Preterm birth, defined at birth before 37 weeks gestation, affects millions of newborns worldwide every year. Preterm birth is a leading cause of infant morbidity and mortality. One major cause of preterm birth is preterm premature rupture of membranes (PPROM), which can be triggered by bacterial infection and inflammation. A bacterial species that has been implicated in preterm birth and other obstetric complications is Sneathia amnii. The goals of this study were to observe cytopathogenic effects caused by S. amnii strain Sn35 and identify putative virulence factors causing those effects. Sn35 was able to adhere to, invade, and damage/kill various host cell lines. We characterized these virulence attributes. A putative virulence determinant was identified, and a fragment of the protein was expressed for polyclonal antiserum production. Antiserum was used to characterize the expression and subcellular localization of the protein in Sn35. However, antiserum was unable to prevent cytopathogenic effects.

Dans un contexte énergétique en crise, les sources alternatives d'énergie et d'économie d'énergie sont primordiales. Fort de ce constat, la station d'épuration de demain se doit d'atteindre un bilan énergétique positif. Dans cet objectif, de nombreux travaux de recherche se focalisent au niveau mondial sur la valorisation matière et énergétique à travers un procédé d'intérêt : la digestion anaérobie des boues. Afin d'optimiser ce procédé, la connaissance de la matière organique entrante est cruciale pour ne plus la subir mais la contrôler et en prédire les impacts sur les performances des digesteurs, notamment grâce à la modélisation. Une méthodologie de caractérisation de la matière organique des boues a donc été mise en place et testée afin de prédire les variables du modèle de digestion anaérobie basées sur la biodégradabilité et la bioaccessibilité. Cette méthode repose sur la mesure de la fluorescence en 3 dimensions réalisée sur les extractions chimiques de la boue, extractions simulant son accessibilité. Les résultats obtenus sur 52 échantillons de boues (primaires, secondaires, digérées, et traitées thermiquement) ont mis en évidence avec succès la corrélation entre cette méthode et la biodégradabilité anaérobie ainsi que la bioaccessibilité des boues. Le temps analytique classique de 30 jours pour les tests de potentiel méthane est par ailleurs réduit à 5 jours. Grâce à ces résultats, les variables d'entrée du modèle des processus biologiques ont pu être caractérisées ainsi que les composés réfractaires à la digestion. Une validation de la méthodologie a également été réalisée par le biais de la modélisation de 2 réacteurs pilotes expérimentaux. Une analyse de scenarios utilisant le modèle calibré a aussi montré que grâce à la prédiction de la bioaccessibilité et de la biodégradabilité, un temps de séjour minimum des digesteurs peut être calculé via une corrélation linéaire et ainsi optimiser le dimensionnement des digesteurs. De plus, cette approche s'est avérée être d'un grand potentiel en termes d'applications pour l'instrumentation et l'aide à la décision afin d'optimiser les performances des procédés de digestion anaérobie. / In an energetic crisis context, alternative sources of energy and saving costs has become of first importance. From this observation, the wastewater treatment plants of the future aim at a positive energetic balance and worldwide research on sludge treatment today focuses on energetic and material valorization through the optimization of anaerobic digestion processes. To this end, knowledge of the input organic matter is crucial to avoid suffering from these disturbances and to control, predict or drive the process through modeling. In the present study, a methodology of sludge characterization is investigated to describe biodegradability and bioaccessibility variables used in anaerobic digestion models. This method is based on the three dimensional fluorescence spectroscopy measurement performed on the chemical extraction of sludge simulating accessibility. Results obtained in 52 sludge samples (primary, secondary digested and thermally treated) show that the method can be successfully correlated with the sludge biodegradability and bioaccessibility within 5 days instead of the 30 days usually needed for the biochemical methane potential tests. Based on these results, input variables of dynamic models of biological processes occurring in anaerobic digestion have been characterized as well as recalcitrant fluorescent compounds. Validation has been performed with modeling of experimental data obtained from two different laboratory scale reactors. Scenarios analysis with the calibrated model have shown that using the measurements of sludge bioaccessibility and biodegradability, a minimal hydraulic retention time could be calculated with a linear correlation leading to the improvement of digesters design. Moreover, this approach has a high potential for applications such as instrumentation or decision support systems to improve both control and optimization of anaerobic digestion processes.

Les représentants de l'ordre des Thermotogales se trouvent généralement dans les puits pétroliers et les sources hydrothermales aquatiques et terrestres. Récemment, des études moléculaires basées sur l'analyse des gènes codant l'ARNr 16S ont prouvé l'existence de représentants thermophiles, mais également mésophiles de cet ordre dans les boues de bioréacteurs et dans les sédiments contaminés par des composés toxiques. Les expériences que nous avons conduites pour traiter notamment le lactosérum en présence de phosphogypse ou de sulfate dans des bioréacteurs anaérobies mésothermiques nous ont permis de mettre en évidence de nouvelles populations de bactéries et plus précisément de Thermotogales par des approches moléculaires et culturales, avec la description de deux nouveaux genres, « Mesotoga sulfurireducens » et Defluviitoga tunisiensis. En ce qui concerne « M. sulfurireducens», il correspond à la première bactérie mésophile isolée chez les Thermotogales avec un métabolisme original centré sur la sulfo-réduction. Toujours dans le but de traiter le phosphogypse, mais cette fois-ci en utilisant les margines comme composantes organiques dans le procédé anaérobie, une nouvelle espèce du genre Fusibacter a pu être isolée, F. tunisiensis. Globalement, nos résultats démontrent le rôle important joué par les Firmicutes fermentaires et sulfato-réductrices (ordre des Clostridiales) et celui des Proteobacteria sulfato-réductrices (deltaproteobacteria) chez les Bacteria, mais également par les Methanoarchaea acétoclastes aux côtés des Thermotogales dans la digestion anaérobie de la matière organique lorsque les effluents sont riches en sulfate. / The representatives of the order Thermotogales are usually found in oil reservoirs and hot aquatic and terrestrial springs. Recently, the existence of thermophilic and mesophilic representatives of the Thermotogales was proved by analysis of SSU rRNA genes of clones from bioreactors sludges and sediments contaminated by toxic compounds.Experiments which were led to treat lactoserum in the presence of phosphogypsum or sulphate in the mesothermic anaerobic digesters permitted to detect new populations of bacteria, in particular, Thermotogales by molecular and cultural approaches, with the description of two new genera, “Mesotoga sulfurireducens” and “Defluviitoga tunisiensis”. “Mesotoga sulfurireducens” is the first mesophilic bacterium isolated in the order of Thermotogales with an original metabolism axed on sulfo-reduction. During the treatment of phosphogypsum in the presence of margines as organic compounds in the anaerobic processus, a new species of Fusibacter was isolated: F.tunisiensis, sp. nov.Our results show the important role played by fermentative and sulphate-reducing Firmicutes (order Clostridiales) and sulphate-reducing Proteobacteria (deltaproteobacteria) within the Bacteria, but also by the acetoclastic Methanoarchaea beside Thermotogales in the anaerobic digestion of organic matter when the effluents are rich in sulphate.

L'objectif de cette thèse est l'étude du métabolisme de Corynebacterium glutamicum, et de ses potentialités, au cours de procédés aéro-anaérobies. Après une première phase avec apport d'oxygène pour permettre la croissance bactérienne, une phase anaérobie est induite par arrêt de l'aération et réduction de la vitesse d'agitation. Dans ces conditions, le lactate est le principal métabolite produit. La synthèse de ce dernier a été améliorée en jouant, essentiellement, sur le moment de la transition entre les 2 phases. C. glutamicum 2262 peut ainsi produire 27 g/l de lactate en mode discontinu et 55 g/l en mode semi-continu, suite à un arrêt de l'aération lorsque la concentration en biomasse est d'environ 2,6 g/l. Afin d'exploiter la voie de synthèse d'acide lactique chez C. glutamicum pour la production d'éthanol, les gènes PDC et ADH de Zymomonas mobilis ont été exprimés sous le contrôle du promoteur ldhA endogène de C. glutamicum 2262 et d'une souche de C. glutamicum 2262 sans ldhA. Bien que les productivités en éthanol de ces souches aient été relativement faibles, la suppression de ldhA a entraîné des augmentations de la concentration en éthanol d'environ 15 fois. Une stratégie similaire a été utilisée pour la production d'itaconate. Comme dans le cas de l'éthanol, la concentration en itaconate obtenue est demeurée très faible malgré des essais d'amélioration du procédé de mise en oeuvre de la souche productrice d'itaconate / The objective of this work is the study of Corynebacterium glutamicum metabolism, and of its potentialities, during an aero-anaerobic process. After a first phase during which the oxygen was supplied to favor the bacterial growth, the anaerobic phase was induced by the stopping of the oxygen supply and the decreasing of the agitation speed. In these culture conditions, lactate was the main metabolite produced. The production of this organic acid has been increased by modifying the transition time between the aerobic and the anaerobic phases. C. glutamicum 2262 was able to produce up to 27 g/l lactate during a batch process and up to 55 g/l during a fed batch process. To exploit the lactic acid synthesis pathway of C. glutamicum for ethanol production, the PDC and ADH genes from Zymomonas mobilis were expressed under the control of the endogenous promoter of ldhA, in the wild-type strain and in a ldhA-disrupted strain of C. glutamicum 2262. Although the ethanol productivities of these engineered strains were relatively low, the depletion of ldhA resulted in the increases of ethanol final concentration up to 15 times. A similar strategy was applied for the production of itaconate. As previously for the ethanol production, the final concentration of itaconate remained very low despite of some modifications of the process

Volatile fatty acids (VFAs) are important building blocks for the chemical industry. These acids can be produced through environmentally friendly processes from a variety of wastes, such as food waste, sludge and cow manure, through anaerobic digestion (AD). The main objective of this thesis was to investigate which operating parameters (e.g. pH, retention time, mix of substrate etc.) are optimal for producing VFAs as efficiently as possible, through AD batch processes. The highest VFA concentration was reached at pH 10 and at day 11 when food waste and sludge were used as substrate to a value of 15.4 g/L, corresponding to 0.77 g VFAs/ g of VSfed. Highest VFA concentration where cow manure was used as substrate was reached on day 10 and with a value of about 10 g/L corresponding to 0.51 g VFAs/ g VSfed. / Flyktiga fettsyror (VFAs) är en viktig byggsten inom den globala kemiindustrin. Dessa fettsyror kan produceras med hjälp av miljövänliga processer där en mängd olika sorters avfall, som t.ex. matavfall, avloppsslam och koavföring kan fungera som substrat, genom anaerobisk rötning. Det huvudsakliga målet med den här kandidatuppsatsen var att utreda vilka de optimala driftförhållanden var för särskilt utvalda driftparametrar (t.ex. pH, retentionstid, mix av substrat etc.) för att producera flyktiga fettsyror så effektivt som möjligt, genom anaerobisk rötning. Högst koncentration av VFAs nåddes vid pH 10 på dag 11 när matavfall och avloppsslam användes tillsammans som substrat till ett värde på 15 g/L, vilket motsvarar en avkastning på 0.77 g VFAs / g VSin. Högst VFAs-koncentration när koavföring användes som substrat nåddes på dag 10 med ett värde på 10 g/L, motsvarande en avkastning på 0.51 g VFA/ g VSin.

A combinação do substrato orgânico e do reator anaeróbio é determinante na produção fermentativa de hidrogênio e de ácidos orgânicos com valor agregado. A utilização do melaço da cana-de-açúcar como substrato orgânico em reatores de leito granular expandido (EGSB) ainda não foi uma alternativa explorada para produção de hidrogênio. Dessa forma, este estudo teve como objetivo analisar a produção biológica de hidrogênio e ácidos orgânicos em três reatores EGSB independentes com concentração de carboidratos de 5 g L-1 (EGSB-5), 10 g L-1 (EGSB-10) e 15 g L-1 (EGSB-15), utilizando melaço da cana-de-açúcar como substrato, sob condição mesofílica de temperatura (30 ºC) e variação do tempo de detenção hidráulica (TDH) de 24 h até 1 h. No EGSB-5, o processo fermentativo não gerou hidrogênio. No entanto, houve produção de metabólitos com valor agregado, principalmente ácido acético, butírico e propiônico. Neste reator, o ácido acético proveniente da reação de homoacetogênese (23 51%) justificou a ausência de hidrogênio. No EGSB-10 a produção de hidrogênio ocorreu na última fase de operação (TDH 1 h), com produção volumétrica de hidrogênio (PVH) máxima de 4,56 L d-1 L-1 e rendimento de hidrogênio (HY) máximo de 0,14 mol H2 mol hexose -1. No EGSB-15, houve PVH no TDH de 2 h e de 1 h , com valor máximo de 13,92 L d-1 L-1 no TDH de 1 h, e HY máximo de 0,25 mol H2 mol hexose-1, também no TDH de 1 h. No EGSB-10 e no EGSB-15, as vias metabólicas responsáveis pela produção de hidrogênio foram semelhantes, associadas à elevação da produção de ácido butírico e ácido lático. O ácido lático foi utilizado como fonte de carbono alternativa em condições de pouca disponibilidade de substrato e de pressão parcial de hidrogênio elevada, o que justifica os valores reduzidos de HY. Os resultados obtidos evidenciaram que o melaço pode ser utilizado para produção de H2 e de ácidos orgânicos em reatores EGSB por processos fermentativos. / The combination of the organic substrate and the anaerobic reactor is determinant in fermentative hydrogen and organic acids production. The use of sugarcane molasses as an organic substrate in expanded granular sludge bed (EGSB) has not yet been explored for H2 production. Thus the objective of this study was to analyze the biological H2 and organic acids production in three independent EGSB reactors with a carbohydrate concentration of 5 g L-1 (EGSB-5), 10 g L-1 (EGSB-10) and 15 g L-1 (EGSB-15), using sugarcane molasses as substrate, under mesophilic temperature (30 °C) and hydraulic retention time (HRT) variation of 24 h - 1 h. In EGSB-5, the fermentation process did not generate hydrogen. However, there was production of volatile fatty acids, mainly acetic, butyric and propionic acid. In this reactor, acetic acid from the homoacetogenesis reaction (23 - 51%) justified the absence of hydrogen. The EGSB-10 produced H2 in the last phase of operation (HTR 1 h), with maximum hydrogen production rate (HPR) of 4.56 L d-1 L-1 and maximum hydrogen yield (HY) of 0.14 mol H2 mol hexose-1. In the EGSB-15, there was HPR in the HPR of 2 h and 1 h, with a maximum value of 13.92 L d-1 L-1 in the HRT of 1 h, and HY maximum of 0.25 mol H2 mol hexose-1, also in the HRT of 1 h. In the EGSB-10 and EGSB-15, the metabolic pathways responsible for hydrogen production were similar, associated with increased production of butyric acid and lactic acid. Lactic acid was used as an alternative carbon source under conditions of low substrate availability and high hydrogen partial pressure, which justifies the reduced HY values. The results showed that molasses can be used to produce H2 and organic acids in EGSB reactors in anaerobic fermentation process.

A banana (Musa spp.) está entre as culturas mais abundantes no mundo, e devido ao seu descarte, desde a colheita até a sua comercialização gera-se grande quantidade de resíduos sólidos. Neste cenário, buscou-se avaliar o potencial uso do resíduo de banana (RB) como substrato e fonte de bactérias fermentativas para produção de H2 e metabólitos solúveis. Obteve-se a partir da fermentação natural do RB biomassa autóctone produtora de H2 sem necessidade do uso de fonte exógena de bactérias e custo adicional de fontes de carbono. Nesse consórcio foram identificadas bactérias semelhantes a Lactobacillus e Clostridium. Ensaios em reatores em batelada foram conduzidos para seleção do meio de cultivo (BAC, Noparati e PCS), das variáveis independentes (pH, temperatura, concentração do substrato, headspace e inóculo), seguido do delineamento composto central rotacional (DCCR) para otimização da produção de hidrogênio. Verificou-se que as condições nutricionais do meio PCS (extrato de levedura, peptona, NaCl e CaCO3) e RB resultaram na produção (P) e rendimento (YH2) máximo de 15,05 mL e 10,03 mL H2.g-1 CT (carboidratos totais), respectivamente. Em relação às variáveis independentes (pH, temperatura, concentração de substrato, volume do headspace e porcentagem de inóculo) obteve-se maiores valores de P e velocidade de produção (Rm) de H2 de 38,08 mL e 3,07 mL.h-1, respectivamente, em pH 7,5, 15 g.L-1, 44ºC, 40% de headspace e 15% inóculo. Em relação às variáveis estatisticamente significativas (pH e temperatura) via realização do DCCR observou-se que o aumento do pH (de 5,09 para 7,5) favoreceu, tanto P, quanto Rm, todavia, maior temperatura (de 27,1 para 46,9ºC) associada ao menor pH (<6,5) foram condições desfavoráveis para esses parâmetros. Por outro lado, obteve-se redução do tempo de início de produção de hidrogênio (&#955;H2) para maior temperatura (44-46,9ºC) associada ao menor pH (5,5) As condições operacionais ótimas estimadas via modelo foram em pH 7,0 e 37ºC, obtendo-se 70,09 mL H2, 12,43 mL H2.h-1 e 93 mL.g-1 CT, para P, Rm e YH2, respectivamente. Bacilllus sp. isolada do RB cresceu em variedade de substratos (glicose, xilose, manose, galactose, frutose, maltose, celobiose, sacarose, amido e RB), e 71 mL H2 foi obtido em 5 g.L-1 de RB, pH 7 a 37ºC. Em todos os ensaios em reatores em batelada, independentemente das condições operacionais, verificou-se que as principais vias metabólicas foram do ácido acético butírico e ácido lático, principalmente com glicose e frutose como fonte de carbono. A acidificação dos reatores resultou na diminuição do pH inicial para valores <4,0 favorecendo a rota solventogênica. Na biomassa fermentativa autóctone e aquela dos reatores em batelada foi possível inferir sobre elevado potencial metabólico, devido a identificação de genes relacionados com enzimas do metabolismo de carboidratos. / Banana (Musa spp.) is among the most abundant crops in the world and, due to its discard, great quantity of solid waste is generated from the harvest until its commercialization. In this scenario, the potential use of banana residue (RB) as substrate and source of fermentative bacteria for the production of H2 and soluble metabolites was evaluated. It was obtained from RB natural fermentation native autochthonous H2-producing biomass without the need to use exogenous source of bacteria and additional costs from carbon sources. In this consortium, bacteria similar to Lactobacillus and Clostridium were identified. Batch reactor experiments were conducted to select culture medium (BAC, Noparati and PCS) and independent variables (pH, temperature, substrate concentration, headspace and inoculum), followed by central composite rotatable design (CCRD) experiments for optimization of hydrogen production. It was verified that the nutritional conditions provided by PCS medium (yeast extract, peptone, NaCl and CaCO3) and RB resulted in the maximum production (P) and yield (YH2) of 15.05 mL and 10.03 mL H2 g-1 CT (total carbohydrates), respectively. Regarding the independent variables (pH, temperature, substrate concentration, headspace volume and percentage of inoculum), higher P and H2 production rate (Rm) were obtained (38.08 mL and 3.07 mL h-1, respectively) at pH 7.5, 15 g L-1 of substrate, 44 °C, 40% headspace and 15% inoculum. In relation to the statistically significant variables (pH and temperature), it was observed through CCRD that the increase in pH (from 5.09 to 7.5) favored both P and Rm, however, a higher temperature (from 27.1 to 46.9ºC) associated with lower pH (<6.5) were unfavorable conditions for these parameters. On the other hand, a reduction in the hydrogen production start time (H2) was obtained with higher temperature (44-46.9ºC) associated to lower pH (5.5). The optimum operational conditions, estimated by modeling, were pH 7.0 and 37 °C, yielding 70.09 mL H2, 12.43 mL H2 h-1 and 93 mL gCT-1 for P, Rm and YH2, respectively. Bacillus sp. isolated from RB grown on a variety of substrates (glucose, xylose, mannose, galactose, fructose, maltose, cellobiose, sucrose, starch and RB), and 71 mL H2 was obtained with 5 g L-1 RB, pH 7 at 37 °C. In all batch reactor experiments, regardless of operating conditions, the main metabolic pathways were acetic acid, butyric acid and lactic acid, mainly with glucose and fructose as carbon sources. Acidification of the reactors resulted in a decrease of the initial pH to values <4.0, favoring the solventogenic pathway. It was possible to infer about the high metabolic potential in the autochthonous fermentative biomass and in the biomass from the batch reactors due to the identification of genes related to enzymes of the carbohydrate metabolism.

Vinasse, a wastewater rich in organic matter, nutrient and water, is commonly used for fertigation of sugarcane plantation. However, this practice is questionable in the environmental sphere because of problems, such as contamination of groundwater and greenhouse gases emission. Researchers have sought for alternatives that use vinasse in a more sustainable way, e.g., biorefineries that recover resources. In general, the pathways considered are the concentration technologies to reclaim water and nutrient, and the anaerobic digestion (AD) to produce biogas. This thesis reports on a study of five designs of vinasse biorefineries that incorporate anaerobic bioreactors followed by a concentration technology (evaporation (EV), reverse osmosis (RO) or forward osmosis (FO)). Different forms of regeneration of the draw solution (DS) namely evaporation, reverse osmosis and membrane distillation (MD) were also analyzed. The alternatives were compared through an exergy analysis, a method that evaluates efficiency in the conversion of resources by systems. The results showed Alternative 2 (anaerobic digestion + reverse osmosis) was the most efficient (64%), since the treatment of 491.76 m3 vinasse h-1 (exergy content of 60513.8 kW) to recover 80% of water reduced 76% of external water requirement and generated 12% more electricity (2601 kW exergy) for the industry. / O desenvolvimento de biorrefinarias voltadas à recuperação de recursos é uma tendência crescente que visa promover sistemas alternativos para obtenção de energia e materiais de forma mais sustentável. Dentro deste conceito está o aproveitamento da vinhaça das indústrias de cana-de-açúcar de modo a recuperar água, nutrientes e energia como produtos de interesse. Para isso, é necessário avaliar as possíveis configurações tecnológicas voltadas a este objetivo. No presente trabalho, foram estudados cinco designs de biorrefinaria de vinhaça incorporando uma rota de produção de metano, formada pelo processo de digestão anaeróbia, e uma forma de concentração do efluente. Os métodos para obtenção de água foram evaporação, osmose reversa e osmose direta. Neste último, foram analisadas diferentes formas de regeneração da solução de separação: evaporação, osmose reversa e destilação por membranas. A comparação das alternativas de biorrefinaria foi feita pelo método da análise de exergia, que atua na avaliação da eficiência de conversão dos recursos em sistemas. Esta ferramenta possui como medida base o trabalho útil que pode ser obtido a partir das correntes envolvidas no processo. Desta forma, observou-se que tecnologias que empregam calor como energia de entrada tendem a ser menos eficientes do que as que empregam eletricidade. Neste caso, as alternativas com processo de osmose reversa apresentaram maiores eficiências exergéticas, por exemplo, ao se recuperar 70% de água, sua eficiência seria de 64%. Portanto, sugere-se que a digestão anaeróbia da vinhaça seguida da concentração por osmose reversa seria a configuração mais interessante para concepção de uma biorrefinaria de vinhaça.

O presente estudo avaliou o efeito do TDH (tempo de detenção hidráulica) (24 a 1 h) na produção de H2 em reator anaeróbio de leito granular expandido (Expanded Granular Slugde Bed) (ESGB) sob condições mesofílicas (30 ± 2 °C), com cultura mista e a partir do caldo de cana nas concentrações: 5, 10 e 15 g L-1, nos reatores EGSB5, EGSB10 e EGSB15, respectivamente. Foram atingidos valores máximos de produção volumétrica de H2 (PVH) ao decrescer o TDH para: 1 h no EGSB5 (6,96 L d-1 L-1); 1 h no EGSB10 (19,14 L d-1 L-1); e 2 h no EGSB15 (52,40 L d-1 L-1). Os resultados corroboram a afirmação de que reatores de alta taxa como o EGSB suportam aplicação de cargas mais elevadas, visto que o rendimento de H2 (Hydrogen Yield) (HY) máximo (0,73 mol H2 mol-1 hexose) foi observado no EGSB15 para a taxa de carregamento orgânico (TCO) igual a 182,9 kgcarboidrato m-3 d-1. Os HY visualizados no presente estudo foram inferiores aos observados nos estudos em que utilizaram culturas puras, isto pode ocorrer devido ao fato de que o tratamento térmico não é capaz de selecionar apenas culturas produtoras de H2. Foram identificados os possíveis consumos de H2 em consequência à homoacetogênese, com percentuais máximos de ácido acético (HAc) de 59,0 %, 50,0 % e 25,0 % em relação aos demais metabólitos produzidos nos EGSB5, EGSB10 e EGSB15, respectivamente. Devido à provável ocorrência de homoacetogênese o H2 detectado não pode ser inteiramente atribuído a presença de HAc, atribui-se então a produção de H2 à rota de produção de ácido butírico (HBu). Coincidentemente com o HY máximo, as concentrações e percentuais de HBu foram de 1,95 g L-1 e 44,0 % para o EGSB10 no TDH de 4 h, e de 4,07 g L-1 e 43,0 % para o EGSB15 no TDH de 2 h. De modo geral, a redução do TDH de 24 a 1 h melhorou a produtividade de H2. Observou-se devido à elevada PVH, que o caldo de cana pode ser uma alternativa viável para a produção de H2 em larga escala. / The present study evaluated HRT (hydrualic retention time) (24 to 1 h) effect on H2 production in anaerobic expanded granular sludge bed reactor (ESGB) under mesophilic conditions (30 &#177; 2&#176;C), with mixed culture and sugarcane juice concentration of 5, 10 and 15 g L-1 in EGSB5, EGSB10 and EGSB15, respectively. Maximum hydrogen production rates (HPR) were visualized by decreasing TDH to: 1 h in EGSB5 (6.96 L d-1 L-1); 1 h at EGSB10 (19.14 L d-1 L-1); and 2 h in EGSB15 (52.40 L d-1 L-1). Results attest that high rate reactors such as EGSB support higher loads application, since maximum hydrogen yield (HY) was observed in EGSB15 for the highest organic loading rate (OLR) applied (0.73 mol H2 mol-1 hexose in OLR 182.9 kgcarboidrato m-3 d-1). HY visualized in present study were lower than those observed in studies using pure cultures, this may occur due to heat treatment is not able to select only H2 producing cultures. Possible H2 intakes were observed as a consequence of homoacetogenesis, with maximum acetic acid (HAc) 59.0%, 50.0% and 25.0% for EGSB5, EGSB10 and EGSB15, respectively. Due to probable occurrence of homoacetogenesis the H2 production can\'t be entirely attributed to HAc, then H2 production is attributed to butyric acid (HBu) route. Coincidentally with maximum HY, the HBu concentrations and percentages were 1.95 g L-1 and 44.0% for the EGSB10 in TDH 4 h, 4.07 g L-1 and 43.0% for EGSB15 in TDH 2 h. Overall, the TDH reduction from 24 to 1 h improved H2 productivity. Due to high HPR observed the sugarcane juice can be a feasible alternative for H2 production on large scale.

La digestion anaérobie est un procédé biologique effectué par un réseau complexe et synergique de communautés microbiennes permettant la dégradation de matière organiques comme les déchets agricoles ou les effluents de station d’épuration en biogaz, un gaz valorisable en énergie. Les mécanismes influençant les communautés microbiennes au cœur de ce procédé mais aussi dans la nature restent incompris du fait de la faible compréhension de leur dynamique. Les objectifs de ce projet visent à donc développer un système de digestion anaérobie permettant de mieux comprendre la dynamique de l’assemblage des communautés microbiennes. Ainsi un nouveau procédé de réacteurs en continu dont les fonctions d’alimentation de soutirage et de dégazage sont automatisées a été développé. L’automatisation et le multiplexage des réacteurs permettent la manipulation de 30 réacteurs en continu en parallèle. Outre l’automatisation ce système, de nombreux paramètres sont flexibles comme le taux de charge (une fois par minute jusqu’à une condition batch), le volume de réacteur (50 à 200mL), la température (pièce – 55°C), mais aussi l’utilisation du système en aérobie ou l’implémentation d’autres outils comme des LEDs pour les cultures phototrophes. Capable de quantifier précisément la performance d’un écosystème méthanogène, ce système nous a permis de tester la structure et la performance d’écosystèmes méthanogènes mis en mélanges et testés de façon individuelle. En mélangeant des écosystèmes méthanogènes différents, la diversité des Archées a augmenté transitoirement. Une corrélation est d’ailleurs observée entre la diversité de ces communautés mélangées et leur performance méthanogène, seulement à même diversité les communautés individuelles ont un meilleur fonctionnement. L’assemblage de certaines communautés mélangées a pourtant permis une meilleure production de méthane que les communautés individuelles, ce qui suggère le développement d’interactions spécifiques de ces communautés. De façon nouvelle par rapport à la littérature, la majorité des communautés bactériennes individuelles sont retrouvées dans les communautés mélangées. Soit contrairement à l’idée d’une sélection d’une communauté plus adaptée ou plus fonctionnelle, ici la majorité des communautés se sont implantées. Ces expériences suggèrent qu’un paramètre tel que la fonctionnalité d’un bioprocédé peut-être amélioré par bioaugmentation. / Anaerobic digestion is a biological process carried out by a complex and synergistic network of microbial communities allowing the degradation of organic matter such as agricultural waste or effluents from wastewater treatment plants, into biogas, a gas recoverable into energy. The mechanisms influencing microbial communities at the heart of this process but also in nature remain misunderstood because of a low understanding of their dynamics. The objectives of this project are therefore to develop an anaerobic digestion system to better understand the dynamics of microbial community assembly. Thus, a new continuous reactor process has been developed with automated feeding, biomass wasting and degassing functions. Automation and multiplexing of reactors allows for the continuous parallel manipulation of 30 reactors in parallel. In addition to the automation, many parameters are versatile, such as the substrate loading (once a minute up to batch conditions), the reactor volume (50 to 200 mL), the temperature (room to 55°C), but also the use of the aerobic system or the implementation of other tools such as LEDs for phototrophic cultures. Capable of accurately quantifying the performance of a methanogenic ecosystem, this system has enabled us to test the structure and the performance of five different methanogenic ecosystems that have been mixed and tested individually. By mixing different methanogenic ecosystems the Archaea diversity has increased transiently. Besides, a correlation is observed between the diversity of mixed communities and their methanogenic performance; yet the individual communities have a better functioning at the same level of diversity. Interestingly, the mixture of some communities has allowed for better methane production than individual communities, suggesting the development of specific interactions in these communities. In a novel way compared to the literature and that the majority of individual bacterial communities are found in mixed communities. Contrary to the idea of selecting a more adapted or functional community, here the majority of communities have settled. These experiments suggest that a parameter such as the functionality of a bioprocess can be improved by bioaugmentation.