We present here the hypothesis of a possible relationship between metal atom clusters and the formation of organic molecules in the interstellar medium and on small bodies as a possible pathway to the origin of such molecules. Two distinct stages are díscussed: a) the possible formation and presence of atom clusters in space and on the primitive Earth, and b) the synthesis of interstellar and terrestrial prebiotic organic molecules, a process in which metalclusters could be the active catalysts. The confirmatíon of these suggestions might be very important in arder to explain the presence of extra-terrestrial organic molecules in the interstellar medium, small bodies and planetary systems, and therefore would have great relevance in cosmochemistry and in the current theories about the origins of life.

Orientador: Francisco Maugeri Filho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-17T10:47:55Z (GMT). No. of bitstreams: 1 Evangelista_SuzanaReis_M.pdf: 565991 bytes, checksum: 28528c122d66dfcdbbc44c47ce50c334 (MD5) Previous issue date: 2011 / Resumo: Existe, atualmente, uma busca pelo consumidor por alimentos que sejam ao mesmo tempo saudáveis e de qualidade. Com isso, diferentes produtos tem sido criados para atender essa demanda. O presente trabalho teve como objetivo estudar a fermentação e a vida-de-prateleira de bebida simbiótica a base de soja, avaliando a influência das concentrações de extrato hidrossolúvel de soja, de fruto-oligossacarídeos (FOS), dos micro-organismos Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus paracasei subsp. paracasei, Lactobacillus rhamnosus, e da temperatura, além de observar alterações no produto pela adição de sacarose e dos micro-organismos Streptococcus thermophilus e Lactobacillus delbrueckii subsp. bulgaricus. As análises realizadas foram: pH, sinérese, viscosidade aparente, contagem de colônias, velocidade especifica de crescimento (µx) e variação da contagem de células (_X). A fermentação foi realizada em fracos estáticos incubados em diferentes temperaturas, tendo a composição do meio e condições do processo definidas por um delineamento fatorial Placket & Burman. O estudo da vida-de-prateleira foi realizado em refrigeração (3-8 oC). Amostras foram retiradas em espaços predefinidos de tempo para as fermentações e nos tempos 0, 10, 20 e 30 dias, no estudo da vida-deprateleira. O extrato hidrossolúvel de soja se apresentou como um bom substrato para produção da bebida, porém na medida em que se aumenta sua concentração ocorre um aumento da sinérese, o mesmo fenômeno foi observado quanto à adição de FOS. Os probióticos ao final da fermentação tiveram contagem maior que 107 UFC/mL atendendo aos requisitos legais, e em sua maioria continuaram apresentando crescimento durante o período de estocagem, contribuindo para obtenção de um produto de qualidade. Temperaturas mais baixas foram melhores para o crescimento dos probióticos e viscosidade aparente do produto. A adição de sacarose provocou um menor consumo de FOS por parte dos probióticos, e a presença de Streptococcus thermophilus e Lactobacillus delbrueckii subsp. bulgaricus mostrou pouca variação no produto. Portanto a partir dos resultados obtidos no estudo da fermentação e vida-de-prateleira da bebida simbiótica a base de soja, pode-se concluir que para obtenção de um produto com maior qualidade ao final da fermentação e que conserve suas características durante a vida-de prateleira deve-se utilizar, de acordo com a faixa estudada, as seguintes condições de processo: temperatura mais baixa (em torno de 35oC), frutooligossacarídeos 3% (m/v) e sacarose 12% (m/v), que devem ser acrescentados ao final da fermentação, extrato hidrossolúvel de soja a 10% (m/v), e concentração dos probióticos de 5,5x106 UFC/mL, exceto para L. paracasei que deve ser de 1x106 UFC/mL / Abstract: Currently, there is a quest for foods that are both healthy and of good quality, so that different products have been designed to meet this demand. The present work aimed to study the fermentation and shelf-life of a soy-based symbiotic drink, assessing the influence of the concentrations of: soymilk, fructooligosaccharides (FOS), Bifidobacterium longum, Lactobacillus acidophilus, Lactobacillus paracasei subsp. paracasei, Lactobacillus rhamnosus, and of the temperature. Additionally, sucrose and the microorganisms Streptococcus thermophilus (ST) and Lactobacillus delbrueckii subsp. Bulgaricus (LB) were further added. The responses were: pH, syneresis, viscosity, cell count, specific growth rate (µx) and variation of cell count (_X). The fermentations were carried out in still flasks, incubated at different temperatures, at medium compositions and process conditions as defined by a Plackett & Burman factorial design. Samples were collected at predefined spaces of time for fermentation and for shelf-life at 0, 10, 20 and 30. It has been shown that the soymilk is a good substrate for the production of the beverage, but at higher concentrations leads to increased syneresis, the same phenomenon observed for addition of FOS. Probiotics at the end of fermentation had ideal concentration, and the most of them went on growing during the shelf-life storage period, helping to maintain the quality of the product. Lower temperatures were better for the probiotics growth and product viscosity. The addition of sucrose resulted in a lower consumption of FOS. On the other hand, the addition of ST and LB showed meaningless variation in the product. So, from the results obtained in the study of fermentation and shelf-life of symbiotic drink soybased, it can be concluded that to obtain a product with the highest quality at the end of fermentation and to retain its characteristics during shelf-life should be used, according to the range studied, the following process conditions: low temperature (around 35oC), FOS 3% and 12% sucrose, which must be appended to the end of fermentation, the aqueous extract of soybean 10% of probiotics and concentration of 5.5 x 106 CFU/mL, except for L. paracasei that should be of 1x106 CFU/mL / Mestrado / Mestre em Engenharia de Alimentos

Les réseaux de molécules interdépendantes sont depuis quelque temps considérés comme de potentiels candidats pour avoir amorcé la transition de la biologie à la chimie. Bien qu'ils aient été intensivement examinés en théorie, il n'existe toujours aucune preuve expérimentale pour confirmer ou infirmer leur supposé rôle crucial dans les origines de la vie. En particulier, il nous manque encore une démonstration empirique des trois ingrédients habituellement présentés comme requis pour l'évolution darwinienne: l'hérédité, la variation et la sélection. Un système qui posséderait les trois tout en étant couplé à un processus de réplication en compartiments serait théoriquement capable d’évoluer au sens darwinien du terme. Par exemple, cela a été montré théoriquement pour les Ensembles Collectivement Autocatalytiques (CAS pour Collectively Aucatalytic Sets en anglais) où chaque molécule de l'ensemble est formée catalytiquement par un autre membre de l'ensemble. Ici, nous utilisons le système de ribozyme Azoarcus, qui catalysent des réactions de recombinaisons, pour former expérimentalement des CASs structurellement divers afin d’explorer leurs propriétés évolutives. Dans ce système, les ribozymes peuvent catalyser la formation d'autres ribozymes à partir de fragments plus petits, présents dans l'environnement. Nous utilisons un dispositif de microfluidique en gouttes associé au séquençage haut-débit pour mener une étude à grande échelle sur des milliers de CASs Azoarcus. Nous développons une approche perturbative pour identifier les paramètres topologiques importants contrôlant les variations observées dans les CAS à la suite de perturbations de l’environnement, ici l'ajout d'une nouvelle espèce. Nous déterminons ensuite l’ensemble restreint de caractéristiques du réseau régissant la mémoire des conditions initiales dans les CASs Azoarcus, un prérequis pour l'hérédité, en utilisant un modèle théorique validé par des données expérimentales. Enfin, nous démontrons qu’il existe dans les CASs Azoarcus des processus cataboliques qui les rendent robustes aux perturbations des fragments qui composent leur substrat et donc plus pertinent d’un point de vue prébiotique. Ces résultats démontrent le rôle crucial des CASs à base d’ARN dans les origines de la vie et illustrent comment la structure de leur réseau peut être adaptée pour obtenir des CASs avec des propriétés intéressantes d’un point de vue évolutif, ouvrant la voie à une démonstration expérimentale de l'évolution darwinienne avec système purement moléculaire. / Networks of interdependent molecules are considered plausible candidates for initiating the transition from biology to chemistry. Though they have been intensively scrutinized theoretically, there is still no experimental evidence for confirming or denying their supposed crucial role in the origins of life. In particular, we are still lacking experimental proofs of any of the three ingredients usually presented as required for Darwinian evolution: heredity, variation and selection. A system that would possess the three while being coupled to some sort of encapsulated replication process would theoretically be able to undergo Darwinian evolution. As a matter of fact, this has been shown theoretically for Collectively Autocatalytic Sets (CAS) where each molecule of the set is catalytically formed by another member of the ensemble. Here we use the Azoarcus recombination ribozyme system to experimentally form structurally diverse CASs to explore their evolutionary properties. In this system, the ribozymes can catalyze the assembly of other ribozymes from smaller fragments, present in the food set. We first use a droplet microfluidics set-up coupled with next-generation sequencing to conduct a large scale study on thousands of Azoarcus CASs. We develop a perturbative approach to identify the important topological parameters that control variations in CASs as a result of environmental perturbations, here the addition of a new species. We then determine the small set of network features governing memory of the initial conditions in Azoarcus CAS, a pre-requisite for heredity, by using a computational model validated by experimental data. Finally, we demonstrate that Azoarcus CAS possess catabolic processes which make them robust to perturbations in the food set and thus more prebiotic relevant. These results provide evidence for the crucial role of RNA CASs in the origins of life and illustrate how the network structure can be tailored to obtain CASs with properties interesting from an evolutionary point of view, paving the way to an experimental demonstration of Darwinian evolution with a purely molecular system.

[ES] Esta tesis aborda la caracterización y posible utilización de la goma de alholva (Trigonella foenum-graecum) (FSG, por sus siglas en inglés) en la nutrición de gazapos durante el período posterior al destete como una alternativa al uso de antimicrobianos, centrándose en el comportamiento de la goma extraída con diferentes niveles de fibra dietaria, tanto in vitro como in vivo. En el primer experimento, a partir de una dieta basal comercial de conejo, se formularon tres dietas experimentales con niveles graduales de inclusión de FSG (0, 0.25, 0.50%) administrados a tres grupos de conejos desde el destete a los 31 días hasta el sacrificio a los 94 días. Se estudió el efecto de las dietas experimentales sobre la digestibilidad fecal en dos edades (38-41 días y 56-59 días), además de los parámetros de fermentación cecal al final del experimento. Por otro lado, a partir de la misma dieta comercial de conejo, se formularon cinco dietas experimentales que contenían 0. 0.125, 0.25, 0.50 y 100% de FSG, que se sometieron a incubación in vitro con inóculo cecal de conejo durante 72 h. Se midieron la producción de gas y las variables de fermentación. La digestibilidad fecal aparente y los parámetros de fermentación cecal no se vieron afectados significativamente por la inclusión in vivo de FSG hasta 0.5%. Sin embargo, los animales alimentados con FSG mostraron valores de pH cecal más bajos. La inclusión gradual en la dieta de FSG aumentó la concentración in vitro de ácidos grasos volátiles (VFA, por sus siglas en inglés), mientras que el FSG puro aumentó la producción asintótica de gas y la tasa máxima de degradación del sustrato y disminuyó el tiempo de incubación en el que se forma la mitad de la cantidad asintótica de gas. La incubación in vitro de FSG puro disminuyó el valor del pH, la concentración de ácido láctico y la concentración de N-NH3, y aumentó la de VFA. En el segundo experimento, el FSG se caracterizó para determinar su composición química, su contenido de galactosa y manosa y su potencial como prebiótico. Se evaluaron tanto FSG puro como niveles graduales (0, 5, 10, 15 y 20 g/kg) incluidos en dietas ricas en fibra soluble (SF, por sus siglas en inglés) de pulpa de remolacha (incluida al 10%) y dietas ricas en fibra insoluble (IF, por sus siglas en ingles) de semilla de uva desengrasada (incluida al 10%). Se sometieron a digestión enzimática con pepsina y pancreatina y luego sus fracciones indigestibles se sometieron a fermentación usando inóculo cecal. Se midieron las fracciones no digestibles después de la digestión enzimática, así como las fracciones no fermentables y las variables de fermentación después del tiempo de incubación (48 h). La FSG se compone principalmente de galactosa y manosa (630 g/kg) en una proporción de 1: 1 y un nivel moderado de proteínas (223 g/kg). El FSG puro se vio poco afectado por la digestión enzimática, ya que solo se disolvieron 145 g/kg. Sin embargo, desapareció casi por completo (984 g/kg) durante el proceso de fermentación. En consecuencia, FSG aumentó la concentración de VFA, disminuyó el valor de pH y la concentración de N-NH3. La inclusión gradual de FSG en las dietas de conejos afectó la digestión de algunos nutrientes, como las fracciones fibrosas, el almidón y las proteínas, además de aumentar la fracción fermentada en la dieta SF, pero sin ningún efecto relevante en el perfil de fermentación. En el tercer experimento, se formularon cuatro dietas de acuerdo con un diseño factorial 2 x 2: una dieta convencional de conejo (C), la misma dieta C suplementada con 10 g / kg de FSG, una dieta de bajo riesgo (LR, por sus siglas en inglés) y la misma dieta LR suplementada con 10 g/kg de FSG. Las dietas C y LR se diferenciaban en el nivel de SF y proteína bruta (CP, por sus siglas en inglés) (104 vs 205 y 156 vs 121 g/kg de SF y CP respectivamente para dietas C y LR). Doscientos dieciséis conejos de la línea LP se alojaron en jaulas individuales, se dividieron aleatoriamente entre los cuatro tratamientos y se les permitió el libre acceso al alimento y al agua. La mortalidad, la morbilidad, el índice de riesgo sanitario (HRi, por sus siglas en inglés), la ingestión diaria de pienso (DFI, por sus siglas en inglés), la ganancia media diaria (ADG, por sus siglas en inglés) y el índice de conversión alimenticia (FCR, por sus siglas en inglés) se controlaron hasta los 63 días de edad. El coeficiente de digestibilidad aparente total del tracto digestivo (CTTAD, por sus siglas en inglés) de los nutrientes se determinó en doce conejos por tratamiento, entre los 49 y 53 días de edad y finalmente se midió el ambiente cecal a los 63 días de edad. La inclusión de FSG en la dieta a 10 g/kg de alimento no afectó al rendimiento durante el cebo ni al CTTAD de los nutrientes, pero aumentó ligeramente la digestibilidad de la fibra neutrodetergente (NDF, por sus siglas en inglés) y la fibra ácido-detergente (ADF, por sus siglas en inglés) en las dietas C. Del mismo modo, los parámetros cecales no se vieron afectados por la inclusión de FSG, excepto la concentración de ácido caproico en las dietas C. Sin embargo, las dietas LR disminuyeron la mortalidad, HRi, DFI, ADG y CTTAD de materia orgánica y CP pero aumentaron FCR y CTTAD de NDF y ADF con respecto a las dietas C. Además, las dietas LR aumentaron la concentración de VFA, la proporción de ácido acético, isobutírico e isovalérico mientras que disminuyeron la materia seca del contenido cecal, NNH3 y la proporción de ácidos butírico, caproico y valérico. En resumen, la FSG responde perfectamente a las dos primeras condiciones para ser un prebiótico, ya que no es digestible por las enzimas gastrointestinales antes del ciego y es altamente fermentado una vez que alcanza el ciego. Parece afectar selectivamente a la microbiota cecal debido a su efecto sobre la concentración de VFA y N-NH3, además de su efecto sobre la proporción de caproico y valérico en dietas convencionales. FSG podría aumentar la viscosidad de la digesta limitando la solubilización de algunos nutrientes como el almidón y la proteína. FSG parece ser más efectivo en dietas comerciales convencionales que en dietas de bajo riesgo. Finalmente, se confirmó que las dietas con alto nivel de SF y bajo de CP podrían ser una buena herramienta contra la enteropatía epizoótica del conejo (ERE, por sus siglas en inglés) en un sistema de producción no medicado, a costa de peores parámetros de crecimiento. / [EN] This thesis tackles the possible characterisation and utilisation of fenugreek (Trigonella foenum-graecum) seed gum (FSG) in the nutrition of young rabbits during the post-weaning period as an alternative to antimicrobials uses. The study was focussed on the behaviour of the extracted gum with different dietary fibre levels, both in vitro and in vivo. In a first trial, starting from a basal commercial rabbit diet, three experimental diets were formulated with gradual levels of inclusion of FSG (0, 0.25, 0.50 %) given to three groups of rabbits starting from weaning at 31 days old to slaughter 94 days old. The effect of the experimental diets was studied on the faecal digestibility of the diet in two ages (38-41 days and 56-59days) and on the caecal fermentation parameters at the end of the experiment. On the other hand, starting from the same commercial rabbit diet five experimental diets were formulated containing 0, 0.125, 0.25, 0.50 and 100% of FSG that were submitted to in vitro incubation with rabbit caecal inoculum during 72h. Gas production and fermentation traits were measured. Apparent faecal digestibility and caecal fermentation parameters were not significantly affected by the in vivo inclusion of FSG up to 0.5%. However, animals fed with FSG showed lower caecal pH values. Gradual dietary inclusion of FSG increased in vitro concentration of volatile fatty acids (VFA), while pure FSG increased the asymptotic gas production and the maximum substrate degradation rate and decreased the time after incubation at which half of the asymptotic amount of gas is formed. In vitro incubation of pure FSG decreased pH value, lactic acid concentration and N-NH3 concentration and increased that of VFA. In a second trial, FSG was characterised determining its chemical composition, galactose and mannose content and prebiotic potential. Pure FSG and gradual levels of FSG (0, 5, 10, 15 and 20 g/kg), included both in diets rich in soluble fibre (SF) from beet pulp (included at 10%) or in diets rich in insoluble fibre (IF) from defatted grape seeds (included at 10 %), were evaluated. They were submitted to enzymatic digestion with pepsin and pancreatin and then their indigestible fractions were submitted to fermentation using caecal inoculum. The indigestible fractions after enzymatic digestion were measured, as well as the nonfermentable fractions and the fermentation traits after incubation time (48 h). FSG was mostly composed of galactose and mannose (630 g/kg) in 1:1 ratio and a moderate protein level (223 g/kg). Pure FSG was weakly affected by enzymatic digestion, only 145 g/kg was dissolved. However, it was almost entirely disappeared (984 g/kg) during the fermentation process. Consequently, FSG increased VFA concentration and decreased both pH value and N-NH3 concentration. Th gradual inclusion of FSG in rabbit’s diets affected some nutrients digestion such as the fibre fractions, starch and protein, besides to increase the fermentation fraction in SF diet but without any relevant effect on the fermentation profile. In a last third trial, four diets were formulated according to 2 x 2 factorial design: a conventional rabbit diet (C), the same C diet supplemented by 10 g/kg of FSG, a low-risk diet (LR), and the same LR diet supplemented by 10 g/kg of FSG. C and LR diets differed in SF and crude protein levels (CP) (104 vs 205 and 156 vs 121 g/kg of SF and CP respectively for C and LR diets). Two hundred and sixteen weaned rabbits (28 days of age) of the LP line were allocated in individual cages and divided randomly between the four treatments and allowed free access to feed and water. Mortality, morbidity, health risk index (HRi), daily feed intake (DFI), average daily gain (ADG) and feed conversion ratio (FCR) were controlled until 63 days of age. Coefficient of total tract apparent digestibility (CTTAD) of nutrients, on twelve rabbits per treatment, was determined from 49 to 53 days of age and finally, caecal environment was measured at 63 days of age. FSG dietary inclusion at 10 g/kg did not affect performance or CTTAD of nutrients but did slightly increased neutral-detergent fibre (NDF) and acid-detergent fibre (ADF) digestibility in C diets. Similarly, caecal parameters were not affected by FSG except caproic acid concentration in C diets. Nevertheless, LR diets decreased mortality, HRi, DFI, ADG and CTTAD of organic matter and CP but increased FCR and CTTAD of NDF and ADF respect to C diets. Moreover, LR diets increased VFA concentration, the proportion of acetic, isobutyric and isovaleric while decreased the dry matter of the caecal content, N-NH3 and the proportion of butyric, caproic and valeric acids. To summarise, FSG perfectly responds to the two first conditions to be prebiotic, being not digestible by gastrointestinal enzymes before the caecum and highly fermented once reached the caecum. It seems to affect selectively caecal microbiota due to its effect on VFA and N-NH3 concentration besides to its effect on caproic and valeric proportions in conventional diets. FSG could increase viscosity of digesta limiting the solubilisation of some nutrients such starch and protein. FSG seems to be more effective in conventional commercial diets than in low-risk diets. Finally, it was confirmed that diets with high SF level and low CP could be a good tool against epizootic rabbit enteropathy (ERE) in a nomedicated breeding system at the cost of impaired growth parameters. / [CA] Aquesta tesi aborda la caracterització i possible utilització de la goma de fenigrec (Trigonella foenum-graecum) (FSG, per les sigles en anglès) en la nutrició del conills durant el període posterior al deslletament com una alternativa a l'ús d'antimicrobians, centrant-se en el comportament de la goma extreta amb diferents nivells de fibra dietària, tant in vitro com in vivo. En el primer experiment, a partir d'una dieta basal comercial de conill, es van formular tres dietes experimentals amb nivells graduals d'inclusió de FSG (0, 0.25, 0.50%) administrats a tres grups de conills des del deslletament als 31 dies fins al sacrifici als 94 dies. Es va estudiar l'efecte de les dietes experimentals sobre la digestibilitat fecal en dues edats (38-41 dies i 56-59 dies), a més dels paràmetres de fermentació cecal a la fi de l'experiment. D'altra banda, a partir de la mateixa dieta comercial de conill, es van formular cinq dietes experimentals que contenien 0. 0.125, 0.25, 0,50 i 100% de FSG, que es van sotmetre a incubació in vitro amb inòcul cecal de conill durant 72 h. Es van mesurar la producció de gas i les variables de fermentació. La digestibilitat fecal aparent i els paràmetres de fermentació cecal no es van veure afectats significativament per la inclusió in vivo de FSG fins a 0.5%. No obstant això, els animals alimentats amb FSG van mostrar valors de pH cecal més baixos. La inclusió gradual en la dieta de FSG va augmentar la concentració in vitro d'àcids grassos volàtils (VFA, per les sigles en anglès), mentre que el FSG pur va augmentar la producció asimptòtica de gas i la taxa màxima de degradació del substrat i va disminuir el temps d'incubació en el qual es forma la meitat de la quantitat asimptòtica de gas. La incubació in vitro d'FSG pur va disminuir el valor del pH, la concentració d'àcid làctic i la concentració de N-NH3, i va augmentar la de VFA. En el segon experiment, el FSG es va caracteritzar per determinar la seva composició química, el seu contingut de galactosa i manosa i el seu potencial com prebiòtic. Es van avaluar tant FSG pur com nivells graduals (0, 5, 10, 15 i 20 g/kg) inclosos en dietes riques en fibra soluble (SF, per les sigles en anglès) de polpa de remolatxa (inclosa al 10%) i dietes riques en fibra insoluble (IF, per les sigles en anglès) de llavor de raïm desgreixada (inclosa al 10%). Es van sotmetre a digestió enzimàtica amb pepsina i pancreatina i després les fraccions indigeribles es van sotmetre a fermentació usant inòcul cecal. Es van mesurar les fraccions no digestibles després de la digestió enzimàtica, així com les fraccions no fermentables i les variables de fermentació després del temps d'incubació (48 h). La FSG es compon principalment de galactosa i manosa (630 g/kg) en una proporció de 1: 1 i un nivell moderat de proteïnes (223 g/kg). El FSG pur es va veure poc afectat per la digestió enzimàtica, ja que només es van dissoldre 145 g/kg. No obstant això, va desaparèixer gairebé del tot (984 g/kg) durant el procés de fermentació. En conseqüència, FSG va augmentar la concentració de VFA, va disminuir el valor de pH i la concentració de N-NH3. La inclusió gradual de FSG en les dietes de conills va afectar la digestió d'alguns nutrients, com les fraccions fibroses, el midó i les proteïnes, a més d'augmentar la fracció fermentada en la dieta SF, però sense cap efecte rellevant en el perfil de fermentació. En el tercer experiment, es van formular quatre dietes d'acord amb un disseny factorial 2 x 2: una dieta convencional de conill (C), la mateixa dieta C suplementada amb 10 g/kg de FSG, una dieta de baix risc (LR, per les sigles en anglès) i la mateixa dieta LR suplementada amb 10 g/kg de FSG. Les dietes C i LR es diferenciaven en el nivell de SF i proteïna bruta (CP, per les sigles en anglès) (104 vs 205 i 156 vs 121 g/kg de SF i CP respectivament per a dietes C i LR). Doscents setze conills de la línia LP es van allotjar en gàbies individuals, es van dividir aleatòriament entre els quatre tractaments i se'ls va permetre el lliure accés a l'aliment i a l'aigua. La mortalitat, la morbiditat, l'índex de risc sanitari (HRi, per les sigles en anglès), la ingestió diària de pinso (DFI, per les sigles en anglès), el guany mitjá diari (ADG, per les sigles en anglès) i l'índex de conversió alimentària (FCR, per les sigles en anglès) es van controlar fins als 63 dies d'edat. El coeficient de digestibilitat aparent total del tracte digestiu (CTTAD, per les sigles en anglès) dels nutrients es va determinar en dotze conills per tractament, entre els 49 i 53 dies d'edat i finalment es va mesurar l'ambient cecal als 63 dies d'edat. La inclusió de FSG en la dieta a 10 g/kg d'aliment no va afectar el rendiment durant l'engreix ni el CTTAD dels nutrients, però va augmentar lleugerament la digestibilitat de la fibra neutre-detergent (NDF, per les sigles en anglès) i la fibra àcid-detergent (ADF, per les sigles en anglès) en les dietes C. De la mateixa manera, els paràmetres cecals no es van veure afectats per la inclusió de FSG, excepte la concentració d'àcid caproic en les dietes C. No obstant això, les dietes LR van disminuir la mortalitat, HRi, DFI, ADG i CTTAD de matèria orgànica i CP però van augmentar FCR i CTTAD de NDF i ADF pel que fa a les dietes C. A més, les dietes LR van augmentar la concentració de VFA, la proporció d'àcid acètic, isobutíric i isovalèric mentre que van disminuir la matèria seca del contingut cecal, N-NH3 i la proporció d'àcids butíric, caproic i valéric. En resum, la FSG respon perfectament a les dues primeres condicions per ser un prebiòtic, ja que no és digestible pels enzims gastrointestinals abans del cec i és altament fermentat un cop que arriba al cec. Sembla afectar selectivament a la microbiota cecal pel seu efecte sobre la concentració de VFA i N-NH3, a més del seu efecte sobre la proporció de caproic i valéric en dietes convencionals. FSG podria augmentar la viscositat de la digesta limitant la solubilització d'alguns nutrients com el midó i la proteïna. FSG sembla ser més efectiu en dietes comercials convencionals que en dietes de baix risc. Finalment, es va confirmar que les dietes amb alt nivell de SF i baix de CP podrien ser una bona eina contra la enteropatia epizoòtica del conill (ERE, per les sigles en anglès) en un sistema de producció no medicat, a costa d'pitjors paràmetres de creixement. / Jihed, Z. (2020). In vitro and in vivo characterization of galactomannanes extracted from fenugreek seeds (Trigonella foenum-graecum) for young rabbit nutrition [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/153714 / TESIS

The composition and metabolic activity of the microbiome affect many aspects of health, and there is current interest in dietary constituents that may affect this system. The purpose of this study was to evaluate the effects of a mix of probiotics, a mix of prebiotics and a bioactive protein fraction on the microbiome, when fed to mice individually and in combination. Mice were fed the total western diet (TWD) supplemented with prebiotics, probiotics, and Tri-Factor (bioactive proteins) individually and in combination for four weeks. Subsequently, effects on the composition of gut microbiome, gut short chain fatty acids (SCFAs) concentration, gut inflammation and integrity of the mucosal barrier were analyzed. Ruminococcus gnavus was increased in mice gut microbiome after feeding prebiotics. Bifidobacterium longum was increased after feeding probiotics. Probiotic was associated with higher level of Clostridium neonatale. The treatments affected beta-diversity with exception of Tri-Factor, but not alpha diversity of microbiome. All treatments were associated with lower plasma zonulin, compared to the control group, indicating an effect on gut permeability. There were no treatment effects on cecal or fecal SCFAs, and the treatments did not affect gut inflammation as measured by fecal calprotectin.

No description available.

With World Health Organization estimation of population increase to over 9 billion by 2050, malnutrition and food insecurity are predicated to be two of the main challenges facing the world in the future. Fish is a source of protein that can have a significant contribution for solving the global food crisis. Fish for human consumption is provided by both the aquaculture industry and the capture fisheries, however, the flat-lined production of seafood from capture fisheries means aquaculture production should double in number to provide enough protein by 2050. Culturing fish at higher densities is being used as a way to increase the global aquaculture production. Modern aquaculture intensified practices expose the fish to various stressors that can negatively impact their welfare. Good nutrition can improve the health status of aquacultured fish while accumulation of specific nutrient can add value to the fillet. In line with that, the studies described in this dissertation aimed to examine the vital role of fish in human health and evaluate strategies to improve the sustainable aquaculture production of fish using novel aquafeeds. This was completed by conducting a survey of the essential minerals and heavy metals of commercially available catfish, salmon, and tilapia fillets in the United States marketplace and three fish nutritional trials to evaluate the impacts of novel aquafeeds on production and health of fish and the food quality of their respective fillets. Selenium with the established health benefit for human and fish was the trace mineral of interest in this dissertation. This element is the main component of a group of selenium containing proteins called selenoproteins that are antioxidant and maintain oxidative homeostasis of fish and human. Additionally, selenium is an antagonist for many heavy metals such as mercury. The market study revealed that catfish, salmon and tilapia samples available in United States marketplace are good source of selenium, zinc and phosphorous. The concentration of heavy metals in all the samples were lower than safety standards. Nile tilapia (Oreochromis niloticus) and rainbow trout (Oncorhynchus mykiss), which are two economically important aquacultured fish, were used as animal models in the fish nutritional trials. Different forms of selenium supplemented to Nile tilapia diet. The form of Dietary Se form did not have any significant (p>0.05) effect on growth, and plasma and hepatic GPX activity of Nile tilapia. However, organic selenium supplement showed significantly (p<0.05) higher bioavailability and accumulated in the fillets at the significantly higher concentration. In the second fish trial selenoneine, a novel selenium containing compound, was supplemented at various concentrations to rainbow trout diet. Other than growth parameters multiple other health biomarkers (lysozyme, glutathione peroxidase, superoxide dismutase activities) were examined to determine whether selenoneine supplementation had a positive impact on fish health. Selenoneine enriched diet significantly(p<0.05) increased the weight gain, lysozyme and oxidative enzymes activities of rainbow trout. Lastly rainbow trout feed was supplemented with commercially available probiotic (Actisaf®), prebiotic (Safmmann®), and their mixture (synbiotic). These dietary supplements did not have any significant effect on fish production but led to a significant increase in activity of oxidative enzymes in plasma when compared to control diet. These results suggest that feed supplements used in this dissertation can be used to promote the fish health raised in recirculating aquaculture systems and support an economically and environmentally sustainable aquaculture. / PHD / Fish contributes significantly to human’s diet in terms of high quality, easily digestible animal protein that helps fight malnutrition and food insecurity. More than half of the fish for human consumption is produced by the aquaculture industry and the growth of the industry is very critical for meeting the future needs for protein. Other than production of high-quality protein the aquaculture industry has made a great contribution to people’s livelihood, poverty alleviation, income generation, employment and, trade globally. To continue contributing effectively to global food security aquaculture industry should overcome various obstacles such as disease and sustainable production of high-quality feed. In this dissertation, important roles of fish in human diet was examined by measuring the mineral composition of commercially available catfish, salmon and tilapia in the United States market place. Also diets of Nile tilapia and rainbow trout were supplemented with various forms of selenium, prebiotics, and/or probiotics which have positive effect on health of both human and fish. These supplementations led to production of valued-added fish fillets enriched in selenium and improved the fish growth and health.

Gastrointestinal tract (GIT) microorganisms play important roles in animal health, including providing energy and vitamins, improving the host immune response and preventing pathogenic microorganisms from colonizing. Prebiotic feed supplementation offers an alternative to antimicrobial growth promoters by stimulating key populations of the GIT bacteria that can ferment these non-digestible compounds, producing various short chain fatty acids used by the animal. The objective of this study was to quantify the effects of a proprietary Saccharomyces cerevisiae fermentation product (XPC, Diamond V Mills, Inc., Cedar Rapids, IA) inclusion in nursery diets on the microbial diversity and growth performance of pigs before, during and after an oral challenge with Salmonella. Pigs (n= 40) were weaned at 21 d of age, blocked by body weight (BW) and assigned in a 2Ã 2 factorial arrangement consisting of diet (control or 0.2% XPC) and inoculation (broth or Salmonella). Diet had no effect on pig growth performance prior to inoculation; however, consumption of XPC altered the composition of the gastrointestinal microbial community resulting in increased growth performance prior to inoculation. After Salmonella infection, XPC altered the composition of the gastrointestinal microbial community resulting in increased (P < 0.05) populations of Bacteroidetes and Lactobacillus. Infection with Salmonella and treatment of the piglets with ceftiofur-HCl resulted in alterations to the species richness and abundance of key members of the GIT community. The addition of XPC to the diets of weaning pigs results in greater compensatory gains after infection with Salmonella and an increase in beneficial bacteria within the GIT. / Master of Science

The series of experiments that comprises this thesis consider the use of prebiotics and probiotics to improve success in European lobster Homarus gammarus culture. Research was conducted at the National Lobster Hatchery and The University of Plymouth, UK between April 2007 and March 2010. Great potential was revealed for the application of biotics as dietary supplements in the culture of larval and juvenile H. gammarus. Specific biotics, namely; prebiotic mannon oligosaccharide (MOS) and probiotic Sanolife® (Bacillus spp.) were revealed to increase growth and survival during the culture of early lobster life stages. Lobsters that showed enhanced development and/or survival were found to possess improved feed conversion, immune status and/or stress tolerance. Furthermore it was found that biotic fed lobsters displayed shifts in gastrointestinal (GI) microbiology and enhanced physical GI structures, which may account for improved feed conversion and consequently growth. The work presented thus demonstrates that by making positive changes in GI structure and bacterial community composition combined with influencing immune status culture success can be positively enhanced through the biotic supplementation of diets. However, it must be considered that the outcome of dietary biotic supplementation is heavily influenced by the situation in question.

Une consommation de fibres alimentaires adéquate semble protéger du risque de développer un diabète de type 2 dont a contrario la prévalence ne cesse de progresser à travers le monde. Parmi les mécanismes d'action pouvant expliquer comment les fibres contribuent à l'homéostasie du glucose et à la sensibilité à l'insuline, l'implication du microbiote intestinal semble aujourd'hui très probable. Cependant il n'est pas toujours aisé de différencier ses effets de ceux pouvant découler d'une réduction de l'indice glycémique voir de ceux induits par des micronutriments parfois associés aux fibres. Les travaux de cette thèse ont permis de confirmer que les fructo-oligosaccharides (FOS), fibres prébiotiques peu visqueuses, peuvent améliorer la sensibilité à l'insuline de différents modèles animaux d'obésité induite par le régime alimentaire. La réduction de la sensibilité à l'insuline induite par le surpoids n'est pas complètement contrebalancée par les FOS mais leurs effets sont visibles même sans perte de poids associée. D'autre part une corrélation directe entre les modifications de la composition et des activités du microbiote intestinale induites par les FOS et le métabolisme de l'hôte a pu être mise en évidence. Au-delà d'une augmentation des bifidobactéries déjà bien documentée, les travaux de cette thèse ont révélé la modulation par les FOS d'autres clusters bactériens plus prépondérants au sein de l'écosystème digestif comme ceux des Clostridium leptum et Clostridium coccoides – Eubacterium rectale. En modulant ces populations, les FOS influencent le métabolisme des acides biliaires et le niveau d'hydroxylation d'acides gras monoinsaturés. / An adequate intake of dietary has proven to protect against the risk to develop type 2 diabetes, for which the prevalence is currently increasing all around the world. Among the different mechanisms that could explain how dietary fibres can contribute to insulin sensitivity and glucose homeostasis, involvement of the gut microbiota seems more than likely. However it is not always possible to differentiate the effects that linked to the microbiota from those induced a reduction of the glycaemic index or those induced by some micronutrients sometimes closely associated to dietary fibres. The experiments conducted during this PhD validate that fructo-oligosaccharides (FOS), poorly viscous prebiotic fibres, can enhance insulin sensitivity if different animal models of diet-induced obesity. Reduction of insulin sensitivity resulting from overweight status is not completely solved by FOS but their effect is not linked to weight loss. Moreover, a direct correlation between the modifications of the composition and activities of the intestinal microbiota triggered by FOS and metabolism of the host has been highlighted. This work reveals that more than a single increase of Bifidobacteria already well documented, FOS can alter other bacterial clusters more predominant within the digestive ecosystem like Clostridium leptum and Clostridium coccoides – Eubacterium rectale. By modulating these populations, FOS will alter the metabolism of biliary acids and the level of monounsaturated fatty acids hydroxylation.