Thermotoga petrophila is a hyperthermophilic anaerobic bacterium that grows optimally at 80?? C. It can utilize plant biomass to produce biofuels, including ethanol and hydrogen, which are alternative and renewable sources of energy. Xylan, microcrystalline avicel PH105, switchgrass, corn husks and wheat straw were used as growth substrates to determine T. petrophila???s capability to use different types of plant biomass for the production of ethanol and hydrogen. The metabolism of cellulosic substrates was analyzed by integrating proteomics analysis, gene identification, cellulase and xylanase activities, growth, metabolic products and cell adhesion. T. petrophila showed best growth on xylan, followed by corn husks, switchgrass, avicel PH105 and wheat straw. The optimal pH for higher biofuel yield was within the range of 8.0 to 8.5. The metabolic end products were H2, CO2, acetate, lactate, formate and succinate when T. petrophila grew on all the tested cellulosic materials. The highest yield of hydrogen (9.6 mM) and the highest yield of ethanol (0.95 mM) were both detected when T. petrophila was grown on xylan. No growth was observed on xylose, which was not expected because T. petrophila grew very well on xylan, a ??-1, 4-xylopryranose polymer from which xylose can be produced upon hydrolysis. The possible reason for this phenomenon may be that T. petrophila has no specific sugar transporters for xylose, although it contains all the genes encoding xylose metabolizing enzymes. The majority of exoglucanases and endoglucanases presented in T. petrophila were extracellular enzymes. The highest specific activities of exoglucanase (1361.3 mU/mg) and endoglucanase (1032.1 mU/mg) in T. petrophila were found in the supernatants of the growth culture with xylan as the sole substrate, indicating that xylan, not cellulose, is the best inducer to increase the expression of extracellular cellulases. Compared to the huge discrepancy of extracellular cellulases activities among different substrates (from 0 to 1361.3 mU/mg), intracellular cellulase (endoglucanase) activity was relatively steady (around 150 mU/mg). Xylanase activity was also detected in both the supernatant and the cell free extract; thus T. petrophila contains both extracellular and intracellular xylanase. The highest xylanase activity was detected in the cell free extract when T. petrophila was grown on cellobiose and xylan (3732.4 mU/mg and 3152.8 mU/mg, respectively), indicating that the majority of xylanase is an intracellular enzyme, and xylan and cellobiose are the best inducers to increase the expression of xylanase. Adhesion of T. petrophila cells to xylan, with many filaments connecting all the cells, was observed using scanning electron microscope and fluorescent staining microscope, whereas there was no attachment between cells and cellulose. This difference may explain why T. petrophila grew much better on xylan than on cellulose because cell adhesion increases enzyme concentration near the substrate to improve the efficiency of cellulosic material utilization. Furthermore, proteomics analysis was used to quantify all the expressed proteins in different growth media with various substrates. The proteomics data revealed that the most important enzymes for cellulose and hemicellulose utilization were ATP binding cassette (ABC) transporters, S-layer proteins and membrane binding proteins, which were up-regulated when T. petrophila was grown on cellulosic materials. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) also indicated the up-regulated proteins from the media with cellulosic substrates were probably ABC transporters and S-layer proteins based on the size of proteins. Based on the gene identification, end product determination and proteomics analysis, the tentative cellulosic material metabolic pathways in T. petrophila were completely profiled. Overall, our results suggest that the ability of T. petrophila to convert cellulosic materials into hydrogen and ethanol exceeds T. maritima, which is a model strain for studying hyperthermophiles. T. petrophila has great potential in applications of producing highly thermostable cellulases and biofuels from cellulosic materials. However, the mechanism of cell adhesion between T. petrophila and xylan and the regulation of the entire cellulosic materials metabolic pathway need further investigation.

FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Neste trabalho foram realizados estudos de adsorÃÃo em batelada e de oxidaÃÃo avanÃada para a remoÃÃo de fenol (F), 2-nitrofenol (2NF) e 4-nitrofenol (4NF) em soluÃÃo aquosa. Nos estudos de adsorÃÃo foram empregados como adsorventes o pà de bagaÃo da casca de coco in natura (BIN), pà de bagaÃo in natura tratado com HCl 1,0 M (BT) e carvÃo ativado (CA) proveniente da carbonizaÃÃo a 250ÂC do pà de bagaÃo tratado com Ãcido. Experimentos de equilÃbrio e cinÃtica de adsorÃÃo foram realizados nas temperaturas de 28, 40 e 50ÂC. Isotermas de Langmuir e Freundlich correlacionaram bem os dados de equilÃbrio, indicando capacidades de adsorÃÃo (qmÃx) que aumentaram na ordem: CA >>> BT > BIN. Este comportamento denota uma adsorÃÃo caracterizada pelas interaÃÃes entre os elÃtrons  dos anÃis aromÃticos e os elÃtrons  das camadas grafÃticas do carvÃo, a qual à mais intensa que a verificada nos materiais celulÃsicos onde predomina a formaÃÃo de complexos doador-receptor entre os sÃtios oxigenados localizados na superfÃcie do adsorvente e o anel aromÃtico dos compostos fenÃlicos. Os melhores resultados de qmÃx em carvÃo ativado e pà de bagaÃo tratado com Ãcido foram obtidos para a adsorÃÃo de 2-nitrofenol à temperatura ambiente (28ÂC), correspondentes aos valores de 17,1 e 1,39 mg/g, respectivamente. Do ponto de vista cinÃtico o modelo de pseudo-segunda ordem apresentou melhor ajuste dos dados experimentais. Por outro lado, processos oxidativos avanÃados (POAs) das molÃculas fenÃlicas foram conduzidos para os tratamentos fotolÃtico (UV), fotoquÃmico (UV/H2O2), Fenton (Fe2+/H2O2) e eletroquÃmico com anodos dimensionalmente estÃveis (ADEs) de Ru0,3Ti0,7O2, Ru0,3Ti0,4Sn0,3O2 e Ru0,3Sn0,7O2. Os processos Fenton e fotoassistidos apresentaram condiÃÃes Ãtimas nas concentraÃÃes de 1,0 mM em Ãons Fe2+e 3,0 mM em H2O2 e taxa de radiaÃÃo (I0) de 64 mW/cm2. Os Ãxidos eletrocatalÃticos foram preparados por termodecomposiÃÃo de cloretos precursores a 500oC atà a formaÃÃo de filmes com 2,0 Âm de espessura sobre um suporte de titÃnio. A caracterizaÃÃo pelas tÃcnicas de EDX, MEV e Voltametria CÃclica mostrou composiÃÃes praticamente estequiomÃtricas, morfologia estrutural tipo cracked mud e elevado sobrepotencial para a reaÃÃo de desprendimento de oxigÃnio (RDO). Estudos de oxidaÃÃo para as molÃculas fenÃlicas mostraram o 2-nitrofenol como a espÃcie mais oxidÃvel e o fenol comum como a espÃcie menos reativa. As eficiÃncias de degradaÃÃo dos processos fotoassistidos foram particularmente elevadas (superiores a 80%) enquanto o sistema Fenton apresentou taxas de remoÃÃo entre 60 e 78%. A modelagem cinÃtica segundo o modelo de pseudo-primeira ordem adotado permitiu um bom ajuste dos dados experimentais. Os valores da constante cinÃtica 1/ (min-1) a 28ÂC mostraram a seguinte ordem: Fenton (8,16 min-1) > fotoquÃmico (6,95 min-1) >> fotolÃtico (1,98 min-1). Em adiÃÃo, estudos usando anodos eletrocatalÃticos (ADEs) a potencial constante de eletrÃlise de 2,0 V mostraram degradaÃÃes superiores a 93% para os nitrofenÃis e entre 65 e 86% para o fenol. Em termos, considerado o tipo de ADE empregado, a eficiÃncia de eletrooxidaÃÃo à temperatura ambiente obedece a seguinte ordem de eficiÃncia: Ru0,3Ti0,7O2 > Ru0,3Ti0,4Sn0,3O2 > Ru0,3Sn0,7O2. A anÃlise espectroscÃpica para identificaÃÃo de co-produtos indicou completa mineralizaÃÃo dos compostos fenÃlicos nos processos fotoquÃmico e eletroquÃmico, enquanto que nos processos Fenton e fotolÃtico foram detectados traÃos de produtos hidroxilados. Em geral, os resultados obtidos confirmam os processos adsortivos e oxidativos como tratamentos promissores para a despoluiÃÃo de sistemas aquosos contendo fenÃis e nitrofenÃis / In the present work the batch adsorption and advanced oxidation of phenol (F), 2-nitrophenol (2NF) and 4-nitrophenol (4NF) in aqueous phase has been studied. The adsorption experiments were conducted onto coconut shell powder (BIN), coconut shell powder treated with HCl 1.0M (BT) and coconut shell-based activated carbon (CA) obtained from carbonization at low temperature (250ÂC). Equilibrium and kinetic studies were carried out at temperatures of 28, 40 and 50ÂC. Langmuir and Freundlich isotherms correlated well the equilibrium data, indicating the adsorption capacity (qmax) increased in the order: AC>>> BT> BIN. This behavior denotes an adsorption characterized by dispersive interactions between the -electrons of the graphitic carbon basal planes and those of the aromatic rings of the adsorbate, which is more intense when compared to the cellulose materials where are dominant the donor-acceptor complex formation between the oxygenated sites onto adsorbent and aromatic rings of phenol compounds. The best results of qmax in activated carbon and coconut shell powder treated with acid were obtained for the adsorption of 2-nitrophenol at room temperature (28ÂC), corresponding to values of 17.1 and 1.39 mg/g, respectively. In all cases, the adsorption kinetics could be satisfactorily fitted by a pseudo-second order model. Advanced oxidation processes (AOP) were carried out for treatments such photolytic (UV), photochemical (UV/H2O2), Fenton (Fe2+/H2O2) and electrochemical oxidation with dimensionally stable anodes (DSA) type Ti/Ru0.3Ti0.7O2, Ti/Ru0.3Ti0.4Sn0.3O2 and Ti/Ru0,3Sn0,7O2. The Fenton and photoassisted tests were performed to optimized conditions of 1.0 mM of Fe2+ ions, 3.0 mM of H2O2 and radiation intensity (I0) of 64 mW/cm2. Particularly, electrocatalytic oxides were prepared by thermal decomposition of chloride precursors to 500oC until the formation of films with thickness constant of 2μm on titanium support. The characterization by EDX, SEM and Cyclic Voltammetry techniques showed a nearly stoichiometric composition, morphology type âcracked mudâ and elevated overpotencial from oxygen evolution reaction (OER). Degradation efficiencies in photoassisted processes were particularly high (> 80%) while in the Fenton system this values ranged between 60 and 78%. The kinetic modelling using the equation of pseudo-first order adopted allowed a good fit of experimental data. The values of kinetic constant 1/ (min-1) at room temperature showed the following order: Fenton (8.16 min-1) > Photochemical (6.95 min-1) >> photolytic (1.98 min-1). In addition, studies using the electrocatalytic anodes at constant potential electrolysis of 2.0 V showed almost total degradation for the nitrophenols (> 93%) and moderate removal efficiencies for phenol (between 65 and 86%). In terms, considered the type of anode employed the electrooxidation efficiency at room temperature increase in the following order of reactivity: Ru0.3Ti0.7O2 > Ru0.3Ti0.4Sn0.3O2 > Ru0.3Sn0.7O2. Thus, the results confirm the applicability of adsorption and advanced oxidation processes as promising treatments in the remediation of aqueous systems containing phenol and nitrophenols

Maîtrise internationale bi-diplômante conjointe avec l'Université Toulouse III - Paul Sabatier et l'Université de Montréal, Maîtrise en co-tutelle / Le traitement de différents polymères issus de sources renouvelables est, depuis relativement récemment, un domaine de très fort intérêt dans les communautés scientifiques. Ce travail aborde le traitement de mousses de microfibrille de cellulose, issues de biomasses forestières, dans des décharges à barrière diélectrique dans l’hélium à la pression atmosphérique. Lorsque la mousse occupe l’entièreté de l’espace inter-électrodes, nous avons montré que la décharge s’amorce et se propage à travers la mousse. L’effet de dégazer la mousse avant le traitement par plasma s’avère aussi bénéfique à la production de décharge de type « homogène ». En effet, en situation dégazée, la décharge à 60 kHz révèle une caractéristique « homogène » tandis qu’à 10 kHz elle devient filamentaire. Toutefois, nettement moins de dommage sont observés sur la mousse sujette à une décharge à 10 kHz par rapport à celle à 60 kHz. En situations non dégazées, le relâchement d’espèces issues de l’air ambiant lors de l’enclenchement de la décharge augmente considérablement la puissance injectée et dissipée dans le plasma, générant plus de dommage qu’en conditions dégazées. Ces connaissances ont ensuite été appliquées à la modification des mousses à l’aide d’un précurseur d’hexaméthyldisiloxane pour ajuster leurs mouillabilités à l’eau et à l’huile. Lorsque la mousse occupait tout l’espace inter-électrodes, le régime de décharge filamentaire produit des dépôts très inhomogènes, bien souvent localisés au voisinage des régions endommagées. Au contraire, lorsque la mousse n’occupe qu’une partie du volume inter-électrodes, une décharge homogène a été observée, induisant une défibrillation des fibres cellulosiques. Ces conditions mènent néanmoins à des surfaces hydrophobes sur les surfaces supérieure et inférieure des mousses, tout en maintenant leur caractéristique oléophile. Ces travaux semblent donc prometteurs pour la séparation efficace d’huile des eaux usées à partir de matériaux verts, biodégradables, et renouvelables. / The treatment of different polymers issued from renewable sources has recently become of high interest in today’s scientific community. This work focused on the treatment of microfibrillated cellulosic foams, issued from wood biomass, in an atmospheric pressure dielectric barrier discharge in helium. When foams occupied all of gas gap volume, we demonstrated that the discharge ignites and propagates through the foams. The act of outgassing before plasma treatment has also been shown to be highly beneficial to the production of homogeneous glow-like discharges. Indeed, it was found that, in outgassed conditions, discharges occurring at a frequency of 60 kHz were glow-like, while those at 10 kHz were filamentary. However, significantly less damage was observed on the foams subjected to a 10 kHz discharge as opposed to those subjected to a 60 kHz discharge. In non-outgassed situations, we have also shown that the release of oxidising species originating from ambient air upon plasma ignition considerably increased injected and dissipated power in the plasma, in turn producing more damage than in outgassed conditions. This knowledge was then applied to the modification of these foams using a hexamethyldisiloxane precursor for plasma deposition to adjust their wettability to water and to oil. When foams occupied all of gas gap volume, the discharge regime was filamentary, and produced inhomogeneous coating, often very localised around damaged regions. When foams took up only a portion of gas gap volume, a homogeneous glow-like discharge was observed, inducing defibrillation of the cellulosic fibers. These conditions produced hydrophobicity on both the top and bottom surfaces of the foams, all while maintaining the foam’s characteristic oleophilicity. This supports the idea of selective adsorption of oily wastewater using a green, biodegradable, and renewable cellulosic product.