Thesis (M.App.Sc.) - Carleton University, 2007. / Includes bibliographical references (p. 115-119). Also available in electronic format on the Internet.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The use of non-Saccharomyces yeasts together with the yeast S. cerevisiae in multistarter wine fermentations has emerged as a useful tool to modulate wine aroma and/or to decrease the concentration of undesirable compounds. However, upon inoculation, these yeast species do not co-exist passively, but interact in various ways. While competition for nutrients and the excretion of killer toxins in an antagonistic relationship are obvious and well established types of interactions, some studies have suggested the existence of other forms of cellular or molecular interactions. One of these includes physical cell-cell contact and to our knowledge, only one previous study has confirmed its existence in wine yeasts. Yeast interactions are also influenced by other factors, such as ethanol concentration, however some studies have highlighted the role that dissolved oxygen plays on the survival of non-Saccharomyces yeasts and their ability to compete for space with S. cerevisiae and little research has focused on this. This study aimed to investigate the occurrence of a physical cell-cell and/or metabolic interaction between S. cerevisiae and L. thermotolerans in mixed culture fermentations of synthetic grape must. For this purpose, fermentations in a Double Compartment Bioreactor (DCB) which separates yeast population through the use of a membrane were compared to mixed fermentations in the absence of the membrane, using the same reactor. Furthermore, the impact of oxygen supply on yeast behaviour was also assessed. Following mixed culture fermentations in a DCB, it was observed that the presence of S. cerevisiae led to a significant decline in viability in L. thermotolerans. This decline was significantly less prominent in mixed cultures where the cells were in indirect contact. Together, the data provided evidence for both cell-cell and metabolic interactions whereby S. cerevisiae had a strong negative influence on the growth of L. thermotolerans. However, it was also observed that L. thermotolerans had some negative impact on the growth of S. cerevisiae, leading to a reduction in biomass (when in indirect contact) and a reduced maximum CFU/mL compared to pure cultures. The data also suggest that direct physical contact may increase the production of glycerol and propanol, but this needs further investigation. By decreasing the frequency at which oxygen pulses were provided, a reduction in biomass and increase in fermentation duration was observed for all fermentations. However, this effect was somewhat reduced in mixed cultures. Here, no impact on fermentation duration was observed and the decrease in biomass was less compared to pure cultures. The impact of these oxygen pulses was also greater on L. thermotolerans. In the latter yeast’s pure culture a slight increase in glycerol was observed when less oxygen was provided and in general there appeared to be no impact on acetic acid production. Furthermore, there was little or no impact on volatile production, however, more repeats might reveal different results and therefore more research is needed to confirm these results. To our knowledge, this is the first study of its kind to confirm a physical cell-cell interaction between the yeast pair S. cerevisiae and L. thermotolerans. / AFRIKAANSE OPSOMMING: Die gebruik van nie-Saccharomyces gis saam met die gis S. cerevisiae in multi-inokuleringskulture het die afgelope paar jaar as n goeie hulpmiddel na vore gekom om wyn aroma te moduleer en/of om die konsentrasie van ongewensde verbindings te verminder. Sodra inokulasie plaasgevind het, het hierdie gis die potensiaal om op verskeie maniere teenoor mekaar te reageer. Kompetisie vir nutriente en die afskeiding van toksiese verbindings in n antagonistiese verhouding is alreeds goed beskryf in die literatuur. Somige studies het, alhoewel, die bestaan van ander vorme van sellulêre of molekulêre interaksies voorgestel. Een van hierdie sluit in n fisiese sell-sell interaksie en so ver as wat ons kennis strek, het nog net een studie van tevore so ‘n interaksie bevestig tussen wyn giste. Gis interaksies word ook beïnvloed deur ander faktore, soos byvoorbeeld etanol konsentrasie. Terwyl sommige studies die rol wat opgelosde suurstof speel in die oorlewing van nie-Saccharomyces gis en hulle vermoë om te kompeteer vir spasie met S. cerevisiae alreeds beklemtoon, het min navorsing al hierop gefokus. Hierdie studie het gestreef om die voorkoms van n fisiese sell-sell en/of metaboliese interaksie tussen S. cerevisie en L. thermotolerans in gemengde kultuur fermentasies van sintetiese druiwe sap te ondersoek. Vir hierdie doeleinde was fermentasies uitgevoer met behulp van ‘n Dubbel Kompartement Bioreaktor (DKB) wat gis populasies skei deur middel van ‘n membraan en hierdie was vergelyk met gemengde kultuur fermentasies sonder die membraan in dieselfde reaktor sisteem. Verder was die impak van suurstof toevoer op gis gedrag ook geassesseer. Na afloop van gemengde kultuur fermentasies in ‘n DKB, was daar waargeneem dat die teenwoordigheid van S. cerevisiae gelei het tot ‘n betekenisvolle afname in lewensvatbaarheid in L. thermotolerans. Hierdie afname was aansienlik minder in gemengde kulture waar die gis in indirekte kontak was. Saam verskaf hierdie data bewyse vir n sell-sell asook metaboliese interaksie waardeur S. cerevisiae ‘n sterk, negatiewe invloed op die groei van L. thermotolerans gehad het. Daar was egter ook waargeneem dat L. thermotolerans tot ‘n mindere mate ‘n negatiewe impak op die groei van S. cerevisiae gehad het en dat dit gelei het tot ‘n verlaging in biomassa (toe die gis in indirekte kontak was) en ‘n verlaagde maksimum CFU/mL in vergelyking met suiwer kulture. Die data dui ook aan dat fisiese kontak kon gelei het tot ‘n verhoging in gliserol en propanol produksie, maar hierdie kort verdere ondersoek. Deur die frekwensie te verminder waardeur suurstof pulse aan die fermentasies verskaf was, was ‘n verlaging in biomassa produksie en ‘n verlenging in fermentasie tydperk waargeneem. Hierdie tendense was waargeneem in almal, behalwe die gemengde kultuur fermentasies. Die effek van suurstof puls verlaging was minder op hierdie fermentasies aangesien daar geen impak op fermentasie tydperk was nie en die verlaging in biomassa minder was. Die impak van hierdie suurstof pulse was ook groter op L. thermotolerans. ‘n Klein toename in gliserol produksie was waargeneem in laasgenoemde gis se suiwer kultuur toe minder suurstof beskikbaar was en oor die algemeen was asynsuur onveranderd. Verder was daar ‘n klein of geen impak op vlugtige verbindings nie, alhoewel, meer herhalings mag verskillende resultate lewer en daarom is meer navorsing nodig om hierde resultate te bevestig. So ver as wat ons kennis strek is hierdie die eerste studie van sy soort om ‘n fisiese sell-sell interaksie tussen die gispaar S. cerevisiae en L. thermotolerans te bevestig.

L'hydrogène est une source d'énergie précieuse en tant que source d'énergie propre et que matière première pour des innombrables industries.Les procédés biologiques de production d'hydrogène gagnent en importance en raison de leurs avantages opérationnelles et de leur polyvalence dans les substrats utilisés (y compris les eaux usées).Dans cette thèse doctoral, on a développé une méthodologie photo-fermentative de production d'hydrogène en utilisant du lactosérum en tant que substrat pour la bactérie Rhodobacter capsulatus IR3::LacZ et B10::LacZ.Ce projet a été réalisé en trois étapes, exposées dans les différents chapitres.Dans la première étape on a identifié les facteurs pertinents pour la production de l'hydrogène avec du sérum synthétique en utilisant la méthodologie de plan d'expériences.Les résultats de cet étape on a obtenu quatre modèles statistiques et on a choisi la souche IR3::LacZ pour les expériences avec du lactosérum industriel.Le rendement volumétrique maximal et le rendement produit / substrat Y P/S obtenus pour la première étape ont été de 64 ml h-1L-1 et 2,08 mol H2 mol-1 C (“C” représente la source de carbone dans ce cas lactose et lactate) pour la solution amortissant le phosphate et 43.01 ml h-1L-1 y 2.52 mol H2 mol-1 C pour la solution Kolthoff.Dans la deuxième étape, on a évalué la production d'hydrogène avec du lactosérum industriel. On a appliqué un pré-traitement de trois étapes avant d'utiliser le lactosérum comme substrat : réduction du contenu gras, déprotéinisation et stérilisation. On a obtenu un modèle validé qui décrit la production d'hydrogène seulement pour la solution amortissant de phosphate. Le rendement volumétrique maximal et le YP/S ont été de 45.93 ml h-1L-1 et de 2.29 mol H2 mol-1 C respectivement. On a déterminé que l'addition d'une étape d’homo-fermentation au processus de prétraitement es avantageuse au rendement du processus. On a obtenu une productivité volumétrique de 69.71 ml h-1L-1 et de YP/S de 2.96 mol H2 mol-1 CLa troisième étape a été la mise à l'échelle des expériences à réacteurs de 1,5 L pour sérum synthétique et de 1L pour serum industriel. On a décelé de la contamination dû à la présence d'un processus de fermentation, lequel a généré une haute production de biogas composé exclusivement par H2 y CO2 ce dernier dans une concentration non superieur à 30% (v/v).Pour ces raisons, on a conclu que conclu que le processus de production intégré, en couplant la fermentation obscure et la photo-fermentation est une option avec un énorme potentiel pour l'utilisation de lactosérum comme substrat dans la production d'hydrogène. / Hydrogen is a valuable gas use as a clean energy source and feedstock for some industries. Biological hydrogen production processes are gaining importance due to their operational conditions and versatility in the substrates (including wastewater). A hydrogen production photo fermentative methodology was developed using cheese whey as a substrate for the bacteria Rhodobacter capsulatus strain IR3::LacZ and B10::LacZ . The project was carried out in three stages.The purpose of the first stage is to identify the relevant factors to produce hydrogen for a synthetic whey medium in a photofermentation process, using the Design of Experiments methodology. The products of this stage are four statistical models, obtained for each strain and buffer solution studied. The strain IR3::LacZ was selected for the experiments with industrial whey as substrate. The maximum volumetric yield and the product/substrate yield YP/S were 64 ml h-1L-1 and 2.08 mol H2 mol-1 C (C is the carbon source in this case lactose and lactate) and 43.01 ml h-1L-1 and 2.52 mol H2 mol-1 C for phosphate buffer and Kolthoff buffer, respectively.In the second stage the production of hydrogen with industrial whey was evaluated. A three-step pre-treatment was applied before using industrial cheese whey as substrate: fat reduction, deproteinization and sterilization. A validate statistical model describing hydrogen production was only obtained for phosphate buffer. The maximum volumetric yield and the product/substrate yield YP/S were 45.93 ml h-1L-1 and 2.29 mol H2 mol-1 C respectively. The addition of an homofermentation to the pretreatment improved the production yield, in this case a volumetric productivity of 69.71 ml h-1L-1 and a YP/S of 2.96 mol H2 mol-1 C were obtained.The third stage was the scale-up to 1.5 and 1 reactor L for synthetic whey and 1L for synthetic and industrial whey respectively. A fermentative process appeared due to a bacterial contamination, leading to a high biogas production. Biogas was exclusively composed of H2 and CO2 the last in a concentration not exceeding 30% (v/v). For this reason, it was concluded that the integrated production process coupling dark and photo fermentations) is an option with great potential for the use of whey as substrate in the production of hydrogen.

Master of Science / Department of Civil Engineering / Prathap Parameswaran / The ever-increasing demand for water, food, and energy and the simultaneous diminishment of our planets’ ecosystems wrought by humans have prompted a more sustainable approach to engineering the built environment. Wastewater treatment systems stand at the interface that connects the built and natural environment where potential solutions for resource and environmental issues exist. Wastewater treatment technologies can address issues involving water, food, energy, and environmental regulation when resources are properly captured from the wastewater while it’s being treated. This way of thought allows wastewater to be perceived as a source of valuable products rather than an obligate waste stream. For this reason, anaerobic wastewater treatment is progressively being considered because of its ability to improve energy and resource recovery, while reducing costs and environmental impacts associated with conventional domestic wastewater treatment. More specifically, anaerobic membrane bioreactors (AnMBRs) hold promise to effectively treat wastewater at low temperatures with low energy and nutrient requirements, low sludge production, while having the benefit of generating methane-rich biogas suitable as an energy source and the potential to capture nutrients used to fertilize cropland. But, at low temperatures the microbial communities that control anaerobic digestion (AD) face biochemical obstacles. Elucidating the microbial community dynamics within AnMBRs with respect to seasonal temperatures will give insight on how to efficiently operate AnMBRs with the goal of energy-neutral wastewater treatment. DNA based tools such as advanced high-throughput sequencing was coupled with AnMBR process data to explicate the mechanism of methane production in the suspended biomass of an AnMBR from a mesophilic startup leading into psychrophilic conditions, and then returning to mesophilic temperatures.

Em caso de envenenamento ofídico, o tratamento no Brasil hoje é realizado pela administração de soros geralmente produzidos por equinos, que apresentam eficácia limitada: são úteis para os efeitos sistêmicos, mas não inibem efetivamente a evolução dos danos locais, podem causar reações adversas e apresentam alto custo de produção. De acordo com a Organização Mundial da Saúde (OMS), trata-se de uma doença negligenciada pelas autoridades científicas mundiais. O presente projeto, em parceria com o Instituto de Pesquisas em Patologias Tropicais da Fundação Oswaldo Cruz - Rondônia, propõe a produção por Escherichia coli de fragmentos de anticorpos de cadeia pesada de camelídeos, denominados VHH, contra as toxinas do veneno de Bothrops jararacussu, utilizando biorreator. Neste trabalho há interesse em produzir VHH, através da otimização do crescimento desta E. coli. A cinética do crescimento bacteriano foi realizada em shaker orbital sob diferentes condições, variando tamanho do frasco, rotação do shaker, composição do meio de cultura e concentração de substrato; e em biorreatores, alternando meios de cultura e modo de operação do reator (descontínuo e descontínuo alimentado), alterando a vazão de alimentação (linear e exponencial) O processo cinético é fortemente limitado pela formação de acetato, por condições auxotróficas da célula e pela transferência de oxigênio. Nos ensaios em frascos agitados, uma melhor condição de crescimento foi obtida utilizando frascos de 1 L, sob rotação a 270 rpm e 5,0 g/L de glicose. Nos ensaios em reator, quando operados em batelada obtiveram-se cerca 5,5 g/L de células finais, contra 9,3 g/L de células em batelada alimentada com vazão constante. Um maior crescimento foi ainda obtido em um reator de 2 L em regime de batelada alimentada exponencialmente. O biorreator varia a agitação do meio e mantém um nível pré-definido de oxigênio dissolvido, evitando a limitação de oxigênio e controlando a oferta de glicose para o crescimento celular. Neste processo, atingimos 25,6 g/L de células e 0,35 g/L de proteína total após purificação, utilizando meio M9 suplementado. / Nowadays in Brazil, the treatment for snakebite poisoning is carried out by the administration of horse sera, which have limited effectiveness: they are useful for systemic effects, but do not effectively inhibit local damage, cause adverse reactions, and present high production costs. According to the WHO, this disease is neglected by the world`s scientific authorities. This project, in partnership with the Institute for Research in Tropical Diseases of Oswaldo Cruz Foundation - Rondonia, proposes the production of heavy chain antibody fragments from camelids, called VHH, using Escherichia coli, to be used against the toxins from the Bothrops jararacussu poison, using a bioreactor. This work is interested in producing VHH through the use of E. coli. The kinetics of bacterial growth were performed in orbital shaker under different conditions, varying vial size, shaker rotation, composition of the culture medium and substrate concentration; and bioreactors, alternating culture media and operation mode of reactor (batch and fed-batch), changing feeding rate (linear and exponential). The kinetic process is statically bound to acetate formation, auxotrophic conditions of the cell and oxygen transfer. In assays in shaken flasks, an output of 270 rpm and 5.0 g/L of glucose. In reactor runs, when operated in a batch 5.5 g/L of final cells were obtained, against 9.3 g/L of final cells in fed-batch with constant flowrate. A larger value was obtained in an exponentially fed-batch reactor of 2 L. The bioreactor varies the agitation of oxygen and controls glucose addition for cell growth. In this process, 25.6 g/L cells and 0.35 g/L total protein after purification were reached, using supplemented M9 medium.

O Streptococcus pneumoniae, também conhecido como pneumococo, é um importante agente etiológico causador de pneumonia, bacteremia, meningite e otite aguda do ouvido médio, acometendo especialmente crianças e idosos. A cápsula polissacarídica (PS) é o fator de virulência mais importante e localiza-se na superfície do microrganismo e tem ação anti-fagocítica in vivo. O pneumococo expressa pelo menos 91 cápsulas diferentes, que são química e sorologicamente distintas. Usualmente, a cápsula é o antígeno das vacinas anti-pneumocócicas, tanto como polissacarídeo livre ou conjugado a proteínas. O sorotipo 6B acomete principalmente crianças e é o segundo mais prevalente no Brasil, e a otimização das condições de cultivo buscando maior produtividade em PS é o alvo desta tese. Simultaneamente, também foi investigada a influência do inóculo e da glicose residual no instante do pulso ou do início da alimentação em cultivos descontínuos alimentados. Nos cultivos descontínuos alimentados foi observado que quanto menor a densidade óptica da cultura do inóculo, maior a concentração de PS obtida. A concentração da glicose residual no momento do pulso provavelmente influenciou a produção de PS: a produção foi maior quando o pulso foi dado ainda em altas concentrações de substrato. Por isso, obteve-se uma produção de PS ~390 mg/L em cultivo descontínuo alimentado com pulso, quando DO 600 nm da cultura do inóculo ~1,6 e o pulso de glicose e acetato de amônio ~15 g/L. Observou-se também que, mesmo com DO do inóculo ~1,65, a produção de PS foi somente 248 mg/L, devido à aplicação do pulso quando a concentração de glicose residual era ~4,5 g/L. A menor produção de PS foi obtida quando a DO da cultura do inóculo foi ~2,6 e a concentração de glicose residual ~3,4 g/L, gerando somente 194 mg/L de PS. Assim, cultivos descontínuos alimentados com pulso renderam melhores resultados que os cultivos descontínuos alimentados. A alimentação constante rendeu maior quantidade de PS quando comparada à alimentação exponencial. E tanto os ensaios descontínuos com ou sem pulso e os descontínuos alimentados foram melhores do que os cultivos contínuos, principalmente se considerarmos a facilidade de operação. O efeito da concentração residual da glicose no instante da alimentação na produção de PS é provavelmente influenciado pela presença de outros componentes do meio, devido aos requerimentos nutricionais do pneumococo. O estado fisiológico do inóculo determinou uma importante correlação entre a produção de PS nos cultivos descontínuos alimentados do sorotipo 6B: cultura do inóculo no meio da fase exponencial rendeu maior produção de PS. Esta correlação poderia ser conseqüência do perfil de crescimento do microrganismo in vitro e da ação de enzimas líticas após a fase exponencial. Foi observado, portanto, um efeito sinérgico entre a DO da cultura do inóculo, a concentração de glicose residual no momento de alimentação e produção de PS nos cultivos descontínuos alimentados. / Streptococcus pneumoniae is a major pathogen commonly responsible for pneumonia, bacteraemia, meningitis and otitis media, especially among young children and older adults. The most prominent pneumococcal virulence factor is the capsular polysaccharide (PS), which coats the surface of the bacterium and acts as an antiphagocytic factor in vivo. S. pneumoniae express at least 91 distinct capsules which are chemically and serologically distinct. The capsule is currently used as antigen in pneumococcal vaccines, either as free polysaccharide or conjugated to proteins. Pneumococcal serotype 6B is the second most prevalent in Brazil and the optimization of cultivation conditions is part of this study. Simultaneously we investigated the influence of the growth phase of the inoculum and the residual glucose concentration at the instant of the pulse or the start of feeding on PS production in batch and fed-batch cultivation. Streptococcus pneumoniae serotype 6B strain ST 433/03 was used. Bench scale experiments were carried out using a variant of the Hoeprich medium, containing glucose, acid-hydrolyzed casein, dialyzed yeast extract, L-glutamine and asparagine as nitrogen sources, choline as a growth factor and salts. The experiments were conducted in bioreactors monitored by the LabView 7.1program. It was observed in fed-batch cultivation, that the lower was the OD of the starter culture, the higher was the PS concentration obtained. The residual glucose concentration at the moment of the pulse also influenced the PS production: the PS production was higher when the pulse was given at higher residual glucose concentration. Hence, in fed-batch culture the highest PS production (387 mg/L) was obtained using an OD=1.6 of the starter culture and giving the pulse when the residual glucose was ~15 g/L. Using a similar inoculum (OD=1.65), the PS concentration reached 248 mg/L after giving the pulse when the residual glucose was 4.5 g/L. The lowest PS production was obtained when a culture with an OD=2.6 was inoculated into the reactor and the pulse was given when the residual glucose was 3.4 g/L (PS=194 mg/L). The effect of the residual glucose concentration at the instant of the start of feeding on PS production was probably influenced by the presence of other components in the concentrated feeding medium, which could better fit the nutritional requirements of the microorganism. The physiological state of the inoculum showed an important correlation to the PS production in batch and fed-batch cultivation of S. pneumoniae serotype 6B: mid-log phase inocula yielded high PS production. This correlation is consequence of the in vitro growth profile, the action of lytic enzymes after the log phase. In fed-batch cultivation, it was also observed a synergic effect of the inoculum OD and the residual glucose concentration in the moment of the pulse on PS production.

Orientador: Flávio Vasconcelos da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-25T15:03:00Z (GMT). No. of bitstreams: 1 Ramos_VictorSantana_M.pdf: 2207177 bytes, checksum: 63cb53e77a107cef5979f71e6c8fb769 (MD5) Previous issue date: 2014 / Resumo: O desenvolvimento da biotecnologia tem proporcionado um crescimento em pesquisas acadêmicas, nas quais desenvolveram-se reatores conhecidos como airlifts, que são aplicados em bioprocessos diversos, tais como a fermentação alcóolica e o tratamento de efluentes. Assim, este trabalho possui como principais objetivos o projeto, a montagem e a instrumentação de um reator airlift de tubos concêntricos, de modo a obter em tempo real a fração de gás retido e a velocidade de circulação do líquido, e ainda estimar o coeficiente volumétrico de transferência de massa no sistema composto por solução aquosa de etanol e ar, aonde separa-se o etanol do meio através do arraste pelo gás carbônico presente no ar injetado (gas stripping). Os resultados obtidos no presente trabalho permitem concluir que o volume total do reator projetado e o design com as dimensões consideradas permitiram operar o airlift no regime hidrodinâmico de recirculação de gás, e capaz de promover a separação do etanol do meio através do arraste pelo ar comprimido alimentado. Os resultados mostraram que os parâmetros hidrodinâmicos, velocidade de circulação de líquido e fração de gás retido, são dependentes da velocidade superficial do gás alimentado e do volume de solução alcoólica presente na coluna (desnível), mostraram também que o coeficiente volumétrico de transferência de massa sofreu influências da concentração de etanol no meio, do desnível, da velocidade superficial de gás e da temperatura, sendo esta última a variável de maior influência entre as consideradas / Abstract: The development of biotechnology has provided an increase in academic research, which evolved reactors known as airlifts, which are applied in several bioprocesses, such as alcoholic fermentation and wastewater treatment. Thus, this work has as main objectives the design, assembly and automation of a concentric tube airlift reactor, in order to obtain in real time the gas hold-up and liquid circulation velocity, and still estimate the volumetric mass transfer coefficient in a system composed of air and aqueous ethanol, the latter was recovered from the carbon dioxide stripping gas in a refrigerated condenser. The results obtained in this study allow is possible to conclude that the airlift designed behaved satisfactorily and as expected, the total volume of the reactor and designed with the dimensions considered design allowed us to operate the reactor in the gas recirculation regime, and capable of promoting the separation of the ethanol by stripping. The results showed that the hydrodynamic parameters, liquid circulation velocity and gas hold-up, are dependent on the superficial gas velocity and the volume of alcohol solution on the column (dispersion height), also showed that the volumetric mass transfer coefficient was influenced by ethanol concentration, dispersion height, superficial gas velocity and temperature, the latter being the most influential among the considered variable / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

Ces travaux de thèse porte sur l'étude d'un procédé de traitement des eaux usées intitulé "anammox". C'est un procédé biologique reposant sur le métabolisme d'un groupe de bactéries du même nom permettant l'épuration de l'azote. Ces travaux développent une méthodologie pour leur identification et leur culture et aboutissent à la mise en application de bio-réacteur de traitement à l'échelle du laboratoire. / This work focuses on the study of a wastewater treatment process entitled "anammox". It is a biological process based on the metabolism of a group of bacteria of the same name allowing the purification of nitrogen. This work develops a methodology for their identification, their culture and for the implementation of bioreactor treatment at the laboratory scale.

Magíster en Ciencias de la Ingeniería, Mención Química / Ingeniero Civil Químico / Resultados experimentales señalan que las células animales pueden alcanzar múltiples estados metabólicos con distintas razones de tasa de producción de lactato a tasa de consumo de glucosa (DL=DG), lográndose razones muy por debajo de la razón estequiométrica igual a 2 [mol=mol]. En el presente trabajo de tesis se planteó y ajustó un modelo metabólico que describe el metabolismo de un cultivo de control y se corroboró su falta de capacidad de alcanzar más de un estado estacionario a través de la comparación con datos experimentales y un análisis de estabilidad posterior. La simplificación de dicho modelo inicial, la obtención de un único punto atractor como estado estacionario y el análisis de variaciones de niveles de expresión génica de ciertas enzimas glicolíticas permitió el planteamiento de un modelo de regulación que varía la concentración de la enzima lactato deshidrogenasa (LDH) con el cual se simuló un cultivo hasta alcanzar estado metabólico alterado (DL=DG <0,1 [mol=mol]). El modelo metabólico regulado se utilizó para la simulación de un cultivo continuo alterado para el diseño y ajuste de controladores proporcional (P), basado en modelo lineal y basado en modelo no lineal para la regulación de la concentración de glucosa de entrada frente a perturbaciones en el crecimiento celular. La simulación de la respuesta de lazo cerrado del sistema mostró una fuerte interacción de lazos con el lazo de control de crecimiento celular y los análisis de robustez y de sensibilidad permitieron concluir que el controlador P posee una mayor robustez que el controlador basado en modelo lineal, pero que este último posee una mejor respuesta frente a limitantes que podrían existir a nivel industrial. Por otra parte, el pobre desempeño del controlador basado en modelo no lineal demuestra un desafío de ajuste del mismo producto de las múltiples posibles fuentes del mal desempeño. Como línea de trabajo futuro se puede mejorar la respuesta simulada de los controladores basados en modelo, analizando la eliminación de offset para el caso lineal y los problemas de rendimiento del basado en modelo no lineal.

O etanol é o combustível que mais se destaca como alternativa à gasolina no setor do transporte. No entanto, a melhoria da eficiência da fermentação, aprimorando o processo de conversão de biomassa em etanol combustível e reduzindo o custo de produção são desafios ainda pertinentes. Neste cenário, as fermentações com alta concentração de açúcar ou VHG (very high gravity) estão sendo cada vez mais estudadas. A adição de compostos como fonte de nitrogênio pode gerar benefícios para a produção de etanol, entretanto, a maioria dos estudos com suplementação de fontes nitrogenadas é realizada em sistema descontínuo simples e em escala laboratorial, embora os processos fermentativos industriais sejam conduzidos em sistema descontínuo alimentado. Neste contexto, este trabalho visou avaliar o perfil fermentativo da linhagem CAT-1 em mosto contendo alta concentração de açúcar fermentescível e suplementado com as fontes nitrogenadas peptona e sulfato de amônio, nas concentrações 5 e 10 g/L, em sistema de descontínuo simples e descontínuo alimentado com reciclo de células, utilizando diferentes escalas produtivas. Nos experimentos em sistema descontínuo simples, os tratamentos controle e peptona (5 g/L) apresentaram uma melhor produção de etanol, maior rendimento e produtividade em comparação com os demais tratamentos. Nos experimentos em sistema descontínuo alimentado não houve diferença significativa entre os tratamentos controle e peptona 5 e 10g/L, porém, o tratamento com sulfato de amônio (10 g/L) apresentou parâmetros fermentativos de produção de etanol e produtividade superiores ao tratamento controle, o oposto do descontínuo simples. Os resultados mostraram que quando as células de levedura foram submetidas a concentrações crescentes de açúcar, como é o caso do sistema descontínuo alimentado, ocorre uma adaptação das mesmas, proporcionando melhores resultados, com uma redução no tempo de fermentação para 16h. Além disso, a alta concentração de etanol no meio fermentativo causa um efeito prejudicial às células, já que nos tratamentos onde houve teores mais elevados de etanol ocorreu menor viabilidade e maior quantidade de açúcar residual. / Ethanol is the fuel that stands out as an alternative to gasoline in the transportation sector. However, improving the efficiency of fermentation, improving the process of converting biomass to fuel ethanol and reducing the cost of production are still relevant challenges. In this scenario, fermentations with high sugar concentration or very high gravity (VHG) are being studied more and more. The addition of compounds as a source of nitrogen can generate benefits for ethanol production, however, most of the studies with nitrogen supplementation are carried out in a simple discontinuous system and in laboratory scale, although the industrial fermentation processes are conducted in a fed batch system . In this context, the objective of this work was to evaluate the fermentation profile of the CAT-1 strain in must containing high fermentable sugar concentration and supplemented with nitrogen peptone and ammonium sulfate at 5 and 10 g / L in a simple discontinuous system and fed batch system, fed with recycle of cells, using different productive scales. In the simple discontinuous system experiments, the control and peptone treatments (5 g / L) presented better ethanol production, higher yield and productivity in comparison to the other treatments. However, the treatment with ammonium sulfate (10 g / L) showed fermentative parameters of ethanol production and productivity higher than the control treatment, the opposite of simple discontinuity. The results showed that when the yeast cells were submitted to increasing concentrations of sugar, as is the case of the fed batch system, an adaptation occurs, providing better results, with a reduction in the fermentation time to 16h. In addition, the high concentration of ethanol in the fermentation medium causes a detrimental effect on the cells, since in the treatments with higher levels of ethanol; less viability and more residual sugar were observed.