Thesis (Ph. D.)--University of Wisconsin--Madison, 1942. / Part I.A. reprinted from Journal of biological chemistry, vol. 137, no. 1 (Jan. 1941), p. 363-372. Part II. reprinted from Industrial and engineering chemistry, Analytical edition, vol. 13 (15 Aug. 1941), p. 566-570. Remainder typescript. Includes abstract and vita. Includes bibliographical references.

Lactobacillus casei es una bacteria del ácido láctico de interés aplicado por su uso como cultivo iniciador en la industria alimentaria y por el carácter probiótico de algunas cepas. Como probiótico, L. casei debe sobrevivir a las condiciones de producción industrial y a su paso por el tracto gastrointestinal manteniendo sus propiedades. Para ello, L. casei posee rutas de reconocimiento de señales ambientales específicas y convierten esta información en una respuesta fisiológica adecuada. Un mecanismo comúnmente encontrado en bacterias para la transducción de señal son los sistemas de dos componentes (Two Components Systems, TCS). Los TCS están formados por una proteína sensora con actividad histidina quinasa (HK) y un regulador de respuesta (RR). La detección de un estímulo específico por la proteína sensora induce su autofosforilación y la transferencia del fosfato al regulador de respuesta, produciéndose la activación del mismo. Los sistemas de dos componentes median la respuesta adaptativa a una amplia gama de estímulos ambientales en bacterias. En el laboratorio de Bacterias Lácticas del Instituto de Agroquímica y Tecnología de Alimentos se ha iniciado el estudio de los TCS codificados por L. casei BL23 dentro del cual se incluye el presente proyecto de tesis doctoral. / Revilla Guarinos, A. (2014). Characterization of Two Component Systems of Lactobacillus casei BL23 and their involvement in stress response [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/43589 / TESIS

No description available.

In order to establish the potential of an esterase from Lactobacillus casei for application in the dairy industry, this study was designed with the following objectives: (1) to determine the optimal cultural conditions for growth and enzyme production, (2) to construct a positive selection vector with low copy number for gene cloning, (3) to clone and sequence the gene encoding for esterase, (4) to biochemically characterize the purified recombinant esterase, and (5) to over-express an esterase of L. casei into Escherichia coli as well as into a methylotrophic yeast, Pichia pastoris using strong promoters. / Maximal growth and enzyme production in L. casei were obtained after 20 h in basal MRS medium containing 1% (w/v) lactose at pH 7.0, 30°C. Among various substrates (C2--C16) tested, the highest activity was towards C6 and C8. Although the enzyme was produced constitutively, tributyrin induced the enzyme production by a 2.5 fold. / A new E. coli and lactic acid bacteria shuttle vector with low copy and positive selection termed pCWL70 was constructed. High transformation efficiency and significant vector stability of pCWL70 were found in L. casei and Lactococcus lactis. / An esterase gene (estI) of L. casei CL96 was localized in a 3.3 kb Bam HI DNA fragment that contains an open reading frame of 1,800 bp. The open reading frame estI was isolated by PCR and subcloned into the E. coli expression vector pET29a, and Pichia expression vector pPICZ B, that allows the inducible expression under the control of the T7 promoter and an alcohol oxidase promoter (AOX1), respectively. E. coli BL21(DE3)pLysS containing estI expressed a novel 67.5 kDa protein corresponding to the EstI in N-terminal fusion with the S · tag peptide. / An esterase of L. casei CL96 was successfully over-expressed in E. coli up to 500 folds (about 25% of total cellular protein) as well as in the P. pastoris. In high cell density fed-batch fermentation, the recombinant Pichia strain containing linearized pCESTc was grown at pH 6.5 and 30°C, and the cell density peaked at about 180 h with 468 g wet cell weight per liter. The final yield was 3.7 x 106 units/ml, which is 980-folds higher than that of native L. casei cells. / The amino acid sequence of EstI indicated that the esterase is a member of a novel GHSMG family of lipolytic enzymes and S-formylglutathione hydrolases (FGH). The putative catalytic triad of EstI consists of residues Ser325, Asp516 and His558 as demonstrated by amino acid sequence alignments. (Abstract shortened by UMI.)

Thesis (Master)--İzmir Institute of Technology, İzmir, 2004 / Includes bibliographical references (leaves. 59).

Thesis (Ph. D.)--Victoria University (Melbourne, Vic.), 2008. / Includes bibliographical references.

Orientador: Maria José Hitomi Nagata / Resumo: Este estudo avaliou os efeitos da ingestão de alimento funcional, queijo Prato contendo Lactobacillus casei-01, no desenvolvimento da periodontite experimental (PE) em ratos. 44 ratos machos Wistar foram divididos em 4 grupos (n = 11): C (controle) - animais sem indução de PE e alimentados com ração convencional (RC) + queijo convencional (CONV); PROB - animais sem indução de PE e alimentados com RC + queijo probiótico (PROB); PE - animais com indução de PE e alimentados com RC + queijo CONV e PE-PROB - animais com indução de PE e alimentados com RC + queijo PROB. O queijo Prato foi fabricado por método tradicional com bactérias lácticas, suplementado ou não com a cepa probiótica Lactobacillus casei-01. No dia 0 do experimento, queijo CONV ou PROB, de acordo com o grupo experimental, foi administrado oralmente para todos os animais 1 x / dia até o final do experimento. No dia 28, a PE foi induzida nos primeiros molares inferiores direito e esquerdo dos animais dos grupos PE e PE-PROB. No dia 42, todos os animais foram submetidos à eutanásia. Foram realizadas análises microtomográfica na região da bifurcação e nos sítios vestibular, lingual e interproximais [volume ósseo (BV), número de trabéculas (Tb.N), espessura das trabéculas (Tb.Th), perda óssea alveolar (ABL)] e análises histológica (parâmetros dos tecidos moles e duros), histométrica [porcentagem de osso na furca (PBF)] e imunoistoquímica [fator de necrose tumoral-α (TNFα), interleucina (IL)-1β, IL-10, fator de crescime... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

No description available.

Ce travail est basé sur l’étude expérimentale, étape par étape, du procédé de lyophilisation, afin de comprendre les impacts des différents paramètres du procédé sur la viabilité d’une souche modèle probiotique de type lactobacillus casei. Nous avons tout d’abord étudié les propriétés thermodynamiques des formulations considérées à base de lactose et de polyvinylpyrrolidone, (PVP) en commençant dans un premier temps par l’obtention du diagramme d’état du système amorphe constitué du binaire eau-PVP, puis le diagramme de fusion du ternaire eau-PVP-lactose afin d’en déduire les paramètres clefs pour l’optimisation des cycles de lyophilisation de ces suspensions bactériennes. Dans la deuxième partie, nous avons caractérisé par microscopie électronique à balayage (MEB) la localisation des bactéries au sein de la phase solide amorphe des lyophilisats poreux. Ensuite, les différentes formulations ont été soumises à différents protocoles de congélation (vitesse de refroidissement ; recuit) afin d’obtenir les meilleurs résultats en termes de taux de survie des bactéries. Avec la formulation sélectionnée précédemment nous nous sommes intéressés à l’influence des paramètres opératoires de sublimation (température étagère et pression totale de sublimation) conduisant aux meilleurs taux de survie des bactéries. Nous avons observé que nos cellules probiotiques, avec ces formulations, pouvaient être lyophilisées, au-dessus de la température limite de collapse, sans impacter la viabilité des cellules présentes ou insérées au sein de la phase matrice poreuse du lyophilisat final, ce dernier présentant de plus, de bonnes propriétés d’usage en termes de stabilité en vue d’une mise en forme galénique ou d’un stockage ultérieur / This work is based on the experimental study, step by step, of the freeze-drying process of a model probiotic strain of lactobacillus caseï type to understand the impact of the numerous factors (formulation; freezing protocol; operating conditions) on the survival rates of these bacteria in the final lyophilisate. Firstly, we investigated the thermo-dynamical and physical properties (vitreous transition and melting temperatures) of formulations based on lactose and polyvinylpyrrolidone (PVP) protectants and their mixture. Thus, we have determined the phase diagrams and the melting diagram of the water+PVP binary system and of the ternary water-PVP-lactose system. Next, we determined the optimal freezing protocol (freezing rates; annealing treatment) with different formulations which led to the best survival rates. Next, in a preliminary study we have characterized by SEM (scanning electron microscopy) the location of the cells inserted inside the solid amorphous phase of the porous matrix of the different lyophilisates. Secondly, with the pre-selected formulation, we experienced the influence of the main operating sublimation parameters (shelf temperature and total gas pressure), leading to highest product quality in terms of bacteria survival ratios of the final lyophilisates. We observed that these probiotics cells, with this formulation, could be freeze-dried above the limit collapse temperature without impacting significantly the viability of the freeze-dried cells and with lyophilisates of high stability attributes

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / A utilizaÃÃo de sucos de frutas para o desenvolvimento de alimentos funcionais probiÃticos tem sido uma alternativa de consumo para indivÃduos que nÃo querem ou nÃo podem fazer uso de produtos lÃcteos fermentados. Desse modo, o objetivo deste trabalho foi desenvolver uma bebida com propriedades probiÃticas à partir da fermentaÃÃo do suco de melÃo Cantaloupe por Lactobacillus casei NRRL B-442. A primeira etapa da pesquisa consistiu na otimizaÃÃo de parÃmetros de pH e temperatura de fermentaÃÃo para o desenvolvimento de L. casei no suco de melÃo. Os resultados mostraram que a linhagem probiÃtica estudada apresentou potencial fermentativo em suco de melÃo, nÃo havendo necessidade de suplementaÃÃo com nutrientes para a obtenÃÃo de valores adequados de pH e nÃmero de cÃlulas viÃveis. A melhor condiÃÃo encontrada que garantisse um bom crescimento do micro-organismo alÃm de assegurar a viabilidade celular necessÃria para que o produto seja considerado probiÃtico foi a temperatura de 31ÂC com o pH inicial do suco de 6,1. Neste trabalho foi demonstrada a vantagem tecnolÃgica do uso de suco de melÃo como substrato para a fermentaÃÃo probiÃtica uma vez que o pH natural do suco proporcionou um meio favorÃvel para o desenvolvimento do micro-organismo. Em uma segunda etapa, investigou-se o efeito do tratamento ultra-sÃnico nos parÃmetros de qualidade do suco de melÃo em funÃÃo da intensidade de energia ultra-sÃnica e do tempo de tratamento. O processamento ultra-sÃnico utilizando intensidade de 372,93 W/cm2 durante 10 minutos melhorou as caracterÃsticas de qualidade do suco reduzindo a atividade de enzimas deteriorantes, aumentando a homogeneidade sem causar danos à cor do produto. Considerando estes resultados, na terceira etapa da pesquisa foram estudadas a cinÃtica da produÃÃo de suco de melÃo sonificado probiÃtico e a influÃncia da estocagem sob refrigeraÃÃo em parÃmetros de qualidade da bebida como: sobrevivÃncia de L. casei, pÃs-acidificaÃÃo e cor. O suco de melÃo foi submetido ao processamento ultra-sÃnico, inoculado com 1% (v/v) da cultura e incubado a 31ÂC por 8 horas. Os sucos foram armazenados sob refrigeraÃÃo a 4ÂC. Foram determinados pH e parÃmetros de cor da bebida, crescimento celular e o nÃmero de cÃlulas viÃveis. As anÃlises foram realizadas em intervalos de 7 dias, atà o 42 dia de estocagem. A maior contagem celular foi atingida nas 12 horas do estudo, chegando a 9,0 log UFC/mL, porÃm a partir de 8 hora nÃo houve um aumento significativo da concentraÃÃo de cÃlulas viÃveis, motivo pelo qual elegeu-se 8 horas como o tempo de fermentaÃÃo ideal para a elaboraÃÃo do suco de melÃo probiÃtico. Durante a estocagem refrigerada, houve produÃÃo de Ãcidos e uma discreta reduÃÃo do nÃmero de cÃlulas viÃveis, porÃm o produto manteve prevalÃncia de cÃlulas viÃveis (com Ãndices acima do preconizado pela legislaÃÃo vigente), durante 42 dias de armazenamento a 4ÂC, independentemente de terem sido estocadas com ou sem aÃÃcar sem prejuÃzos à coloraÃÃo do produto. O suco de melÃo foi considerado um veÃculo adequado para a ingestÃo de micro-organismos probiÃticos, pois apresentou contagem de cÃlulas viÃveis superior a 8 log UFC/mL durante todo o perÃodo de estudo. / The use of fruit juices for the development of functional foods has been an alternative for people who do not want or cannot make use of fermented dairy products. The objective of this research was the development of a drink with probiotic properties trough the fermentation of melon juice by Lactobacillus casei NRRL B-442. The first stage of the work consisted of the optimization of pH and temperature of fermentation for the L. casei cultivation in melon juice. Results showed that this strain has fermentative potential in melon juice, with no need of nutrient supplementation to reach the appropriated values of pH and viable cells. The best operating condition found to guarantee a good growth of the microorganism and ensure the cellular viability necessary for the product to be considered probiotic was the temperature of 31ÂC with initial pH of 6.1. The technological advantage of using melon juice as a substrate for probiotic fermentation was demonstrated in this work because the natural pH of the juice provided a favorable environment for the probiotic microorganism development. In a second stage, the effect of ultrasound treatment on quality parameters of melon juice was investigated as a function of intensity of ultrasonic energy and treatment time. The ultrasonic processing intensity using 372.93 W/cm2 for 10 minutes improved the quality of the juice reducing the spoilage due to enzyme activity, increasing homogeneity without damaging the product color. In the third phase of the research, the kinetics of probiotic melon juice fermentation and the influence of the product storage under refrigeration on the beverage quality parameters such as survival of L. casei, post-acidification and color were studied. The melon juice was subjected to ultrasonic processing (372.93 W/cm2/10min) and inoculated with 1% (v/v) and incubated at 31ÂC for 8 hours. The fermented juice was stored at 4ÂC, and pH, color, cell biomass, and viable cells number were evaluated. Analyses were performed at intervals of 7 days until 42 days of storage. The highest cell count was achieved within 12 hours of study, reaching 9.0 log CFU/mL, but from the 8th of fermentation there was no significant increase in the concentration of viable cells. Thus, 8 hours was elected as the optimal fermentation time to prepare the probiotic melon juice. During refrigerated storage there was acid production and a slight reduction in the number of viable cell. However, the product kept the number of viable cells above the level recommended by the current legislation during 42 days of storage at 4ÂC, regardless of having been stocked sugar-free or with sugar addition and no damage to the product color was observed. Melon juice was considered a good vehicle for probiotic microorganism as it showed viable cell count higher than 8 log CFU/mL throughout the studied period.