Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Biosurfactants are microbially produced molecules that show excellent surface-active properties. Bacillus subtilis ATCC 21332 produces the biosurfactant, surfactin, which exhibits antimicrobial activity against bacteria as well as fungi. Although antimicrobial activity has been exhibited by a number of bacterially produced biosurfactants, notably the rhamnolipid from the pathogen Pseudomonas aeruginosa, the GRAS status B. subtilis makes the use of this organism preferable for large scale bioprocesses. The objectives of this study were to: (1) evaluate the effect of different nutrient conditions on growth and surfactin production; (2) evaluate the growth of B. subtilis ATCC 21332 and associated surfactin production on a hydrocarbon substrate; (3) evaluate the antimicrobial activity of surfactin against Mycobacterium aurum, and (4) to establish whether active growth of B. subtilis ATCC 21332 and associated surfactin production can be extended during fed-batch culture. B. subtilis ATCC 21332 was grown on low-nitrate; phosphate-limited and nutrient rich media with glucose as substrate during shake flask culture. Nitrate, phosphate, glucose and surfactin were quantified by HPLC analyses and growth via CDW and optical density measurements. Growth and surfactinproduction were further evaluated during shake flask cultureon a hydrocarbon substratereplacing the glucose in the nutrient rich medium with an equivalent amount of n-hexadecane. The antimicrobial activity was quantified by growth inhibition of M. aurum. Bioreactor batch and fed-batch studies were conducted to evaluate growth and surfactin production under controlled conditions. The fed-batch experiments included four constant dilution rate (D=0.40h-1; D=0.15h-1; D=0.10h-1 and D=0.05h-1) and two constant feed rate (F=0.40L/h and F=0.125L/h) fed-batch strategies. The nutrient rich medium was used for these experiments and also as the feed medium for fed-batch experiments. A CDW of 12.6 g/L was achieved in the nutrient rich medium during shake flask culture and was 2.5- and 1.6-fold higher than that achieved in the phosphate-limited medium and the lownitrate medium respectively. A surfactin concentration of 652 mg/L was achieved in the nutrient rich medium, while a maximum surfactin concentration of 730 mg/L was achieved in the phosphate-limited medium. A surfactin concentration of only 172 mg/L was achieved in the low-nitrate medium. Subsequently, growth and surfactin production were evaluated on n-hexadecane as sole carbon source. After inoculation, the CDW did not increase over a period of 119 h, which indicated that B. subtilis ATCC 21332 was unable to utilize n-hexadecane for growth and surfactin production. The maximum CDW (27 g/L) and maximum surfactin concentration (1737 mg/L) achieved in the bioreactor batch experiments were 2.1- and 2.6-fold higher respectively than that achieved in the nutrient rich medium during shake flask experiments. These results served as a benchmark for further fed-batch experiments. During the fed-batch phase of the D=0.40h-1 experiment, the biomass further increasedby 9 g/h, which was 3.5-, 3.1- and 5.3-fold higher compared to the fed-batch phases of the D=0.15h-1, D=0.10h-1 and D=0.05h-1 experiments respectively. Similarly, the biomass increased by 10.7 g/h during the fed-batch phase of the F=0.40L/h experiment, which was 4.6-fold higher than that of the F=0.125L/h experiment. The average rate of surfactin production was 633 mg/h during the fed-batch phase of the D=0.40h-1 experiment, 29.4-, 5.4- and 34.2-fold higher compared to the fed-batch phases of the D=0.15h-1, D=0.10h-1 and D=0.05h-1 experiments respectively. Analogously, the average rate of surfactin production (544 mg/h) of the F=0.40L/h experiment was 9.4 fold higher than that of the F=0.125L/h experiment. The antimicrobial assay showed that surfactin inhibits M. aurum growth. An inhibition zone diamater of 4mm was measured at a surfactin concentration of 208 mg/L, which linearly increased to 24mm at a surfactin concentration of 1662 mg/L. High feed flow rate strategies achieved higher rates of biomass increase and surfactin production and will thus decrease the production time required for large scale surfactin production.The antimicrobial activity of surfactin against M. aurum indicates that this biosurfactant has the potential to be used against M. tuberculosis, and as such has the potential to be used in the medical industry to reduce the spread of this, and other deadly diseases. / AFRIKAANSE OPSOMMING: Biosurfaktante is oppervlak-aktiewe molekules wat deur sekere mikro-organismes geproduseer word. Bacillus subtilis ATCC 21332produseer ‘n biosurfaktant genaamd surfactin, wat antimikrobiese eienskappe toon teen bakterieë sowel as fungi.Menige bakterieël geproduseerde biosurfaktante toon antimikrobiese eienskappe, vernaam die rhamnolipied van die patogeen Pseudomonas aeruginosa, maar die algemene veiligheids-status van B. subtilis gee voorkeur aan hierdie organisme vir grootskaalse bioprosesse. Die doelwitte van hierdie studie was: (1) om die effek van verskillende medium samestellings (in terme van voedingstowwe) ten opsigte van bakteriële seldigtheid en surfactin-produksie te evalueer; (2) om die bakteriële seldigtheid van B. subtilis ATCC 21332 en geassosieerde surfactin produksie vanaf ‘n alkaan-substraat te evalueer; (3) om die antimikrobiese aktiwiteit van surfactin teen Mycobacterium aurum te evalueer; (4) om vas te stel of die aktiewe groei van B. subtilis ATCC 21332 en geassosieerde surfactin-produksie gedurende voer-lot kultuur verleng kan word. B. subtilis ATCC 21332 was op lae-nitraat; fosfaat-beperkte en voedingstofryk-media met glukose as substraat in skudflesse gekultiveer. Nitraat, fosfaat, glukose en surfactin was deur hoëdruk vloeistofchromatografie gekwantifiseer en die seldigtheid deur middel van seldroëmassa en optiese digtheid metings. Verder was die groei van B. subtilis, en geassosieerde surfactin produksie, vanaf ‘n alkaan-substraat in skudflesse ge-evalueer deur die glukose in die voedingstofryke medium met ‘n ekwivalente hoeveelheid van n-heksadekaan te vervang. Die antimikrobiese aktiwiteit van surfactin was deur die geїnhibeerde groei van M. aurum gekwantifiseer. Bioreaktor lot en voer-lot studies was uitgevoer om die groei en surfactin produksie onder beheerde toestande te evalueer. Die voer-lot eksperimente het vier konstante verdunningstempos (D=0.40h-1; D=0.15h-1; D=0.10h-1 en D=0.05h-1) en twee konstante voertempos (F=0.40L/h and F=0.125L/h) ingesluit. Die voedingstofryke medium was vir hierdie eksperimente en ook as die voermedium vir dievoer-lot eksperimente gebruik. ‘n Seldigtheid van 12.6 g/L is bereik gedurende skudfleskultuur in die voedingstofryk-media en was 2.5- en 1.6-voud hoër as die seldigthede wat in die fosfaat-beperkte en lae-nitraat media bereik is. ‘n Surfactin konsentrasie van 652 mg/L is bereik in die voedingstofryke medium, terwyl ‘n maksimum surfactin konsentrasie van 730 mg/L in die fosfaat-beperkte medium bereik is. ‘n Surfactin konsentrasie van slegs 172 mg/L is in die lae-nitraat medium bereik.Hierna was bakteriële seldigtheid en surfactin produksie geuvalueer met slegs n-heksadekaan as die enigste koolstof bron. Die bakteriële seldigtheid het geen verandering getoon na inokulasie nie, wat aangedui het dat B. subtilis ATCC 21332 nie die vermoë beskik om n-heksadekaan vir groei en surfactin produksie te gebruik nie. Die maksimum seldigtheid (27 g/L) en maksimum surfactin konsentrasie (1737 mg/L) bereik in die bioreaktor lot eksperimente was 2.1- en 2.6-voud hoër onderskeidelik as dit bereik in die voedingstofryke medium gedurende skudfles eksperimente. Hierdie resultate dien as ‘n basis vir verdere voer-lot eksperimente. Gedurende die voer-lot fase van die D=0.40h-1 het die biomassa verder verhoog teen 9 g/h, wat 3.5-, 3.1- en 5.3-voud hoër was as dit van die D=0.15h-1, D=0.10h-1 en D=0.05h-1 eksperimente onderskeidelik. Die biomassa het soortgelyk tydens die voer-lot fase van die F=0.40L/h eksperiment teen 10.7 g/h verhoog, wat 4.6-voud hoër was as dit van die F=0.125L/h eksperiment. Die gemiddelde tempo van surfactin produksie was 633 mg/h gedurende die voer-lot fase van die D=0.40h-1 eksperiment, 29.4-, 5.4- en 34.2-voud hoër vergeleke met die voer-lot fases van die D=0.15h-1, D=0.10h-1en D=0.05h-1 eksperimente onderskeidelik. Die gemiddelde tempo van surfactin produksie (544 mg/L) was soortgelyk 9.4-voud hoër gedurende die voer-lot fase van die F=0.40L/h eksperimente, vergeleke met die die F=0.125L/h eksperiment. Die antimikrobiese toetse van surfactin teen M. aurum het positief getoets, wat aandui dat surfactin die groei van hierdie organisme inhibeer. ‘n Inhibisie sone deursnee van 4mm was gemeet teen ‘n surfactin konsentrasie van 208 mg/L, wat lineêr verhoog het tot 24 mm teen ‘n surfactin konsentrasie van 1662 mg/L. Hoë voertempo strategieë het hoër biomassa verhogingstempos en surfactin produksie tempos getoon en sal dus die produksietyd aansienlik verkort tydens grootskaalse surfactin produksie. Die antimikrobiese aktiwiteit van surfactin teen M. aurum toon dat hierdie biosurfaktant die vermoë het om gebruik te word teen M. tuberculosis. Daarom het surfactin die potensiaal om gebruik te word in die mediese industrie om die verspreiding van Tuberkulose, en ander dodelike patogene, te voorkom.

Solar Energy and Hydrogen (energy carrier) are possible replacement options for fossil fuel and its associated problems of availability and high prices which are devastating small, developing, oil-importing economies. But a major drawback to the full implementation of solar energy, in particular photovoltaic (PV), is the lowering of conversion efficiency of PV cells due to elevated cell temperatures while in operation. Also, hydrogen as an energy carrier must be produced in gaseous or liquid form before it can be used as fuel; but its‟ present major conversion process produces an abundance of carbon dioxide which is harming the environment through global warming. In search of resolutions to these issues, this research investigated the application of Thermal Management to Photovoltaic (PV) modules in an attempt to reverse the effects of elevated cell temperature. The investigation also examined the effects of coupling the thermally managed PV modules to a proton exchange membrane (PEM) Hydrogen Generator for the production of hydrogen gas in an environmentally friendly and renewable way. The research took place in Kingston, Jamaica. The thermal management involved the application of two cooling systems which are Gravity-Fed Cooling (GFC) and Solar-Powered Adsorption Cooling (SPAC) systems. In both systems Mathematical Models were developed as predictive tools for critical aspects of the systems. The models were validated by the results of experiments. The results of the investigation showed that both cooling systems stopped the cells temperatures from rising, reversed the negative effects on conversion efficiency, and increased the power output of the module by as much as 39%. The results also showed that the thermally managed PV module when coupled to the hydrogen generator impacted positively with an appreciably increase of up to 32% in hydrogen gas production. The results of this work can be applied to the equatorial belt but also to other regions with suitable solar irradiation. The research has contributed to the wider community by the development of practical, environmentally friendly, cost effective Thermal Management Systems that guarantee improvement in photovoltaic power output, by introducing a novel way to use renewable energy that has potential to be used by individual household and/or as cottage industry, and by the development of Mathematical Tools to aid in photovoltaic power systems designs.

This paper uses Federal Funds Futures and the industry returns to analyze the Federal Reserve Policy's influence on Wall Street firms. According to the results, Wall Street produces high returns in response to the monetary policy when compared to other industries. While this positive response is consistent to both interest hikes and cuts, there exists significant cross-firm and cross-period variation. Besides, the result is robust to the alternative measure of event days and employment release.

Growth, that is a sensitive indicator of children's health, should be evaluated in relation to suitable reference data. Under the term "physiological growth of chidren" is understood growth of long-term breast-fed infants that is - in the first months of their life - different from the growth of infants, who were not breast fed. This Thesis is focused on evaluation of impacts the long-term breast-feeding has on the growth of children in their pre-school age and on the differences in comparison with the children, who were breast- fed only minimally or not at all. Data used for this Thesis elaboration were obtained from a questionnaire and by measuring the essential physical proportions of children in different nursery and primary schools in Prague. Thereafter; by analysing the received data, we have come to the conclusion that long-term breast-feeding does not have any significant impact onto stature, weight nor head circumference of pre-school children. Some differences were detected concerning the BMI values and thickness of skin folds; however, the results were out of accord with our expectations that the long-term breast-fed children will have lower BMI values than the children, who were breast-fed just minimally. Comparing the Z-score of the long-term breast-fed children with regard to the data from the...

This graduation thesis focuses on analyzing the impact(s) of the recent American mortgage crisis. The main goal is to study measures that have been taken to overcome this crisis andv evaluate them. The thesis is divided into four parts. The aim of the first part is to quantify the size of the United States housing bubble. The second part brings in the estimates of losses to individual financial institutions in the USA. The third part concentrates on detailed analysis of the arrangements that have been used to overcome mortgage crisis and consequential financial crisis. The last part compares the measures taken in order to solve the recent crisis with the ones that had been taken to overcome the Great Depression.

O presente trabalho teve como objetivo o estudo do processo fermentativo de produção de retamicina, em biorreatores de bancada, utilizando-se a linhagem mutante Streptomyces olindensis So20, visando a obtenção de elevadas quantidades deste antibiótico, em processo descontínuo alimentado (fed-batch) e contínuo, bem como a implementação de técnicas de análise de imagens para a caracterização morfológica do microrganismo durante os cultivos. Os ensaios descontínuos alimentados visaram o controle da velocidade específica de crescimento durante a alimentação em três valores distintos (0,03 1/h, 0,10 1/h e 0,17 1/h), por meio do emprego de vazões exponenciais de alimentação. Foram realizados três conjuntos de ensaios descontínuos alimentados. No primeiro conjunto, foi verificada a influência da concentração de nutrientes utilizada na alimentação, mantendo-se a velocidade específica de crescimento em 0,03 1/h, durante a alimentação. De uma maneira geral, o aumento da concentração de nutrientes na alimentação, levou a um aumento na produção do antibiótico. No segundo conjunto de ensaios, foi estudada a influência da velocidade específica de crescimento sobre a produção de retamicina, empregando-se como alimentação o meio R5 modificado com apenas a concentração de glicose quadruplicada. Nesse conjunto de ensaios, ocorreu limitação de outros nutrientes, o que prejudicou o controle da velocidade específica de crescimento durante a alimentação. No entanto, essa limitação nutricional mostrou-se importante para a produção do antibiótico. No terceiro conjunto de ensaios, foi novamente estudada a influência da velocidade específica de crescimento sobre a produção de retamicina, empregando-se como alimentação o meio R5 modificado, agora com as concentrações de todos os nutrientes quadruplicadas, o que evitou limitações nutricionais e permitiu o controle da velocidade específica de crescimento durante a alimentação. Estes ensaios mostraram que o processo de produção de retamicina é favorecido pela manutenção de baixas velocidades específicas de crescimento, por ser este um metabólito secundário. A maior produção de retamicina ocorreu quando a velocidade específica de crescimento foi fixada em 0,03 1/h, durante a alimentação. Nos ensaios contínuos realizados, foi estudada a influência da vazão específica de alimentação (D) e, conseqüentemente, da velocidade específica de crescimento (µx) sobre a produção do antibiótico retamicina. Foram, realizados quatro ensaios contínuos, variando-se D entre 0,03 1/h e 0,30 1/h. A máxima produção de retamicina (tanto em termos de concentração, como em termos de produtividade e produção específica em retamicina total) ocorreu para D = 0,05 1/h. O aumento de D levou a uma diminuição da produção do antibiótico, a qual cessou para D = 0,30 1/h, mostrando um comportamento típico de um metabólito secundário. Foram utilizadas técnicas de análise de imagens na caracterização morfológica do microrganismo. O cisalhamento mostrou-se um importante fator no rompimento de pellets e na formação de clumps e hifas livres, principalmente nos ensaios contínuos. Em geral, a maior produção do antibiótico esteve associada a altas porcentagens de clumps no meio de cultivo. / The objective of the present work was to study retamycin production in fed-batch and continuous cultivations of Streptomyces olindensis So20, a mutant strain, in order to obtain high antibiotic concentrations and analyse microorganism morphology employing image analysis techniques. The fed-batch runs were performed in order to control the specific growth rate in three different values, during feed (0.03 1/h, 0.10 1/h, and 0.17 1/h), employing exponential feed rates. Three sets of fed-batch runs were carried-out. The first set, feed composition was varied, controlling the specific growth rate in a low value (0.03 1/h) during feed. In general, higher nutrient concentrations in the feed led to higher antibiotic production. In the second set of fed-batch runs, the control of the specific growth rate in three different values during feed was studied. The feed was composed by R5 Modified medium, with four-fold the glucose concentration only, which led to nutrient limitation during runs. This nutrient limitation prejudiced the specific growth rate control, but led to high antibiotic production. This fact showed that nutrient limitation is an important factor in retamycin production. In the third set of fed-batch runs, the control of the specific growth rate in three different values during feed was studied. In these runs, the feed was composed by R5 Modified medium, with four-fold all the nutrient concentrations, which avoided nutrient limitation, during runs. In these runs, the control of the specific growth rate during feed was possible. Results showed that retamycin production is favored by the maintenance of low specific growth rates, since it is a secondary metabolite. Higher antibiotic production was achieved controlling the specific growth rate in 0.03 1/h, during feed. In the continuous runs, the influence of the dilution rate (D), and consequently, of the specific growth rate (µx) on the retamycin production was studied. Four continuous runs were performed, varying D in the range from 0.03 1/h to 0.30 1/h. The highest antibiotic production (in terms of retamycin concentration, retamycin productivity and retamycin specific production) was obtained at D = 0.05 1/h. The increase in the dilution rate led to lower antibiotic production, which ceased at D = 0.30 1/h, showing a typical behavior of a secondary metabolite. Image analysis was used to assess the morphological characteristics of the microorganism. Shear showed to be an important factor in pellet disruption and in clump and free filaments formation, mainly in the continuous runs. In general, higher antibiotic production was obtained with the growth mainly in the form of clumps.

A microalga Spirulina platensis, fornece uma biomassa rica em proteínas, ácidos graxos polinsaturados, vitaminas e outros componentes de alto valor como a clorofila, a qual pode ser utilizada como corante em medicamentos, cosméticos e alimentos. No presente trabalho, estudou-se a influência da iluminação, simultaneamente com a utilização de uréia como fonte de nitrogênio por meio de processo descontínuo alimentado, no crescimento de Spirulina platensis e conteúdo de clorofila da biomassa. Foram utilizados tanques abertos, com volume de cultivo de 5L. Dentre os ensaios realizados, o melhor crescimento ocorreu com a utilização de 2500mg de uréia a 5600lux de iluminância, e o pior com 2500mg de uréia a 1400lux de iluminância. O maior conteúdo de clorofila na biomassa, por sua vez, foi obtido com 2500mg de uréia a 1400lux de iluminância, e o menor com 2500mg de uréia a 5600lux de iluminância. Uma regressão estatística para a produtividade em clorofila (mg.L-1.dia-1)foi realizada, a partir de valores codificados para os parâmetros em estudo, obtendo-se a seguinte equação de regressão: PCla= 1,53 - O,16.Mutc2 - 0,28.Ec2 + 0,2.Mutc + 0,13.Ec A partir da derivada da equação, calculou-se os valores dos parâmetros estudados correspondentes ao ponto ótimo de produtividade em clorofila para as condições deste trabalho, os quais foram 2902mg de uréia e 3845lux de iluminância, o que mostra que valores intermediários de iluminância promovem um equilíbrio entre crescimento celular e biossíntese de clorofila. / The microalga Spirulina platensis gives a high protein, fatty acids and vitamins contents biomass, besides other high value components like chlorophyll, that can be produced and used like a color in medicines, cosmetics and food. In this work, the influence of iIIuminance and utilization of urea as nitrogen source by fed-batch system in the Spirulina platensis growth and chlorophyll content was studied. Cultivates were carried out in open ponds with a 5L fermentation volume. The best growth result happened with the utilization of 2500mg of urea at 5600lux of iIIuminance, and the worst with 2500mg of urea at 1400lux of iIIuminance. The highest biomass chlorophyll content, otherwise, was observed with 2500mg of urea and 1400lux of iIIuminance, and the lowest with 2500mg of urea at 5600lux of iIIuminance. Statistical regression for chlorophyll productivity (mg.L-1.dia-1),using the studied parameters codified values was done, giving the equation below: PCla= 1,53 - O,16.Mutc2 - 0,28.Ec2 + 0,2.Mutc + 0,13.Ec From the derivative of the function, the studied parameters values correspondents to the optimal chlorophyll productivity point was calculated, concerning to the conditions of this work, being obtained 2902mg of urea and 3845lux of iIIuminance. This shows that intermediate iIIuminance values provides equilibrium between cellular growth and chlorophyll biosynthesis.

O objetivo deste estudo foi avaliar a ocorrência de diarreia e suas consequências no metabolismo animal em bezerros consumindo concentrado inicial contendo coprodutos como polpa cítrica, melaço e xarope de glicose; ou bezerros suplementados com probiótico. Dois experimentos foram conduzidos para avaliar o efeito da substituição de milho por coprodutos. No primeiro experimento, 24 bezerros com idade média de 2 semanas, foram distribuídos em 3 tratamentos e receberam concentrado inicial contendo doses crescentes de polpa cítrica em substituição ao milho. No segundo experimento, 32 bezerros foram divididos em 4 tratamentos, recebendo concentrado inicial contendo xarope de glicose e doses crescentes de melaço em substituição ao milho. Em ambos os experimentos, os animais foram alojados em abrigos individuais, receberam 4 L de sucedâneo lácteo por dia, dividido em duas refeições e tiveram livre acesso à água e concentrado. Após o diagnóstico da ocorrência de diarreia, foram realizadas avaliações de escore fecal, escore clínico, além de medição dos parâmetros fisiológicos, nas seguintes 24, 48 e 72 horas. Foram colhidas amostras de sangue para realização de hemograma, análises bioquímicas, análises gasométricas e eletrolíticas. A adição de coprodutos no concentrado inicial não afetou (P>0,05) o escore fecal, as características das fezes e os sinais clínicos dos animais diarreicos. As análises plasmáticas bioquímicas (glicose, proteínas totais, albumina, ?-hidroxibutirato, nitrogênio ureico plasmático, lactato total, D- e L-lactato) apresentaram valores normais e não sofreram efeito negativo (P>0,05) em resposta da substituição de milho por coprodutos no concentrado. Não houve diferença entre os tratamentos (P>0,05) nas análises gasométricas e no eritrograma, com resultados indicando ausência ou baixo nível de acidose metabólica e desidratação nos animais. De acordo com o leucograma realizado, foi constatada leucocitose e neutrofilia na maioria dos casos, significando que a diarreia foi de origem infecciosa, descartando a possibilidade que o consumo de coprodutos no concentrado fosse a etiologia da diarreia. Um terceiro experimento foi realizado para avaliar o desempenho geral de bezerros suplementados com probíóticos contendo bactérias ruminais. Foram utilizados 20 bezerros divididos em 2 tratamentos (controle e fornecimento oral de 2 gramas de probiótico/dia), sendo os animais avaliados até a 10ª semana de vida. Os animais alojados em abrigos individuais, receberam 6 L de sucedâneo lácteo por dia, e tiveram livre acesso à água e concentrado. O desaleitamento foi realizado na 6ª semana de vida, de forma a causar uma situação de estresse nos animais. O consumo diário de concentrado, ganho de peso, desenvolvimento corporal e escore fecal foram avaliados. Nas semanas 2, 4, 6, 8 e 10 foram colhidas amostras de sangue para determinação de parâmetros bioquímicos e realização do hemograma. O fornecimento de probióticos via oral não afetou (P>0,05) o escore fecal, o desempenho dos animais (ganho de peso e consumo de concentrado). Como conclusão, a substituição de milho por polpa cítrica, melaço ou xarope de glicose no concentrado inicial não apresentou efeitos negativos relacionados à diarreia e não agravou os quadros de desidratação e acidose metabólica. O fornecimento de 2 gramas diários de probióticos de bactérias ruminais não resultou em melhorias no desempenho de bezerros desaleitados precocemente. / The objective of this study was to evaluate the occurrence of diarrhea and the consequences on animal metabolism of calves consuming starter feed containing coproducts such as citrus pulp, molasses and glucose syrup; or calves supplemented with direct-fed microbial (DFM). Two trials were performed to evaluate the effect of replacing corn by coproducts. In the first trial, 24 calves were divided into three treatments, and received starter feed containing increasing doses of citrus pulp replacing corn. In the second trial, 32 calves were divided into four treatments, and received starter feed containing glucose syrup and increasing doses of molasses replacing corn. In both experiments, animals were housed in individual hutches, received 4 L/d of milk replacer, divided into two meals and had free access to water and starter feed. After the diagnosis of the occurrence of diarrhea fecal score, clinical score, and the measurement of physiological parameters were evaluated during the following 24, 48 and 72 hours.Blood samples were taken for complete blood count (CBC), biochemical, electrolytes and gases analysis. The addition of coproducts in the starter feed had no effect (P>0.05) on fecal score, characteristics of the faeces and clinical signs of diarrheic animals. The plasma biochemical analysis (glucose, total protein, albumin, ?-hydroxybutyrate, urea nitrogen, lactate total D-and L-lactate) showed normal values and were negativelly affected (P>0.05) in response to the substitution of corn by coproducts in the stater feed for calves. No alterations (P>0.05) were noted in the erythrocyte and blood gases results, suggesting absence or low level of dehydration, and metabolic acidosis in animals. According to the white blood cell count (WBC), leukocytosis and neutrophilia were observed in most cases, suggesting infectious diarrhea and rejecting the possibility that the consumption of coproducts in the starter feed were the etiology of diarrhea cases. A third trial was performed to evaluate the overall performance of dairy calves supplemented with a probiotic containg ruminal bacterias. Twenty calves divided into two treatments (control and oral and daily supply of 2 grams of probiotic), animals were evaluated up to 10 weeks of age. Animals were housed in individual hutches, received 6 L/d of milk replacer, and had free access to water and starter feed. Weaning was done at the 6th week of age, as a meaning of causing stress in animals. Daily starter feed intake, weight gain, body development, and fecal score were evaluated. At 2nd, 4th, 6th, 8th and 10th weeks, blood samples were collected for biochemical analysis and WBC. The oral supply of probiotic had no effect (P>0.05) on fecal score or animal performance (weight gain and starter feed intake). In conclusion, the substitution of corn by citrus pulp, molasses or glucose syrup in the starter feed for dairy calves had no negative effects related to diarrhea or the agravation of dehydration and metabolic acidosis. The oral and daily supply of 2 grams of probiotics containg ruminal bacteria resulted in no improvements in performance of early-weaned dairy calves.

O presente trabalho teve como objetivo avaliar a influência da intensidade de agitação e tipo de impelidor, bem como a estratégia de alimentação, em reator anaeróbio operado em batelada seqüencial, escala piloto (\'da ordem de\' 1 \'M POT.3\'), com agitação mecânica e em duas configurações: uma com biomassa granulada (ASBR) e outra com biomassa imobilizada em suporte inerte de espuma de poliuretano (ASBBR), aplicadas ao tratamento de esgoto doméstico. No estudo da intensidade de agitação e tipo de impelidor, para cada reator foram avaliadas três tipos de impelidores (turbina de pás planas, turbina de pás inclinadas 45º e hélice) associados a duas intensidades de agitação (40 e 80 rpm), obtendo uma combinação de 6 (seis) condições experimentais. A combinação da intensidade de agitação e tipo de impelidor que apresentou melhor desempenho no processo foi utilizado no estudo da estratégia de alimentação, na qual foi avaliada as seguintes condições: batelada alimentada durante 25%, 50%, 75% e 100% do ciclo. Os resultados obtidos permitiram concluir que: no ASBBR o aumento da intensidade de agitação de 40 rpm para 80 rpm permitiu uma melhoria nos fluxos de transferência de massa e, portanto, aumentou a velocidade de consumo de substrato; no ASBR o aumento da intensidade de agitação de 40 rpm para 80 rpm proporcinou uma desestabilização do sistema, provavelmente por causa da ruptura dos grânulos provocada pela maior agitação; os sistemas operados com impelidor do tipo hélice apresentaram vantagens, tais como: melhor eficiência de remoção de sólidos, maior valor da constante cinética de primeira ordem (melhor fluxo de transferência de massa e conseqüentemente maior consumo de substrato) e maior produção de alcalinidade, ou seja, maior estabilidade para o sistema; tanto o sistema ASBR como o ASBBR quando operados nas condições de batelada típica, batelada alimentada durante 50% e 75% do ciclo apresentaram melhores desempenhos no processo de tratamento, mostrando a flexibilidade operacional dos reatores anaeróbios operados em bateladas seqüenciais; e comparando os sistemas ASBBR e ASBR verificou-se que estes apresentaram comportamentos similares em todas as condições de operação de batelada alimentada avaliadas, não sendo possível, estatisticamente apontar um sistema com melhor desempenho. / The objective of this work was to assess the effect of the stirring speed, the type of impeller and the feed strategy in a mechanically stirred pilot-scale (\'da ordem de\' 1 \'M POT.3\') anaerobic sequencing batch reactor to two configurations: a containing granulated biomass (ASBR) and the other containing immobilized biomass (AnSBBR). Domestic wastewater was treated in 8-h cycles. Three impeller types (turbine with six-flat blades, turbine with six 45º-inclined blades and helix with three blades) were assessed at two different stirring speeds (40 and 80 rpm), totaling six experimental conditions. The stirring speed and the impeller that resulted in the best combination was used in work of the feed strategy . The reactors were operated at room temperature at four different feed strategies (fed batch during 25%, 50% and 75% of the cycle, and conventional fed-batch). The results allowed conclude that: in the AnSBBR increasing the stirring speed from 40 rpm to 80 rpm showed to improve mass transfer, with consequent increase in substrate consumption; in the ASBR increasing the stirring speed from 40 rpm to 80 rpm showed desestabilization in system, because of the disruption caused in the granules witth greater agitation; operation with the helix impeller showed some advantages over the turbine impellers, such as: improved efficiency in solids removal, higher value of the first order kinetic constant and higher alkalinity production; both for the ASBR as for the ASBBR the best performance in wastewater treatment was obtained when the reactors were operated at conventional batch, fed-batch during 50% and 75% of the cycle; no significant difference in performance was observed among these three conditions. Despite poor performance of the conventional fed-batch and fed-batch during 25% of the cycle compared to the other conditions, both these conditions presented operational stability. Hence, the anaerobic sequencing batch reactors presented operational flexibility as far as feed strategy is concerned.

A Cianobactéria Spirulina platensis representa uma fonte de proteínas e ácidos graxos que a tornam importante como suplemento alimentar. A fonte de nitrogênio é um nutriente que exerce influência em seu metabolismo. Neste trabalho, observou-se o crescimento de S. platensis e a composição da biomassa obtida, com a utilização de cloreto de amônio como fonte de nitrogênio por processo descontínuo alimentado. Com a utilização de planejamento fatorial, foi realizado o estudo do tempo de alimentação do cloreto de amônio e da intensidade luminosa no cultivo da S. platensis. Os resultados foram avaliados com auxílio da metodologia de superfície de resposta. Menores teores de proteínas e lipídios na biomassa final foram encontrados nos cultivos submetidos a maiores intensidades luminosas. A condição ótima calculada, obtida pela análise estatística, para a obtenção da concentração celular máxima (Xm) e fator de conversão de nitrogênio em células (YX/N) foi encontrada no cultivo sob intensidade luminosa de 13 klux e tempo de alimentação de 17,2 dias. Nessas condições foram obtidos Xm igual 1771 ± 2,3 mg/L e YX/N igual a 5,7 ± 0,17 mg/mg, 3,4% e 4,0% menores que os valores máximos estimados pelo modelo matemático, respectivamente. Maiores produtividades foram obtidas nos cultivos submetidos a maiores intensidades luminosas e menores tempos de alimentação. / Cyanobacterium Spirulina platensis represents a protein and fatty acid source that becomes it important as food supplement. The nitrogen source is a nutrient that influences in its metabolism. In this work, it was observed the S. platensis growth and biomass composition using ammonium chloride as nitrogen source in fed-batch process. Using factorial experimental design, it was carried out the study of the ammonium chloride feeding time and light intensity in the S. platensis culture. The results were evaluated by response surface methodology (RSM). Lower protein and lipids contents were found in cell cultures cultivated at higher light intensity. The predictive optimal condition, obtained by statistic analysis, for maximum cellular concentration (Xm) and nitrogen-cell conversion factor (YX/N) was obtained in the culture grown at 13 klux and feeding time of 17.2 days. In these conditions, Xm of 1771 ± 2.3 mg/L and YX/N of 5.7 ± 0.17 mg/mg were obtained. These values are 3.4 % and 4.0 % lower than that ones predicted by mathematical model, respectively. Higher productivities were observed in the culture grown at higher intensity light and lower feeding time.