No description available.

Using mixed-culture fermentation, the carboxylate platform produces carboxylic acids, which are chemically converted into chemicals and fuels. To optimize the mixed-acid fermentation, different bioreactor configurations and operating modes were investigated. Intermittent air exposure did not affect fermentation performance and bacterial profiles, but reduced the high-molecular-weight carboxylic acids. The microbial flora contained strict and facultative microbes, suggesting the presence of a facultative anaerobic community existing in a biofilm. Compared to countercurrent trains, propagated fixed-bed fermentations have similar selectivity and acid distribution, but lower yield, conversion, productivity, and acid concentration. One- to six-stage countercurrent fermentations were operated with similar conditions. Fewer stages increased conversion, whereas more stages increased acid concentration and selectivity. One to four stages achieved similar yield, and four to six stages achieved similar maximum acid concentration. Maximum conversion was achieved with a single stage. Recycling residual biomass retained microorganisms and nutrients and increased yield and productivity. Relative to lower biomass reflux, higher reflux increased conversion, decreased selectivity, and did not affect yield. The recommended carbon-nitrogen ratio is ~24 g carbon/g nitrogen. In four-stage fermentations, recycle to the second fermentor and in parallel to the first three fermentors was optimal. Fermentations with excess or insufficient nitrogen had higher selectivity, but decreased yield and conversion. The glucose-utilization assay is a rapid and repeatable method for determining the amount of microbial activity in a sample. This method determined ~25% efficiency of a new cell separation method. In continuous fermentation, compared to no cell recycle, recycling cellular biomass increased selectivity and yield, but decreased conversion. Compared to lower cell reflux, higher reflux increased productivity, yield, and conversion, but decreased selectivity. Compared to residual biomass recycle, cell recycle had increased selectivity and yield, but decreased conversion. A new method to screen and rank inoculum sources from natural environments was successfully developed and tested.

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No. of bitstreams: 1 DissARFKM.pdf: 5277245 bytes, checksum: eb3373a6818032ff6003ee650addae1a (MD5) Previous issue date: 2016-08-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Chagas Disease is a sickness that affects the population present of Latin America and it is classified by the World Health Organization as a Neglected Tropical Diseases. Chagas disease is caused by the flagellated parasite Trypanosoma cruzi, which belong to the same family as Trypanosoma brucei and Leishmania sp., and has a complex life cycle, going from an invertebrate host to a vertebrate one. In order to survive and proliferate in these host changes, T. cruzi must adapt itself to osmotic and oxidative stresses, changes in the environmental ion composition and shifts in energy sources. To perform this adaptation, the amino acid Lproline has presented an important and essential participation that affects the protozoan life cycle, such as support of the mitochondrial metabolism, the host-cell invasion and metacyclogenesis. T. cruzi 1-Delta-Pyrroline-5-Carboxylate Dehydrogenase (TcP5CDH) is involved in the catabolism of proline holding a major role in its conversion by transforming pyrroline-5-carboxylate into L-glutamate (the second step of the catabolic path) and, thus, seeming to be a promising molecular target for new drug development. The amino acids sequence of PP5CDH was used for conservation analysis, secondary structure prediction, identification of functional domains, and building of tertiary structure computer models with the techniques of Molecular Modeling and Molecular Docking. The TcP5CDH (MW: 60 kDa) was expressed in a heterologous fashion in Escherichia coli, and purified with affinity and size exclusion chromatography, resulting in approximately 2 mg/L of expression. The Dynamic Light Scattering assays where carried out with the recombinant P5CDH in the concentrations of 0.5, 1.0, 1.5 e 2.0 mg/mL, and presented an apparent molecular weight of 223,4 kDa (Rh: 12,01 nm), 246,4 kDa (Rh: 12,53 nm), 310,5 kDa (Rh: 13,83 nm) e 312,0 kDa (Rh: 12,13,86 nm), respespectively. The Circular Dichroism spectroscopy was performed with 0.2 mg/mL of TcP5CDH in the presence and absence of 100 μM of NAD+, L-Glu, and its inhibitor Disulfiram, presenting a Tm of Tm 60,01 ºC, 59,76 ºC, 57,76 ºC e 58,18 ºC, showing that TcP5CDH has a more thermic stability without ligands. Also, a deconvolution was made showing that TcP5CDH has 23% of alfa-helix, 12,3% of antiparallel beta-sheetst and 12,4% parallel beta-sheets, 18,3% of turns 41,7% of disorganized structures. These results will contribute to the understanding of the pathway of L- proline in T. cruzi and the possible future development of new drugs. / A Doença de Chagas é uma enfermidade que afeta a população presente nos países da América Latina e é classificado pela Organização Mundial da Saúde como uma Doença Tropical Negligenciada. A Doença de Chagas é causada pelo parasita flagelado Trypanosoma cruzi, pertencente à mesma família dos parasitas Trypanosoma brucei e a Leishmania sp., organismo que possui um complexo ciclo de vida, passando de um hospedeiro invertebrado para um vertebrado. Para sobreviver e proliferar nessa mudança de hospedeiro, o T. cruzi precisa se adaptar a estresses oxido-redutivos e osmóticos, mudanças da composição iônica do ambiente e mudanças na fonte de energia. Para realizar essas mudanças, o aminoácido Lprolina apresenta uma importante participação que afeta o ciclo de vida do parasita como suporte no metabolismo mitocondrial, invasão de células hospedeiras e na metaciclogênese. A 1-Delta-Pyrrolina-5-Carboxilato Desidrogenase de T. cruzi (TcP5CDH) está envolvida no catabolismo da prolina tendo um papel importante na sua conversão através da transformação da pirroline-5-carboxilato em L-glutamato (a segunda etapa da via) e, assim, parece ser um alvo molecular promissor para desenvolvimento de novos fármacos. A sequência de aminoácidos da P5CDH foi utilizada para análises de conservação, predição de estruturas secundárias, identificação de domínios funcionais e modelos computacionais da estrutura terciária através da técnicas de Modelagem por Homologia e Ancoramento Molecular. A TcP5CDH (MW: 60 kDa) foi expressa de forma heteróloga em Eschericia coli, purificada por cromatografia de afinidade e cromatografia de exclusão molecular e, em seguida, concentrada, resultando em aproximadamente 2 mg/L de expressão. Os experimentos de Espalhamento Dinâmico da Luz foram realizados com a P5CDH recombinante nas concentrações de 0.5, 1.0, 1.5 e 2.0 mg/mL e apresentaram uma massa molecular aparente de 223,4 kDa (Rh: 12,01 nm), 246,4 kDa (Rh: 12,53 nm), 310,5 kDa (Rh: 13,83 nm) e 312,0 kDa (Rh: 12,13,86 nm), respectivamente. A Espectroscopia de Dicroísmo Circular foi realizado utilizando 0,2 mg/mL da TcP5CDH e com a proteína na presença de 100 μM de NAD+, L-Glu e do inibidor Dissulfiram, apresentando uma Tm 60,01 ºC, 59,76 ºC, 57,76 ºC e 58,18 ºC, respectivamente. Além disso, uma deconvolução foi realizada mostrando que a TcP5CDH possui 23% de alfa-hélices, 12,3% de folhas-beta antiparalelas, 12.4% de folhas-beta paralelas, 18,3% de voltas e 41,7% de regiões desorganizadas Estes resultados irão contribuir no entendimento da via da L-prolina em T. cruzi e no possível desenvolvimento futuro de novos fármacos.

Made available in DSpace on 2014-07-29T15:12:46Z (GMT). No. of bitstreams: 1 Dissertacao Matheus O Silva.pdf: 1871317 bytes, checksum: 107d9682b5740efb71b189bbf5920c37 (MD5) Previous issue date: 2012-08-13 / In this work it was described the synthesis and characterization of rhodium(II) succinate complex unpublished and adsorption study in maghemite nanoparticles. The rhodium(II) succinate was synthesized from a precursor rhodium(II) carboxylate, rhodium(II) trifluoracetate with a yield of 48.2%. The complex has become completely soluble in aqueous medium only when neutralized with 0,01 molL-1 NaOH solution to produce the sodium rhodium(II) succinate. The complex was characterized as the composition and structure by C and H elemental and thermogravimetric analysis, potentiometric titration, infrared and UV/visible spectroscopy. The data agree with a dimeric structure with four free carboxyl groups and suggest the molecular formulas [Rh2(O4C4H5)4(H2O)4] and [Na4Rh2(O4C4H4)4(H2O)5] to the rhodium(II) succinate and sodium rhodium(II) succinate respectively. Magnetite nanoparticles in aqueous media was prepared by coprecipitation method of Fe2+ and Fe3+ ion which was oxidized with oxygen gas. The solid obtained was characterized as crystalline phase by X-ray diffraction and as structure by infrared spectroscopy. The mean diameter of the nanoparticles (8 nm) was calculated by the Sherrer equation and lattice parameter was obtained through UnitCell program. It was obtained adsorption isotherm witch profile suggests the formation of multilayer adsorption having physical and chemical adsorption. The chemical adsorption was confirmed by infrared spectroscopy. The experimental data corresponding to monolayer were best fitted by the Freundlich adsorption isotherm with linear coefficient, R2, equal to 0,965. The functionalized nanoparticles were evaluated by measuring colloidal stability through hydrodynamic diameter and their surface properties by zeta potential measurements. The data showed strong dependence of the shifting of the IEP and the range of colloidal stability as a function of the amount of adsorbed complex and pH. / Neste trabalho foi descrito a síntese e caracterização do complexo inédito succinato de ródio (II) e um estudo da adsorção deste complexo em nanopartículas de maghemita. O succinato de ródio (II) foi sintetizado a partir de um carboxilato de ródio precursor, o trifluoracetato de ródio (II), com rendimento de 48,2%. O complexo tornou-se completamente solúvel em meio aquoso somente quando neutralizado com solução de NaOH 0,01 molL-1 produzindo o succinato de ródio (II) de sódio. O complexo foi caracterizado quanto à composição e estrutura por análise elementar de C e H, análise termogravimétrica, titulação potenciométrica, espectroscopia na região do infravermelho e na região do UV/VIS. Os dados obtidos concordam com uma estrutura dimérica com quatro grupos carboxílicos livres e sugerem as fórmulas moleculares [Rh2(O4C4H5)4(H2O)4] e [Na4Rh2(O4C4H4)4(H2O)5] para o succinato de ródio (II) e succinato de ródio (II) de sódio, respectivamente. Foi preparada uma suspensão de nanopartículas de magnetita pelo método da coprecipitação em meio alcalino dos íons Fe2+ e Fe3+ a qual foi oxidada à maghemita com gás oxigênio. O sólido obtido foi caracterizado quanto à fase cristalina por difratometria de raios-X e quanto a estrutura por espectroscopia na região do infravermelho. O diâmetro médio das nanopartículas (8 nm) foi calculado pela equação de Sherrer e o parâmetro de rede foi obtido pelo programa UnitCell. Foi obtida a isoterma de adsorção cujo perfil sugere a formação de múltiplas camadas de adsorção havendo adsorção química e física. A adsorção química foi confirmada por espectroscopia na região do infravermelho. Os dados experimentais correspondentes a monocamada se ajustaram melhor ao modelo de Freundlich com coeficiente de regressão linear, R2, igual a 0.965. As nanopartículas funcionalizadas foram avaliadas quanto a estabilidade coloidal por medida de diâmetro hidrodinâmico e suas propriedades de superfície por medidas de potencial zeta. Os dados mostraram forte dependência do deslocamento do IEP e da faixa de estabilidade coloidal em função do teor de complexo adsorvido e do pH.

No presente trabalho foram realizados estudos de regiosseletividade das reações de abertura de 2,3-epoxipropanoato de etila (1) utilizando diferentes nucleófilos de selênio e algumas dessas reações foram desenvolvidas com a adição do ácido de Lewis trifluoreto de boro dietil éter (BF3·Et2O). A abertura desse oxirano ao utilizar os nucleófilos MeSeMgCl e MeSeLi-BF3·Et2O ocorreu seletivamente no Carbono C-3 formando o composto de interesse (3-metilseleno 2-hidroxipropanoato de etila), já ao utilizar MeSeLi (em ausência ácido de Lewis) a abertura procedeu-se seletivamente no carbono C-2 formando 2-metilseleno-3-hidroxipropanoato de etila. A reação com o nucleófilo (Na[PhSeB(OEt)3]) levou à mistura desses regioisômeros. O ácido de Lewis BF3·Et2O em presença do selenolato levou a inversão de regiosseletividade da reação de abertura do epóxido 1 e a razão estequiométrica de BF3·Et2O adicionada ao meio reacional correspondeu, proporcionalmente, a porcentagem de obtenção do produto de abertura em C-3 (Tabela 1). Os resultados obtidos sugeriram que BF3·Et2O altera a nucleofilicidade do selenolato (RMN de 77Se) a partir de uma interação selênio-boro. A formação da ligação Se-B pode ocorrer com ou sem a liberação de fluoreto e esse mecanismo foi investigado por meio do emprego de uma sonda fluorescente seletiva desse haleto. O mecanismo dessas reações também foram investigados por cálculos teóricos, os quais mostram-se totalmente coerentes com os resultados experimentais. / In the present work was studied reactions of regioselective opening of 2,3-epoxyester using different selenolatos and some of this reactions were developed by adding Lewis acid BF3·Et2O. The opening reaction of this oxirane using the nucleofilms MeSeMgCl and MeSeLi-BF3·Et2O occurred selectively in carbon C-3 forming the compound of interest (ethyl 3-methylselene 2-hydroxypropanoato of ethyl), already using MeSeLi (in Lewis acid absence) the reaction was selectively on C-2 carbon to form ethyl 2-methylselene-3-hydroxypropanoate. The reaction with the nucleophile (Na[PhSeB(OEt)3]) formed a mixing of these regioisomers. The Lewis acid BF3·Et2O in presence of selenolate reverses the regioselectivity of opening epoxide (1) reaction and the stoichiometric value of BF3·Et2O added in the reaction corresponded proportionally with the percentage of C-3 product (Table 1). The results suggested that BF3·Et2O alters the nucleophilicity of selenolate (77Se NMR) from a selenium-boron interaction. Se-B bond formation may occur with or without fluoride release and this mechanism has been investigated by the use of a selective fluorescent probe of that halide. The mechanism of these reactions was also investigated by theoretical calculations, which are fully consistent with the experimental results.

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No. of bitstreams: 1 victorhugofelipebernardes.pdf: 4330159 bytes, checksum: 8ed0f32ccd734b911991c27470472e98 (MD5) Previous issue date: 2012-08-03 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Este trabalho descreve a síntese e caracterização de oito complexos envolvendo os ligantes N,O doadores, piridino-3,5-dicarboxilato (3,5-pdc); piridino2,5-dicarboxilato (2,5-pdc); piridino-2,6-dicarboxilato (2,6-pdc) e isonicotinato (iso). Todos os compostos foram caracterizados por espectroscopia de absorção atômica de chama, espectroscopia vibracional na região do infravermelho e Raman, análise elementar de CHN e análise térmica (TG/DTA). As caracterizações indicam que seis desses complexos são heterobimetálicos do tipo 3d-4f, ou seja, apresentam em sua fórmula molecular um metal do bloco d [Co(II) ou Cu(II)] e um metal do bloco f [Eu(III) ou Sm(III)]. As caracterizações sugerem ainda que os complexos EuCo(3,5pdc) e EuCu(3,5-pdc) sejam isoestruturais, assim como os compostos SmCu(2,5pdc), EuCo(2,5-pdc) e EuCu(2,5-pdc). Outros dois complexos intitulados Co(3,5-pdc) e Eu(iso) tiveram suas estruturas determinadas através da difração de raios X por monocristal. A estrutura do complexo Co(3,5-pdc) pertence ao sistema cristalino monoclínico, grupo espacial P21/n, apresentando a fórmula molecular [Co(3,5pdc)(H2O)5]dmso. O sítio de Co(II) apresenta geometria octaédrica distorcida, sendo a esfera de coordenação composta por cinco ligantes aqua e um átomo de nitrogênio do ligante 3,5-pdc. Nesse caso, os grupos carboxilatos do 3,5-pdc não estão envolvidos na coordenação. O composto Eu(iso) com fórmula mínima [Eu(iso)3(H2O)2]n cristalizou-se no sistema monoclínico, pertencendo ao grupo espacial P21/c e mostrou-se como um polímero de coordenação 1D. O íon Eu(III) está coordenado a oito átomos de oxigênio apresentando geometria antiprismática quadrada distorcida. Os ligantes iso adotam dois modos de coordenação: bidentado quelato e em ponte. Os compostos heterobimetálicos juntamente com o complexo Eu(iso), foram estudados por espectroscopia de luminescência. Os espectros de luminescência indicam que a excitação direta no comprimento de onda da transição π→π* do ligante é mais eficiente que a excitação direta no metal, caracterizando a sensibilização do lantanídeo. O diagrama de cromaticidade CIE revela que as emissões apresentam alta pureza, com coordenadas X e Y próximas da borda. / This work describes the synthesis and characterization of eight complexes involving the N,O-donor ligands, pyridine-3,5-dicarboxylate (3,5-pdc); pyridine-2,5dicarboxylate (2,5-pdc); pyridine-2,6-dicarboxylate (2,6-pdc) and isonicotinate (iso). All compounds were characterized by atomic absorption spectroscopy, infrared and Raman vibrational spectroscopies, CHN elemental analysis and thermal analysis (TG/DTA). The characterization techniques indicate that six of these are 3d-4f heterobimetallic complexes, in other words, present in their molecular formulae a dblock metal [Co (II) or Cu (II)] and a f-block metal [Eu (III) or Sm (III)]. The characterization techniques also suggest that complexes EuCo(3,5-pdc) and EuCu(3,5-pdc) are isostructural, as well as compounds SmCu(2,5-pdc), EuCo(2,5pdc) and EuCu(2,5-pdc). Two other complexes entitled Co(3,5-pdc) and Eu(iso) had their structures determined by single-crystal X-ray diffraction analysis. Complex Co(3,5-pdc) structure belongs to the monoclinic crystal system, space group P21/n, with molecular formula [Co(3,5-pdc)(H2O)5]dmso. Co(II) sites adopt a distorted octahedral geometry, with the coordination sphere composed of five aqua ligands and one nitrogen atom from 3,5-pdc ligand. In this case, the 3,5-pdc carboxylate groups are not involved in coordination. Eu(iso) compound, with molecular formula [Eu(iso)3(H2O)2]n crystallized in the monoclinic system, belonging to space group P21/c and appeared as a 1D coordination polymer. The Eu(III) ion is coordinated to eight oxygen atoms displaying distorted square antiprismatic geometry. The iso ligands adopt two coordination modes: bidentate chelate and bridging. The heterobimetallic compounds along with the complex Eu(iso), were studied by luminescence spectroscopy. The luminescence spectra indicate that the direct excitation wavelength of the π → π* transition of the ligands is more efficient than direct excitation into the metal, characterizing lanthanide sensitization. The CIE chromaticity diagram shows that the emissions have high purity, with X and Y coordinates near the edge.

Die vorliegende Arbeit beschäftigt sich mit der Synthese von Kupfer(I)- und Silber(I)- Carboxylaten der Form [MO2CR] und [LmMO2CR] (L = 2-Elektronen-Donorligand; m = 1, 2, 3; M = Cu, Ag; R = org. Rest). Die Verwendung dieser Komplexe zur Abscheidung von Metallen wird anhand ausgewählter Verbindungen mittels unterschiedlicher Abscheideprozesse beschrieben. Die Darstellung von neuartigen Ethinylferrocen-funktionalisierten Phosphanen und deren Koordinationsverhalten in Bezug auf Übergangsmetalle ebenfalls Thema der Arbeit. Das elektrochemische Verhalten wurde mittels Cyclovoltammetrie näher untersucht und der Einsatz von Ethinylferrocen-funktionalisierten Phosphan-Palladium(II)-Komplexen in der Suzuki- Miyaura- und Heck-Mizoroki-Kreuzkupplungsreaktion getestet. 2,2’-Bipyrimidin als Chelat- bzw. als μ-1,2,3,4-verbrückender Ligand ist in der Lage heterotetrametallische Übergangsmetallkomplexe mit z. B. Platin(II)-Bisalkinyleinheiten zu bilden. An ausgewählten Verbindungen werden die elektrochemischen Eigenschaften vorgestellt. Weiterer Bestandteil dieser Arbeit ist die Synthese und Charakterisierung von heterobimetallischen Komplexen aufgegriffen, in welchen frühe und späte Übergangsmetalle über eine Fulvalenideinheit verknüpft sind.

京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第20303号 / 薬科博第72号 / 新制||薬科||8(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 川端 猛夫, 教授 高須 清誠, 教授 竹本 佳司 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DGAM

No description available.

L'intensification des activités industrielles et les besoins en énergie font des hydrocarbures pétroliers (HP) un enjeu majeur mondial mais augmentent aussi considérablement les risques environnementaux dans divers écosystèmes. La phytoremédiation est une phytotechnologie qui a fait ses preuves en tant que solution verte pour faire face aux contaminations des sols par des HP. La phytoremédiation des sols contaminés par les HP repose principalement sur l’activité des communautés microbiennes associées aux racines des plantes au niveau de la rhizosphère, qui peuvent non seulement favoriser la croissance des plantes hôtes mais aussi augmenter leur tolérance à divers stress biotiques et abiotiques. Parmi les défis majeurs de la phytoremédiation des sols contaminés par les HP, on compte la forte toxicité de certains composés des HP qui entravent la croissance des plantes et par conséquent l’efficacité de la phytoremédiation. Cependant, la croissance des plantes peut être positivement stimulée par la présence de rhizobactéries favorisant leur croissance (PGPR) qui sont capables d'atténuer le stress des plantes par divers mécanismes. Dans cette thèse, un total de 438 bactéries PGPR dégradant les hydrocarbures pétroliers, ont été isolées de la rhizosphère et du sol de deux espèces de plantes, Salix purpurea et Eleocharis obusta, dans un site d'une ancienne raffinerie pétrochimique à Varennes, QC, Canada. Les isolats bactériens ont été classés en 62 genres, appartenant aux phylums Actinobacteria, Bacteroidetes, Firmicutes et aux sous-groupes Alpha-, Beta- et Gamma-Proteobacteria. De plus, cette collection de cultures contient 438 isolats bactériens avec de multiples caractéristiques de dégradation et de stimulation de croissance (PGPR), représentant une diversité fonctionnelle de dégradation des HP et de caractéristiques PGPR qui pourraient être utilisées dans la phytoremédiation assistée par les bactéries, des sols contaminés par les HP. Parmi ces 438 isolats bactériens, 50 isolats représentant une large diversité taxonomique, ont été sélectionnées pour une caractérisation approfondie supplémentaire concernant leur capacité à favoriser la croissance des plantes en présence de différentes concentrations de n-hexadécane (0%, 1%, 2%, 3%) dans des conditions contrôlées. Les résultats ont indiqué que les isolats bactériens Nocardia sp. (WB46), Pseudomonas plecoglossicida (ET27), Stenotrophomonas pavanii (EB31), Bacillus megaterium (WT10) et Gordonia amicalis (WT12) ont significativement augmenté la croissance des plantes cultivées dans 3% de n-hexadécane par rapport au traitement témoin. De plus, ces isolats possèdent plusieurs traits favorisant la croissance des plantes (PGPR) tels que l'activité 1-aminocyclopropane-1-carboxylate (ACC) désaminase (ACCD), la production d'acide indole-3-acétique (IAA) et la fixation de l'azote. De plus, ces isolats étaient capables d'utiliser le n-hexadécane comme seule source de carbone et possédaient des gènes cataboliques liés à la dégradation des hydrocarbures tels que le gène de l'alcane monooxygénase (alkB), le cytochrome P450 hydroxylase (CYP153) et le gène de la naphtalène dioxygénase (nah1). Nocardia sp. isolate WB46, a été sélectionné pour le séquençage de son génome afin de déterminer sa diversité génétique et fonctionnelle relatives à la dégradation des HP et les potentiels PGPR. Les résultats ont indiqué que, sur la base des analyses du gène de l'ARNr 16S, l'hybridation ADN-ADN in silico (DDH) et l'identité moyenne des nucléotides (ANI), Nocardia sp. isolate WB46 représente une nouvelle espèce bactérienne. De plus, l'annotation fonctionnelle de son génome révèle que celui-ci contient de nombreux gènes responsables de la dégradation des hydrocarbures pétroliers tels que l'alcane 1-monooxygénase (alkB) et la naphtalène dioxygénase (ndo) ainsi que d'autres gènes liés à ses potentiels PGPR. En conclusion, la rhizosphère des espèces S. purpurea et E. obusta poussant dans un site fortement pollué par les HP représente un biotope diversifié et comprenant des bactéries PGPR avec de multiples potentiels de dégradation des HP. De plus, plusieurs isolats bactériens tels que Nocardia sp. (WB46), Pseudomonas plecoglossicida (ET27) et Stenotrophomonas pavanii (EB31) démontrent un potentiel d'utilisation comme bioinoculants pour de futures études de phytoremédiation à grande échelle. / Petroleum hydrocarbons (PHCs), as a result of intensification of industrial activities, are a global environmental issue especially in soil environments. Phytoremediation represents an ideal solution to tackle this global crisis. Phytoremediation of PHC-contaminated soils proceeds mainly through the activities of microbial communities that colonize the plant rhizosphere which might promote host plants growth and increase its tolerance to various biotic and abiotic stresses. A main challenge in phytoremediation of PHC-contaminated soils is the high toxicity of PHCs which hinder plant growth and reduce the efficiency of phytoremediation. However, plant growth may be positively stimulated by the presence of plant growth-promoting rhizobacteria (PGPR) that are able to alleviate stresses in plants through various mechanisms. In this thesis, a total of 438 petroleum hydrocarbons degrading-PGPR bacterial isolates were recovered from the rhizosphere and the surrounding bulk soil of Salix purpurea and Eleocharis obusta plants from the site of a former petrochemical plant in Varennes, QC, Canada. Bacterial isolates were classified into 62 genera, belonging to the phyla Actinobacteria, Bacteroidetes, Firmicutes and the Alpha, Beta and Gamma-subgroups of Proteobacteria. Additionally, this culture collection holds 438 bacterial isolates with multiple degradative and PGP features, representing a rich reservoir of metabolically versatile PGPR-PHC degraders that could be used in holistic, bacterial-aided phytomanagement of PHC-contaminated soils. Among the above 438 bacterial isolates, 50 bacterial strains representing a wide phylogenetic range were selected for an additional in-depth characterization regarding their ability to promote plant growth under the presence of different concentrations of n-hexadecane (0%, 1%, 2%, 3%) under gnotobiotic conditions. Results indicated that bacterial isolates Nocardia sp. (WB46), Pseudomonas plecoglossicida (ET27), Stenotrophomonas pavanii (EB31), Bacillus megaterium (WT10) and Gordonia amicalis (WT12) significantly increased the growth of plants grown in 3% n-hexadecane compared with the control treatment. Additionally, these isolates possess several plant-growth-promoting (PGP) traits such as 1-aminocyclopropane-1-carboxylate (ACC) deaminase (ACCD) activity, indole-3-acetic acid (IAA) production and nitrogen fixation. Also, these isolates were able to use n-hexadecane as sole source of carbon and have catabolic genes related to hydrocarbon degradation such alkane monooxygenase (alkB) gene, the cytochrome P450 hydroxylase (CYP153) and the naphthalene dioxygenase (nah1) gene. The isolate that showed the highest growth stimulation of plants grown in 3% n-hexadecane under gnotobiotic conditions, Nocardia sp. isolate WB46, was selected for de novo genome sequencing to unveil its genetic versatility and the mechanisms of PHCs biodegradation and PGP potentials. Results indicated that based on the 16S rRNA gene analyses, in silico DNA-DNA hybridization (DDH) and average nucleotide identity (ANI) Nocardia sp. isolate WB46 is a new species. Additionally, the functional annotation of the genome of Nocardia sp. isolate WB46 reveals that its genome contains many genes responsible for petroleum hydrocarbon degradation such as alkane 1-monooxygenase (alkB) and naphthalene dioxygenase (ndo) as well as other genes related to its PGP potentials. In conclusion, S. purpurea and E. obusta growing in a site highly polluted with PHCs are rich reservoir of diverse PGPR with multiple PHC-degradation and PGP potentials. In addition, several bacterial isolates such as Nocardia sp. (WB46), Pseudomonas plecoglossicida (ET27) and Stenotrophomonas pavanii (EB31) demonstrate potential for use as bioinoculants in future large-scale phytoremediation studies.