L’objectif de cette thèse est d’encapsuler dans une matrice polyosidique des probiotiques sous forme de biofilm en utilisant comme modèle Lactobacillus paracasei ATCC334. La matrice d’encapsulation (billes) est obtenue par gélification ionique d’une pectine amidée et faiblement méthylée en présence d’ions calcium. Nous avons remarqué que le réseau de pectine dans ces billes d’un diamètre d’environ 500 µm permet la formation de microcolonies sphériques (biofilm-like) avec une taille de 25 µm de diamètre. Une augmentation de la concentration bactérienne de L. paracasei ATCC334 de 3 Log d’UFC après 24 h de croissance des bactéries immobilisées est observée pour atteindre au sein de ces billes une concentration supérieure à 10 Log d’UFC/g humide. Nous avons également noté une distribution homogène des microcolonies dans les billes et une organisation structurée des bactéries au sein des microcolonies. En effet, une adhésion des bactéries à la matrice pectine est observée ainsi que la présence de substances polymériques permettant de lier les bactéries les unes aux autres. Les résultats suggèrent donc des phénomènes d’interaction entre le réseau formé par la pectine et les bactéries dans les billes. Nous avons montré que L. paracasei ATCC334 formulée en biofilm dans ces billes de pectine présente une résistance accrue à un stress gastrique (pH 2) et au séchage par lyophilisation. La capacité d’adhésion des bactéries formulées à des cellules épithéliales est conservée et la pectine semble stimuler cette adhésion aux cellules de l’hôte. Des résultats in-vivo utilisant un modèle murin d’inflammation intestinale montrent que les biofilms de L. paracasei ATCC334 sont libérés au niveau intestinal où ils s’implantent notamment dans le côlon. Des microcolonies de tailles approchant les 20 µm sont retrouvées au niveau du côlon suggérant que les billes de pectine ont libéré les bactéries sous forme de biofilm. Par ailleurs, l’administration aux souris de la formulation à base de pectine avec des biofilms de probiotiques a entrainé chez les souris ayant reçu un traitement DSS (une molécule capable de déclencher une inflammation intestinale) : une perte de poids moindre, un état de santé général amélioré, une muqueuse colique moins altérée ainsi qu’une diminution de la réponse inflammatoire. / The aim of this thesis is to encapsulate biofilm probiotics in a polysaccharide matrix using Lactobacillus paracasei ATCC334 as a model. The encapsulation matrix (beads) is obtained by the ionotropic gelation of amidated low-methoxylated pectin with calcium ions. We noticed that the pectin network in these beads with a diameter of approximately 500 microns, allow the formation of spherical microcolonies (biofilm-like) with a diameter of 25 microns. An increase of 3 Log CFU in the bacterial concentration of L. paracasei ATCC334 is observed after 24 hours of growth of the immobilized bacteria, while the observed concentration in these beads reaches more than 10 Log of CFU/g wet. We also noticed that the microcolonies within the beads are homogeneously distributed and the bacteria within the microcolonies are well structured. Moreover, a bacterial adhesion to the pectin matrix is observed as well as the presence of polymeric substances that bind the bacteria to each other. Our results suggest that interaction phenomenon may take place between pectin network and bacteria within beads. We also showed that biofilms of L. paracasei ATCC334 formulated in these pectin beads exhibit increased resistance to the gastric stress (pH 2) and to the freeze-drying process. In addition, the adhesion capacity of the formulated bacteria to epithelial cells is conserved and pectin seems to stimulate this adhesion to host cells. In-vivo results using a murine model presenting intestinal inflammation showed that L. paracasei ATCC334 biofilms are released in the intestinal level and are specifically implanted in the colon. Moreover, microcolonies of sizes approaching 20 μm are found in the colon suggesting that the bacteria are released in their biofilm form. In addition, the administration of pectinate beads containing probiotic biofilms to mice which have received a DSS treatment (inducing intestinal inflammation) resulted in: less weight loss of mice, improved their overall health status, less injured colonic mucosa and a decrease in the inflammatory response.

Corn is widely used as animal feed as well as for fuel ethanol production. Fiber present in corn is not digested well by non-ruminants such as chicken and swine. Also, this fiber does not participate in conversion of starch to ethanol. Fiber separation from corn flour using the Elusieve process, a combination of sieving and air classification, would result in high starch animal feed and increase ethanol productivity. The objective of the first part of this dissertation was to understand the effect of retention screen size in the hammer mill on fiber separation from corn flour using the Elusieve process. Four different retention screen opening sizes were studied. The highest starch content of 65.2% was in the enhanced flour obtained by using 3.2 mm (8/64") retention screen; starch content of the original corn flour was 62.5%. The objective of the second part was to evaluate Elusieve process for sorghum flour. The combination of hammer milling and Elusieve process was less effective for sorghum flour compared to corn flour. The objectives of the third part were to determine the operating air velocities for corn particles and to compare physical properties of corn particles with that of Distillers’ dried grains with soluble (DDGS) particles. The operating air velocities for large, medium and small corn size fractions were 2.9 to 3.8, 2.8 to 3.0 and 2.5 to 2.6 m/s, respectively. Densities of nonfiber particles for corn flour were higher than for DDGS (earlier study). Compared to DDGS, the difference between fiber and nonfiber particle terminal velocities was higher for corn, signifying relative ease of operability for fiber separation from corn flour. The objective of the fourth part was to study the effect of corn moisture content on fiber separation. There was no effect of moisture content on fiber separation. The objective of the fifth part was to assess the economics of the Elusieve process. For ethanol plant of 50 million gallons/year capacity (50 MGY), payback period would be 3.1 years. The payback period for implementing Elusieve process in an integrated broiler operation with 8 million birds capacity would be 0.4 to 1.3 years.

Current practices support the use of probiotic and prebiotic supplementation to improve chronic gastrointestinal distress (GID). The aim of this study was to determine the tolerance and benefits of GlutenShield (GS), a prebiotic, probiotic, and enzyme supplement, on adults with GID. Subjects (n=20) took either GS or the placebo for 30 days and completed a pre-treatment FFQ as well as a pre- and post-treatment GID questionnaire, blood draw, and stool sample. Participants consumed more total and saturated fat, and less fiber and whole grains compared to the recommended intake. A significant reduction in IgG2 was observed in the GS group (p=0.008) as well as a significant reduction in self-reported bloating (p=0.038) with no change observed to cytokines or SCFAs (p>0.05). GS was well tolerated and perceived to be beneficial; however, further research is needed to identify the specific population of GID patients who could most benefit from GS supplementation.

This study turns to what is for many an everyday item – yogurt – as a critical zone observatory, a synergistic, place-based laboratory which aims to integrate heterogenous representations of planetary phenomena as they are registered at a common surface. Yogurt has an impressive cultural endurance largely derived from its prominence in various paradigms of health. The product has culturally endured in another sense: as a common cultural medium where humans and microbes have met for generations. This study begins with a profile of yogurt as most encounter it today to consider how normative notions of health interface with the temporal and spatial imaginaries entailed in commodity geographies. Commoditized yogurt is characterized by a low and limited microbial biodiversity compared to yogurts produced outside of the commodity context. Yogurt is therefore presented as a micro case study to consider modes by which we sense and valuate ecological phenomena beyond the perceptible surface, how such sens-abilities intersect models of health, and to what effect. To trace a history of yogurt along these contours, I introduce it as a particular kind of artefact: a global object. As an object of environmental history, I define a global object as a global commodity with a high potential to be re-localized, and therefore with a high potential to re-shape commodity geographies. However, this trajectory is contingent upon framing yogurt as a critical zone observatory – a site where global phenomena like human-microbial interaction may become familiar and intimate. Guided by new materialist theory, I weave together historical and ethnographic case studies from the following consortium: resident yogurt bacteria, artisanal yogurt producers and home fermenters, a mystical immunologist, and an 11th century linguistic scholar. Through these perspectives, I both sketch and apply a framework for de-centered, interspecies histories of cultural (re)production through an extended metaphor of biofilm: the coagulative bacterial structure giving yogurt its characteristic texture. In so doing I provide a re-articulation of “the probiotic” as an integrative case of human and more-than-human health. The study concludes by directing these implications towards a consideration of aesthetic engagement by displaying how fermentation practice may enliven matters of re-diversification and re-localization.

The small intestine and yolk sac (YS) are important organs for nutrient absorption and innate immunity in chickens during the post-hatch or prehatch periods. These organs share a similar structure of epithelial cell-lined villi with tight junctions between adjacent cells. Probiotics have been reported to improve chicken growth performance and gut health including promotion of intestinal morphology. However, there are few studies that show the effect of probiotics on ontogeny of intestinal epithelial cells and antimicrobial peptides, or intestinal integrity in young healthy chicks. Heat stress during incubation was shown to increase mortality and decrease hatchability of chicks, while no studies have investigated the effect of heat stress on the integrity of the YS, which might be related to hatching performance. There were four studies conducted in this research: 1) a comparison of the effect of two probiotics on the ontogeny of small intestinal epithelial cells in young chicks; 2) the effect of two probiotics on mRNA abundance of tight junction proteins in the small intestine of young chicks; 3) the effect of high incubation temperature on mRNA abundance of tight junction proteins in the YS of broiler embryos; and 4) comparison of avian defense peptide mRNA abundance in the YS of broilers and layers. In study 1, Probiotics transiently decreased body weight gain (BWG) from day 2 to day 4, but did not affect body weight (BW) from day 2 to day 8, and small intestinal weight and intestinal morphology from day 2 to day 6. Probiotics did not affect marker gene expression of intestinal stem cells (Olfm4) and goblet cells (Muc2) in all small intestinal segments, but did increase expression of a marker gene of proliferating cells (Ki67), and decreased an antimicrobial peptide (liver-enriched antimicrobial peptide 2, LEAP2) in the jejunum at day 4. Probiotic 1 decreased PepT1, a marker of enterocytes in the duodenum at day 4. These results suggest that probiotics did not improve growth performance and intestinal morphology in young healthy chicks, but temporarily promoted intestinal epithelial cell proliferation and decreased LEAP2 antimicrobial peptide expression in the jejunum. In situ hybridization (ISH) showed that Ki67+ proliferating cells were mainly located in the crypt region and the blood vessels of villi. In study 2, Probiotic supplementation to newly hatched chicks for less than one week did not affect mRNA abundance of the tight junction proteins in the small intestine. Occludin (OCLN) mRNA, which was detected by ISH to be expressed in intestinal epithelial cells in both the villus and crypt regions, was greater in the duodenum of female chicks than males. In study 3, high incubation temperature starting from embryonic day 12 (E12) affected mRNA abundance of the tight junction proteins in the YS, including increased zonula occluden 1 (ZO1) at E13, increased junctional adhesion molecule A (JAMA) and heat shock protein 90 (HSP90) at E17, but decreased tight junction protein JAMA at E19 and OCLN at day of hatch (DOH). These results showed that the YS tight junction proteins were increased by short term heat exposure but decreased by long term heat exposure. In study 4, the expression of avian β defensin 10 (AvBD10), CATHs and toll-like receptors in the YS was examined. Toll-like receptors were highly expressed in the YS at early incubation stages (E7), while CATHs showed a peak expression from E9 to E13, which was similar to the expression pattern of AvBD10. CATHs and AvBD10 mRNA temporal expression patterns were similar in broilers and layers, while their expression levels were different. Layers, especially brown layers, had greater mRNA abundance for antimicrobial peptides such as AvBD10, CATH1, and CATH2 in the YS. These results demonstrate that the antimicrobial peptide temporal expression patterns in the YS are not affected by breed, but their expression levels are affected by breed. In summary, the small intestine and the YS are essential for nutrient uptake, innate immunity, and maintenance of integrity. The ontogeny of intestinal epithelial cells, such as proliferating cells can be modulated by probiotic supplementation. Similar to the small intestine, the YS can also express tight junction proteins, which can be affected by high incubation temperature. Antimicrobial peptide expression in the intestine of healthy young chicks is also transiently decreased by probiotic supplements. Avian defensin and cathelicidin expression patterns in the YS were not affected by breed. / Doctor of Philosophy / The small intestine and yolk sac are important organs for nutrient absorption in hatched chicks or embryonic chicks. These organs also serve as a barrier to prevent pathogens from entering the blood circulation. Intestinal epithelial cells along the villi renew rapidly by proliferation and differentiation. In this research, probiotics which are also known as direct fed microbials temporarily increased expression of the proliferating cell marker Ki67 in the jejunum of healthy young chicks, which suggests that probiotics promote intestinal epithelial cell proliferation. However, probiotics transiently decreased expression of an antimicrobial peptide, which may reduce immune protection in the gut. The yolk sac can also express tight junction proteins. The expression of tight junction proteins was affected by elevated incubation temperature in broiler embryos, which might be related to low hatchability of eggs exposed to heat stress. Avian defense peptides and pathogen recognition receptors were expressed in the YS, which implied that the yolk sac contained an innate immune function. The expression pattern of avian defense peptides was affected by breed (broilers and layers), while the expression level of avian defense peptides was greater in layers than broilers. In summary, the small intestine and the yolk sac are multifunctional organs. Their cell composition, structural integrity, and secretion of antimicrobial peptides can be affected by environmental factors, such as probiotic supplementation or high incubation temperature.

Akamu is a lactic acid bacteria fermented cereal-based food that complements infant diets in most African countries. Uncontrolled fermentation increases the variability in quality and safety of akamu. This study was aimed at the controlled fermentation of akamu with selected lactic acid bacteria (LAB), investigation of the probiotic potential of the LAB and the effect of variation in production method on the product quality and sensory properties. PCR-DGGE analysis of traditional akamu samples revealed LAB community dominated by Lactobacillus fermentum, L. plantarum, L. delbrueckii subsp. bulgaricus and L. helveticus. Isolated yeasts were Candida tropicalis, C. albicans, Clavispora lusitaniae and Saccharomyces paradoxus. The isolated Lactobacillus plantarum strains (NGL5 and NGL7) fermented irradiated ground maize slurries and produced significant levels of lactic acid (>73 mmol L-1) and low pH ≤3.63 displaying inhibitory activity against Salmonella enterica serovar Enteritidis NCTC 5188, Escherichia coli 1077 (NCTC 11560), Bacillus cereus NCIMB 11925, Staphylococcus aureus NCTC 3750 and Listeria monocytogenes NCTC 7973 in MRS agar and E. coli 1077 in maize slurry fermentation. Viability of both strains of L. plantarum at pH 2 after 3 h was reduced from ≥8.26±0.05 to ≤4.94±0.49 Log10 CFU mL-1 while incubation in 0.3% bile allowed growth to 5.73±0.13 and 7.93±0.12 Log10 CFU mL-1 after 6 h for NGL5 and NGL7 respectively. Auto-aggregation of the L. plantarum strains at 37oC (≥25 after 5 h) correlated with adhesion to hydrocarbons (<15, 26, 33 and 64% for Hexane, Hexadecane, Ethyl acetate and Chloroform respectively). The strains failed to exhibit gelatinase or haemolytic activity but adhered to porcine mucin (OD403 nm ≥0.63 with viability ≥6.52 Log10 CFU mL-1) and Caco-2 cells (≥5.13 Log10 CFU mL-1). The ash, mineral (Ca, K, Mg, Na, S and Zn), IDF, SDFP and TDF content of the L. plantarum fermented ground maize slurries were significantly (p≤0.05) higher than that of the traditional akamu but the peak and final viscosities (139.5 and 68.5 cP respectively) were significantly (p≤0.05) the least. The aroma, appearance, colour, flavour and texture of the resultant porridges were liked moderately by 75% of the assessors. This study demonstrated that fermentation with the L. plantarum strains would contribute towards product safety and the L. plantarum strains possessed some probiotic potential that could be beneficial to the consumers particularly in those developing countries were the main staple foods are fermented cereals.

O objetivo deste trabalho foi avaliar os efeitos da inclusão de leveduras, na forma de parede celular e hidrolisada, na dieta de poedeiras sobre o desempenho produtivo, qualidade dos ovos e viabilidade econômica da suplementação destes aditivos. Dois experimentos foram realizados, para cada um deles foram alojadas 256 poedeiras distribuídas em delineamento inteiramente casualizado em 8 repetições com 8 aves. Foram avaliados os níveis de 0, 225, 450 e 900 g/t de parede celular de levedura na dieta das aves durante o período de 21 a 67 semanas de idade. Os resultados demonstraram um aumento no consumo de ração, produção e massa de ovos, além de uma maior altura do albúmen e unidade Haugh. A espessura da casca e a cor da gema também foram influenciadas pelos tratamentos. A análise da viabilidade econômica demonstrou que mesmo despendendo mais com a alimentação houve um aumento da margem bruta média, devido ao aumento da produção de ovos. Portanto, o uso da parede celular de levedura apresentou efeitos benéficos sobre o desempenho produtivo das poedeiras, como uma melhora na qualidade interna e externa dos ovos, aliado a uma maior rentabilidade da atividade. Para a levedura hidrolisada foram avaliados os níveis de 0, 1, 2 e 4 kg/t. Dois períodos foram analisados, 21 a 40 e 48 a 67 semanas de idade. A adição de levedura hidrolisada na dieta de poedeiras não apresentou melhoria das características analisadas no primeiro período, porém os benefícios surgiram a partir do segundo período. O uso da levedura além de gerar uma menor quantidade de ovos não comerciais, promoveu o aumento do consumo de ração, produção, massa e peso dos ovos, melhoria na qualidade dos ovos em relação a unidade Haugh, altura do albúmen, espessura e resistência da casca; e ainda melhorou a conversão alimentar por massa e dúzia de ovos. A suplementação de levedura hidrolisada para poedeiras proporcionou incremento da margem bruta total média em todos os níveis testados, demonstrando-se viável economicamente. A inclusão de levedura hidrolisada na dieta de poedeiras de 48 a 67 semanas de idade exerceu efeito maximizador do desempenho produtivo e qualidade de ovos, sendo economicamente viável seu uso. / The purpose of this study was to evaluate the effects of including yeast in the form of cell wall and hydrolyzed, in the diet of laying hens on production performance, egg quality and economic viability of these feed additives. Two experiments were conducted, for each of them 256 laying hens were housed and distributed in a completely randomized design with 8 repetitions of 8 birds. The level of 0, 225, 450 and 900 g/t of yeast cell wall were evaluated in the diet of birds from 21 to 67 weeks of age. The results showed an increase in feed intake, egg production and mass as well as a higher albumen height and Haugh unit. The shell thickness and yolk color were also affected by treatments. The economic viability analysis demonstrated that even spending more on feed an increase in the average gross margin due to increased egg production was observed. Therefore, the cell wall yeast showed a beneficial effect on production performance of laying hens, represented by an improvement of internal and external egg quality, combined with higher profitability. Hydrolyzed yeast was evaluated at the levels of 0, 1, 2 and 4 kg/t. Two periods were analyzed, 21-40 and 48-67 weeks of age. The addition of hydrolyzed yeast in the diet of laying hens did not show improvement of the analyzed characteristics in the first period, however the benefits occurred in the second period. The use of yeast although generate a minor amount of non-commercial eggs, promoted an increase in feed consumption, production, egg mass and weight, improving quality of eggs in relation to Haugh unit, albumen height, shell thickness and resistance; and also improves the feed conversion by eggs mass and dozen. The supplementation of hydrolyzed yeast for laying hens provided increase overall average gross margin on all tested levels, demonstrating to be economically viable. The inclusion of hydrolyzed yeast in the diet of laying hens from 48-67 weeks of age maximized production performance and egg quality, being its use economically viable.

O experimento foi realizado na unidade de creche do Laboratório de Pesquisa em Suínos (LPS) da Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo (FMVZ-USP), campus de Pirassununga (SP), sendo utilizados setenta e dois leitões recém desmamados (21 dias), com peso médio de 6,5 kg. O delineamento experimental foi em blocos casualizados, num arranjo fatorial 2 x 2, sendo os fatores: probiótico e desafio, os quais definiram os tratamentos: T 1 - emprego do probiótico, com desafio (CPCD); T 2 - emprego do probiótico, sem o desafio (CPSD); T 3 - ausência do probiótico, com desafio (SPCD); T 4 - ausência do probiótico e sem o desafio (SPSD). As faixas de ganho médio de peso diário consideradas foram: dos 21 aos 35 dias (GMPD 35); dos 35 aos 49 dias (GMPD 49); dos 49 aos 63 dias (GMPD 63) e dos 21 aos 63 dias (GMPD Total). Os leitões foram submetidos ao desafio em sala separada, 14 dias após a distribuição nos tratamentos. O desafio foi realizado com uma amostra de E. coli positiva para as toxinas LT e ST b e para as fímbrias K 88 e F 18. A colheita das fezes foi feita após o desafio, em três períodos (35, 42 e 49 dias de idade dos leitões), para contagem de coliformes fecais, sendo analisadas pelo Laboratório de Sanidade Suína da FMVZ-USP, em São Paulo. A ração oferecida aos leitões foi semelhante à empregada comercialmente nas criações, havendo somente suplementação ou não do probiótico. O experimento avaliou o desempenho dos leitões através do ganho de peso diário (GMPD) e peso (P), acrescido da verificação da consistência das fezes e da contagem de coliformes fecais. Os resultados mostraram interação significativa entre probiótico e desafio quanto ao GMPD 49, indicando nesse período, o ponto de inflexão que caracterizou o início da mudança no comportamento desta variável. Com relação à consistência das fezes, o probiótico agiu reduzindo o percentual de fezes cremosas, confirmando sua ação protetora da mucosa intestinal, reduzindo a perda de líquido e, conseqüentemente, a diarréia. Além de atuar melhorando os parâmetros relativos ao desempenho e à consistência das fezes, a utilização do probiótico promoveu uma alteração na contagem de E. coli, reduzindo-a para um valor inferior, 14 dias após o desafio, reforçando assim a sua ação benéfica junto á manutenção da integridade intestinal / The experiment was conducted in the nursery unit at the Swine Research Laboratory from the FMVZ, University of São Paulo, Pirassununga campus, where we used 72 piglets recently weaned (about 21 days) with the average weight of 6,5 kg. The experiment was outlined in random blocks system, 2 x 2 factorial arrangements, being the factors: probiotic and challenge. The treatment was: T1 ? use of the probiotic, with challenge (CPCD); T2 ? use of the probiotic, without the challenge (CPSD); T3 ? no probiotic, with challenge (SPCD); T4 ? no probiotic and no challenge (SPSD). The intervals of weight daily gain considered were 21 to 35 days (GMPD 35); 35 to 49 days (GMPD 49); 49 to 63 days (GMPD 63) and 21 to 63 days (GMPD Total). The piglets were kept in two different rooms. One of the groups was challenged 14 days after the distribution in the treatments, in a separated room and for the challenge we used a sample of E.coli positive for the toxins LT and ST b and also for the pilli K88 and F18. The samples of feces were collected after the challenge in three periods (35, 42 and 49 days of age of the piglets) and sent to the Swine Health Laboratory at the FMVZ-USP, São Paulo campus, where the count of some species of intestinal bacteria was performed. The feed offered to the piglets was the same used in commercial swine herds. The only difference was the use or not of the probiotic. The experiment evaluated the development of the piglets through the amount of weight (AW) they gained and the average daily gain (ADG) of weight, plus the verification of the consistency of the feces and the count of some intestinal bacteria. The results showed a significant interaction between the probiotic and the challenge, as related to GMPD 49, indicating in this period the point of inflexion that characterized the beginning of the change in behavior of this variable. Analyzing the consistency of the feces we have notice that the probiotic has reduced the percentage of creamy feces, confirming its protective action in the intestinal mucus, reducing the loss of liquid and consequently the diarrhea. Together with the positive effect on the performance, the probiotic reduced the abnormal consistency of the feces, specially the creamy ones, as well as decreased the counting of E.coli 14 days after the challenge, keeping the intestinal integrity

Sorvetes são alimentos que apresentam grande potencial como veículo de espécies de micro-organismos probióticos, tendo em vista que apresentam elevada aceitabilidade em todas as faixas etárias. Os alimentos elaborados a base de soja se destacam no mercado devido às inúmeras evidências científicas sobre seus efeitos benéficos à saúde humana. Desta forma, no presente trabalho objetivou-se o desenvolvimento de sorvetes probióticos formulados com diferentes extratos solúveis de soja (in natura e fermentados), utilizando-se a cepa Lactobacillus delbrueckii UFV H2B20. Primeiramente, avaliou-se o desempenho fermentativo (pH e acidez titulável) de 5 cepas de Lactobacillus em meio formulado com os extratos solúveis de soja ESL e ES60, cujos resultados demonstraram que estes extratos são adequados para a formulação de meios de fermentação. Na sequência foram processados sorvetes probióticos formulados com os respectivos extratos in natura (ESL e ES60) e fermentado (ESL F e ES60 F) por Lactobacillus delbrueckii UFV H2B20. Nos sorvetes confeccionados com os extratos na forma in natura, uma suspensão de células da referida cepa foi adicionada à calda previamente ao processo de batimento e congelamento. Os sorvetes foram estocados a -23 ºC por 5 meses e avaliados periodicamente quanto às características físico-químicas (pH, acidez titulável, composição centesimal e overrun), microbiológica (viabilidade celular) e sensoriais. Os resultados demonstram que a cepa de Lactobacillus avaliada foi capaz de fermentar os açúcares presentes nos respectivos extratos de soja produzindo ácido láctico, atingindo a concentração de 0,90% no meio formulado com o extrato de soja desengordurado ES60. Os sorvetes confeccionados com os respectivos extratos fermentados apresentaram diferenças significativas (P<0,05) quanto ao pH e acidez titulável em relação aos sorvetes com extratos in natura, atingindo valores de pH inferiores a 4,0 com produção máxima de ácido láctico de 1,36%. A composição centesimal dos sorvetes desenvolvidos está de acordo com o padrão mínimo estabelecido pela ANVISA, apresentando uma composição média de 2,5% de proteínas, 5,0-6,0% de gordura e 36,0% de sólidos totais. As características probióticas dos sorvetes estudados foram preservadas, apresentando contagens de células viáveis superiores a 106 UFC/g, com redução do número de células inferior a um ciclo logarítmico ao longo de 150 dias de estocagem a -23ºC. A análise sensorial revelou que os sorvetes formulados com os respectivos extratos in natura não apresentaram diferenças significativas entre si (P>0,05) para os atributos avaliados e apresentaram maior aceitabilidade, sendo o sorvete formulado com o extrato ESL o que obteve maior aceitação, com médias acima de 6,0 correspondente a \"gostei ligeiramente\". Os resultados demonstraram ainda que a fermentação dos extratos interferiu negativamente nas características sensoriais dos respectivos sorvetes, apresentando diferenças significativas em relação aos extratos in natura, além de resultar nos menores escores de aceitação, tendo o sorvete fermentado ES60 F sido avaliado como \"desgostei moderadamente\". Estes resultados permitem concluir que o extrato solúvel de soja é um insumo adequado para a formulação de meio de cultivo de espécies de microorganismos probióticos, além de apresentar potencial para a confecção de sorvetes probióticos mediante adaptações da tecnologia de produção de gelados comestíveis. / Ice creams are foods that have great potential as a vehicle for species of probiotic microorganisms due to its high acceptability by all age people. Foods made with soybeans byproducts stand out in the market due to the numerous scientific evidences that show its beneficial effects on human health. Therefore, this study aimed to the development of probiotic ice cream formulated with different soybean soluble extracts (in natura and fermented), using the strain Lactobacillus delbrueckii UFV H2B20. Primarily, it was evaluated the fermentation performance (pH and titratable acidity) of 5 Lactobacillus strains in media formulated with soluble soybean extracts ESL and ES60 (Olvebra®), and the results showed that these soybean byproducts are suitable for the formulation of fermentation media. The probiotic ice cream were formulated with the soybean extracts in natura (ESL and ES60) and fermented (ESL F and ES60 F) by Lactobacillus delbrueckii UFV H2B20. For the manufacture of ice cream with the soybean extracts in natura, a cell suspension was added to the basic ice cream formulation before beating and freezing procedures. The ice creams were stored at -23 ° C for 5 months and evaluated periodically regarding the physico-chemical characteristics (pH, titratable acidity, chemical composition and overrun), microbiological (cell viability) and sensorial evaluation. The results shown that the Lactobacillus strain were capable to metabolize the sugars presented in the soluble soybean extracts producing lactic acid reaching a concentration of 0.90% in the media formulated with defatted soybean extract ES60. The ice creams made with fermented extracts showed significant differences (P <0.05) regarding pH (< 4,0) and titratable acidity (1,36%) in relation to the ice creams manufactured with extracts in natura. The results concerned to the chemical composition of the ice cream, showed that the values obtaneid are in accordance with those stablished by ANVISA, presenting an average composition of 2.5% protein, 5,0-6,0% fat and 36,0% total solids. The probiotic characteristics, of the formulated ice creams, were preserved presenting viable cell counts greater than 106 UFC/g, and a decreasing in the cell number lower than one log cycle after 150 days of storage at -23 ºC. Regarding the sensorial evaluation, the results revealed that the ice creams formulated with soybean extracts in natura showed no significant differences between them (P> 0.05) for the evaluated attributes and they showed higher acceptability. The ice cream formulated with ESL extract presented higher acceptance, with average notes greater than 6.0, corresponding to \"like slightly\". The results also showed that the fermentation of the extracts influenced negatively on the sensory properties of the ice cream, showing significant differences regarding the ice cream made with the extracts in natura, and lower acceptance scores, being the fermented ice cream ES60 F evaluated as \"moderately disliked\". These results indicate that the soluble soybean extracts evaluated in the present work are suitable for culture medium formulation for probiotic microorganisms, and also shown its potential for making probiotic ice cream by adaptation of the technology.

Les bactéries lactiques présentent un grand intérêt économique de par leur large utilisation dans l’industrie agroalimentaire. Parmi elles, Streptococcus thermophilus (ST) est d’une importance majeure puisqu’elle est la plus utilisée après Lactococcus lactis, pour la fabrication de produits laitiers fermentés et de fromages. De plus, cette bactérie est le seul streptocoque à bénéficier du statut GRAS (Generally Recognized As Safe). Outre son intérêt en industrie laitière, ST présente des effets bénéfiques sur la santé intestinale de l’Homme. Bien que ces effets soient largement documentés, le statut probiotique de ST reste encore à conforter. C’est pourquoi des études sont actuellement menées afin de sélectionner des souches de ST à fort potentiel probiotique. Parmi les critères importants figurent leur capacité à survivre aux conditions drastiques du tube digestif (TD) et leur capacité à adhérer aux cellules intestinales. Dans cette optique, les objectifs de cette thèse étaient d’étudier, dans un premier temps, la capacité d’adhésion in vitro de la souche ST LMD-9 à différentes lignées cellulaires intestinales d’origine humaine et d’évaluer la survie de cette souche au stress biliaire. Afin de mettre en évidence un rôle potentiel de certaines protéines de surface dans ces deux processus, trois mutants issus de cette souche et inactivés dans les gènes prtS (protéase pariétale), srtA (sortase A) et mucBP (protéine de liaison aux mucines), ont été inclus dans cette étude. Dans un second temps, l’impact de l’adhésion de LMD-9 a été analysé, d’une part sur l’expression de gènes codant certaines mucines dans les cellules eucaryotes, et d’autre part sur l’expression de gènes qui seraient spécifiquement induits durant le processus d’adhésion, ceci en utilisant la technologie R-IVET (Recombinase-based In Vivo Expression Technology). Les résultats obtenus ont permis de montrer que la souche LMD-9 était capable de survivre jusqu’à une concentration de 3 mM en sels biliaires et que les protéines de surface PrtS, SrtA et MucBP seraient impliquées dans la résistance à ce stress. Nos résultats ont également montré que LMD-9 adhérait aux trois différentes lignées cellulaires, suggérant ainsi que la souche pourrait interagir avec les différentes mucines qu’elle peut rencontrer dans le TD. De plus, l’implication de certaines protéines de surface dans l’adhésion de LMD-9 s’est avérée dépendante des caractéristiques de ces lignées, qu’il s’agisse de cellules entérocytaires (Caco-2) ou productrices de mucus (HT29-MTX et HT29-CL.16E). Concernant l’impact de l’adhésion de la souche LMD-9 sur l’expression des gènes MUC2 et MUC5AC, aucun effet sur le taux de transcrits n’a été observé dans nos conditions expérimentales. Par ailleurs, nos résultats ont permis, pour la première fois, d’identifier les gènes spécifiquement induits dans la souche LMD-9 durant l’adhésion aux cellules épithéliales. Nous avons ainsi montré que l’adhésion de la souche LMD-9 ne dépend pas uniquement des protéines de surface, mais d’autres fonctions et voies métaboliques seraient également impliquées. Ce travail de thèse contribue ainsi à apporter de nouvelles connaissances liées (i) au choix du modèle cellulaire dans les études d’adhésion bactérienne in vitro, (ii) à l’aptitude de la souche LMD-9 à survivre au stress biliaire en faisant intervenir certaines protéines de surface et (iii) à la compréhension des mécanismes moléculaires de l’adhésion de LMD-9 aux cellules épithéliales intestinales / Lactic acid bacteria are of great economic interest because of their use in the food industry. Among them, Streptococcus thermophilus (ST) is of major interest since it is the most used after Lactococcus lactis, for the manufacture of fermented dairy products and cheese. In addition, this bacterium is the only streptococcus to benefit from GRAS status (Generally Recognized As Safe). Beside its interest in the dairy industry, ST has beneficial effects on human intestinal health. Although these effects are widely documented, the probiotic status of ST remains to be consolidated. Therefore, studies are currently being conducted in order to select strains of ST with a high probiotic potential. Among criteria that are important to select ST strains include their ability to survive stress the drastic conditions of the digestive tract (DT) and their ability to adhere to intestinal cells. In this context, the aim of this thesis was to investigate firstly the in vitro adhesion capacity of the ST LMD-9 strain to different human intestinal cell lines and to evaluate the survival of this strain to bile salt stress. In order to highlight the potential role of some surface proteins in these two processes, three mutants derived from this strain and inactivated in the genes prtS (parietal protease), srtA (sortase A) and mucBP (Mucin Binding-protein) were also included in this study. Secondly, the impact of LMD-9 adhesion was analyzed, on one hand on the expression of some mucin-encoding genes in eukaryotic cells, and on the other hand on the expression of genes that would be specifically induced during adhesion process using the R-IVET (Recombinase-based In Vivo Expression Technology) approach. The results obtained demonstrated the ability of LMD-9 to survive up to the concentration of 3 mM of bile salts and that the PrtS, SrtA and MucBP surface proteins would be involved in the resistance to this stress. Our results also showed that the LMD-9 strain was capable of adhering to three cell lines used suggesting that this strain could interact with different mucins that may encounter in the DT. Moreover, the involvement of some surface proteins in the adhesion of LMD-9 has been found to be dependent on the surface characteristics of these cell lines, whether they are enterocytic (Caco-2) or mucus-secreting cells (HT29-MTX and HT29-CL.16E). Regarding the impact of LMD-9 adhesion on MUC2 and MUC5AC gene expression, no effect has been observed on the transcript level under our experimental conditions. Furthermore, for the first time, our results allowed us to identify genes specifically induced in the LMD-9 strain during adhesion process to epithelial cells. We have thus shown that the LMD-9 adhesion does not depend solely on surface proteins, but other functions and metabolic pathways are also involved. This thesis work contributes thus to new knowledge related to (i) the choice of the cellular model in in vitro bacterial adhesion studies, (ii) the ability of LMD-9 to survive bile salt stress by involving some surface proteins and (iii) understanding the molecular mechanisms of LMD-9 adhesion to epithelial cells