Dissertations / Theses on the topic 'Streptococcus thermophilus'
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Tremblay, Denise. "Caractérisation génomique d'un phage de Streptococcus thermophilus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0004/MQ44975.pdf.
Full textBergeron, Claudia. "Transcriptome du bactériophage DT1 de Streptococcus thermophilus." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/24042/24042.pdf.
Full textVaillancourt, Katy. "Étude comparative des opérons galactose de Streptococcus salivarius et Streptococcus thermophilus." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ56776.pdf.
Full textSturino, Joseph Miland. "Bacteriophage Defense Systems and Strategies for Streptococcus thermophilus." NCSU, 2003. http://www.lib.ncsu.edu/theses/available/etd-12152003-034319/.
Full textGarneau, Josiane. "Caractérisation du système CRISPR-CAS chez Streptococcus thermophilus." Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26441/26441.pdf.
Full textHUSSON, KAO CLARA. "Etude des mecanismes moleculaires d'autolyse de streptococcus thermophilus." Massy, ENSIA, 1999. http://www.theses.fr/1999EIAA0097.
Full textMorice, Michel. "Étude de la congélation de streptococcus thermophilus : influence des cations sur la croissance en chaînes et la détermination de la cryorésistance, hétérogénéité du comportement de variants morphologiques." Nancy 1, 1990. http://www.theses.fr/1990NAN10486.
Full textLarbi, Derouiche Djela. "Études génétique et biologique de neuf bactériophages de streptococcus salivarius ssp thermophilus : études des interactions phages-bactéries." Nancy 1, 1991. http://www.theses.fr/1991NAN10013.
Full textVarga, Ferenc. "The origins, production and control of acetaldehyde in yoghurt." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271185.
Full textDoco, Thierry. "Les exopolysaccharides des bactéries lactiques : isolement, structure et propriétés de l'exopolysaccharide excrété dans un milieu lacté par Streptococcus thermophilus." Lille 1, 1989. http://www.theses.fr/1989LIL10139.
Full textLayec, Séverine Decaris Bernard. "Le gène cse, de création récente, code une hydrolase du peptidoglycane impliquée dans la séparation des cellules de Streptococcus thermophilus." S. l. : Nancy 1, 2008. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2008_0066_LAYEC.pdf.
Full textColmin, Catherine. "Polymorphisme génétique et typage moléculaire chez la bactérie streptococcus salivarius subsp. Thermophilus." Nancy 1, 1991. http://www.theses.fr/1991NAN10135.
Full textAlmiron-Roig, Eva. "The exopolysaccharide from Streptococcus thermophilus NCFB2393 : structure, biochemistry and genetics." Thesis, University of East Anglia, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323337.
Full textBERRUTI, GIANGIACOMO. "Caratterizzazione molecolare di geni per l'antibiotico resistenza in Streptococcus Thermophilus." Doctoral thesis, Università Cattolica del Sacro Cuore, 2007. http://hdl.handle.net/10280/78.
Full textThe aim of the present work was to assess the AR diffusion in a total of 70 different strains of Streptococcus thermophilus, collected between 1950 and 2004 and from different environments; in this way we had the possibility to obtain a clear overview of the response of these bacteria to a large variety of antibiotics, having been able to analyze a significant number of different strains, originated from different areas and distributed over a wide time period, since before the use of antibiotics up to the present day. The phenotypic expression has been evaluated by using three different methods: microdilution, E-test and disk diffusion. The genetic analysis was performed using 50 and 60-mer oligonucleotides DNA based micro array for the identification of AR genes; the AR genes represented by the oligonucleotides on the micro array belong to: Aminoglycoside, Extended Spectrum ?-lactamase (ESBL), Chloramphenicol, Macrolide Lincosamides and Streptogramin (MLS) group, Sulfonamide, Tetracycline, Trimethoprim and Vancomycin. tetS and ermB genes were found and sequenced in 4 out of the total of the S. thermophilus investigated. Furthermore we have wanted to establish the genetic location of above-mentioned genes and assess their transfer intra and inter species adopting the conjugation technique in plate.
BERRUTI, GIANGIACOMO. "Caratterizzazione molecolare di geni per l'antibiotico resistenza in Streptococcus Thermophilus." Doctoral thesis, Università Cattolica del Sacro Cuore, 2007. http://hdl.handle.net/10280/78.
Full textThe aim of the present work was to assess the AR diffusion in a total of 70 different strains of Streptococcus thermophilus, collected between 1950 and 2004 and from different environments; in this way we had the possibility to obtain a clear overview of the response of these bacteria to a large variety of antibiotics, having been able to analyze a significant number of different strains, originated from different areas and distributed over a wide time period, since before the use of antibiotics up to the present day. The phenotypic expression has been evaluated by using three different methods: microdilution, E-test and disk diffusion. The genetic analysis was performed using 50 and 60-mer oligonucleotides DNA based micro array for the identification of AR genes; the AR genes represented by the oligonucleotides on the micro array belong to: Aminoglycoside, Extended Spectrum ?-lactamase (ESBL), Chloramphenicol, Macrolide Lincosamides and Streptogramin (MLS) group, Sulfonamide, Tetracycline, Trimethoprim and Vancomycin. tetS and ermB genes were found and sequenced in 4 out of the total of the S. thermophilus investigated. Furthermore we have wanted to establish the genetic location of above-mentioned genes and assess their transfer intra and inter species adopting the conjugation technique in plate.
CHEGDANI, FATIMA. "Effects of Streptococcus Thermophilus Bacteria on rat gene expression profiles." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/962.
Full textIn this study we have investigated the impact of Streptococcus thermophiluds on the rat colonic epithelium. After generation of the model axenic rat and inoculated with S. thermophilus we have investigated the interplay between bacteria and host colon. Colonic epithelium gene expression was investigated also, with two different approaches: Suppressive Subtractive Hybridization. The subtraction library was prepared subtracting mRNA between epithelial cells from colonic mono-associated rats and germ-free rats. The transcripts generated by SSH were grouped into divers Functional groups: cell-cycle arrest and induction of differentiation; cell-communication and binding. Tow candidates genes were privileged, krupel like factor 4 and 14-3-3σ. These candidate genes were tested by RT-PCR, qRT-PCR and Western blot in mono-associated animals and in germ-free animals. The tests confirmed that candidate genes increase their expression in the presence of S. thermophilus. Microarray analysis. Gene expression was measured in tow groups of animals: i) germ-free rats; ii) mono-associated rats inoculated with LMD9 strain of Streptococcus thermophilus. The results of microarray analysis data show that Streptococcus thermophilus remarkably affected gene expression in the colonic epithelial cells. Streptococcus thermophilus enhanced the expression of genes involved in different pathways in the host, compared to the gem free group.
CHEGDANI, FATIMA. "Effects of Streptococcus Thermophilus Bacteria on rat gene expression profiles." Doctoral thesis, Università Cattolica del Sacro Cuore, 2011. http://hdl.handle.net/10280/962.
Full textIn this study we have investigated the impact of Streptococcus thermophiluds on the rat colonic epithelium. After generation of the model axenic rat and inoculated with S. thermophilus we have investigated the interplay between bacteria and host colon. Colonic epithelium gene expression was investigated also, with two different approaches: Suppressive Subtractive Hybridization. The subtraction library was prepared subtracting mRNA between epithelial cells from colonic mono-associated rats and germ-free rats. The transcripts generated by SSH were grouped into divers Functional groups: cell-cycle arrest and induction of differentiation; cell-communication and binding. Tow candidates genes were privileged, krupel like factor 4 and 14-3-3σ. These candidate genes were tested by RT-PCR, qRT-PCR and Western blot in mono-associated animals and in germ-free animals. The tests confirmed that candidate genes increase their expression in the presence of S. thermophilus. Microarray analysis. Gene expression was measured in tow groups of animals: i) germ-free rats; ii) mono-associated rats inoculated with LMD9 strain of Streptococcus thermophilus. The results of microarray analysis data show that Streptococcus thermophilus remarkably affected gene expression in the colonic epithelial cells. Streptococcus thermophilus enhanced the expression of genes involved in different pathways in the host, compared to the gem free group.
Burrus, Vincent. "Identification d'éléments intégratifs et potentiellement conjugués chez Streptococcies thermophilus : évolution par échange-acquisition de modules et de domaines." Nancy 1, 2001. http://www.theses.fr/2001NAN10027.
Full textBOUNAIX, STEPHANE. "Taxinomie biochimique, physiologique et moleculaire d'une collection de souches de streptococcus thermophilus et de streptococcus salivarius." Caen, 1992. http://www.theses.fr/1992CAEN2019.
Full textMaazouzi, Nadia. "Étude du métabolisme du saccharose et production de polyosides chez streptococcus salivarius subsp thermophilus." Nancy 1, 1991. http://www.theses.fr/1991NAN10206.
Full textLetort, Catherine. "Relation entre croissance et nutrition azotée de deux bactéries lactiques thermophiles : streptococcus thermophilus et lactobacillus delbrueckii subsp. bulgaricus." Poitiers, 2001. http://www.theses.fr/2001POIT2326.
Full textPetit, Chantal. "Régulation de la biosynthèse de métabolites d'intérêt industriel par les bactéries lactiques : 1. production de didactyle chez lactococcus lactis subsp. diacetylactis : 2. production de polyosides chez streptococcus thermophilus." Nancy 1, 1991. http://www.theses.fr/1991NAN10308.
Full textKebouchi, Mounira. "Caractérisation des propriétés d'adhésion de Streptococcus thermophilus LMD-9 aux cellules épithéliales intestinales : 1. Rôle des protéines de surface dans la résistance aux sels biliaires et dans l’adhésion, 2. Impact de l’adhésion sur l’expression des gènes eucaryotes et bactériens." Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0209.
Full textLactic 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
Desiere, Frank. "Ecology and evolution of Streptococcus thermophilus bacteriophages in industrial milk fermentations /." [S.l.] : [s.n.], 1999. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13332.
Full textDupuis, Marie-Ève. "Caractérisation du mode d'action du système CRISPR1/Cas de Streptococcus thermophilus." Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28652/28652.pdf.
Full textRul, Françoise. "Contribution a l'etude du systeme peptidasique de streptococcus thermophilus cnrz 302." Caen, 1994. http://www.theses.fr/1994CAEN2022.
Full textAltay, Dede Neslihan. "Characterization Of Lactobacillus Delbrueckii Subspecies Bulgaricus And Streptococcus Thermophilus As Lactic Cultures Isolated From Traditional Turkish Yogurts And Subtyping Of Streptococcus Thermophilus Using Crispr Analysis And Mlst." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12612009/index.pdf.
Full textThevenard, Benoît. "Implication des systèmes à deux composants dans les réponses de Streptococcus thermophilus à des changements environnementaux, dont la coculture avec Lactobacillus bulgaricus." Phd thesis, AgroParisTech, 2011. http://pastel.archives-ouvertes.fr/pastel-00734426.
Full textGalia, Wessam. "Caractérisation de la variabilité du système protéolytique de surface de la bactérie lactique Streptococcus thermophilus." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL053N/document.
Full textThe variability of the cell envelope-associated proteolytic system was studied in 30 strains of St. thermophilus. Variations in strains consist in the presence or absence of the gene prtS, the presence of two allelic forms of prtS, the presence of an anchored and/or soluble form of the protease PrtS and in the variable expression of the gene prtS and other genes involved mainly in nitrogen metabolism, thus in the variability of the regulation genetic of this system. Expression of the genes prtS, pepX, pepC, pepN, amiA1CDEF, dtpT, livJHMGF, ilvC, ilvDBN, bcaT, ackA, ldh, codY and relA was quantified in the PB302 and PB18O strains. The strain PB302 is representative of strains which exhibit a rapid growth in milk. The strain PB18O is representative those with intermediate growth in milk. In M17 medium, where both strains have similar growth, little difference in the expression of genes tested was observed. Conversely, the two strains did not express the selected genes in the same way when grown in milk. Overall, the difference in growth observed between strains in milk could result from variable proteolytic activities and variable expression of genes encoding, for example, the proteinase PrtS, the regulator CodY, transporters of oligo- or di-tri- peptides (Ami or DtpT) or branched chain amino acids, or BCAA (LivJ) and enzymes in the biosynthetic pathway of BCAA (IlvC, IlvB et BcaT) which are necessary for growth in milk. All these genes have a potential CodY box at the upstream of their promoter and could therefore belong to the regulon CodY
Uriot, Ophelie. "Etude de la survie et identification des fonctions exprimées par la bactérie lactique Streptococcus thermophilus dans le tractus digestif." Thesis, Clermont-Ferrand 1, 2016. http://www.theses.fr/2016CLF1PP06/document.
Full textStreptococcus thermophilus is the lactic acid bacterium most commonly used after Lactococcus lactis in the dairy industry for the production of yogurt and cheese. It is the only streptococcus strain to have the GRAS status (Generally Recognized As Safe). Despite recent studies showing its ability to survive through the human digestive tract and valuable health effects, the probiotic status of S. thermophilus remains questioned. Thus, the objectives of this pHD work were (i) to increase knowledge on the survival of S. thermophilus in human digestive environment, by using the dynamic multi-compartmental TIM system (TNO gastro-intestinal model) and (ii) to identify the genes from S. thermophilus that are specifically activated in complex digestive environment using the R-IVET technology (Recombinase-based In Vivo Expression Technology). R-IVET is based on the excision of a reporter gene and consists of a plasmid vector carrying the promoterless recombinase cre and a chromosomal cassette composed of a marker gene flanked by loxP recognized by Cre. First, we introduced the R-IVET technology in S. thermophilus LMD-9. Its functionality was tested and validated in vitro and in the mice digestive tract. Then, the survival of four S. thermophilus strains was investigated in the TIM system and we showed that 3 of these strains were more resistant than the other one, very sensitive to gastrointestinal stresses. These results strengthen the idea that the survival of S. thermophilus is strain-dependent. We also highlighted that the survival of S. thermophilus was influenced by the food matrix, being higher in fermented compared to liquid milk. Lastly, we constructed a first genomic R-IVET library, by cloning upstream of cre genomic DNA fragments from LMD-9. This library was tested only in gastric condition (TIM). After optimization of our tool in S. thermophilus (improvement of the method allowing identification of the activated genes), a second R-IVET library was tested throughout the gastrointestinal system (TIM) and in batch system including intestinal microbiota. By identifying bacterial genes specifically activated in human digestive conditions, this work contributes to extend our knowledge on the behavior of S. thermophilus in the human gastrointestinal tract. This could open up opportunities in determining survival markers for S. thermophilus and better describing its metabolic activity in the human gut, then facilitating the selection of strains that can be included in functional foods
Carraro, Nicolas. "Analyse comparative de la dynamique de deux éléments intégratifs conjugatifs de streptococcus thermophilus." Thesis, Nancy 1, 2011. http://www.theses.fr/2011NAN10080/document.
Full textIntegrative and Conjugative Elements (ICEs) are genomic islands, which excise from the chromosome, self-transfer by conjugation and integrate. They harbor a modular organization: genes and sequences involved in the same biological process are grouped in the same region. This work concerns the modality of transfer and maintenance of ICESt1 and ICESt3, two ICEs of Streptococcus thermophilus that share closely related core region. ICESt1 excises much less frequently than ICESt3. Nevertheless, excision of the two elements is activated by the same stimuli (DNA damage, stationary phase and/or cell density) and depends of the host strain. Bioinformatical and transcriptional analyses highlight several differences in their organization. However, each of these two ICEs would encode two different regulators, cI and ImmR, suggesting that a complex and original pathway govern to ICESt1' and ICESt3' regulation. This regulation would be shared with numerous ICEs that we identified in the genome of various commensal or pathogenic streptococci. According to the original definition, ICE's maintenance would be exclusively due to their integration in the host chromosome, and ICEs would not be able of extracellular replication. However, in addition to the induction of ICESt3' excision and transfer, DNA damage cause replication of its extrachromosomal form. This unexpected property is encoded by the core region and would be implicated in the maintenance of the element. Comparision with data recently published on other ICEs suggest that intracellular replication could be involved in the maintenance of numerous ICEs, besides their integration
Telles, Francisco Jose Siqueira. "Proteolytic changes in goat's milk during yogurt manufacture." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184282.
Full textGirard, Florence. "Caracterisation biochimique, serologique et genetique d'une collection de souches de streptocoques thermophiles : mise au point d'une methode rapide d'hybridation adn-adn." Caen, 1987. http://www.theses.fr/1987CAEN2037.
Full textChaves, Ana Carolina Sampaio Doria. "Engenharia metabolica de Streptococcus thermophilus para produção de acetaldeido em leites fermentados." [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256713.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: o processo de formação de acetaldeído pela bactéria láctica Streptococcus thermophilusfoi investigadonestatese.O cetaldeídoresponsávelpelo sabore aroma característicosde iogurte,é produzidopor diferentesvias metabólicaspelas diversas bactérias lácticas. Neste trabalho, a atenção foi focada especificamente na reação para a formação de acetaldeído, catalisada pela enzima serina hidroximetil transferase (SHMT), codificada pelo gene glyA. A enzima SHMT cataliza diversas reações e no caso da bactéria S. thermophilus, ela exerce também a atividade característica da enzima treonina aldolase (TA), definida como a interconversão do aminoácido treonina em glicina e acetaldeído. Neste estudo, 34 linhagens selvagens de S. thermophilus da coleção do NIZO Food Research foram avaliadas quanto à produção de acetaldeído na presença e na ausência do aminoácido L-treonina. A suplementação do meio com L-treonina levou ao aumento da produção de acetaldeído. Foi detectada uma clara diferença na quantidade de acetaldeído formado pelas diversas linhagens; enquanto algumas produziram pouco ou não produziram quantidades detectáveis, outras formaram quantidades consideráveis de acetaldeído. A capacidade de produção de acetaldeído durante a fermentação foi correlacionada com a atividade da enzima treonina aldolase. Com o objetivo de se estudar a função da enzima SHMT, foi construída uma linhagem com o gene glyA interrompido. A inativação deste gene resultou em acentuada redução da atividade TA assim como também na perda completa da capacidade de produção de acetaldeído durante a fermentação. Subseqüentemente, foi construída uma linhagem de S. thermophilus na qual o gene glyA foi clonado sob o controle de um forte promotor (PLacA)' Quando esta linhagem foi cultivada em meio M17 e em leite foi observada a super expressão do gene glyA, constatada por meio do aumento da atividade TA, da produção de acetaldeído e ácido fólico. Estes resultados mostraram que, em S. thermophilus, a enzima SHMT apresenta atividade de treonina aldolase, sendo esta a principal via para a formação de acetaldeído nas condições destes experimentos
Abstract: The process of acetaldehyde formation by the yogurt bacterium Streptococcus thermophilus is described here. The typical yogurt flavor is caused by acetaldehyde produced through many difIerent pathways by the yogurt starter bacteria Lactobacillus bulgaricus and S. thermophilus. In this thesis, the attention was focused on one specmc reaction for acetaldehyde formation catalyzed by serine hydroxymethyltransferase(SHMT), encoded by the glyA gene. In S. thermophilus, this enzyme SHMT also plays the typical role of the enzyme threonine aldolase (TA) tOOtis the interconvertion of threonine into glycine and acetaldehyde. In this work, 34 wild type S. thermophilus strains ftom the NIZO Food Research Collection were screened for acetaldehyde production in the presence and absence of L-threonine. Supplementation of the growth medium with L-threonine led to an increase in acetaldehyde production. A clear difIerence in the amount of acetaldehyde formed could be detected among the difIerent strains. While some strains produce very small or no detectable amounts other strains produce a considerable high amount of acetaldehyde. Furthermore, acetaldehyde formation during fermentation could be correlated to threonine aldolase activity of SHMT. To study the physiological role of SHMT, aglyA mutant was constructed by gene disruption. lnactivation of glyA resulted in a severe reduction of TA activity and complete loss of acetaldehyde formation during fermentation. Subsequent1y,aS. thermophilus strain was constructed in which the glyA gene was cloned under control of a strong promoter (PLacA)' When this strain was used for fermentation it was possible to observe tOOtglyA gene was overexpressed through the increase in TA activity, in acetaldehyde and folic acid production. These results show tOOt, in S. thermophilus, SHMT, displaying threonine aldolase activity, constitutes the main pathway for acetaldehyde formation under our experimental conditions. These findings can be used to control and improve acetaldehyde and folic acid production in fermented (dairy) products with S. thermophilus as starter culture
Doutorado
Doutor em Tecnologia de Alimentos
Lingeswaran, Abarna. "Rôle clé du transporteur PptAB dans le quorum sensing chez Streptococcus thermophilus." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASB013.
Full textIn Streptococcus thermophilus, the life cycle of signaling peptides called pheromones contributing to communication mechanisms named quorum sensing (QS) is divided into four steps. The synthesis of pheromones is followed by their maturation by the protease Eep and their secretion. At last, their re-internalisation by the oligopeptide transporter Ami is essential for their intracellular detection by transcriptional regulators called Rgg-like controlling the expression of target genes. The aim of my thesis was to valid the role of the transporter PptAB in the secretion of pheromones before identifying genes whose expression is dependent of this transporter in S. thermophilus.First, we confirmed the role of the transporter PptAB in the activation of three QS systems involving Rgg-like regulators. For that we used transcriptional fusions between a reporter gene coding the luciferase and the promoter of three target genes of these systems. We then showed that the transporter PptAB exports more likely only the mature form of pheromones by LC-MS/MS. Finally, we discovered that the expression of a set of genes located downstream of genes coding Rgg-like regulators is dependant of the transporter PptAB and also of the transporter Ami and the protease Eep by a global transcriptomic approach. Thereby, the transporters PptAB and Ami and the protease Eep regulate these targets by a same mechanism.Our work brought light on cross-talks between these systems which need to be deciphered
Pébay, Mireille. "Instabilité chromosomique chez la bactérie, streptococcus thermophilus cnrz368 : variabilité du phénotype des colonies et du nombre de Loci RRN." Nancy 1, 1993. http://www.theses.fr/1993NAN10021.
Full textCebeci, Aydin Aysun. "Molecular Identification And Typing Of Lactobacillus Delbrueckii Subspecies Bulgaricus And Streptococcus Thermophilus." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609333/index.pdf.
Full textS. thermophilus and L. delbrueckii subsp. bulgaricus. In this study, identification and typing of yoghurt starter bacteria were aimed. Traditional home made yoghurts were collected from different areas of Turkey, identification of those isolates at species and subspecies level and typing at strain level were achieved using PCR based methods. In our study, identification of yogurt starter bacteria was studied using species specific primers and ARDRA. These methods were inefficient in identification of yoghurt starter bacteria, at species and subspecies level. Consequently, a reliable and quick method for accurate identification of yoghurt starter bacteria was developed. The new method focuses on amplification of methionine biosynthesis genes, for selective identification of yoghurt starter bacteria together with some cheese starters. Further discrimination by ARDRA enabled differentiation of yoghurt starter bacteria from cheese starters. Confirmation of the proposed method has been accomplished by partial sequencing of the 16S rRNA gene. After correct identification of starter bacteria had been achieved, the strains were typed at strain level using RAPD-PCR and MLST. RAPD-PCR with primer 1254 resulted better fingerprints, compared to primer M13 at strain level. Comparisons of the two typing methods showed that RAPD-PCR revealed strain diversity better than MLST, however MLST was a more robust and reliable method and resulted in clustering of the strains depending on the isolation source.
Garault, Peggy. "Les fonctions essentielles à la croissance dans le lait de Streptococcus thermophilus." Paris 11, 2001. http://www.theses.fr/2001PA112128.
Full textCarvalho, Juliane Doering Gasparin. "Caracterização da microbiota latica isolada de queijo de coalho artesanal produzido no Ceara e suas propriedades tecnologicas." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255732.
Full textTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: O conhecimento da microbiota lática dos queijos de Coalho produzidos de forma artesanal a partir de leite cru, e suas propriedades tecnológicas são fundamentais para preservar as características originais do produto tradicional em queijos de Coalho industrializados, elaborados com leite pasteurizado. Para alcançar este conhecimento, foi realizado um trabalho de pesquisa dividido em três etapas: I) caracterização físico-química de queijos de Coalho artesanais produzidos no Ceará e de sua microbiota lática; II) estudo do comportamento das bactérias ácido láticas (BAL) durante o processamento do queijo; III) caracterização de propriedades tecnológicas das culturas láticas isoladas a partir deles. As análises físico-químicas caracterizaram as amostras avaliadas como sendo queijo de médio conteúdo de umidade (42%), baixa acidez (0,24%), com pH de 6,30; elevada atividade de água (0,959) e teor de NaCl de 2,88%. Dentre as BAL (643) isoladas destas amostras, foram encontrados os gêneros Enterococcus (59,6%), Lactobacillus (22%), Streptococcus (12,8%), Lactococcus (1,7%) e Leuconostoc (0,6%). A identificação de gênero não foi conclusiva para 3,3% de isolados. As espécies prevalecentes foram Enterococcus faecium, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus e Lactococcus lactis subsp. lactis. O acompanhamento da evolução da microbiota lática em amostras de leite cru, massa de queijo e do produto final, coletadas em duas unidades produtoras, revelou a presença de Lactococcus no leite e sua ausência no queijo. A presença de Enterococcus aumentou das amostras de matéria-prima para o queijo, indicando a transferência e multiplicação destes microrganismos ao longo do processamento. Estes resultados evidenciaram uma seleção de microrganismos resistentes às temperaturas elevadas no processamento do queijo, durante o cozimento da massa. Quanto às propriedades tecnológicas avaliadas, 15 isolados foram considerados produtores rápidos de ácido, com predominância dos Lactococcus e Streptococcus (40% cada). Os Lactobacillus exibiram maior variabilidade e extensão proteolítica, além de maior produção de aroma. As culturas analisadas mostraram boa tolerância a 3 e 4% de sal. As cepas de Enterococcus faecium apresentaram a maior produção de bacteriocinas ativas contra Listeria spp., com potencial de emprego na produção de queijo de Coalho, como cultura protetora
Abstract: Understanding the lactic microbiota of the artisanal Coalho cheeses produced from raw milk, and its technological properties, is important to preserve the characteristics of the traditional product in the industrialized Coalho cheeses, elaborated with pasteurized milk. In order to achieve such knowledge, a research work was carried out in three stages: I) the physical-chemical characterization of the artisanal Coalho cheeses from Ceara-Brazil and its lactic microbiota, II) the study of the behaviour of the lactic acid bacteria (LAB) along the processing of cheese, III) characterization of technological properties of the lactic cultures isolated from the cheese. The physical-chemical analyses characterized the evaluated cheese samples with medium moisture content (42%), low acidity (0.24%), pH of 6.30, high water activity (0.959) and 2.88% NaCl content. Amongst the 643 LAB isolated from these samples, Enterococcus (59.6%), Lactobacillus (22%), Lactococcus (1.7%), Leuconostoc (0.6%) and Streptococcus (12.8%) genera were found. The identification was not conclusive for 3.3% of the isolates. The main species were Lactococcus latis subsp. latis, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus and Enterococcus faecium. Following the evolution of lactic microbiota in raw milk, curd and cheese samples collected in two dairies, Lactococcus was found to be present in the milk, but absent in the cheese. The presence of Enterococcus increased from the raw material to the cheese samples, indicating the transference and multiplication of these microorganisms throughout the cheesemaking. Such results evidenced a selection of high temperature resistant microorganisms at the curd cooking stage of cheesemaking. According to the technological properties evaluated, 15 isolates were considered fast producers of acid, with predominance of the Lactococcus and Streptococcus (40% each). The Lactobacillus showed high variability and provided the widest range of proteolytic activity and production of flavour. The lactic cultures also showed good tolerance to 3 and 4 % of NaCl. Strains of Enterococcus faecium produced active bacteriocins against Listeria spp., with potential use in the production of Coalho cheese like protective culture
Doutorado
Doutor em Tecnologia de Alimentos
Souza, Cínthia Hoch Batista de. "Influência de uma cultura \'starter\' termofílica sobre a viabilidade de \'Lactobacillus acidophilus\' e as características de queijo minas frescal probiótico." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/9/9133/tde-07122006-153517/.
Full textFunctional foods are foods that claim to promote human health over and above the provision of basic nutrition. Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, improving his intestinal microbial balance. Lactobacillus acidophilus strains have been shown to be able to survive at favorable concentrations for a probiotic food in a variety of cheeses, including fresh cheeses. The objective of this study was to verify the viability of Lactobacillus acidophilus La-5 added solely or in co-culture with a Streptococcus thermophilus starter culture during production of minas fresh cheese. Three different trials of minas fresh cheese were prepared (in triplicates): T1 (produced with no addition of cultures), T2 (supplemented with L. acidophilus) and T3 (supplemented with L. acidophilus + S. thermophilus). T2 and T3 were also produced with reduced fat milk in order to verify the influence of reduced fat on viability of L. acidophilus added to minas fresh cheese (T2L and T3L). The physicochemical (moisture, pH and titratable acidity) and microbiological (counts of L. acidophilus, S. thermophilus, coliforms, E. coli and Staphylococcus spp.) properties were monitored during 21 days of refrigerated storage at 5±1ºC. The instrumental texture profile (TA-XT2 Texture Analyser) was also determined. In addition, the proteolytic index after the 1st and the 21st day of storage was determined. Counts of L. acidophilus and S. thermophilus were also monitored in cheeses T2L and T3L. Sensory evaluation was performed for cheeses T1, T2 and T3, after 7 and 14 days of storage at 5±1°C, employing the acceptability test, with a 9-point hedonic scale, by 30 untrained panelists. All cheeses supplemented with L. acidophilus presented populations above 6 log cfu/g, during the whole storage period, except for T3, which presented counts of 5.74 log cfu/g, but only in the 1st day of storage. Cheeses T2L and T3L, presented initials counts above 6 log cfu/g, which increased after the 7th day of storage, remaining above 7 log cfu/g up to the last day of storage. Cheeses produced only through direct acidification of milk (T1) presented increase in counts of Staphylococcus spp. during storage, whereas the presence of lactic acid cultures inhibited the growth of these contaminants in cheeses T2 e T3. All cheeses presented an increase in the proteolytic index between the first and the last day of storage. However, the major increase was detected for T3 (95.4%) due to the presence of S. thermophilus. With respect to sensory evaluation, no significant differences were detected among cheeses after 7 days of storage (p>0.05). After 14 days, cheeses T2 and T3 presented higher acceptance and differed significantly from cheeses T1. A decrease in acceptability was observed for cheeses T1 between 7 and 14 days of storage (p<0.05), whereas probiotic cheeses T2 and T3 revealed to be stable in the same period (p>0.05). The supplementation of minas fresh cheese with Lactobacillus acidophilus La-5, either solely or in co-culture with a thermophilic starter culture (S. thermophilus), resulted in a product with great potential as a functional food, with populations above the minimum required for a probiotic product (particularly when produced with reduced fat milk), improving sensory performance of the product during storage, as well as microbiological and textural properties.
Gandara, Ana Lourdes Neves 1953. "Caracteristicas de crescimento de uma linhagem selvagem de Streptococcus thermophilus, sua adesão em superficie de aço inoxidavel e comportamento frente a detergencia e sanificação." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/254614.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Microrganismo selvagem isolado de leite pasteurizado, obtido de processo contínuo de pasteurização HTST com 4 h de operação foi identificado como Streptococcus thermophilus, formando a maior densidade celular em caldo M11 a 45°C em 6h. O número de células viáveis desse microrganismo foi avaliado em meios de cultura PCA, APT, MRS e Ml1 sendo os meios M11 e MRS os que permitiram melhor crescimento. Menores contagens do microrganismo foram observadas no meio APT em relação aos meios anteriores, não ocorrendo crescimento em meio PCA. Em leite foram avaliados o tempo de geração, destruição térmica a 12°C, armazenamento da cultura a 10°C e formação de estruturas de adesão. O microrganismo apresentou um tempo de geração de 15,2 minutos a 45°C e um valor Dn de 1,4 minutos. Na temperatura de 10°C, armazenado por 6 dias, 51,1% das células desse Streptococcus permanecem viáveis; esse microrganismo também forma em 20 h estruturas de adesão em superfícies de aço inoxidável, observada através de microscopia eletrônica de varredura. A produção de ácido lático em leite foi avaliada a 35,40, 45 e 50°C por 8 h, os maiores teores foram obtidos a 45°C (0,35%) e 40°C (0,34%), menores teores ocorreram respectivamente a 50 e 35°C. Em leite a adesão desse S. thermophilus em superfícies de aço inoxidável foi estudada em 6 h de contato a 45°C sob agitação e uma higienização com etapas de limpeza com detergentes alcalino e ácido, seguidas de sanificação foi utilizada para avaliação do comportamento das células aderidas frente à higienização. Esse microrganismo aderiu às superfícies de aço inoxidável produzindo uma carga de 104 células/cm2. Após a limpeza alcalina não foram detectadas células aderidas, porém, em seguida a limpeza ácida, 6 células/cm2 ainda foram detectadas nessa superfície. A sanificação com hipoclorito de sódio a 100 ppm após a limpeza foi suficiente para reduzir a níveis não detectáveis a carga de S. thermophilus selvagem aderidas às superfícies de aço inoxidável
Abstract: A wild microorganism, isolated from HTST pasteurized milk processed in a continuous 4 hour operation, was identified as Streptococcus thermophilus, giving greater celular growth in M17 broth, incubated for 6 hours at 45°C. The viable cell count was evaluated in PCA, APT, :MRS e M17, the media M17 and MRS being shown to allow for better growth. Microorganism lower count was observed in APT in relation to M17 and MRS and no growth occurred in PCA medium. The generation time, thermal destruction at 72°C, storage of the culture at 10°C and formation of adhesive structures were evaluated in milk The organism showed a generation time of 15.2 minutes at 45°C and a Dn value of 7.4 minutes. After storage at 10°C for 6 days, 57.1% of Streptococcus cells remained viable, and organism formed adhesive structures on stainless steel surfaces in 20 hours, these being observed using a scanning eletronic microscope. The production of lactic acid was determined after 8 hours incubation at 35,40,45 and 50°C, greatest values being obtained at 45°C ( 0.35%) and at 40°C (0.34%), lower values being obtained at 50 and 35°C respectively. The adhesion of this S. thermophilus onto stainless steel surfaces was studied afier 6 hours of contact at 45°C with agitation. A cleansing process involving cleaning stages with alkaline and acid detergents followed by sanification was used to evaluate the resistence of the adhered cells. The microorganism adhered to stainless steel surfaces producing a cell load of 104 cells/cm2. After alkaline cleasing, no adhered cells were detected but afier acid cleasing, 6 cells/cm2 were still detected on surface. Cleasing followed by sanification with 100 ppm sodium hypochorite was sufficient to reduce the load of wild S. thermoplilus on the stainless steel surface to non detectable levels
Mestrado
Mestre em Tecnologia de Alimentos
Hervé, Luciana. "Une nouvelle vision de la proto-coopération entre Streptococcus thermophilus et Lactobacillus delbrueckii spp. Bulgaricus par des approches post-génomiques." Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0034.
Full textTOSI, LORENZO. "Antibiotico resistenza in S. thermophilus, tratti fenotipici, coniugazione e aggregazione." Doctoral thesis, Università Cattolica del Sacro Cuore, 2007. http://hdl.handle.net/10280/77.
Full textIn the last decades, the use of antibiotics in human therapy or in animal husbandry as growth promoters has induced the development and the diffusion in antibiotic resistant micro-organisms. In this context antibiotic resistant Lactic Acid Bacteria (LAB) do not represent a clinical risk in themselves. However, the possibility that S. thermophilus cultures might transfer antibiotic resistance genes to pathogenic species either present in food or in the gastrointestinal tract (including enterococci, streptococci and listeria) represents a potential clinical risk that needs to be carefully evaluated. The aim of this study was to evaluate by means of phenotypic methods (microdilution, E-test, disc-diffusion) the levels of antibiotic resistance for S. thermophilus and L. plantarum species against the antibiotic tetracycline, erythromycin, clyndamicin, streptomycin, gentamycin and ampicillin. The atypical resistant S. thermophilus strains were subjected to genetic analyses in order to characterise and to localise the antibiotic resistance determinants. Furthermore the ability of the resistant S. thermophilus strains in transferring the antibiotic resistant determinant was assessed in mating experiments using as recipients the Gram-positive bacteria E. faecalis and Listeria monocytogenes. In same resistant S. thermophilus strains, special bacterial fitness related with the presence of the antibiotic resistance determinants in the bacterial hosts were observed and studied.
TOSI, LORENZO. "Antibiotico resistenza in S. thermophilus, tratti fenotipici, coniugazione e aggregazione." Doctoral thesis, Università Cattolica del Sacro Cuore, 2007. http://hdl.handle.net/10280/77.
Full textIn the last decades, the use of antibiotics in human therapy or in animal husbandry as growth promoters has induced the development and the diffusion in antibiotic resistant micro-organisms. In this context antibiotic resistant Lactic Acid Bacteria (LAB) do not represent a clinical risk in themselves. However, the possibility that S. thermophilus cultures might transfer antibiotic resistance genes to pathogenic species either present in food or in the gastrointestinal tract (including enterococci, streptococci and listeria) represents a potential clinical risk that needs to be carefully evaluated. The aim of this study was to evaluate by means of phenotypic methods (microdilution, E-test, disc-diffusion) the levels of antibiotic resistance for S. thermophilus and L. plantarum species against the antibiotic tetracycline, erythromycin, clyndamicin, streptomycin, gentamycin and ampicillin. The atypical resistant S. thermophilus strains were subjected to genetic analyses in order to characterise and to localise the antibiotic resistance determinants. Furthermore the ability of the resistant S. thermophilus strains in transferring the antibiotic resistant determinant was assessed in mating experiments using as recipients the Gram-positive bacteria E. faecalis and Listeria monocytogenes. In same resistant S. thermophilus strains, special bacterial fitness related with the presence of the antibiotic resistance determinants in the bacterial hosts were observed and studied.
Fayard, Blandine. "Caractérisation de 69 bactériophages de Streptococcus salivarius subsp. Thermophilus, incluant 10 bactériophages tempérés." Nancy 1, 1993. http://docnum.univ-lorraine.fr/public/SCD_T_1993_0011_FAYARD.pdf.
Full textTwelve of the 118 strains of Streptococcus salivarius subsp. Thermophilus of the CNRZ collection exhibited a Iytic phase after mitomycin C induction and contained active phages. The corresponding temperate phages were multiplied on indicator strains and compared to 56 phages isolated as Iytic. All Iysogenic strains were characterized by autolytic properties in certain conditions of culture. Morphologically, the 69 temperate or virulent phages studied all belonged to Bradley's (1967) group B, or to the family of the Siphoviridae of the International Committee on Taxonomy of Viruses (Matthews, 1982). There were 2 types of virion protein profiles. Most phage DNA were linear with cohesive ends, and size varied trom 35 to 50 kb. There was considerable restriction polymorphism. Homology existed among all phage DNA, in particular between the DNA of temperate phages and those of virulent phages. The study of phage-bacteria interactions showed that some Iysogenic strains were sensitive to superinfections by numerous phages and that in this case, these Iysogenic strains rearranged the genome of infecting phages. The results suggest that Iysogenic strains of S. Salivarius subsp thermophilus could play a major role in the genesis of phage infections and in the evolution of the phage population specific to this streptococcus
Pavlovic, Guillaume. "Evolution d'une famille d'éléments intégratifs potentiellement conjugatifs et/ou mobilisables de Streptococcus thermophilus." Nancy 1, 2004. http://www.theses.fr/2004NAN10009.
Full textIn this work, four types of genomic islands related to ICESt1 were characterized. They are integrated in the same location as ICESt1 in seven other strains of S. Thermophilus. One of these elements, ICESt3, is probably an ICE. Two other types of elements, CIME19258 and CIME302, are flanked by site-specific attachment sites closely related to attL and attR of ICESt1 and ICESt3 whereas DCIME308 only possesses a putative attR site. They have arisen from ICEs by deletion of there conjugation and recombination modules. Comparisons between ICE and CIME (cis-mobilizable element) from Streptococcus thermophilus and functional analysis, using plasmids harbouring the entire or a part of the recombination module of ICESt1, suggest that these elements evolve by a novel model. ). The circular form of an ICE, acquired by conjugation, integrates by site-specific in the attR site of the CIME, leading to the structure attL-CIME-attI'-ICE-attR'. Then partial or entire deletion of the attI site would stabilise the composite element. The whole structure would be a novel ICE and could be excised by recombination between attL and attR and transferred to a new host bacterium. This suggests that ICEs have acquired novel modules by a new mechanism: accretion / mobilization of CIMEs. In conclusion, ICE and probably CIME would be important in the evolution of bacterial genomes by horizontal gene transfer and contribute to the acquisition of new functions by these genomes
Low, Deborah. "Influence of Streptococcus thermophilus MR-1 C Capsular Exopolysaccharide on Cheese Moisture Level." DigitalCommons@USU, 1998. https://digitalcommons.usu.edu/etd/5440.
Full textArioli, S. "Carbon dioxide metabolism in Streptococcus thermophilus : physiological and ecological importance, and dairy applications." Doctoral thesis, Università degli Studi di Milano, 2008. http://hdl.handle.net/2434/50715.
Full textBen, Yahia Leila. "Étude du dialogue hôte/bactéries lactiques du yaourt chez des rats gnotobiotiques." Thesis, Paris, AgroParisTech, 2012. http://www.theses.fr/2012AGPT0028/document.
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Bédard, Nathalie. "Rejet de galactose par Streptococcus thermophilus au cours d'une croissance sur milieu lactosé : role de GaIM." Master's thesis, Université Laval, 2007. http://hdl.handle.net/20.500.11794/19110.
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