El origen de la vida en la Tierra es una de las preguntas más difíciles presentadas a la ciencia. En los últimos 60 años, ha habido un progreso considerable en entender cómo moléculas relativamente sencillas, que son relevantes para la vida, pueden ser generadas espontáneamente o pueden llegar a la Tierra desde el espacio. Además, los análisis de la evolución de la historia de ácidos nucleicos, los cuales almacenan la información genética, apuntan a un ancestro común universal ya extinto. Los estudios del origen de la vida ofrecen muchas pistas que apuntan hacia un origen común, quizás no solo en el Tierra sino también en algún otro punto del sistema solar. Debido al largo tiempo transcurrido desde que la Tierra empezó a albergar vida, las pistas más antiguas de los primeros organismos se han perdido. Es muy poco probable encontrar exactamente cómo fue este primer organismo. Sin embargo, en los últimos años la biología sintética ha logrado progresar mucho en la modificación de biomoléculas, en particular, los ácidos nucleicos. Es posible que pronto podamos construir y comprender un sistema minimalista en el cual las moléculas puedan copiarse a sí mismas dentro de una célula rudimentaria. El estudio de un sistema así podría permitirnos develar el origen de los primeros organismos. / The origin of life on Earth is one of the most challenging questions in science. In the last 60 years, considerable progress has been made in understanding how simple molecules relevant to life can be generated spontaneously or are known to arrive to Earth from space. Additionally, analysis of the evolution history of nucleic acids, which are the repository of genetic information, points to a now extinct, universal common ancestor for all life on Earth. The studies of the origin of life offer many clues towards a common origin, perhaps not just on Earth but somewhere else in the solar system. However due to the length of time that the Earth has harbored life, the oldest clues of the first organisms are mostly gone. It is unlikely to find exactly what this first organism was like. Nevertheless, in the last few years, synthetic biology has made remarkable progress at modifying biomolecules, particularly nucleic acids. It is possible that soon we will be able to construct and understand a minimalistic system in which molecules can copy themselves in a protocell. The study of such systems could shed light into the origin of the first organisms.

OligossacarÃdeos prebiÃticos sÃo carboidratos capazes de chegar ao intestino grosso onde sÃo metabolizados pelas bidifidobactÃrias e lactobacilos ali presentes estimulando o seu crescimento. A importÃncia destes microrganismos està associada a sua relaÃÃo com a melhoria da intolerÃncia à lactose, melhora da funÃÃo intestinal, melhoria do sistema imunolÃgico, reduÃÃo de enzimas mutagÃnicas e sÃntese de vitaminas do complexo B. A enzima dextrana-sacarase pode ser facilmente obtida a partir da fermentaÃÃo do Leuconostoc mesenteroides em meio contendo sacarose como fonte de carbono. Esta enzima catalisa a formaÃÃo de dextrana em meio contendo sacarose como Ãnico substrato. Quando um aceptor està presente no meio de cultura, parte das unidades de glicose da sacarose sÃo desviadas da sÃntese de dextrana formando oligossacarÃdeos. A utilizaÃÃo do suco de caju, rico em glicose e frutose, visa o aproveitamento de excedentes agrÃcolas, reduzindo assim o custo do processo final. Este trabalho teve por objetivo estudar a sÃntese de oligossacarÃdeos prebiÃticos a partir da fermentaÃÃo de duas linhagens de Leuconostoc mesenteroides; B512F e B742, ambas nÃo patogÃnicas e seguras do ponto de vista alimentar. Com base nos resultados obtidos pode-se concluir que o processo fermentativo utilizando o suco de caju como substrato apresentou bons resultados, principalmente no que se refere ao crescimento microbiano, produÃÃo da enzima dextrana-sacarase e crescimento de Lactobacillus sendo sua utilizaÃÃo, portanto viÃvel. / Prebiotic oligosaccharides are carbohydrates able to reach the large intestine being metabolizated by bidifidobacterium and lactobacillus and stimulating their growth. The importance of these microorganisms is related with its improvement of the intolerance to the lactose, improvement of the intestinal function and the imunologic system, mutagenic enzyme reduction and vitamin synthesis of the complex B. The enzyme dextransucrase can be easily obtained through the fermentation of Leuconostoc mesenteroides in a medium containing sucrose as carbon source. This enzyme catalyzes the formation of dextran in a medium containing sucrose as the only substrate. When an acceptor is present in the culture medium, part of the glucose moieties from sucrose are deviated from the dextran synthesis forming prebiotic oligosaccharides. The use of the cashew juice, rich in glucose and fructose, aims to the use of an agriculture excess, reducing the cost of the final process. This work had as objective the study of synthesis of prebiotic oligosaccharides from the fermentation of Leuconostoc mesenteroides, B512F and B742, both non pathogenic and safe from the alimentary point of view. Based on the obtained results it can be concluded that the fermentative process using the cashew juice as substratum presented good results, mainly for the microbial growth, production of the enzyme dextransucrase and growth of Lactobacillus being its use, therefore viable.

Made available in DSpace on 2017-07-10T17:48:17Z (GMT). No. of bitstreams: 1 Eder_Morschbacher.pdf: 604897 bytes, checksum: 185b7a10312912e21907fcdb57556daf (MD5) Previous issue date: 2009-05-25 / This present study aimed to evaluate the use of prebiotic mannanoligosaccharide (Bio-Mos®) during the sexual reversion to larvae of Nile tilapia. The study was realized in the Laboratory of Aquaculture of the Western Parana State University (Unioeste). Onethousand nd eighty larvae of Nile tilapia with three days old and initial average weight of 10.9 ± 1.2 mg were used. The larvae were distributed in 36 aquariums with 30 liters of usable volume each, in a completely randomized experimental design with six treatments and six replications. The treatments consisted of five levels, 0.2%, 0.4%, 0.6%, 0.8% and 1% for inclusion of Bio-Mos® and a control without the inclusion.The ad libitum feeding was carried out six times a day with diet formulated to obtain 38.6% of digestible protein, 3,500 kcal of digestible energy and 60 mg/kg of hormone masculine 17-α- methyltestosterone, keeping them isocaloric, isonitrogenous and isophosphoric. Aquariums were cleaned two times a day for withdrawal of surplus of feed and feces, and water renewal. The temperature was measured daily in the early morning and late afternoon. Dissolved oxygen, pH and conductivity were measured weekly. At the end of 30 days of reared period the fish were weighed and measured individually to obtain the zootechnical parameters as to final average weight, length, final biomass, survival, specific growth, condition factor and homogeneity of the lots. Ten fish from each replicate were preserved in formalin (10%) for later determination of sex ratio. The water quality parameters such as temperature, dissolved oxygen, pH and conductivity ranged from 24.76 to 26.16 °C, 5.7 to 5.85 mg/L, 7.32 to 7.65 and 87.67 to 111.33 μS/cm, respectively. The values of productive performance did not differ significantly (P>0.05). The values of final average weight, length, survival, specific growth and condition factor were 620 mg, 32.62 mm, 91.85%, 13.34%/day and 1.31, respectively. The effectiveness of sex reversal was 100% and there was not difference (P>0.05) in uniformity of lots of fish fed with different levels of inclusion of prebiotic in the ration. The average values of dry matter, ash, ether extract and crude protein from carcasses of fingerlings ranged from 22.93 to 28.45%, 11.80 to 13.61%, 23.67 to 29.97% and 60, 64 to 64.34%, respectively, but did not differ significantly (P>0.05) between the levels of prebiotic studied. The inclusion up to 1.0% Bio-Mos® did not affect the parameters of performance, sex ratio, survival, uniformity of lots and chemical composition of carcass of Nile tilapia during the sexual reversion. / O presente estudo teve como objetivo avaliar a utilização do prebiótico mananoligossacarídeo (Bio-Mos®) durante a fase de reversão sexual de tilápia do Nilo. O estudo foi realizado no Laboratório de Aquicultura da Universidade Estadual do Oeste do Paraná (Unioeste). Foram utilizadas 1.080 larvas de tilápia do Nilo com três dias de idade e peso médio inicial de 10,9 ± 1,2 mg. As larvas foram distribuídas em 36 aquários de 30 litros de volume útil cada, em um delineamento experimental completamente casualizado com seis tratamentos e seis repetições. Os tratamentos foram constituídos de cinco níveis, 0,2%, 0,4%, 0,6%, 0,8% e 1,0% de inclusão de Bio-Mos® e um tratamento controle. A alimentação foi realizada ad libitum seis vezes ao dia com ração formulada para se obter 38,6% de proteína digestível, 3.500 kcal de energia digestível e 60 mg/kg de hormônio masculinizante 17-α-metiltestosterona, mantendo-as isocalóricas, isoprotéicas e isofosfóricas. Os aquários foram sifonados duas vezes ao dia para retirada das sobras de ração e fezes e para renovação da água. A temperatura foi aferida diariamente no início da manhã e final da tarde. Oxigênio dissolvido, pH e condutividade foram mensurados semanalmente. Ao final de 30 dias de cultivo os peixes foram pesados e medidos individualmente para se obter os parâmetros zootécnicos de peso médio final, comprimento, biomassa final, sobrevivência, crescimento específico, fator de condição e uniformidade dos lotes. Dez peixes de cada repetição foram conservados em formalina (10%) para posterior determinação da proporção sexual. Os parâmetros de qualidade de água como a temperatura, oxigênio dissolvido, pH e condutividade variaram entre 24,76 a 26,16 ºC, 5,7 a 5,85 mg/L, 7,32 a 7,65 e 87,67 a 111,33 μS/cm, respectivamente. Os valores de desempenho zootécnico não diferiram significativamente (P>0,05). Os valores médios finais de peso, comprimento, sobrevivência, crescimento específico e fator de condição foram, 620 mg e 32,62 mm, 91,85%, 13,34%/dia e 1,31, respectivamente. A efetividade da reversão sexual foi de 100% e não houve diferença (P>0,05) na uniformidade dos lotes dos peixes alimentados com diferentes níveis de inclusão de prebiótico na ração. Os valores médios de matéria seca, matéria mineral, extrato etéreo e proteína bruta das carcaças dos alevinos variam de 22,93 a 28,45%, 11,80 a 13,61%, 23,67 a 29,97% e 60,64 a 64,34%, respectivamente, porém não diferiram significativamente (P>0,05) entre os níveis de prebióticos estudados. A inclusão até 1,0% de Bio-Mos® não afetou os parâmetros de desempenho, proporção sexual, sobrevivência, uniformidade dos lotes e composição química da carcaça de tilápia do Nilo durante a fase de reversão sexual

Les probiotiques sont des microorganismes vivants qui, lorsqu’ils sont ingérés en quantité adéquate, peuvent exercer des propriétés bénéfiques sur la santé de l’hôte. Les souches de Bacillus utilisées en tant que probiotiques ne sont pas colonisatrices du tractus intestinal, mais sont des résidents transitoires du microbiote. Ce travail fait l’investigation in vitro de l’association, qualifiée de synbiotique, entre une souche probiotique de Bacillus subtilis et une source carbonée prébiotique, composé alimentaire peu digéré par les enzymes intestinales mais utilisable par les bactéries dans l’intestin. L’étude de cette association met en évidence la capacité de la souche à utiliser les isomaltooligosaccharides (IMOS) prébiotiques comme unique substrat carboné. L’effet positif de ce substrat sur la tolérance à la bile de la souche a été démontré in vitro. Les résultats d’une analyse protéomique faisant l’étude des enzymes clés impliquées dans le métabolisme des IMOS, ainsi que d’autres biomarqueurs d’intérêt probiotique, sont en cours d’exploitation. Ce travail préliminaire d’investigation de l’association synbiotique entre les IMOS prébiotiques et la souche probiotique B. subtilis, aboutira à des essais in vivo. Les effets bénéfiques des probiotiques du genre Bacillus, notamment au niveau de la modulation du système immunitaire, résultent de l’interaction entre les molécules de la surface bactérienne et les cellules de l’intestin. Les mécanismes moléculaires à l’origine de l’immunomodulation sont mal connus, alors que leur compréhension est nécessaire à l’optimisation de l’utilisation du probiotique. Un deuxième volet de ce travail concerne la comparaison des structures d’entités moléculaires de surface de trois Bacilli probiotiques, les acides lipotéichoïques (LTAs), et leurs activités immunologiques respectives. Une étude structurale des LTAs par des méthodes biochimiques et par RMN a permis de mettre en évidence la diversité structurale au sein du même genre Bacillus. Le rôle clé de la D-alanine dans l’activité biologique de ces antigènes bactériens a été démontré. / Probiotics are live microorganisms, which when administered in adequate amounts confer a health benefit on the host. Bacillus probiotic strains are not able to colonize the gut, and are considered as transient residents of the microbiota. Prebiotic are non-digestible food ingredients that could stimulate growth of bacteria in the gut. This work investigates the in vitro effect of a prebiotic isomaltooligosaccharide (IMOS) on the growth of a probiotic strain Bacillus subtilis. This study highlights the ability of the strain to use IMOS as unique carbon source. A comparative proteomic analysis investigates the main enzymes implicated in the prebiotic metabolism, and biomarkers possibly involved in probiotic effects. This preliminary work, which studies the synbiotic association between a probiotic and a prebiotic, will lead to in vivo assays. Beneficial effects of probiotic Bacilli, mainly modulation of intestinal immune system, result from interaction between bacterial cell-wall molecules and intestinal cells. The molecular origin of immunomodulatory mechanisms are poorly understood, while understanding is needed to optimize the use of probiotics. A second part of this work consists in comparing the structure of a molecular cell-wall component named lipoteichoic acids (LTA) from three Bacillus probiotic, a molecular cell-wall component of Gram positive bacteria, and their immunological activity. A structural study, using biochemical determinations and NMR spectroscopic analysis, highlights the structural diversity between LTAs from different Bacillus species. The key role of D-alanine substituents in the biological activity of these bacterial antigens has been demonstrated.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the current work it was developed a technology for the production of probiotic microparticles where three formulations containing Lactobacillus acidophilus La-14 were prepared by external ionic gelation, using sodium alginate as the primary coating material, also adding to the capsule resistant starch (Hi-maize), and chitosan. The aim of this study was to evaluate the microcapsules in wet and dry form, analyzing the resistance of microorganisms to the drying process by freeze-drying, storage at room temperature (25° C), cooling (7° C), and freezing (-18° C) for 135 days for the wet microcapsules and 60 days for lyophilized microcapsules, and "in vitro" tolerance when inoculated in solutions of pHs simulating the human gastrointestinal tract, besides the morphology of the microcapsules by optical and electronical microscopy of scanning, as well as the average diameter. After the drying by freeze-drying there was significant logarithmic reduction for all treatments, indicating that for a better viability it is necessary the addition of a cryoprotectant agent. Regarding the viability assessed by the storage time for the wet microcapsules, the room temperature kept for 135 days the viability of the microcapsules, and the addition of prebiotic and chitosan in the capsule and improved significantly the viability. For freezing temperatures and cooling also showed better results for the treatments that contained the composition the addition of prebiotic and chitosan. Analyzing the lyophilized microcapsules, the temperature was more harmful to the viability of the microorganisms, and the temperature of refrigeration and freezing was viable for 60 days for the treatments with addition of prebiotic and chitosan. Regarding to the tests in vitro simulating the gastrointestinal conditions, both wet and lyophilized microcapsules were resistant to acid pH increasing their viability as increasing pH, whereas to the wet microcapsules the number of viable cells for all treatments was 106 log UFC/g, being within the required standards so that benefits occur exercised by the probiotics. In relation to the diameter, the wet microparticles had diameters less than 70.37 μm for both treatments, while lyophilized exhibited larger diameters in function of hydration and swelling. The microparticles developed in this study may be a viable alternative for obtaining a probiotic food product be incorporated into half, to allow a higher survival of the bacteria. / No presente trabalho foi desenvolvida uma tecnologia para a produção de micropartículas probióticas onde três formulações contendo Lactobacillus acidophilus La-14 foram elaboradas por gelificação iônica externa, utilizando alginato de sódio como principal material de revestimento, adicionando-se também à cápsula amido resistente (Hi-maize) e quitosana. O objetivo deste estudo foi avaliar as microcápsulas na forma úmida e liofilizada, analisando a resistência dos microrganismos ao processo de secagem por liofilização, de estocagem a temperatura ambiente (25° C), de refrigeração (7° C), e de congelamento (-18° C) por 135 dias para as microcápsulas úmidas e 60 dias para as microcápsulas liofilizadas, e a tolerância in vitro quando inoculados em soluções de pHs simulando o trato gastrointestinal humano, além da morfologia das microcápsulas por microscopia ótica e eletrônica de varredura, bem como o diâmetro médio. Após a secagem por liofilização houve redução logarítmica significativa para todos os tratamentos, indicando que para uma melhor viabilidade é necessário à adição de um agente crioprotetor na formulação das microcápsulas. Em relação à viabilidade avaliada pelo tempo de estocagem para as microcápsulas úmidas, a temperatura ambiente manteve durante 135 dias a viabilidade das microcápsulas, sendo que a adição de prebiótico e quitosana na cápsula melhorou positivamente a viabilidade. Para as temperaturas de congelamento e refrigeração também houve melhores resultados para os tratamentos que continham na composição a adição de prebiótico e quitosana. Analisando as microcápsulas liofilizadas, a temperatura ambiente foi a mais nociva para a viabilidade dos microrganismos, e as temperaturas de refrigeração e congelamento foram viáveis por 60 dias para os tratamentos com adição de prebiótico e quitosana. Em relação aos testes in vitro simulando as condições gastrointestinais, tanto as microcápsulas úmidas como as liofilizadas foram resistentes ao pH ácido aumentando sua viabilidade conforme aumento do pH, sendo que para as microcápsulas úmidas o número de células viáveis para todos os tratamentos foi 106 log UFC/g, estando dentro dos padrões exigidos para que ocorram os benefícios exercidos pelos probióticos. Em relação ao diâmetro, as micropartículas úmidas apresentaram diâmetros inferiores a 70,37 μm para ambos os tratamentos, enquanto as liofilizadas apresentaram diâmetros maiores em função da hidratação e intumescimento. As micropartículas desenvolvidas neste estudo podem ser um meio alternativo e viável para a obtenção de um produto probiótico a ser incorporado em alimentos, de modo a permitir uma maior sobrevivência das bactérias.

The experiment was conducted at the Laboratory of Poultry (LAVIC) of the Department of Animal Science at Federal University of Santa Maria - RS, from November of 2003 to January of 2004 aiming to evaluate the use of prebiotics, organic acids (acidifiers), enzymes and garlic (phytotherapeutic) as alternative growth promoters, instead of the conventionals (antibiotics) commonly used in broilers feed. The amount of 480 males, day old, Cobb chicks were used, which were submitted to six experimental treatments: T1= Basic Diet (BD) without any growth promoters; T2= BD with 0.1% of garlic in powder; T3= BD with 0.2 % of garlic in powder; T4= BD with antibiotics (Zinc Bacitracina (10 g/ton) and Olaquindox (70 g/ton);T5= BD with prebiotic (mananoligossacarídeos(MOS)) and acidifier (fórmic acids (50%) + propionic acids (50%) and T6= BD whit prebiotic (mananoligossacarídeos(MOS)) and enzymes. The amount of prebiotic, acidifier and enzymes used were rated by the technical advise of the commercial products used. Twenty four experimental boxes of the 1.5 X1.5m, with 20 fowls each were used, with four replicates by treatment in a completely randomized design. The fowls were sheltered on reutilized bed wood shavings, in a mansory shed raised with animal feed based on corn and soy bean meal, ad libitum , isonutritives and divided in three phases: initial (1-21 days) bearing 22% Crude Protein (CP) and 3050 Kcal ME/Kg, growth (22-35 days) with 20% CP and 3100 Kcal ME/Kg, final (36- 43 days) with 18.5 % of CP and 3150 Kcal ME/Kg. The treatments did not show any statistic difference for the parameters: weigh gain (WG) and production factor (PF). There wasn t a significant effect on the feed intake (FI), in the phases of 1-21 and 22-35 days of live, but in the phase of 36-43 days there was a significant effect (P<005), with difference only between the treatments without growth promoters (T1) and the treatments with garlic (T2 and T3), but they did not diverge significantly from the others. Introductory the period of 1-43 days, to come different significant (P<0.05), at the feed intake (FI), of the fowls the treatments without growth promoters (T1) and with antibiotics (T4), but they did not diverge significantly from the others. The feed conversion (FC), did not differ statiscally (P>0.05) in the phases of 1-21 and 36-43 days of live the fowls. The phase of 22-35 days to come different significant (P<0.05), where the fowls submitted to treatment with antibiotics (T4) and with prebiotics + acidifier (T5), showed better feed conversion (FC) and it was statistically relevant (P<0.05), when compared with fowls of the treatment prebiotics + enzymes (T6), but the treatment with prebiotics + acidifier (T5), was not differences between them (P>0.05). In the period of 1-43 days, the fowls submitted to treatment with antibiotics (T4) showed better feed conversion (FC) and it was statistically relevant (P<0.05), when compared with fowls of the control treatments (T1) and prebiotics + enzymes (T6), but there were no differences between them (P>0.05). The feed conversion (FC) of the fowls submitted to the other treatments (T2, T3 and T5) did not differ statiscally (P>0.05). The results according to the intestinal morphology and carcass yield did not show significant effects (P>0.05) between the different growth promoters tested. Based on the results obtained, taking in to account the conditions of what the experiment was conducted, it was concluded that the alternative growth promoters tested did not affect negatively the characteristics of the intestinal morphology of the broilers validating them as substitutes to the conventional promoters. / O experimento foi conduzido no Laboratório de Avicultura (LAVIC) do Departamento de Zootecnia da Universidade Federal de Santa Maria - RS, no período de novembro de 2003 a janeiro de 2004, com o objetivo de avaliar o uso de prebióticos, ácidos orgânicos (acidificantes), enzimas e alho (fitoterápico) como promotores de crescimento alternativos, em substituição aos convencionais (antibióticos), usualmente utilizados nas dietas para frangos de corte. Foram usados 480 pintos de corte, machos, com um dia de vida, da linhagem Cobb 500, os quais foram submetidos a seis tratamentos experimentais: T1= Dieta Base (DB) sem adição de promotor de crescimento; T2= DB com 0,1% de alho em pó; T3= DB com 0,2% de alho em pó; T4= DB com Bacitracina de Zinco (10g/ton) e Olaquindox (70g/ton); T5= DB com prebiótico (mananoligossacarídeos (MOS)) e acidificante orgânico (ácido fórmico (50%) + ácido propiônico (50%)) e T6= DB com prebiótico (mananoligossacarídeos (MOS)) e complexo enzimático (proteases, amilases e celulases). Os níveis utilizados de prebióticos, acidificantes e enzimas foram obtidos através das recomendações técnicas dos produtos comerciais usados. Foram usados 24 boxes experimentais de 1,5 X 1,5 m, contendo 20 aves cada, com quatro repetições por tratamento, distribuídos num delineamento experimental inteiramente casualizado. As aves foram alojadas em cama de maravalha reutilizada, num galpão de alvenaria, alimentadas com ração isonutritiva , à base de milho e farelo de soja, fornecida à vontade e dividida em três fases: inicial (1-21 dias), contendo 22% PB e 3050 Kcal de EM/Kg, crescimento (22-35 dias) com 20% PB e 3100 Kcal EM/Kg e final (36-43 dias) com 18,5% de PB e 3150 Kcal EM/Kg. Os tratamentos não apresentaram diferença estatística nos parâmetros de: ganho de peso (GP) e fator de produção (FP). Para o consumo de ração (CR), não se observaram diferenças significativas nas fases de 1-21 e 22-35 dias, mas na fase de 36-43 dias verificou-se efeito significativo (P<0,05), com diferença apenas entre os tratamentos sem adição de promotores de crescimento (T1) e os tratamentos com adição de alho (T2 e T3), estes com a adição de alho não diferiram significativamente dos demais tratamentos (T4,T5 e T6). Considerando o período total (1-43 dias), ocorreu diferença significativa (P<0,05), no consumo de ração entre as aves dos tratamentos sem adição de promotores de crescimento (T1) e com a adição de antibióticos (T4), nos demais tratamentos não houve efeito significativo em relação ao consumo de ração. A conversão alimentar (CA) não foi afetada nas fases de 1-21 e 36-43 dias de idade das aves. Na fase de 22-35 dias verificou-se efeito significativo, onde as aves com antibióticos convencionais (T4) e com MOS + Acidificantes (T5) obtiveram a melhor conversão alimentar, porém sem diferir significativamente entre ambas. Entretanto, as aves do tratamento T5 foram mais eficientes, diferindo significativamente (P<0,05) em relação as aves do T6 (MOS + enzimas), mas não diferiram significativamente das aves dos tratamentos ( T1, T2 e T3 ). Sendo que no período de 1-43 dias, as aves submetidas ao tratamento com antibióticos (T4) apresentaram melhor conversão alimentar (CA) estatisticamente significativa (P<0,05), quando comparadas as aves dos tratamentos sem adição de promotores de crescimento (T1) e prebiótico + complexo enzimático (T6), sendo que estes não diferiram entre si (P>0,05). A conversão alimentar das aves submetidas aos demais tratamentos (T2, T3 e T5) não diferiram entre si (P>0,05). Os resultados referentes à altura de vilos intestinais e rendimento de carcaça não apresentaram efeitos significativos (P>0,05) entre os diferentes promotores de crescimento avaliados. Com base nos resultados obtidos, levando em consideração as condições em que o experimento foi conduzido, conclui-se que os promotores de crescimento alternativos testados são uma opção aos antibióticos. Os promotores de crescimento alternativos testados não afetaram negativamente as características de carcaça e morfometria intestinal dos frangos de corte.

L'élongation de peptides ou d'acides aminés N-acylés via une activation C-terminale (par exemple par un carbodiimide) est délaissée en synthèse peptidique à cause de l'épimérisation rapide des intermédiaires 5(4H)- oxazolones issus de cette activation. Au contraire, cela représente une voie prometteuse en chimie prébiotique où les substrats sont a priori racémiques, et où une étape d'épimérisation peut favoriser un scénario protométabolique / autocatalytique d'émergence de l'homochiralité. Partant de travaux récents qui montraient clairement que l'activation C-terminale de peptides en milieu aqueux procède surtout via une 5(4H)-oxazolone, nous avons étudié la stéréosélectivité des couplages peptidiques qui en résultent dans des conditions prébiotiques plausibles (milieu aqueux dilué à pH faiblement acide). Notre étude sur des peptides modèles (préparés par des méthodes classiques de synthèse peptidique et comportant un résidu tyrosine qui facilite l'analyse par HPLC) visait à évaluer l'effet de la configuration des résidus voisins ou des nucléophiles ; elle a montré la formation d'excès diastéréomériques significatifs en faveur de dérivés homochiraux, sous l'influence prépondérante de la chiralité du nucléophile.Nous avons ensuite étudié la réactivité de dipeptides libres dans les mêmes conditions, pour évaluer la formation compétitive de dicétopipérazine (DCP), qui est susceptible de bloquer l'élongation au-delà du dipeptide. La formation de DCP est prépondérante à partir de dipeptides faiblement activés, mais n'a pas lieu en présence d'agents d'activation de potentiel élevé (e.g. l'EDC) qui favorisent la formation plus rapide d'oxazolone et permet l'élongation peptidique ; ces derniers résultats soulignent l'importance prébiotique de potentiels d'activation élevés. / The elongation of peptides or N-acylamino acids through C-terminus activation is usually avoided in peptide synthesis, because of the fast epimerisation of 5(4H)-oxazolones intermediates resulting form such activation. Conversely, it represents a promising perspective in prebiotic chemistry where substrates are assumed to be racemic, and where an epimerisation step may favour a protometabolic / autocatalytic scenario of emergence of homochirality.Based on recent works which clearly showed that the C-terminus activation of peptides in aqueous media mostly proceed through a 5(4H)-oxazolone, we investigated the stereoselectivity of peptide couplings resulting therefrom under plausible prebiotic conditions (dilute aqueous medium at weakly acidic pH). Our study on model peptides (prepared by classical peptide synthesis methods, and bearing a tyrosine residue which facilitates HPLC analysis), aimed at assessing the influence of the configuration of the vicinal peptide residue or of the nucleophile; we observed significant diastereomeric excesses in favour of homochiral sequences, under the preponderant influence of the chirality of the nucleophile.Then we investigated the reactivity of free dipeptides under the same conditions, to assess the extent of diketopiperazine (DKP) formation, which may prevent further elongation beyond dipeptides. While DCP formation is preponderant from weakly activated peptides, id does not occur in the presence of high potential activation agents (e.g. EDC), which favour the faster formation of oxazolone and allow subsequent peptide eleongation; these last results undeline the prebiotic importance of high activation potentials.

Les surfaces minérales auraient eu un rôle important dans la chimie prébiotique, grace à leurs propriétés catalytiques, tel que le champ électrique de surface. Dans ce travail, le champ électrique à la surface de MgO et à l'interface MgO/eau est étudié en utilisant la dynamique moléculaire ab-initio. Ce champ est local et intense, de l'ordre de V/Å, même lorque la surface est recouverte d'eau. Une réaction prébiotique modèle est ensuite étudiée, à la surface de MgO : une molécule de monoxide de carbone et une molécule d'eau, donnant une molécule d'acide formique. En utilisant la métadynamique, et sans connaissance des états de transition en amont, des chemins de réaction sont trouvés et leurs profils d 'énergie libre sont calculés à 5 kcal/mol près, avec l'aide d'un échantillonage dans l'espace des configurations par « umbrella sampling ». La présence de la surface minérale stabilise l'acide formique d'au moins 15 kcal/mol par-rapport au cas en solution sans surface. La même réaction a aussi été étudiée sous un champ électrique homogène de 0,3 V/Å, afin de comparer l'effet de ce champ à l'effet du champ de surface sur le paysage d'énergie libre. Le champ homogène stabilise aussi le produit, et l'acide formique se trouve orienté dans la direction du champ électrique de surface ainsi que dans le champ électrique homogène. Ce travail montre que les conditions proche d'une surface minérale, même sans adsorption directe, peut modifier considerablement le paysage d'énergie libre de réactions chimiques, ce qui pourrait avoir de l'importance en chimie prébiotique. / Mineral surfaces are thought to be of importance to prebiotic chemistry due to their catalytic properties, which include a strong electric field at the interface. In this work the electric field at the surface of MgO and at the interface of MgO and water is studied through ab-initio molecular dynamics. The spontaneous electric field from the surface is found to be local and intense, on the order of V/Å, even when completely covered with water. A model prebiotic reaction is then studied on the model MgO surface : carbon monoxide and water yielding formic acid. Using metadynamics, reaction pathways were found with no a priori knowledge of the transition states, and umbrella sampling was then used to compute free energy landscapes to about 5 kcal/mol accuracy. The presence of the mineral surface was found to stabilise formic acid by at least 15 kcal/mol compared to the bulk case. The reaction was also studied in solution with an applied electric field of 0.3 V/Å, in order to estimate to impact of the surface electric field on the free energy landscape. The field is also found to stabilise the product, and formic acid is found to have a preferred orientation in the direction of both the applied electric field and the surface electric field. This work shows that near surface conditions (without direct adsorption) can significantly alter the free energy landscapes of chemical reactions, in a way which could be of importance for prebiotic chemistry.

Le développement d’outils de détection in situ (IDT) est indispensable pour rapporter entemps réel la présence d’une signature moléculaire spécifique. L’efficacité d’un IDT estliée à son affinité, à sa spécificité, mais aussi à son potentiel à opérer dans des conditionsimposées par le contexte d’application. Parmi les contraintes imposées, la variation detempérature, le pH et la présence de solvant d’extraction. Le but du projet est dedévelopper des aptamères capables d’opérer en présence de solvant organique ; à ceteffet, nous avons opté pour une sélection en présence de méthanol. La limitation decette stratégie est principalement liée à la nature chimique des acides nucléiques. Parconséquent, nous avons choisi d’utiliser une banque ADN incorporant le (5-(octa1,7-diynyl)-2’-deoxyuridine) dDOTP, au lieu du dTTP. Notre stratégie expérimentale aabouti à la sélection d’un aptamère qui lie spécifiquement l’adénine en présence de 25 %de méthanol. Nous avons montré que les dDOTP sont essentiels à l’interaction del’aptamère avec l’adénine ; l’aptamère sélectionné comporte un motif riche en G partagéavec l’aptamère anti-adénosine, cependant, l’aptamère sélectionné dans le méthanolcomporte un motif structural indispensable à l’interaction avec la cible en présence deméthanol. Par ailleurs, nous avons montré que l’aptamère sélectionné pourraitfonctionner comme un module de reconnaissance spécifique d’un biocapteur. / Development of in situ detection tools (IDT) is required for specific real time monitoringof chemical species. Efficient IDT is not only related to its affinity and ability todiscriminate between molecular variants, but moreover it must be adapted for operatingunder conditions imposed by the context of application. Among others, hightemperature, pH variation and presence of organic solvents may be mentioned. The aimof our project is to develop an aptamer operating in the presence of organic solvents. Forthis purpose, we opted for selection in presence of methanol. Limitations of this strategyare adaptability of SELEX technology and chemical diversity of nucleic acids. For thispurpose, we used library incorporating (5-(octa1,7-diynyl)-2’-deoxyuridine) dDOTPinstead of conventional thymine nucleotide. Our experimental strategy led to theselection of an aptamer that specifically recognises adenine in the presence of 25 % ofmethanol. dDOTP nucleotides are essential for adenine recognition; the selectedaptamer shares a purine rich motif with a previously described adenosine aptamer, butdisplays a specific structure motif, essential for operating in the presence of methanol.Furthermore, the ability of truncated variants of the selected aptamer to form arecognition module of biosensor was assessed in this study.

O objetivo deste trabalho foi desenvolver e avaliar diferentes formulações de sorbets probióticos e simbióticos a base de polpa de juçara (Euterpe edulis), de modo a combinar os efeitos benéficos à saúde dos compostos fenólicos deste fruto com os benefícios dos probióticos e prebióticos. Para isso, foram utilizados os microrganismos L. acidophilus e L. paracasei e a fibra polidextrose, além da elaboração de uma amostra controle sem tais elementos para efeito de comparação. Primeiramente, a polpa de juçara pasteurizada utilizada na produção dos sorbets foi avaliada de acordo com suas características físico-químicas e seus compostos bioativos, tendo apresentado resultados adequados para o emprego na matriz alimentícia em questão. Em seguida, os sorbets foram caracterizados através de diversos parâmetros. Assim, a análise centesimal mostrou sorbets com alto índice de carboidratos e baixo valor calórico, enquanto os teores de sólidos solúveis apresentaram-se coerentes em todas as formulações analisadas. Os valores de overrun e densidade aparente relevaram que a incorporação de ar dos sorbets não foi tão elevada quanto de um sorvete lácteo, embora as amostras adicionadas de polidextrose - capaz de mimetizar as propriedades de corpo e espessamento da gordura - tenham obtido resultados mais próximos aos gelados tradicionais. Foram ainda mensurados os efeitos do armazenamento dos produtos a -18 °C durante 120 dias, através de avaliações de pH, coloração instrumental, estabilidade dos compostos fenólicos e antocianinas e viabilidade dos probióticos. O pH das amostras manteve-se constante durante todo o experimento, com valores entre 4,4 e 4,8, enquanto os parâmetros de coloração caracterizaram as amostras como vermelhas e apontaram tendência à perda de luminosidade. Já os polifenóis e antocianinas apresentaram teores elevados, decorrentes da adição da polpa de juçara, sem a ocorrência de degradação destes compostos ao longo da estocagem das amostras sob congelamento. As populações de ambos os microrganismos adicionados apresentaram-se estáveis em cerca de 8 log UFC/ g durante todo o período de armazenamento, o que corresponde a um resultado bastante satisfatório e superior ao recomendado pela legislação brasileira. Por outro lado, a sobrevivência in vitro de tais probióticos quando submetidos aos fluidos gastrointestinais não apresentou resultados adequados para a garantia da funcionalidade destes produtos, com queda de viabilidade superior a 4 ciclos logarítmicos. A aceitabilidade sensorial e intenção de compra apresentaram resultados positivos para todas as formulações, com maior aceitação das amostras probióticas em relação ao controle e menor interesse pelas amostras com adição de prebiótico. Tal resultado demonstra que a incorporação destas bactérias em sorbets de juçara é capaz de melhorar a qualidade do produto, enquanto a adição de polidextrose pode diminuir sua aceitabilidade nas condições empregadas. Em síntese, os sorbets elaborados apresentaram resultados satisfatórios, demonstrando a viabilidade na produção deste tipo de alimento funcional adicionado de probióticos, prebiótico e rico em polifenóis, sendo a combinação de tais elementos capaz de potencializar os efeitos benéficos destes compostos e trazer vantagens fundamentais à microbiota intestinal e à saúde de quem os consome. / This work aimed to develop and evaluate different formulations of probiotic and synbiotic jussara (Euterpe edulis) sorbets in order to combine the beneficial effects of the fenolic compounds of this fruit with the benefits of probiotics and prebiotics. For this, the microorganisms L. acidophilus and L. paracasei and the fiber polydextrose were used and a control sample without such elements was developed for comparison. First, the pasteurized jussara pulp used in the production of sorbets was evaluated according to its physicochemical characteristics and its bioactive compounds and the results obtained showed that it was appropriate for employment in the food matrix. Then, sorbets were characterized by various parameters. The centesimal composition showed high levels of carbohydrates and low caloric value, while the soluble solids content were consistent in all analyzed formulations. The overrun and apparent density values showed that the air incorporated into sorbets was not as high as a dairy ice cream, although the samples with polydextrose - able to mimic the body and thickening properties of fat - have obtained results closer to traditional ice cream. The effects of storage of the products at -18 ° C for 120 days were also measured by pH assessments, instrumental color, stability of phenolic compounds and anthocyanins and viability of probiotics. The pH of the samples remained constant throughout the experiment, with values between 4.4 and 4.8, while the color parameters characterized the samples as red and showed a tendency to lose brightness. The levels of polyphenols and anthocyanins were elevated as a result of the addition of jussara pulp, without degradation of these compounds during storage of samples under freezing. The populations of both added microorganisms were stable at about 8 log CFU/ g throughout the storage period, which is a very satisfactory result and better than the recommended by Brazilian legislation. On the other hand, in vitro survival of the probiotics through simulated gastrointestinal fluids did not present appropriate results to guarantee the functionality of these products, with decrease of viability higher than 4 log cycles. The sensory acceptability and purchase intent showed positive results for all formulations, with greater acceptance of probiotic samples compared to control and less interest in the samples with prebiotic. This result demonstrates that the incorporation of these bacteria in jussara sorbets is able to improve the quality of the product while the addition of polydextrose may decrease the acceptability in conditions employed. In short, sorbets showed satisfactory results, demonstrating the viability of production of functional food with addition of probiotics, prebiotics and rich in polyphenols. The combination of these elements can enhance the beneficial effects and bring fundamental benefits to intestinal microbiota and to health of those who consume them.