetics. / text

The aim of this research was to identify the mechanisms that underpin changes in respiratory capacity during acclimation to temperature. Dark respiration, enzyme activities and leaf ultrastructure were measured from ryegrass (Lolium perenne) in controlled environmental chambers and two species of native grass (Chionochloa rubra & C. pallens) growing at different altitudinal ranges on Mount Hutt, Canterbury, New Zealand. The overall hypothesis was that the changes in both mitochondrial numbers and enzyme activity underpin the greater respiratory capacity observed in response to decreasing temperatures. Gas exchange measurements were carried out to measure rates of dark respiration (Rd) in leaves of both ryegrass and tussocks. Respiratory homeostasis (full acclimation) was achieved in ryegrass leaves but only partial acclimation in both species of tussock plants. Dark respiration rates for warm-grown ryegrass were greatly reduced compared to cool-grown grasses. Rd was lower for C. rubra growing at the base of the mountain (450m) compared to plants at a higher altitude (1060m). The dark respiration rates were also lower for C. pallens growing at 1070m than at 1600m. When comparing Rd between high and low altitude plants, it was significantly lower in low altitude plants at 450m than at 1600m. Oxygen consumption was measured in intact leaves and roots, crude mitochondria and isolated mitochondria from ryegrass to investigate whether a change in respiratory capacity was involved with changes in Rd. Mitochondrial respiratory capacity was slightly reduced in warm leaves and roots (not significantly). The respiratory capacity results from isolated mitochondria for C. rubra (at 450m and 1060m) and C. pallens (at 1070m and 1600m) were consistent with the hypothesis that plants from warm sites have lower respiratory capacity in comparison to plants from cool sites. Based on these results and those of previous studies, it was concluded that respiratory flux for any given temperature is not simply determined by maximal capacities of the respiratory apparatus but rather a combination of the availability of substrate supply, the demand for respiratory products (i.e. ATP) and/or the maximal capacity of respiratory enzymes. Utilizing transmission electron micrographs, it was found that mitochondria were significantly less abundant in warm-grown than cool-grown ryegrass mesophyll cells. Mitochondria dimensions increased slightly between the cool and warm treatment. At lower altitudes (C. rubra), there was a significant decrease in mitochondria numbers with decreasing elevation. At higher altitudes (C. pallens), there was no noticeable change in mitochondria numbers between 1070m and 1600m. It was concluded that mitochondrial abundance for the controlled and field experiments, and mitochondrial sizes in the field, were associated with changes in Rd. The maximal activities of fumarase and succinate dehydrogenase (SDH) in isolated mitochondria from leaves of ryegrass and tussock were measured spectrophotometrically. The results in the controlled experiment indicate that enzymes other than fumarase and SDH could be responsible for the increased respiratory capacity observed in cold acclimated leaves of ryegrass. However, fumarase maximal activity was significantly reduced in C. rubra at low altitude compared with C. pallens growing at high altitude - this suggests that it may be involved in the differences in respiratory capacity and Rd between the two sites. Succinate dehydrogenase did not differ significantly in response to altitude. The large difference between the two field sites for fumarase activity is comparable to the large difference in Rd and reduction in mitochondrial abundance and dimensions seen between the two sites. This supports the overall hypothesis that cool-grown plants keep up with energy demands at low temperatures by increasing enzyme concentrations/capacity. The results of this study are supportive of the hypothesis that growth in low altitudes and warm conditions will result in the reduction of Rd as a consequence of: (1) temperature sensitivity of the respiratory apparatus, resulting in the reduction of the respiratory capacities of mitochondria; (2) a reduction in mitochondria size and numbers; and as a consequence of this (3) a reduction in the activities of mitochondrial enzymes. However, these responses are species specific and vary according to the range of temperatures experienced by plants in the field and controlled environments.

A tendência atual do mercado cosmético é desenvolver produtos que contenham insumos de origem vegetal. O objetivo deste trabalho foi a aplicação da Tecnologia da Química Verde na síntese da rutina visando o aumento da estabilidade dessa em formulações cosméticas com sua eficácia antioxidante e fotoprotetora. Realizou-se a síntese química por meio da introdução de grupos carboxilatos às hidroxilas do dissacarídeo na molécula de rutina, gerando como produto final o succinato de rutina. Este derivado e/ou a rutina foram incorporados em 74 formulações-teste e, selecionadas 12 (sistemas emulsionados O/A), após serem submetidas à Avaliação Preliminar de Estabilidade (APE) e ao Teste de Estabilidade Acelerada (TEA), sob variações de temperatura e umidade. Utilizou-se agentes emolientes e silicones para facilitar a solubilização e/ou dispersão dos filtros químicos e físicos. A segunda etapa deste trabalho foi a avaliação da segurança do succinato de rutina, tendo como padrão a rutina, por meio do método alternativo de toxicidade in vitro, o XTT. Após o screening das concentrações ensaiadas, as que apresentaram menor nível de morte celular foram respectivamente, 0,1% ou 1 mg/mL (rutina) e 0,4% ou 4 mg/mL (succinato de rutina). Segundo os resultados do TEA, as formulações contendo succinato de rutina associada ou não aos filtros solares em ambas as bases cosméticas (A - Crodafos®CES + Uniox®C e B - Hostacerin®SAF) foram selecionadas para a continuidade do Teste de Estabilidade Normal (TEN). Neste teste, as emulsões fotoprotetoras foram avaliadas frente aos parâmetros: propriedades organolépticas (aspecto, cor e odor), aspectos físico-químicos (medição de pH e de viscosidade) e funcionais (atividade antirradicalar e eficácia fotoprotetora in vitro). Os resultados apresentados pela formulação MS (succinato de rutina associado aos filtros químicos e físico) foram: homogeneidade, a não modificação de cor e odor em temperatura ambiente, a não alterações significativas de valores de pH, de área de histerese, de atividade antirradicalar e de FPS. Esta estabilidade ocorreu principalmente quando incorporada à base cosmética A num período de 90 dias em 45ºC e 75% de umidade, 5ºC e 25ºC. Concluiu-se que a funcionalidade desta associação MS mostrou-se mais estável, mantendo a eficácia quanto à proteção solar e dentro de suas características reológicas poderia ser a mais bem aceita pelo consumidor. / The current cosmetic market trend is to develop products containing vegetables raw materials. This work proposed to use the Technology of Green Chemical to increase the rutin stability in cosmetic formulas as regards of its antioxidant and photoprotective properties. The chemical synthesis was realized by the introduction of carboxylate groups on sugar moiety of rutin producing in rutin succinate. This derivative and/or rutin were incorporated into 74 test formulas. After the undergoing to preliminary and accelerated stabilities under different temperature and humidity conditions were selected 12 formulas (O/W emulsions). Emollient agents and silicones were used to improve the solubility and/or dispersion of the chemical and physical filters. The second stage of this work was to evaluate the safety of rutin succinate, rutin used as an internal standard, using the alternative method of in vitro toxicity, the XTT. After the screening of tested concentrations, the concentrations of the samples with the lowest level of cell death were 0.1% or 1 mg/mL (rutin) and 0.4% or 4 mg/mL (rutin succinate), respectively. According to results obtained in accelerated stability testing, the formulations containing rutin succinate in combination or not with UV filters in both O/W emulsions (A - Crodafos®CES + Uniox®C and B - Hostacerin®SAF) were selected for the long term stability test. In this test the sunscreens were evaluated in the following parameters: the organoleptic properties (appearance, color and odor), physico-chemical aspects (pH value and viscosity) and functional (antiradicalar activity and in vitro photoprotection efficacy). The results presented by the MS formula (rutin succinate associated with physical filter and chemical filters) were: uniformity, stability of color and odor at room temperature and showed no significant difference, as well stability in: pH and SPF (Sun Protection Factor) values, hysteresis area, antiradicalar activity. These results were observed mainly when it was incorporated to O/W emulsion A (90 days of analyses at 45°C and 75% humidity, 5°C and 25°C). It was observed the functionality of MS association was more stable, maintaining photoprotective efficacy and within their rheological properties could be more accepted by consumers.

A tendência atual do mercado cosmético é desenvolver produtos que contenham insumos de origem vegetal. O objetivo deste trabalho foi a aplicação da Tecnologia da Química Verde na síntese da rutina visando o aumento da estabilidade dessa em formulações cosméticas com sua eficácia antioxidante e fotoprotetora. Realizou-se a síntese química por meio da introdução de grupos carboxilatos às hidroxilas do dissacarídeo na molécula de rutina, gerando como produto final o succinato de rutina. Este derivado e/ou a rutina foram incorporados em 74 formulações-teste e, selecionadas 12 (sistemas emulsionados O/A), após serem submetidas à Avaliação Preliminar de Estabilidade (APE) e ao Teste de Estabilidade Acelerada (TEA), sob variações de temperatura e umidade. Utilizou-se agentes emolientes e silicones para facilitar a solubilização e/ou dispersão dos filtros químicos e físicos. A segunda etapa deste trabalho foi a avaliação da segurança do succinato de rutina, tendo como padrão a rutina, por meio do método alternativo de toxicidade in vitro, o XTT. Após o screening das concentrações ensaiadas, as que apresentaram menor nível de morte celular foram respectivamente, 0,1% ou 1 mg/mL (rutina) e 0,4% ou 4 mg/mL (succinato de rutina). Segundo os resultados do TEA, as formulações contendo succinato de rutina associada ou não aos filtros solares em ambas as bases cosméticas (A - Crodafos®CES + Uniox®C e B - Hostacerin®SAF) foram selecionadas para a continuidade do Teste de Estabilidade Normal (TEN). Neste teste, as emulsões fotoprotetoras foram avaliadas frente aos parâmetros: propriedades organolépticas (aspecto, cor e odor), aspectos físico-químicos (medição de pH e de viscosidade) e funcionais (atividade antirradicalar e eficácia fotoprotetora in vitro). Os resultados apresentados pela formulação MS (succinato de rutina associado aos filtros químicos e físico) foram: homogeneidade, a não modificação de cor e odor em temperatura ambiente, a não alterações significativas de valores de pH, de área de histerese, de atividade antirradicalar e de FPS. Esta estabilidade ocorreu principalmente quando incorporada à base cosmética A num período de 90 dias em 45ºC e 75% de umidade, 5ºC e 25ºC. Concluiu-se que a funcionalidade desta associação MS mostrou-se mais estável, mantendo a eficácia quanto à proteção solar e dentro de suas características reológicas poderia ser a mais bem aceita pelo consumidor. / The current cosmetic market trend is to develop products containing vegetables raw materials. This work proposed to use the Technology of Green Chemical to increase the rutin stability in cosmetic formulas as regards of its antioxidant and photoprotective properties. The chemical synthesis was realized by the introduction of carboxylate groups on sugar moiety of rutin producing in rutin succinate. This derivative and/or rutin were incorporated into 74 test formulas. After the undergoing to preliminary and accelerated stabilities under different temperature and humidity conditions were selected 12 formulas (O/W emulsions). Emollient agents and silicones were used to improve the solubility and/or dispersion of the chemical and physical filters. The second stage of this work was to evaluate the safety of rutin succinate, rutin used as an internal standard, using the alternative method of in vitro toxicity, the XTT. After the screening of tested concentrations, the concentrations of the samples with the lowest level of cell death were 0.1% or 1 mg/mL (rutin) and 0.4% or 4 mg/mL (rutin succinate), respectively. According to results obtained in accelerated stability testing, the formulations containing rutin succinate in combination or not with UV filters in both O/W emulsions (A - Crodafos®CES + Uniox®C and B - Hostacerin®SAF) were selected for the long term stability test. In this test the sunscreens were evaluated in the following parameters: the organoleptic properties (appearance, color and odor), physico-chemical aspects (pH value and viscosity) and functional (antiradicalar activity and in vitro photoprotection efficacy). The results presented by the MS formula (rutin succinate associated with physical filter and chemical filters) were: uniformity, stability of color and odor at room temperature and showed no significant difference, as well stability in: pH and SPF (Sun Protection Factor) values, hysteresis area, antiradicalar activity. These results were observed mainly when it was incorporated to O/W emulsion A (90 days of analyses at 45°C and 75% humidity, 5°C and 25°C). It was observed the functionality of MS association was more stable, maintaining photoprotective efficacy and within their rheological properties could be more accepted by consumers.

A suitable management of the pharmaceutical property is needed and helpful to design a desired nanoparticulate delivery system, which includes the carrier nature, particle size and size distribution, morphology, surfactant stabiliser according to the technique applied, drug-loading ratio and encapsulation efficiency, surface property, etc. All will influence the in vitro release, in vivo behaviour and tissue distribution of administered particulate drug loaded nanoparticles. The main purpose of the present work was to determine the effect of drug loading ratio when employing TPGS as surfactant stabiliser and/or matrix material to improve the nanoparticulate formulation. The model drug employed was paclitaxel. / Singapore-MIT Alliance (SMA)

Dans le but de développer des matériaux à partir d'une ressource renouvelable de moindre coût que l'amidon, des matériaux à base de farine de maïs ont été élaborés par extrusion-injection. La caractérisation des propriétés physico-chimiques de ces matériaux a révélé que le taux de glycérol (ajouté à la farine de maïs en tant que plastifiant) et le profil des zones de cisaillement employé lors de l'extrusion influencent significativement le taux de déstructuration de l'amidon et des protéines de la farine de maïs. Ceci a pu être établi en croisant notamment les résultats de l'analyse par diffraction aux rayons X, par spectroscopie infra-rouge à transformée de Fourier, de l'analyse calorimétrique différentielle à balayage à des observations par microscopie confocale à balayage laser des matériaux. De plus, le suivi des cinétiques d'hydrolyse en sucres réducteurs de l'amidon par des enzymes amylolytiques en présence et en absence d'enzymes protéolytiques a pu être relié à la déstructuration des protéines. Les matériaux obtenus présentent cependant des inconvénients rédhibitoires pour certaines applications comme l'hygroscopie élevée et le vieillissement rapide dans le temps. L'ajout de polybutylène succinate (PBS) au mélange farine-glycérol a cependant permis de conduire à une amélioration des propriétés mécaniques et à une réduction de l'hygroscopie de ces matériaux. Les observations de la morphologie de ces matériaux par microscopie électronique à balayage ont montré que la farine de maïs et le PBS sont incompatibles et présentent une morphologie qui varie selon le taux de PBS dans le mélange (30, 50 ou 70%). L'étude de la cinétique d'hydrolyse de l'amidon de la farine de maïs par des enzymes amylolytiques a permis de mettre en évidence l'influence de plusieurs facteurs : (i) la cristallinité de l'amidon, (ii) l'aire spécifique, (iii) la porosité et (iv) la morphologie des matériaux. De plus, l'évaluation de la biodégradation par voie microbienne en milieu liquide et solide par voie aérobie ou anaérobie a montré les mêmes tendances globales que les résultats obtenus par voie enzymatique. Ainsi, les matériaux élaborés à partir des formulations présentant des proportions de PBS excédant 50 % ne sont pas biodégradables au sens de la norme ISO 14855/1999 et sont également faiblement hydrolysés par les enzymes amylolytiques.

名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成5年9月14日 加藤亨嗣氏の博士論文として提出された