The total removal of antibiotic growth promoters (AGP) from poultry feed is underway in the United States. Feed additive strategies will be utilized to maintain the efficient growth, health, and economic value found with current commercial broiler production. Experiment 1 investigated the effects of feeding an encapsulated butyric acid and zinc product (EBAZ) at 3 inclusions on d 0- 49 Ross x Ross 708 male and female broiler performance, blood chemistry, and cecal short-chain fatty acid content. These data suggest that EBAZ can be safely included at 0.5 g/kg and at 2.5 g/kg into diets for Ross x Ross 708 male and female broilers. The objective of the second experiment was to examine the efficacy of 2 commercially available carbohydrases in commercial diets on d 0-57 male broiler performance and processing. The resulting data demonstrates that the inclusion of xylanase (CE2) improved broiler performance thus, increased potential gross profits.

No description available.

The components of soil CO2 efflux are affected by many soil properties including temperature, moisture, microbial abundance and activity, and other soil physical and chemical properties. Changes in these factors can result in high spatial and temporal variability of total soil CO2 efflux. Low molecular weight organic acids (LMWOAs), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), microbial biomass and activity were measured to evaluate the impact of intercropping switchgrass (Panicum virgatum L.) in a loblolly pine (Pinus taeda L.) plantation. Surface soil samples (0-15 cm) were collected on the bed (PSG-B), interbed (PSG-I) and edge (PSG-E) of pine-switchgrass intercropped treatments, as well as pine only (P-B) and switchgrass only (SG-I) treatments. Differences in most soil properties and processes of intercropped treatments were sporadic and most did not show clear trends. However, significant correlations between DOC, soil temperature, oxalic and acetic acids and soil CO2 efflux were present. In an multiple regression model these factors explained 57% of the variance in total soil CO2 efflux. Therefore we think that LMWOAs, as a labile component of DOC, are influencing total CO2 efflux because they are being consumed by microbial community, increasing heterotrophic respiration and as a result overall total CO2 efflux. The amount and distribution of labile C controls microbial community dynamics, heterotrophic respiration as well as the stabilization of soil C. / Master of Science

The antibacterial efficacy of hydrogen peroxide treatments in four fruit juices was determined. Preservative free apple cider, white grape, and purple grape juice were inoculated with ~ 6.4 log CFU/ml of a five strain, acid adapted, nalidixic acid resistant E. coli O157:H7 cocktail. Orange juice was inoculated with a comparable Salmonella spp. cocktail. In the first study, 0.017% and 0.012% H₂O₂ was added in combination with 0.1% and 0.3% of the dominant organic acid (OA) to 4°C and 25°C juices, with samples taken each day for 21 days. H₂O₂ was a significant factor in all juices (p < 0.05) except white grape (lack of data), and both 0.017% H₂O₂ treatments reduced counts in apple cider, orange juice, and white grape to undetectable numbers within 48 hrs as cultured on tryptone soy agar + 0.05% nalidixic acid (TSAN). Treatments in purple grape juice were less effective overall, and more dependent on OA concentration (p < 0.001) than H₂O₂. There were instances where bacterial survival in apple cider, purple grape, and orange juice continued for 21 days after treatment, and sometimes outlasted the control. These occurrences were dependent on temperature (25°C) and H₂O₂ (0.012%), but not on OA. However, OA concentration was a significant factor (p < 0.05) overall in apple cider and purple grape juice, but not in orange juice. In the second study, 0.015% and 0.03% H₂O₂ was added to 10, 25, and 40°C apple cider and orange juice inoculated with 6.4 log CFU/ml E. coli O157:H7 and Salmonella spp. respectively. Only 0.03% H₂O₂ was effective in reducing counts to undetectable numbers in both juices. However, both temperature and H₂O₂ were significant factors (p < 0.0001) in bacterial destruction, with 0.03% H₂O₂ at 40°C giving undetectable numbers at ≤ 3 and ≤ 6 hours in orange juice and apple cider respectively. It has been demonstrated that at ~ ≥ 0.017%, H₂O₂ can provide a 5 log reduction of these pathogens in fruit juice. Increasing temperature and organic acid concentration can improve its rate of effectiveness in certain juices. However, sensory concerns may negate its use in some products. / Master of Science

Orientador: Valquíria Cação Cruz-Polycarpo / Resumo: Os ácidos orgânicos protegidos têm mecanismo de ação diferenciado dos ácidos orgânicos não protegidos, permitindo que sua atuação aconteça em uma área específica do intestino, possibilitando maior eficácia em sua ação como antimicrobiano, o que influenciará as condições do trato gastrintestinal, e consequentemente o desempenho. Para tanto, foram utilizados 1.320 pintos de corte machos, Cobb, distribuídos em um delineamento inteiramente casualizado, com cinco tratamentos e seis repetições. Os tratamentos consistiram em: T1 - Ração Basal (RB); T2 - RB + ácido butírico livre (L); T3 - RB + ácido butírico microencapsulado (M); T4 - RB + ácido butírico L+M; T5 - RB + antibiótico e anticoccidiano. Aos 16 dias de idade, todas as aves foram desafiadas por meio da inoculação de um pool de Eimerias. Foi observado efeito dos ácidos fornecidos de forma isolada no GP e CR das aves nas fases de 1 a 14 e 1 a 21 dias, quando comparado com o os ácidos na forma associada. Aos 42 dias, aves que foram suplementadas com o ácido butírico, independente da forma, apresentaram queda no desempenho. Após o desafio, os aditivos proporcionaram recuperação da mucosa, mostrando melhorias na altura das vilosidades em relação ao grupo controle negativo, além do aumento de células caliciformes por vilo no jejuno das aves suplementadas com o ácido na forma livre. O número de oocistos excretados por grama de fezes mostrou interação entre aditivo e período de coleta. Na leitura de escore de lesão foi observado q... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Por se tratar de um elemento essencial às plantas e um metal pesado ao mesmo tempo, o níquel requer atenção quanto aos aspectos da fisiologia de plantas e ambiental. Além disso, existe um intervalo estreito entre as exigências nutricionais e os teores tóxicos às plantas. Neste contexto, objetivou-se avaliar o efeito do Ni no sistema solo-planta, com foco no ciclo do N e a disponibilidade do elemento no solo, por meio de experimento em condições controladas, utilizando vasos distribuídos inteiramente ao acaso, utilizando-se esquema fatorial 2 x 5, com sete repetições cada tratamento. O primeiro fator foi constituído de duas saturações por base (50 e 70%) e o segundo de cinco doses de Ni (0; 0,1; 0,5; 1,0 e 10,0 mg dm-3 de solo). Os vasos foram preenchidos com 8 dm3 de terra e cultivados com soja [Glycine max (L.) Merrill] sucedida por girassol (Helianthus annuus L.). Os parâmetros qualitativos e quantitativos: altura de plantas (AP), diâmetro do caule (DC), número de nós (NN), estádio fenológico (EF), índice SPAD e, diâmetro do capítulo (DCap) (para girassol) foram avaliadas aos 30 e 60 dias após a emergência (d.a.e.) de cada cultivo. Plantas inteiras de soja, amostradas em quatro vasos de cada tratamento, foram coletadas no estádio R1. Na mesma ocasião foram coletadas amostras de solo da rizosfera. Em seguida, as plantas coletadas foram divididas em: folhas; raízes (nódulos na soja) e parte aérea. Foram determinados nas folhas utilizadas para diagnose em soja e girassol: os teores de macro e micronutrientes, as atividades da redutase do nitrato e da urease e as concentrações dos ácidos orgânicos: oxálico, malônico, succínico, málico, tartárico, fumárico, oxaloacético, cítrico e lático. Os mesmos ácidos orgânicos foram determinados em raízes secundárias de girassol e nódulos de soja. Foram realizadas avaliações ultraestruturais por meio de microscopia eletrônica de transmissão (MET) em raízes de girassol, e estruturais e de tonalidade em nódulos de soja, por meio de microscopia de luz. No solo, foram determinadas: atividade urease, desidrogenase, Ni total e fitodisponível pelos métodos: Mehlich-1, Mehlich-3 e DTPA. No período de maturidade fisiológica de cada cultura foi realizada a colheita das plantas dos vasos restantes para determinação de produção de grãos, teores de Ni na planta inteira e Ni e N nos grãos. Ao final dos dois experimentos foi realizada nova coleta de solo para extração sequencial de Ni. O índice SPAD em soja aos 60 d.a.e., a produção de massa seca da parte aérea da soja e da raiz de girassol foram influenciados pela saturação por bases, doses de níquel e pela a interação destes. Foram influenciados pelas saturações por base e doses de níquel (fatores isolados): para soja: AP aos 60 d.a.e., NN aos 30 e 60 d.a.e., SPAD aos 30 d.a.e.; para girassol: AP e NN aos 30 e 60 d.a.e., DC e SPAD aos 30 d.a.e. As demais variáveis avaliadas aos 30 e 60 d.a.e. foram influenciadas apenas pela saturação por bases, ou doses de Ni separadamente. As plantas de soja e girassol apresentaram maiores teores de Ni nos diferentes tecidos avaliados (exceto grãos) quando cultivadas sob V50%. A produção de grãos de soja e girassol não foi influenciada pelos tratamentos, porém o teor de N dos grãos de soja influenciado pelas doses de Ni na V70%. A atividade da enzima urease nas folhas de soja e girassol foi responsiva positivamente ao aumento das doses de Ni. Quatro dos ácidos orgânicos avaliados e o teor de N nas folhas e nos grãos foram maiores nas plantas cultivadas sob V70% com a dose de 0,5 mg dm-3 de Ni. As doses de Ni bem com as saturações por bases influenciaram diretamente o balanço de nutrientes das plantas. Os extratores Mehlich-1, Mehlich-3 e DTPA apresentaram elevado coefienciente de correlação entre a fração de Ni disponível no solo e a concentração do elemento nas plantas de soja e girassol, sendo o extrator DTPA o que apresentou maior coeficiente de correlação. O Ni apresentou distribuição variável entre as diferentes frações do solo em função dos tratamentos. Os solos dos tratamentos com saturação por bases de 70% apresentaram maior concentração de Ni ligado a carbonato, comparado aos tratamentos sob saturação por bases de 50%. A distribuição do Ni entre as frações do solo seguiu a seguinte orgem: ligado a carbonato < trocável < ligado a óxidos < matéria orgânica < residual. A saturação por bases exerceu efeito diferenciado para a atividade da urease no solo em função da cultura avaliada. Por sua vez, o Ni exerceu efeito diferenciado sobre a atividade de desidrogenase em função da cultura estudada / As an essential element for plants and a heavy metal at the same time, nickel requires attention on the aspects of the physiology of plants and environmental. Furthermore, there is a narrow range between nutritional requirements and toxic levels to plants. In this context, the aim was to evaluate the effect of Ni in soil-plant system through experiment under controlled conditions, using soil pots distributed entirely at random, using a factorial 2 x 5, with seven repetitions each treatment. The first factor was formed of two saturations base (50 and 70%) and the second of five Ni rates (0, 0.1, 0.5, 1.0 and 10.0 mg dm-3 of soil). The pots were filled with 8 dm3 of soil and sown with soybean [Glycine max (L.) Merrill] succeeded by sunflower (Helianthus annuus L.). The agronomic traits: plant height (PH), stem diameter (SD), number of nodes (NN), phenological stage (PS), SPAD index, head diameter (HD) (Sunflower) were evaluated at 30 and 60 days after emergence (dae) of each crop. Whole soybean plants, sampled in four pots of each treatment were collected at the R1 stage for analysis of soil samples from the rhizosphere. Then, the collected plants were divided into: sheets; roots (nodules on soybean) and shoot. Were determined in the leaves used for diagnosis in soybean and sunflower: macro and micronutrients, activities of nitrate reductase, and urease and concentrations of organic acids: oxalic, malonic, succinic, malic, tartaric, fumaric, oxaloacetic, citric and lactic. The same organic acids were determined in secondary roots of sunflower and nodules of soybean. They were conducted ultrastructural evaluations by means of transmission electron microscopy (TEM) in sunflower roots, and color in soybean nodules, using light microscopy. In the soil were determined: urease activity dehydrogenase, the total Ni and available by methods: Mehlich-1, Mehlich-3 and DTPA. At physiological maturity period of each culture was performed to harvest the plants of other pots in order to determine grain dry matter yield, Ni content in the whole plant and Ni and N content in grains. At the end of the two experiments it were carried out new soil sampling for Ni sequential extraction. The SPAD index taken on soybean leaves at 60 d.a.e., the dry matter production of the aerial part of soybean and sunflower root were influenced by the base saturation, nickel doses and the interaction among them. They were influenced by the saturation for base and nickel doses (single factor): soybean: HP d.a.e. to 60, NN at 30 and 60 d.a.e., SPAD to 30 d.a.e.; Sunflower: PH and NN at 30 and 60 d.a.e., HD and SPAD to 30 d.a.e. The other variables assessed at 30 and 60 d.a.e. They were influenced only by base saturation, or Ni doses separately. Sunflower soybean plants had higher Ni contents at the different tissues (except grain) when grown under V50%. The production of soybean and sunflower grains was not affected by the treatments, but the N content of the soybeans was changed by Ni rates V70%. The urease enzyme activity in soybean and sunflower leaves was responsive to increased doses of Ni. Four of the organic acids and the N content in leaves and grains were higher in plants grown under V70% at the dose of 0.5 mg dm-3 Ni. Ni rates as well as the cation base saturation directly influenced the balance of plant nutrients. The Mehlich-1, Mehlich-3 and DTPA presented higher coefiencient correlation between available Ni soil fraction with nutrient concentrations in both soybean and sunflower, with the DTPA solution showing the highest correlation coefficient in this analysis. Ni showed variable distribution among different soil fractions in the treatments. The treatments presented soil under cation bases saturation of 70% showed higher Ni concentration linked to carbonate, as compared to treatments under cation base saturation of 50%. The distribution of Ni between the soil fractions followed the following order: bound to carbonate <exchangeable < bound to oxides <organic matter <residual. The cation base saturation showed different effects on the urease activity according to the plant evaluated. Ni exerted on the differential effect dehydrogenase activity according to the plant specie

Atualmente os supermercados vêm utilizando para a exposição de carnes frescas, bandejas rígidas revestidas de filmes plásticos permeáveis a gases. Esse sistema protege a superfície da carne de possíveis contaminações e permite a seleção dos cortes pelo consumidor. No entanto, essa forma de acondicionamento limita a vida útil da carne, especialmente dos cortes com osso. Dessa maneira, o presente trabalho de pesquisa objetivou estudar a interação entre as diferentes tecnologias - embalagem com atmosfera modificada, ácidos orgânicos e antioxidante - aplicando-se diferentes concentrações de dióxido de carbono (CO2) combinado com o nitrogênio (N2) e monóxido de carbono (CO) (composições gasosas: C1: 99,6%CO2/0,4CO; C2: 19,6%N2/80%CO2/0,4%CO; C3: 49,6%N2/50%CO2/0,4%CO e C4: 50%CO2/50%N2;) e seus efeitos nas características físico-químicas, sensoriais e microbiológicas de bisteca e de costela suína, armazenadas a temperatura de 2+ 2 ºC por um período de 32 dias. Após a obtenção dos referidos cortes na sala de desossa, metade foram pulverizados com a solução de ácidos orgânicos (1% de ácido acético, 1% de ácido lático e 1% de ácido cítrico) e antioxidante (0,8% de ácido ascórbico), e a outra metade não foi pulverizada. A seguir, as amostras pulverizadas ou não, foram colocadas em bandejas plásticas rígidas dentro de saco-filme impermeável a gases. O conjunto, produto mais bandeja foi submetido a três diferentes misturas gasosas, sendo C1, C2 e C3 para costela e C2, C3 e C4 para bisteca. Foram realizadas avaliações físico-químicas, microbiológicas e sensoriais nos 0 (caracterização da matéria-prima), 1º, 5º, 13º, 19º, 25º e 32º dias. Concluiu-se que o uso das composições gasosas: 19,6%N2/80%CO2/0,4%CO e 49,6%N2/50%CO2/0,4%CO, para a bisteca, e a três composições para costela, mantiveram a estabilidade da cor visual e instrumental da carne, do osso e da gordura durante todo o período de estudo. O odor foi predominantemente ácido em todas as amostras desde o primeiro dia de análise. As concentrações de CO2 usadas não foram efetivas na redução das contagens microbianas devido a elevada carga microbiana inicial da matéria-prima. Houve prevalência de bactérias láticas em todas as amostras após o 19º dia, e a vida útil foi de no mínimo 13 dias para todos os tratamentos. / Supermarkets have been using rigid trays covered with gas permeable films to expose fresh meat. This system keeps the meat surface free from contamination and allows the consumer choice, although this type of packaging shortens the meat shelf life, especially cuts with bone in. Thus, the aim of the present was to evaluate the interaction among the followed different technologies: modified atmosphere and spraying of organic acids with antioxidants solution in the meat surface. The effect of four types of modified atmosphere containing different carbon dioxide concentrations combined with nitrogen (N2) and carbon monoxide (CO) (C1: 99,6%CO2/0,4CO; C2: 19,6%N2/80%CO2/0,4%CO; C3: 49,6%N2/50%CO2/0,4%CO e C4: 50%CO2/50%N2) on physical, chemical, sensory and microbiological characteristics were evaluated in portioned pork chops and pork ribs stored during 32 days in a cooling chamber at 2+ 2 ºC. Half of the cuts obtained from the carcasses deboned at CTC were randomly assigned for spraying with a solution containing acetic acid (1%), lactic acid (1%), citric acid (1%) and ascorbic acid (0,8%) while the rest was not sprayed. Following, the samples were packaged in rigid plastic trays covered with impermeable film/bag and subjected to three different atmospheres (pork chops - C1, C2 and C3 and pork ribs - C2, C3 and C4). During storage the physical, chemical, microbiological and sensory evaluations were conducted in the following periods: 0 (raw material), 1, 5, 13, 19, 25 e 32 days. It was concluded that the use of following gas composition: 19,6%N2/80%CO2/0,4%CO and 49,6%N2/50%CO2/0,4%CO kept the color stability for pork chops and the three compositions for pork ribs, either subjective or objective, of the meat, bone and fat during all the period of the experiment. The odor was acid in all samples from the first day of analysis. The percentages of CO2 used in the experiment were not effective to reduce bacterial count because the raw material had high initial count. There was prevalence of lactic acid bacteria in all samples after the 19º day and shelf life was at least 13 days for all treatments.

A salmonelose é uma das mais importantes causas de toxinfecção alimentar em humanos, provocando sérios problemas à saúde pública, além de ser uma das doenças de maior impacto na produção avícola. Em vista disso, este estudo objetivou avaliar o uso de ácido fórmico no controle de Salmonella Enteritidis (SE). Assim, foram utilizados 360 pintinhos de um dia de idade: 50% das aves foram inoculadas via inglúvio com 3x107 UFC/0,1mL de SE e 50% não (aves contactantes). As aves foram divididas em cinco (05) grupos com seis (06) repetições cada: T1) controle sem o aditivo; T2) ácido fórmico 0,3% na ração; T3) ácido fórmico 0,2% na ração; T4) ácido fórmico diluído em água de beber até que a mesma atingisse um pH 4; T5) ácido fórmico 0,2% protegido na ração. As aves receberam ácido do 1º ao 7º dia e do 35º ao 42º dia. A cada sete dias, amostras de fezes foram colhidas da cama em todos os grupos para se avaliar o isolamento de SE. Aos 42 dias foram colhidas à necropsia amostras de inglúvio, fígado/baço e ceco para o isolamento de SE e sangue para a avaliação sorológica. Nas aves do T1, do T2 e do T5 SE foi isolada do inglúvio, fígado/baço e ceco das aves inoculadas e das contactantes. Houve isolamento de SE no T3 apenas em inglúvio e ceco das aves inoculadas e, no T4, apenas do ceco das contactantes. Em todos os grupos SE foi reisolada do material da cama, embora não em todas as semanas. A avaliação sorológica realizada com teste comercial de ELISA revelou aves sororeagentes no T1 (inoculadas e contactantes), no T2 (inoculadas) e no T3 (contactantes). Nenhuma ave foi sororeagente no T4 e T5. A transmissão horizontal foi evidenciada em todos os grupos estudados. Os dados foram comprovados por ANOVA e teste LCD. Nos grupos T3 e T4 o ácido fórmico foi eficaz em reduzir a presença e a transmissão horizontal de SE. / Salmonellosis is one of the most common and widely distributed foodborne diseases, with tens of millions of human cases occurring worldwide every year. Furthermore, this disease is responsible to significant economic losses to the poultry industry. Endemic infection of broiler chickens with Salmonella. Enteritidis (SE) and consequential human illness has been well documented. For these reasons the aim of this study was to evaluate the use of formic acid to control SE in broilers experimentally infected. Thus 360 day-old chicks were used in the experiment: 50% (180) of birds were inoculated in crop with 3x107CFU/0.1 mL of SE and 50% (180) were used as controls and kept in contact with the infected chicks. For the formic acid treatment the birds were divided into five (05) groups with six (06) replicates as follows: T1) control without additive; T2) 0.3% formic acid in the diet ; T3) 0.2% formic acid in the diet ; T4) formic acid diluted in drinking until it reached pH 4 water; T5) 0.2% formic acid microencapsulated in the food. The birds received the formic acid from the 1st to 7th day and from the 35th to 42nd days. Every seven days faeces samples were collected from the chick\'s litter and SE isolation was attempted. In the 42 day blood samples were collected for serological evaluation by means of Elisa. Additionally samples from the crop, liver/spleen and cecum were collected at necropsy and submitted to culture for SE detection. SE was isolated from crop, liver/spleen and cecum of the inoculated and contacts birds belonging to the T1, T2 and T5. Regarding the T3, SE was isolated in the crop and cecum of the inoculated birds and in the T4 only in the contacts chicks cecum. In all groups SE was isolated from the litter, although not in every week. Serological evaluation revealed serum positive birds in T1 (inoculated and contacts), T2 (inoculated) and T3 (contacts). Antibodies anti-SE were not detected in the serum from the birds of T4 and T5. Horizontal transmission was observed in all groups. The data were confirmed by ANOVA and LCD test. In groups T3 and T4 formic acid was effective in reducing the presence and horizontal transmission of SE.

Made available in DSpace on 2017-07-21T18:53:07Z (GMT). No. of bitstreams: 1 Jessica Teles.pdf: 1283462 bytes, checksum: 5784cdcc4b339768e1ee02500a793d75 (MD5) Previous issue date: 2016-04-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Propionic acid is an organic acid used as a preservative in foods and seeds, and as an ingredient in thermoplastics, medicaments, perfumes, fragrances and solvents. Its production takes place by conventional chemical synthesis that uses petroleum as raw material. Finding alternatives and more sustainable ways than the use of petroleum products has been shown an interesting option to the production of organic acids. The purpose of this study was to evaluate the propionic acid production from agroindustrial effluents by fermentation, using a culture of Propionibacterium acidipropionici CCT 4843. Whey, corn steep liquor and animal feed effluent were used as substrate. The substrates composition was based on an experimental design mixture, resulting in 10 samples. The substrates were fermented in batch borosilicate glasses at a temperature of 35°C, initial pH 6.5 and 20 mL.L-1 suspension of inoculum. After choose the substrate, a 33-1 factorial design was carried out, to see how the variable hydraulic retention time, inoculum concentration and pH affected the production of propionic acid. The propionic and other organic acids were detected using a high-performance liquid chromatography (HPLC). The corn steep liquor was chosen as the best a substrate for the factorial design, because it showed the highest propionic acid yield, 0.79 g. g substrate-1,propionic acid productivity of 5.20 mg.L-1.h-1 and production of 0.40 gL-1. It was found that hydraulic retention time and initial pH influenced on the yield and propionic acid productivity, but the initial inoculum concentration did not influence the answers. The highest propionic acid yield of 0.6275 g.g- 1, was obtained with 96 hours of hydraulic retention time, inoculum of initial concentration of 20 mL.L-1 and initial pH of 6.0.The best propionic acid productivity was obtained for hydraulic retention time of 60h, initial inoculum concentration of 30 mL.L-1 and initial pH of 6.5. It was concluded that propionic acid production is possible from agroindustrial waste, but the process conditions should be optimized to make it economically viable. / O ácido propiônico é um ácido orgânico utilizado como conservante em alimentos e sementes e como ingrediente em termoplásticos, drogas, perfumes, aromas e solventes. Sua produção convencional ocorre por síntese química, utilizando-se matérias primas obtidas do petróleo. Porém, com o aumento da preocupação ambiental e procura por alternativas ao uso de produtos derivados de petróleo, a produção de ácidos orgânicos por fermentação tem se mostrado uma opção interessante. O objetivo dessa pesquisa foi avaliar a produção de ácido propiônico a partir da fermentação de efluentes agroindustriais, utilizando a cultura Propionibacterium acidipropionici CCT 4843. Os efluentes utilizados como substrato foram soro de leite, milhocina e efluente da produção de ração animal. A composição dos substratos foi determinada a partir de um planejamento experimental de misturas, resultando em 10 ensaios. Os substratos foram fermentados em batelada em reatores de vidro borosilicato à temperatura de 35°C, pH inicial de 6,5 e 20 mL.L-1 de inóculo em suspensão. Após definida a composição do substrato, foi realizado o planejamento fatorial 33-1, para verificar como as variáveis Tempo de Detenção Hidráulica (TDH), concentração de inóculo e correção inicial de pH afetam a produção de ácido propiônico. A determinação do ácido propiônico e demais ácidos orgânicos foi realizada por Cromatografia Líquida de Alta Eficiência(CLAE). No planejamento fatorial para estudo das variáveis de processo foi utilizado como substrato apenas a milhocina, pois nos ensaios do planejamento experimental de misturas foi o que possibilitou o maior rendimento, com 0,79 g ácido propiônico. g substrato-1, com uma produtividade de ácido propiônico de 5,20 mg/L.h e produção de 0,40g.L-1. No segundo planejamento foi constatado que as variáveis tempo de detenção (TDH) e o pH inicial influenciam no rendimento e na produtividade de ácido propiônico, porém a concentração inicial de inóculo não influenciou nas respostas. O melhor rendimento obtido foi de 0,6275 g.g-1, com o ensaio com TDH de 96h, concentração inicial de inóculo de 20mL.L-1 em suspensão e pH inicial 6,0 ; e o melhor valor de produtividade obtido foi para o ensaio com tempo de detenção hidráulica de 60h, concentração inicial de inóculo de 30 mL.L-1 e pH inicial de 6,5. Foi concluído que é possível a produção de ácido propiônico a partir de efluentes agroindustriais, porém as condições de processo devem ser otimizadas para torná-lo economicamente viável.

La chromatographie en phase gazeuse couplée à la spectrométrie de masse simple quadripolaire (GC-qMS) est la technique la plus utilisée dans l’exploration des acides organiques urinaires dans le cadre du diagnostic des aciduries organiques (AO). Cependant, après analyse par GC-MS de plus de 1000 échantillons d'urines recueillis auprès d'enfants atteints de troubles neurologiques, moins de 0,5% d'entre eux ont reçu un diagnostic positif. Ceci témoigne de l’urgence de rechercher de nouveaux biomarqueurs dans le domaine des troubles neurologiques associés à des erreurs innées du métabolisme (EIM).L'objectif principal de cette thèse a été de développer une nouvelle méthode d’analyse des échantillons urinaires par chromatographie bidimensionnelle couplée à la spectrométrie de masse (GCxGC-qMS) et d'évaluer son apport dans le profilage métabolique de ces échantillons. Par ailleurs, dans le cadre du diagnostic des AO, dans un objectif de simplification de la procédure de préparation de l’échantillon, nous avons évalué une autre approche d’analyse directe en temps réel couplée à la spectrométrie de masse « DART-MS » des acides organiques urinaires. La première étape de notre travail a été de développer un protocole de préparation de l’échantillon compatible avec une méthode de séparation bidimensionnelle. Puis, grâce à l’étude systématique des différentes conditions de séparation, nous avons développé une méthode par CGxCG-qMS parfaitement adaptée à la séparation des composés extraits.Après validation analytique, la méthode proposée a été ensuite évaluée par le profilage des composés organiques présents dans des échantillons urinaires prélevés chez des volontaires sains. Par rapport aux profils obtenus par une méthode par GC-qMS classique, optimisée, les profils chromatographiques obtenus par la méthode proposée présentent une sensibilité et une résolution nettement plus élevées. Ceci se traduit par la détection en GCxGC-qMS de nombreux composés supplémentaires, jusqu’à 92, selon les échantillons. Parmi les composés supplémentaires détectés et caractérisés, certains sont d’un intérêt diagnostic reconnu.Malgré les difficultés liées à l’étape de préparation de l’échantillon et au traitement des données, l’ensemble des résultats obtenus par la méthode proposée sur de nombreux échantillons urinaires a confirmé les potentialités et la nécessité d’utiliser la chromatographie bidimensionnelle dans le domaine de la découverte de candidats biomarqueurs. Il s’agit maintenant de poursuivre l’identification des composés supplémentaires détectés dans les échantillons urinaires étudiés et d’appliquer la méthode proposée à un plus grand nombre d’échantillons témoins et pathologiques afin d’essayer d’identifier des candidats biomarqueurs.Enfin, les essais préliminaires par la technique DART-MS, effectués dans un laboratoire de la Direction des Applications Militaires (DAM) du CEA, ont été axés sur la détection d’un panel d’acides organiques représentatifs des différentes anomalies rencontrées lors des AO. Malgré les effets de suppression ionique qui restent à éliminer, les résultats obtenus montrent que cette approche mérite d’être approfondie. / Among inherited metabolic diseases, organic acidemia (OA) or organic aciduria is characterized by urinary excretion of abnormal amounts or types of organic acids. OA is mostly associated with genetic conditions resulting in a specific step of amino acid catabolism dysfunction. Such alterations can produce disease states that range from mild to lethal neurological involvement. Gas chromatography coupled to mass spectrometry (GC-MS) remains the most used analytical technique for detecting specific urinary organic metabolites related to OA. However, after analyzing more than 1,000 urine samples collected from children with neurological disorders, by this technique less than 0.5% of them were positive. Thus, the discovery of new biomarker candidates for other metabolic diseases is urgently needed. The main objective of this thesis was to evaluate a new method using two-dimensional gas chromatography coupled to mass spectrometry (GCxGC-MS) for the both qualitative and quantitative metabolic profiling of children’s urine. As compared to GC-MS, GCxGC-MS shows great resolution power and high peak capacity. For this purpose, we first developed a GCxGC-MS method with an appropriate sample preparation protocol for urinary organic acids profiling. Applied to urine samples of healthy children and children with neurological disorders, the proposed method showed high sensitivity and peak capacity thus opening new possibilities for the characterization of new biomarker candidates. For instance, by this technique, we were able to detect in urines samples more than ninety additional compounds, which are not detected by a conventional GC-MS method. However, taken together the obtained results show that while the GCxGC technique has unmatched power to separate compounds in a complex mixture, the sample preparation protocol remains a limiting step for the precise quantification of the detected compounds. On another hand, in order to reduce the sample preparation step, we evaluated the direct analysis in real time (DART) method for the urinary organic acids screening. The obtained results are very promising.