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1
Jin, Su. "Physiological characteristics and applications of Lactobacillus pentosus strains in selected dairy products". AgroParisTech, 2010. http://pastel.archives-ouvertes.fr/docs/00/55/22/70/PDF/These_Su_JIN.pdf.
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Deux souches de Lactobacillus pentosus, Ind1 et Ind3, ont été isolées à partir de « Naigeda », un fromage traditionnel Chinois produit dans la région du Xinjiang. Les propriétés probiotiques de L. Pentosus étant peu connues, la présente étude a été conduite afin de déterminer si ces 2 souches, Ind1 et Ind3, sont susceptibles d’être utilisées comme probiotiques. Les propriétés physiologiques de L. Pentosus Ind1 et Ind3 ont fait l’objet d’essais in vitro afin de déterminer leur tolérance à l’environnement gastro-intestinal et leur adhérence à l’épithélium intestinal. Leurs propriétés de dégradation de 3 substances carcinogènes (phénol, p-crésol et indole ; concentrations comprises entre 50 et 150 µg/mL) ainsi que leur inhibition éventuelle par ces mêmes substances ont été étudiées. Les effets des 2 souches de L. Pentosus sur la microflore intestinale de souris, après administration orale de 109cfu/mL dans 0. 5mL de lait écrémé, ont été analysés. A cet effet, les populations de Lactobacilles, Bifidobactéries, Entérobacilles, Entérocoques et Clostridium perfringens, contenues dans les fèces des souris, avant, pendant et après leur alimentation en probiotiques, ont été considérées. Enfin, les capacités des 2 souches de L. Pentosus à produire de l’acide -amino butyrique ont été étudiées, et les conditions de milieu et de culture assurant la meilleure production définies. Les résultats montrent que les 2 souches de L. Pentosus, Ind1 et Ind3, présentent des taux de survie élevés : plus de 90 % en milieu acide et de 80% dans une solution de bile. Les aptitudes à l’adhérence sont souches dépendantes, avec pour Ind3 un potentiel similaire à celui de souches probiotiques reconnues (NCFM et Lp115). Ind1 et Ind3 ont également montré une bonne résistance aux substances carcinogènes (phénol, p-crésol, indole à 150 μg/mL). Enfin, ces 2 souches permettent un accroissement des concentrations de Lactobacilles et de bifidobactéries, dans le tractus intestinal des souris, tout en inhibant la croissance des Entérobacilles et de C. Perfringens. Ces résultats démontrent les aptitudes potentielles des deux souches de L. Pentosus étudiées pour une utilisation comme souches probiotiques au sein de régimes diététiques ou pour l’élaboration de produits laitiers fermentésTwo Lactobacillus pentosus strains, Ind1 and Ind3, were isolated from a traditional Chinese cheese product called Naigeda, collected from Xinjiang region of China. Since there is little information regarding the probiotic properties of L. Pentosus strains, this study was designed to provide more supporting data for L. Pentosus as a potential probiotic strain application. The physiological properties of the two L. Pentosus strains, Ind1 and Ind3, such as the in vitro test on the intolerance under the gastro-intestinal environment, the ability of adherence on the intestinal epithelium were studied. Their intolerance as well as inhibition and degradation ability under presence of pre-carcinogenic substances existing in human gut such as phenol, p-cresol and indole at different concentrations were also determined. The effects of the two L. Pentosus strains on modulation of the mice intestinal micro flora, by oral administration of 109cfu/ml of strains in 0. 5ml of skim milk, were investigated: the amounts of Lactobacillus spp. , Bifidobacterium spp. , Enterobacilli, Enterococcus and Clostridium perfringens in the feces of mice during and after the feeding of probiotic strains were counted. Furthermore, the technological properties of the two L. Pentosus strains on their GABA producing ability were studied: the medium and process parameters optimization was carried out in order to try to obtain the highest GABA content in the fermented dairy products. Results showed that the two L. Pentosus strains had high survival rates (higher than 90% in acid and 80% in bile solution). The adhesive ability is strain independent: Ind3 adherence was comparable with those of two commercial probiotic strains (NCFM and Lp115). Ind1 and Ind3 showed good resistance mutagenic substances phenol, p-cresol, indole at concentration below 150 μg/mL). Ind1 and Ind3 also showed certain effect on promoting the increase of Lactobacillus and Bifidobacteria counts, and inhibiting the growth of Enterobacilli and Clostridium in mice gut. These results displayed positive properties that the two L. Pentosus strains can be good candidates to be used as probiotic strains potentially used in dietary supplement application or Chinese-style dairy products
2
Harris, Lyle Keenan. "Comparison of plasmids from clinical Lactobacillus strains". University of the Western Cape, 2018. http://hdl.handle.net/11394/6439.
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Magister Scientiae - MSc (Biotechnology)The vaginal mucosa is dominated by Gram positive, rod shaped lactobacilli which serve as a natural barrier against infection. In both healthy and BV infected women Lactobacillus crispatus and Lactobacillus jensennii has been found to be the predominant Lactobacillus species. Many studies have been conducted to assess factors influencing lactobacilli dominance in the vaginal microbiome. However, no study has evaluated the impact of plasmids on the vaginal lactobacilli. In the present study two plasmids, pLc17 and pLc4, isolated from vaginal Lactobacillus species of both healthy and BV infected women were characterized. pLc4 was present in both Lactobacillus crispatus and Lactobacillus jensennii while pLc17 was only present in Lactobacillus crispatus. pLc17 (16663 bp in size) encoded a ribonucleotide diphosphate reductase (RNR), a filamentation induced by cAMP-like (FIC-like) protein and numerous mobile elements.
3
Regulski, Krzysztof. "Influence of peptidoglycan metabolism on immunomodulatory properties of Lactobacillus casei". Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112313.
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Le peptidoglycane (PG) est le composant majeur de la paroi des bactéries à Gram positif. Il assure la forme et l’intégrité de la cellule bactérienne. Le PG ou des fragments dérivés sont connus pour être des inducteurs du système d’immunité innée de l’hôte, en particulier au travers des récepteurs Nod2. Au cours de ce travail, nous avons étudié l’influence du métabolisme du PG sur les propriétés immunomodulatrices de Lactobacillus casei BL23, en étudiant principalement sa capacité à moduler la réponse des cellules dendritiques humaines. Nous avons tout d’abord caractérisé les hydrolases du PG (PGHs) majeures de L. casei BL23. Une recherche in silico a révélé que L. casei possède un système de PGHs relativement complexe comprenant treize enzymes putatives avec des domaines catalytiques variés. Une analyse protéomique d’extraits de paroi de L. casei BL23 a permis de détecter la production de sept d’entre elles pendant la croissance bactérienne. Quatre d’entre elles ont été étudié plus en détails. La PGH la plus fortement exprimée, Lc-p75, a une activité de -D-glutamyl-L-lysyl-endopeptidase et est responsable de la séparation des cellules après division. De plus, Lc-p75 associée à la paroi est localisée au niveau des septa cellulaires. Il s’agit également de l’une des protéines majeures secrétée dans le surnageant de culture de L. casei BL23. Lc-p75 possède la particularité d’être une glycoprotéine. La PGH Lc-p40 possède un domaine CHAP doué d’une activité endopeptidase avec un site de clivage situé au niveau des ponts interpeptidiques du PG. Lc-p40 parait localisée au niveau de la paroi latérale des cellules de L. casei. Lc-p45 est une deuxième -D-glutamyl-L-lysyl-endopeptidase avec un rôle dans le maintien de la forme de la bactérie. Enfin nous avons caractérisé deux enzymes de prophages, Lc-Lys et Lc-Lys2, codée par le génome de L. casei BL23, qui possède toute deux un domaine de liaison au PG d’un nouveau type qui possède la particularité de lier spécifiquement le D-Asp amidé présent dans les ponts interpeptidiques du PG de L. casei BL23. La délétion des deux gènes qui codent pour les endopeptidases Lc-p75 et Lc-p45 chez L. casei BL23 conduit à l’absence de disaccharide dipeptide dans la structure du PG du mutant, tandis que la délétion de Lc-p75 seulement conduit à une réduction de la quantité du disaccharide-dipeptide. Ce disaccharide dipeptide est un ligand des récepteurs Nod2. Les deux mutants obtenus par délétion de Lc-p75 ou bien par délétion des deux endopeptidases ont été comparés avec la souche sauvage BL23 pour leur capacité à activer in vitro des cellules dendritiques humaines dérivées de monocytes sanguins. Suite à l’activation des cellules dendritiques par les souches de L. casei, quatre cytokines pro-inflammatoires, les interleukines IL-6, IL-8, IL-12 et le TNF- ont été produites. La quantité de chaque cytokine sécrétée en réponse aux mutants simple Lc-p75 et double Lc-p75/Lc-p45 était diminuée par rapport à celle induite par la souche sauvage L. casei BL23.En conclusion, L. casei BL23 est doté d’un équipement complexe en PGHs. Les PGHs caractérisées au cours de ce travail présentent des caractéristiques uniques et jouent un rôle important dans la division des bactéries ainsi que dans le maintien de leur morphologie. Nos résultats indiquent que la souche sauvage de L. casei Bl23 et les mutants dérivés obtenus par inactivation d’enzymes à activité endopeptidase, qui diffèrent à la fois au niveau de leur contenu enzymatique ainsi qu’au niveau de la structure de leur PG, ont des effets différents sur les cellules dendritiques humaines, avec un caractère anti-inflammatoire plus élevé pour les mutantsPeptidoglycan (PG) is the major component of the Gram-positive bacteria cell wall. It ensures bacterial cell shape and integrity. PG or PG-derived fragments have been shown to stimulate the host innate immune system, through Nod-2 receptors. In this work, we studied the influence of PG metabolism on immunomodulatory properties of Lactobacillus casei BL23, mainly its ability to modulate the response of human dendritic cells (DCs).We have first characterized the main peptidoglycan hydrolases (PGHs) of L. casei BL23. In silico search revealed that L. casei BL23 has a rather complex PGH complement including thirteen predicted PGHs with various catalytic domains. Proteomic analysis of bacterial cell wall extracts revealed the expression of seven of them during bacterial growth. We characterized four of them in details. Lc-p75 is the major PGH with a γ-D-glutamyl-L-lysyl-endopeptidase specificity and is responsible for daughter cell separation. Lc-p75 associated to the cell wall localizes at the cell septa. It is also one of the major secreted proteins of L. casei found in culture supernatant. Besides, we showed that L. casei Lc-p75 is a glycosylated protein. Lc-p40 is a PGH with a CHAP-domain endowed with endopeptidase hydrolytic specificity toward peptidoglycan cross-bridges and appears to localize on lateral cell wall. Lc-p45 is a second γ-D-glutamyl-L-lysyl endopeptidase with a role in cell shape maintenance. We further demonstrated that two prophage endolysins Lc-Lys and Lc-Lys2, encoded in L. casei BL23 genome, share a common novel type peptidoglycan-binding domain that recognizes specifically D-Asn cross-bridge, present in L. casei BL23 peptidoglycan.Deletion of the two endopeptidases, Lc-75 and Lc-p45, resulted in a complete loss ofdisaccharide-dipeptide, which is a ligand of Nod-2 receptor, in the muropeptide structure of L. casei BL23, whereas deletion of Lc-p75 gene led only to a reduction of disaccharide dipeptide. The two PGH-mutants, obtained by deletion of Lc-p75 gene alone or both Lc-p75 and Lc-p45 endopeptidase genes were compared with wild type L. casei BL23 for their capacity to stimulate signaling pathways in vitro in DCs derived from human monocytes. As a consequence of DC activation by L. casei strains, four pro-inflammatory cytokines IL-6, IL-8, IL-12 and TNF-α were produced. The concentrations of secreted cytokines in response to the single Lc-p75 and Lc-p75/p45 double mutant were lower than those induced by wild type L. casei BL23.In conclusion, L. casei BL23 has a complex PGH complement. The PGHs described in this work present unique features and play important role in cell division and morphology of L. casei. Our results indicate that wild type L. casei and endopeptidase-negative mutants, which differ in their PGH content and in their PG structure, have distinct effects on human DCs, with a higher anti-inflammatory character of the endopeptidase-negative mutants
4
Egervärn, Maria. "Antibiotic resistance in Lactobacillus reuteri and Lactobacillus plantarum /". Uppsala : Swedish University of Agricultural Sciences, 2009. http://diss-epsilon.slu.se/archive/00002017/01/Acta_Thesis%2C_Egerv%C3%A4rn_090508.pdf.
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Lönnermark, Elisabet. "Lactobacilli in the normal microbiota and probiotic effects of Lactobacillus plantarum /". Göteborg : Department of Infectious Medicine, Sahlgrenska Academy, University of Gothenburg, 2010. http://hdl.handle.net/2077/21480.
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Allain, Thibault. "Rôle des Bile Salt Hydrolases (BSH) des lactobacilles probiotiques dans le contrôle de la giardiose". Thesis, Paris, AgroParisTech, 2016. http://www.theses.fr/2016AGPT0018.
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Giardia duodenalis est le protozoaire responsable de la giardiose, la parasitose intestinale la plus répandue dans le monde. Cette infection se caractérise par une malabsorption intestinale, des diarrhées, une perte de poids et des douleurs abdominales intenses chez l’Homme et de nombreux mammifères. Par ailleurs, cette maladie dont l’impact en santé publique et vétérinaire est reconnu, peut entraîner d’importantes déficiences nutritionnelles en particulier chez les sujets jeunes. L’infection est causée par l’ingestion de kystes de Giardia duodenalis (syn. G. lamblia, G. intestinalis) présents dans les aliments ou l’eau contaminée. Infectieux à très faibles doses, ces kystes survivent pendant plusieurs semaines dans l’environnement et sont résistants aux différents désinfectants. Suite au dékystement, la forme végétative de Giardia, le trophozoïte, adhère à l’épithélium intestinal au niveau des parties supérieures de l’intestin grêle et se multiplie, causant les symptômes. Cette phase se termine par un nouvel enkystement et l’excrétion de kystes par les fèces. Le nombre croissant d’infections liées à la contamination de l’eau potable, à l’émergence de souches résistantes aux médicaments disponibles, à la fréquence des échecs thérapeutiques et à l’importance des effets secondaires associés aux traitements font de cette maladie un sujet d’actualité de plus en plus préoccupant qui nécessite le développement de traitements alternatifs. Il est désormais bien établi que le microbiote et/ou certaines souches de bactéries probiotiques ont un impact bénéfique dans la giardiose. En particulier, la bactérie probiotique Lactobacillus johnsonii La1 (LjLa1) a un rôle protecteur contre la croissance de Giardia in vitro et in vivo. Nous avons cherché dans ce travail de Thèse à décrypter les mécanismes moléculaires associés à l’effet inhibiteur des facteurs sécrétés par LjLa1. Nous avons montré qu’in vitro, LjLa1 agissait en libérant des enzymes de type Bile Salt Hydrolases (BSH) qui modifient alors des composants de la bile non-toxiques pour le parasite (sels biliaires conjugués) en des composants toxiques (sels biliaires déconjugués). Les 3 gènes BSH codés dans le génome de LjLa1 ont été clonés chez Escherichia coli et les protéines taguées histidine purifiées pour étudier leurs propriétés biochimiques et biologiques. Obtenues sous forme active, nous avons pu en définir les spécificités de substrats et montrer qu’elles sont capables d’inhiber significativement la croissance de G. duodenalis in vitro et in vivo, dans un modèle murin de la giardiose (souriceaux OF1 non sevrés). En parallèle, nous avons identifié, à l’issue d’un large criblage de souches de lactobacilles selon leur activité anti-Giardia in vitro, une souche probiotique aux effets inhibiteurs comparables à ceux de LjLa1 : Lactobacillus gasseri CNCM-4884. Administrée in vivo dans le modèle murin de la giardiose, cette souche a réduit de 93% la charge parasitaire dans l'intestin grêle des nouveaux nés et a également réduit de façon significative le nombre de kystes libérés dans l’environnement, permettant ainsi de réduire la transmission de Giardia. Des travaux parallèles ont été réalisés au cours de ce projet de Thèse, notamment le développement d’outils de moléculaire pour l’expression hétérologue de molécules d’intérêt en santé animale chez divers lactobacilles. Le développement de ces « vecteurs mucosaux » permettra à terme de proposer une stratégie de surexpression de BSH par les lactobacilles afin d’accroitre l’activité BSH in vivo, et renforcer ainsi l’élimination du parasite. Ces résultats permettent de proposer de nouvelles pistes thérapeutiques originales contre les giardioses humaines et animales, basées sur l’utilisation de lactobacilles probiotiques ou sur les activités BSH qui en sont dérivées. Ces traitements offrent alors une alternative sérieuse aux antibiotiques et permettront de pallier aux actuels fréquents échecs thérapeutiquesGiardia duodenalis is a protozoan parasite responsible for giardiasis, the most common intestinal parasitic disease worldwide. This infection is characterized by intestinal malabsorption, diarrhea, weight loss and abdominal pain in humans and various mammalian species. Besides, this disease has a high veterinary and public health impact, leading to important nutritional deficiencies in young subjects. The infection is caused by the ingestion of food or water contaminated with infectious cysts of the parasite. Giardia cysts can survive for several weeks in the environment and are highly resistant to disinfectants. Giardia excysts in the intestinal tracts of its host and replicates under the trophozoite stage causing the symptoms. Trophozoites adhere to the intestinal epithelium of the small intestine and multiply, causing the symptoms. The cycle ends by a new encystment and infectious cysts are released in environments with feces. The increasing number of giardiasis cases, mainly due to water contaminations, the emergence of parasite strains resistant to drugs and therapeutic failures, make research on alternative therapeutic strategies and treatments highly needed. Nowadays, it is well known that the microbiota and probiotics play an important role in protection against this parasite. For instance, the probiotic strain Lactobacillus johnsonii La1 (LjLa1) prevents the establishment of Giardia in vitro and in vivo. In this thesis, we have tried to point out the molecular mechanism(s) involved in this inhibitory effect(s). We showed in vitro that LjLa1 was releasing "Bile Salt Hydrolases" (BSH) – like activities that modify some components of bile (conjugated bile salts) into toxic compounds (deconjugated bile salts) for Giardia. We have cloned and expressed each of the three bsh genes present in the genome of LjLa1 in Escherichia coli in order to study their enzymatic and biological properties. Two BSH were obtained as recombinant active enzymes and biochemical tests showed that they have distinct substrate specificities despite similar predicted 3D structures. Moreover, these two BSHs of LjLa1 exhibited anti-giardial effects in vitro and in vivo in a murine model of the giardiasis (OF1suckling mice), comforting the hypothesis of the biological role of active BSH, derived from probiotics, against Giardia. A wide collection of diverse lactobacilli strains was screened to assess their effectiveness to also display both anti-giardial and BSH activities. This screening allowed the identification of several strains exhibiting strong anti-giardial effects such as Lactobacillus gasseri CNCM I-4884. In a murine model of giardiasis, this strain dramatically reduced the parasite burden in the small intestine of treated animals and significantly reduced the number of cysts in the colon, which could contribute to blockage of parasite transmission in environments. Additional studies were realized in parallel in order to explore the potency of lactobacilli to exert beneficial effects on health. For this, molecular tools were successfully developed in various lactobacilli strains to express and deliver therapeutic molecules at mucosal surfaces. The development of these tools will further allow the overexpression of BSH by lactobacilli to increase their in vivo BSH-activity and strengthen the elimination of the parasite. Altogether, this thesis work proposes new original therapeutic strategies against human and animal giardiasis, based on the use of BSH-positive lactobacilli strains or recombinant BSH- derived from probiotic strains, to counteract the frequent therapeutic failures, offering a serious alternative to antibiotics
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Aoudia, Nabil. "Caractérisation de l'impact de la croissance en biofilm sur l'activité probiotique de souches du genre Lactobacillus". Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS017.
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Une approche in vitro a consisté à étudier la formation de biofilm de souches d’origine du genre Lactobacillus d’intérêt probiotique. Nous nous sommes également attachés à évaluer l’impact de conditions de stress mimant l’environnement intestinal sur la formation du biofilm pour l’ensemble de ces souches. Les effets antagonistes des surnageants de cultures en biofilm ou en planctonique contre des agents pathogènes alimentaires ont été appréhendés. Non seulement toutes les souches testées forment des biofilms mais ce mode de croissance génère un effet antagoniste accentué pour certaines d’entre elles. Parmi les critères de sélection des bactéries à intérêt probiotique, les effets immunomodulateurs des probiotiques sont souvent recherchés. L. casei ATCC334 connue pour ses effets anti-inflammatoires a été retenue pour notre étude. A l’aide du modèle de lignée cellulaire THP-1 et en présence de LPS, le surnageant de culture de L. casei ATCC334 cultivée en biofilm s’est avéré présenter un effet anti-inflammatoire bien supérieur à celui des cultures planctoniques. Une approche utilisant des techniques biochimique et immunologique a permis d’identifier un des principes actifs responsable de l’effet anti-inflammatoire de cette souche. L’utilisation du modèle poisson zèbre a permis de montrer la colonisation de l’intestin des larves et de confirmer le rôle anti-inflammatoire de L. casei ATCC334 avec une diminution de la production des interleukines pro-inflammatoires et une augmentation de la production d'IL-10. Le recrutement des macrophages fluorescents mesuré en cytométrie de flux est également atténué chez la larve nourrie auparavant par le probotique en présence d’un agent inflammatoire. Le résultat majeur de cette étude est l’identification de la protéine GroEL qui contribue de façon significative à l’effet anti-inflammatoire de la souche L. casei ATCC334 lorsque qu’elle est cultivée en biofilmAn in vitro approach was used to study biofilm formation by bacterial strains with probiotic properties and belonging to the Lactobacillus genus. We also evaluated the impact of stress conditions mimicking the intestinal environment on biofilm formation for all of these strains. The antagonistic effects of supernatants from cultures in biofilm or planktonic conditions against food-borne pathogens were apprehended. This growth mode generates an antagonistic effect accentuated for some of them. Among the selection criteria of interest probiotic bacteria, the immunomodulatory effects of probiotics are often sought. L. casei ATCC334 known for its anti-inflammatory effects was selected for our study. Using the model cell line THP-1 and in the presence of LPS, the culture supernatant of L. casei ATCC334 grown in biofilm was found to have an anti-inflammatory effect much greater than planktonic cultures. An approach using immunological and biochemical techniques has allowed the identification of the active substances responsible for the anti-inflammatory effect of this strain. Using the zebrafish model, we showed the colonization of the gut of the larvae and confirmed the anti-inflammatory role of L. casei ATCC334 with a decreased production of pro-inflammatory interleukins, and increased IL-10 production. Recruitment of fluorescent macrophages measured by flow cytometry was also mitigated in larvae fed previously by probotic in the presence of an inflammatory agent. The major result of this study is the identification of the GroEL protein that contributes significantly to anti-inflammatory effect of the strain L. casei ATCC334 when it is grown in biofilm
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Storelli, Gilles. "Caractérisation de l’interaction mutualiste liant Drosophila melanogaster à son symbionte Lactobacillus plantarum". Thesis, Lyon, École normale supérieure, 2015. http://www.theses.fr/2015ENSL1041.
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Le microbiote a un impact majeur sur la physiologie de son hôte, cependant notre compréhension des mécanismes régulant la relation hôte/microbiote reste limitée. Nous utilisons un hôte modèle simple, la Drosophile, afin de répondre à ces questions. Durant mon doctorat, je me suis attaché à une étape particulière du cycle de vie de la Drosophile, sa phase larvaire. Celle-ci constitue sa phase de croissance et est influencée par le contexte nutritionnel. Le microbiote influence également cette étape: l’association avec la bactérie Lactobacillus plantarum tempère les effets de la carence alimentaire en soutenant un taux de croissance élevé et une maturation rapide, en modulant chez l’hôte l’activité de l’hormone Ecdysone et de l’insuline. En retour, L.plantarum bénéficie de l’association, les larvesassurant sa persistance dans la niche (la niche étant le substrat nutritif, les larves et les bactéries associées). Pour caractériser les mécanismes mis en jeu dans ce mutualisme nous avons décrit les réponses transcriptomiques et métaboliques de la larve et avons également étudié les perturbations métaboliques de la niche. Nos résultats mettent en avant l’optimisation de l’extraction des acides aminés du substrat comme facteur clef du mutualisme. L.plantarum active l’expression des protéases intestinales de l’hôte via la voie IMD/NF-κB, et bénéficierait en retour d’une quantité d’acides aminés plus importante assurant sa persistance. Ainsi, nos travaux contribuent à l’effort de compréhension desmécanismes régulant l’interaction hôte/microbiote et pourraient conduire à de nombreuses applications thérapeutiques, notamment dans le cadre de déséquilibres nutritionnelsSymbiotic bacterial populations (also called the “microbiota”) have a dramatic impact on their host’s physiology. However, our understanding of the mechanisms shaping host/microbes mutualism remains limited. We took advantage of Drosophila tractability to characterize the host’s and the microbial factors engaged in mutualism. During my PhD, I focused on the impact of the microbiota during the Drosophila larval phase, which constitutes its juvenile growth period. Drosophila larval phase is influenced by nutrition, but also by symbiotic microbes: specific association with the bacterium Lactobacillus plantarum buffers the deleterious effects of nutrient scarcity on the host’s juvenile growth, by sustaining greater growth rates and hastening maturation. L.plantarum mediate these effects by modulating the activity of the steroid hormone Ecdysone and the Insulin/Insulin-like Signaling pathway in its host. In return, L.plantarum benefits from Drosophila presence, as larvae ensure its long-term persistence in the niche (the niche being the nutritive substrate, the larvae and the bacteria dwelling on it). To characterize the mechanisms engaged in this mutualistic relationship, we described the host’s transcriptomic and metabolic responses to L.plantarum presence and characterized the metabolic perturbations occurring in the niche. Our results put forward the optimization of amino-acids extraction from the nutritive substrate as a cornerstone of mutualism. L.plantarum activates the expression of the host’s digestive proteases via IMD/NF-κB signaling and would benefit in return from an enhanced AA availability, which would help sustaining its long-term persistence. Altogether, our studies contribute to the understanding of the mechanisms regulating host/microbiota interaction and could lead to numerous therapeutic applications, notably aiming at counteracting the deleterious effects of nutritional imbalances
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Lagrafeuille, Rosyne. "Activités anti-biofilm de Lactobacillus vis-à-vis de Klebsiella Pneumoniae". Thesis, Clermont-Ferrand 1, 2016. http://www.theses.fr/2016CLF1PP03/document.
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Dans la nature, les micro-organismes sont organisés en communautés agrégées dénommées biofilms, particulièrement adaptées à la survie en milieu hostile. Les difficultés pour prévenir la formation ou éliminer des biofilms matures par des stratégies conventionnelles ont encouragé le développement de nouvelles approches inspirées des mécanismes de compétition entre différents micro-organismes au sein de biofilms naturels. Au cours de ce travail, nous nous sommes intéressés à l'effet anti-biofilm de bactéries bénéfiques appartenant aux genres Lactobacillus et Bifidobacterium. Dans un premier temps, nous avons testé l'effet anti-biofilm de surnageants neutralisés vis-à-vis de deux pathogènes Klebsiella pneumoniae et Staphylococcus epidermidis dans un modèle expérimental statique. Si les extraits des quelques souches de Bifidobacterium testées stimulaient la formation de biofilm par K. pneumoniae sur surface abiotique, la majorité de ceux des 140 souches de Lactobacillus exerçait un effet inhibiteur et nous avons retenu une des souches dont le surnageant de culture entraînait une inhibition majeure (70%), Lactobacillus plantarum CIRM653. Cet extrait s'est également avéré capable de disperser des biofilms préformés à K. pneumoniae sur surface abiotique mais aussi d’inhiber la formation de biofilms sur surface biotique, et ce indépendamment d’un effet bactéricide. La formation de biofilms mixtes formés par L. plantarum et K. pneumoniae dans des modèles expérimentaux cinétiques a permis, comparativement à l'observation de biofilms mono-espèce à K. pneumoniae, de mettre en évidence des défauts de structuration du biofilm associés à une diminution de la biomasse de K. pneumoniae et une augmentation de celle de L. plantarum. Grâce à une approche transcriptionnelle ciblée, nous avons montré que L. plantarum induisait, par le biais de son surnageant, des modifications de l’expression de gènes impliqués dans la formation de biofilm chez K. pneumoniae. Quatre gènes impliqués dans le quorum-sensing (opérons lsr) étaient sous-exprimés et trois gènes de structure du pilus de type 3 étaient sur-exprimés. L'augmentation de la production de pili de type 3 fonctionnels a été validée par Western-blot et des tests d’hémagglutination. Cette surexpression est probablement responsable du niveau élevé des capacités d’adhésion sur surface abiotique d'agrégats de K. pneumoniae issus de la dispersion induite par L. plantarum.Le comportement des deux souches a également été testé in vivo, dans un modèle murin de colonisation intestinale par K. pneumoniae avec administration orale quotidienne de L. plantarum. Le dénombrement du pathogène dans les selles des animaux a montré qu'en présence de L. plantarum, K. pneumoniae maintient des niveaux de colonisation élevés, contrairement au contrôle (sans Lactobacillus) où une diminution graduelle est observée.Enfin, nous avons initié le développement d'un modèle expérimental tripartite permettant d'associer les deux partenaires bactériens avec des cellules épithéliales dans un système en flux continu. La réponse spécifique des cellules eucaryotes a également été abordée : nous avons pu mettre en évidence que L. plantarum exerçait un effet inhibiteur vis-à-vis de la réponse inflammatoire épithéliale pulmonaire induite par K. pneumoniae. En conclusion, la description d'une activité anti-biofilm in vitro ne serait pas synonyme d'une réduction in vivo de la colonisation de surfaces biotiques, mais à une plus grande capacité de dissémination. Ces observations démontrent l’importance d’une expertise précise de l’action des bactéries bénéfiques et de la maitrise du ratio bénéfice-risque pour leur utilisationIn the natural environment microorganisms are organized in aggregated communities called biofilms, which are particularly adapted to the survival in harsh conditions. The difficulties to prevent the formation or elimination of mature biofilms by conventional strategies have encouraged the development of new approaches inspired by competition mechanisms occurring between microorganisms within natural biofilms.In this work, we looked for anti-biofilm effects of beneficial bacteria belonging to Lactobacillus and Bifidobacterium genus. We first tested the anti-biofilm effect of neutralized supernatants against both pathogens Klebsiella pneumoniae and Staphylococcus epidermidis in a static experimental model. The few Bifidobacterium extracts tested led to an increase in biofilm formation by K. pneumoniae on abiotic surface, whereas the majority of the 140 strains of Lactobacillus exerted an inhibitory effect. Lactobacillus plantarum CIRM653 was selected for further experiments because its culture supernatant displayed major inhibition (70%). This extract was also capable of dispersing preformed biofilms of K. pneumoniae on abiotic surface, but also able to inhibit biofilm formation on biotic surface, independently of a bactericidal effect. The formation of mixed biofilm containing L. plantarum and K. pneumoniae in kinetic experimental models highlighted the biofilm structure defects associated with a decrease of K. pneumoniae biomass and an increase of that of L. plantarum, compared to a monospecies K. pneumoniae biofilm. Targeted transcriptional approach was used to assess changes in the expression of genes involved in biofilm formation by K. pneumoniae after contact with L. plantarum supernatant. Four genes involved in quorum-sensing (operons lsr) were under-expressed and three type 3 pili structural genes were over-expressed. The increase of functional surface located type 3 pili was validated by Western blotting and hemagglutination tests. This overexpression was probably responsible for the observed high level of adhesion capacity to abiotic surfaces of K. pneumoniae aggregates recovered after dispersion induced by L. plantarum.The behavior of the two strains was also tested in vivo in a K. pneumoniae murine intestinal colonization model with daily oral administration of L. plantarum. Viable cells counting of the pathogen in the animals’ feces showed that K. pneumoniae maintained high levels of colonization in the presence of L. plantarum, unlike the control (without Lactobacillus) where a gradual decrease was observed.Finally, we initiated the development of a tripartite experimental model allowing the combination of the two bacterial partners with epithelial cells in a continuous flow system. In parallel, the specific response of eukaryotic cells to these bacteria was addressed: L. plantarum exerted an inhibitory effect on the pulmonary epithelial inflammatory response induced by K. pneumoniae.In conclusion, these results highlight the discrepancy between in vitro anti-biofilm activity of L. plantarum and its in vivo behavior leading to increased dissemination of the pathogen. Substantial expertise of beneficial bacteria is therefore necessary to fully assess their benefit-risk ratio
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Lamarque, Mauld. "Spécificité du transport et de l'hydrolyse des peptides chez les bactéries lactiques : aspects nutritionnel et moléculaire". Lyon 1, 2003. http://www.theses.fr/2003LYO10213.
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Pour se développér dans le lait, les bactéries lactiques possèdent un système protéolytique comprenant une protéiase de surface PrtP, un transporteur d'oligopeptides Opp et des peptidases cytoplasmiques. Pour mieux comprendre le contôle de ce système par des peptides du milieu extracellualire, nous avons étudié la spécificité du transport des peptides chez les lactocoques. Cette spécificité est différente selon les souches et ne repose pas exclusivement sur le système Opp. Elle pourrait dépendre d'un second transporteur, Opt, dont la spécificité recouvre partiellement celle d'Opp et dont la biosynthèse est variable selon les souches. La source de carbone joue aussi un rôle sur l'expression de certains composants du système protéolytique. En effet, chez Lactobacillus bulgaricus, l'expression du géne pepQ est soumise à un mécanisme d'activation catabolique, dépendant d'une protéine CcpA-like (PepR1) et de la séquence cre située en amont du promoteur du géne pepQ.
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FARIAS, Thaísa Gabriela Silva de. "Viabilidade de Lactobacillus rhamnosus e Lactobacillus casei encapsulados em sorvete de cajá". Universidade Federal de Pernambuco, 2017. https://repositorio.ufpe.br/handle/123456789/25011.
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O interesse crescente por uma vida mais saudável tem proporcionado o desenvolvimento de alimentos que forneçam benefícios à saúde, como os que contêm microrganismos probióticos. A técnica de microencapsulação pode oferecer às células probióticas proteção e isolamento das condições adversas do produto, aumentando sua sobrevivência em ambientes extremos, como o trato gastrintestinal. Desta forma, o presente estudo propôs-se a desenvolver microcápsulas de alginatoquitosana contendo Lactobacillus rhamnosus ASCC 290 e Lactobacillus casei ATCC 334 para aplicação em sorvete de cajá. As cápsulas foram produzidas pelo método de extrusão, utilizando a matriz alginato de sódio e quitosana como revestimento adicional. O sorvete foi adquirido na forma liofilizada e reconstituído em laboratório, sendo dividido em quatro grupos: L. rhamnosus livres, L. rhamnosus encapsulados, L. casei livres e L. casei encapsulados. As amostras foram armazenadas a -18 °C e analisadas mensalmente durante 150 dias através de avaliações físico-químicas (pH e acidez titulável) e microbiológica (viabilidade celular). Foi realizada uma simulação gastrintestinal in vitro, utilizando solução ácida com pepsina e solução alcalina com sais biliares. Testes de aceitabilidade e intenção de compra foram aplicados ao sorvete contendo L. rhamnosus encapsulados. Com relação às células livres, o L. rhamnosus logo após o congelamento a -18 apresentou redução significativa (p < 0,05) da concentração inicial, com perda de 1,77 log UFC/g de sorvete. Nos meses seguintes, houve queda gradativa da viabilidade, contabilizando ao fim do experimento redução de 3,48 log. A espécie microencapsulada com alginatoquitosana não apresentou perda significativa (p > 0,05) após o congelamento a -18 °C, com diferença estatística apenas após 30 dias. O L. casei livre também sofreu redução significativa de 1,63 log UFC/g logo em seguida ao processo de congelamento. A cepa manteve-se a 10⁷ UFC/g até 150 dias de estocagem. Com redução de 1,49 log UFC/g ao final, as cápsulas promoveram a sobrevivência de 84,5% das cepas de L. casei. As espécies, tanto livres quanto encapsuladas, diferiram significativamente entre si nos tempos avaliados; o L. rhamnosus encapsulado conferiu maior viabilidade em relação ao L. casei, enquanto que na forma livre o L. casei apresentou menor perda celular comparado à outra espécie. Nenhum grupo causou alterações físico-químicas significativas no produto até 150 dias. Na simulação gastrintestinal, as células livres de L. rhamnosus apresentaram redução significativa de 2,04 log ainda na fase ácida. O L. casei livre decaiu 1 ciclo logarítmico a cada etapa gástrica, finalizando o teste intestinal com 6,31 ± 0,21 log UFC/mL. Com 118 voluntários, a análise sensorial apontou aceitabilidade de 7,58 ± 0,55, correspondendo a “gostei muito” e “gostei moderadamente”. Em relação à intenção de compra, os provadores atribuíram uma média de 3,94 ± 1,00, que significa que “provavelmente compraria” e “tenho dúvida se compraria” na escala. Os resultados obtidos demonstraram que microcápsulas otimizam a viabilidade celular no armazenamento congelado e nas condições gastrintestinais simuladas. A adição de 10% de cápsulas não interferem sensorialmente no sorvete probiótico.
The growing interest in a healthier life has provided the development of foods that offer health benefits, such as those containing probiotic microorganisms. The microencapsulation technique can provide protection and isolation from the adverse conditions to probiotic cells, increasing their survival in extreme environments such as gastrointestinal tract. Thus, the present study aimed to develop alginate-chitosan microcapsules containing Lactobacillus rhamnosus ASCC 290 and Lactobacillus casei ATCC 334 for application in yellow mombin ice cream. The capsules were produced by extrusion method, using as matrix sodium alginate and chitosan as additional coating. The ice cream was obtained in lyophilized form and reconstituted in laboratory, posteriorly divided into four groups: free L. rhamnosus, encapsulated L. rhamnosus, free L. casei and encapsulated L. casei. Samples were stored at -18 °C and analyzed monthly for 150 days by physico-chemical (pH and titratable acidity) and microbiological (cell viability) evaluations. In vitro gastrointestinal simulation was performed using acidic solution with pepsin and alkaline solution with bile salts. Acceptability and purchase intention tests were carried out in order to obtain information about the consumer's acceptance of the ice cream containing the capsules. In relation to the free cells, L. rhamnosus shortly after the slow freezing presented significant reduction (p < 0.05) from the initial concentration, with loss of 1.77 log CFU/g of ice cream. In following months, there was a gradual reduction of 3.48 log. The microencapsulated species with alginate-chitosan showed no significant loss (p > 0.05) after freezing at -18 °C, with statistical difference only after 30 days. Free L. casei also suffered a significant reduction (p < 0.05) of 1.63 log CFU/g soon after the freezing process. The strain was maintained at 10⁷ CFU/g for up to 150 days of storage. With a reduction of 1.49 log CFU/g at the end, the capsules promoted the survival of 84.5% of L. casei strains. The species, both free and encapsulated, differed significantly among themselves at the evaluated times. No group has caused significant physical-chemical changes in the product for up to 150 days. In gastrointestinal simulation, the free cells of L. rhamnosus presented significant reduction of 2.04 CFU/g in acid phase. Free L. casei declined 1 logarithmic cycle at each gastric stage, ending the intestinal test with 6.31 ± 0.21 log CFU/mL. with 118 volunteers, sensory analysis indicated acceptability of 7.58 ± 0.55, corresponding to “like very much” and “like moderately”. Regarding purchase intent, the tasters attributed an average of 3.94 ± 1.00, which means "probably would buy" and "might buy" on the scale. The results obtained demonstrated that microcapsules optimize the cell viability in the frozen storage and in the simulated gastrointestinal conditions. Addition of 10% capsules does not interfere sensorially in the probiotic ice cream.
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Al, Kassaa Imad. "Recherche et caractérisation du potentiel antiviral et probiotique de nouvelles souches de bactéries lactiques d'origine vaginale". Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10096/document.
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Dans ce travail, nous avons déterminé la composition de la flore vaginale d'un échantillon signatificatif de femmes Libanaises, puis évaluer l’effet antagoniste des souches lactiques notamment des lactobacilles contre certains pathogènes vaginales. Ainsi, sur les 135 prélèvements effectués, 53 isolats ont été identifiés par les méthodes de galerie API50 CH et pyroséquençage des régions variables (V1 et V2) du gène ADNr 16S. Les résultats obtenus ont montré une discordance entre les deux méthodes utilisées et sus-citées. Les résultats de l'effet antagoniste montrent que 7 souches sont antagonistes. L’identification des souches antagonistes a été confirmée par séquençage complet du gène ADNr 16S. En sus du potentiel antagoniste de ces lactobacilles, nous avons regardé d'autres propriétés biologiques de ces souches pouvant permettre une application probiotique. Trois isolats ont montré des propriétés intéréssantes d'hydrophobicité, d'autoaggrégation et dépourvues des caractères pathogènes. Afin d’évaluer l’effet antiviral de ces 3 isolats, des tests de cytotoxicité et d’adhésion sur une lignée cellulaire "Véro cell" ont été effectués. L’activité antivirale a été évaluée in vitro, vis-à-vis du virus herpétique de type-2 (VHS-2) et du virus non enevelopé CVBE4 comme virus contrôle. l'activité antivirale des lactobacilles a été evaluée dans 3 temps d'addition differents (Pre-infection, co-incubation et post-infection). On a choisi la souche qui a montré la meilleure activité anti-VHS-2, il s’agit de L. gasseri CMUL57. L’activité antivirale de cette souche (CMUL57) a été étudiée profondément afin d’expliquer le mécanisme de cette interaction bactérie/virusThe aim of this work is to determine the diversity of Lactobacillus species in vaginal flora in samples from Lebanese women and to evaluate the antagonistic effect of these strains against several vaginal pathogens in women. Thus, of the 135 samples collected, 53 isolates were isolated and identified by the gallery API50 CH (BioMerieux, France) and by pyrosequencing of the variable regions (V1 and V2) of the 16S rDNA gene. The results showed a large discrepancy between the two methods used. The antagonism results obtained showed the presence of 7 antagonistic strains against four pathogenic strains. The complete identification of these strains was confirmed by complete sequencing of the 16S gene (16S rDNA). Note that L. plantarum CMUL140 showed a strong anti-S. aureus activity and was used in a co-culture test. In addition to the potential antagonism of these lactobacilli, we looked at other features that can help in using these strains as probiotics. Therefore, we evaluated their probiotic and safe characteristics. To assess the antiviral effect of these three isolates, cytotoxicity and adhesion tests were performed on a "Vero cell" cell line. The results showed that none of three isolates were cytotoxic and carried a strong adhesion. Antiviral activity in vitro was evaluated against the herpes simplex virus type-2 (HSV-2) and CVBE4 as virus control. In order to investigate the anti-HSV-2 activity of lactobacilli, the strains were added to the infected cells at different intervals: pre-infection, co-incubation and post-infection. L.gasseri CMUL57 showed the strongest anti-HSV-2 activity and showed the capacity to trap HSV-2 on their cell wall
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Wall, Torun. "Environmental interactions of Lactobacillus reuteri : signal transduction, gene expression and extracellular proteins of a lactic acid bacterium /". Uppsala : Dept. of Microbiology, Swedish University of Agricultural Sciences, 2005. http://epsilon.slu.se/2005104.pdf.
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Samot, Johan. "Evaluation du potentiel probiotique de lactobacilles buccaux". Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21970/document.
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La cavité buccale est un écosystème dynamique et complexe à l'équilibre fragile. A l'occasion de modifications des conditions environnementales ou d'une augmentation de la sensibilité de l'hôte, il y a rupture de cet équilibre. L'altération des conditions locales va permettre la croissance et le développement d'espèces pathogènes jusqu'alors faiblement représentées, ce qui va autoriser la survenue de diverses pathologies infectieuses orales. Devant l'insuffisance des solutions apportées par une prise en charge uniquement mécanique, des moyens supplémentaires doivent être envisagés. La stratégie probiotique ouvre une voie séduisante puisque l'on se propose de remplacer des bactéries pathogènes par des microorganismes ayant des effets bénéfiques sur la santé orale. L'objectif de ce travail vise donc à identifier des souches probiotiques parmi des isolats oraux de lactobacilles. Pour cela, soixante six souches ont été évaluées. Afin de prédire leur persistance orale, trois méthodes différentes d'évaluation de l'adhérence ont été utilisées : une méthode sur tube de verre, la méthode MATS et un modèle de biofilm monoespèce. Des études in vitro ont été conduites pour déterminer si les lactobacilles pouvaient inhiber des pathogènes carieux (Streptococcus mutans et Actinomyces viscosus) et certains pathogènes parodontaux (Fusobacterium nucleatum et Porphyromonas gingivalis) et pour identifier les mécanismes impliqués. Enfin, les capacités fermentaires de certaines souches ont été appréciées, afin d'éviter l'apparition d'effets délétères comme la déminéralisation carieuse. Trois souches seulement ont montré des capacités d'adhérence intéressantes. Selon les critères que nous avions défini pour caractériser une activité comme antibactérienne, aucune souche n'a inhibé P. gingivalis et 9 souches ont été retenues pour leur pouvoir inhibiteur contre les autres pathogènes. Le mode d'action précis de l'inhibition reste encore à préciser. Dans les conditions de cette étude, aucune des souches évaluées pour son activité fermentaire n'a présenté un risque cariogène. Ce travail a permis de mettre en évidence des souches intéressantes soit de part leur adhérence soit de part leur activité inhibitrice. Des études in vitro complémentaires semblent nécessaires (évaluation de la stimulation immunitaire, précision sur les mécanismes impliqués dans les effets observés) avant de poursuivre sur un modèle animal ou des études cliniques chez l'HommeThe oral cavity is a complex and dynamic ecosystem with a delicate balance. On the occasion of changes in environmental conditions or an increase in the sensitivity of the host, a break can occur. The alteration of local conditions will allow the growth and development of pathogenic species hitherto poorly represented, which will allow the occurrence of various oral infectious diseases. Due to the lack of solutions given by a purely mechanical support, additional resources should be considered. Probiotic strategy appears as an attractive way since it proposes to replace pathogenic bacteria by microorganisms having beneficial effects on oral health. The aim of this study was therefore to identify probiotic strains among oral lactobacilli isolates. To this end, sixty-six strains were evaluated. To predict persistence in mouth, three different methods of assessing adherence were used: a method on glass tube, the MATS method and a monospecie biofilm model. In vitro studies were conducted to determine whether lactobacilli could inhibit caries pathogens (Streptococcus mutans and Actinomyces viscosus) and some periopathogens (Fusobacterium nucleatum and Porphyromonas gingivalis) and to identify the mechanisms involved. Finally, the fermentation capacity of certain strains was assessed in order to avoid the occurrence of adverse effects such as carious demineralization. Only three strains showed adhesion interesting capabilities. According to the criteria we defined to characterize an activity as antibacterial, no strain inhibited P. gingivalis and 9 strains were selected for their inhibitory potency against the others pathogens. The precise mode of action of the inhibition remains unclear. Under the conditions of this study, none of the strains tested for its fermentative activity has introduced a cariogenic risk. This work has highlighted interesting strains because of their adhesion or because of their inhibitory activity. Additional in vitro studies seem necessary (evaluation of immune stimulation, precision of the mechanisms involved in the observed effects) before continuing in an animal model and clinical studies in humans
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Jakobsson, Tell. "Lactobacillus iners and the normal vaginal flora". Doctoral thesis, Linköping : Department of Clinical and Experimental Medicine, Linköping University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11334.
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Ricci, Luca. "Antibiotico resistenza di Lactobacillus sakei". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16829/.
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L’attenzione degli organismi di controllo nei confronti della problematica dell’antibiotico resistenza sta diventando sempre più pressante e l’individuazione di ceppi lattici che hanno mostrato resistenze e che potrebbero costituire una riserva di geni trasmissibili ad eventuali patogeni lungo la catena alimentare è diventato uno dei temi caldi della ricerca mondiale. Infatti, il consumo di batteri vivi attraverso gli alimenti fermentati (e non) può essere un potente veicolo di disseminazione di resistenza agli antibiotici, attraverso il passaggio di elementi genetici mobili tra specie che vengono a trovarsi in un medesimo habitat (compreso l’intestino umano). La possibilità di acquisire nuove resistenze è stata dimostrata anche per lattobacilli utilizzati per le fermentazioni alimentari ma pochi lavori sono stati condotti su Lactobacillus sakei, estensivamente utilizzato come starter dall’industria dei salumi e caratterizzato da un’ampia variabilità genetica che si riflette in una grande variabilità fenotipica. Poiché la conoscenza dell’antibiogramma è un aspetto cruciale indicato da EFSA per le colture starter, in questo elaborato è stato preso in considerazione il profilo di antibiotico resistenza di L. sakei, attraverso i dati riportati in letteratura e tramite specifiche analisi condotte su ceppi di collezione o isolati da fermentazioni spontanee. I dati sottolineano un’ampia variabilità fenotipica mettendo in luce differenti capacità dei ceppi studiati di reagire alla presenza di questi antimicrobici e mostrando alcuni casi di resistenza, ad esempio al cloramfenicolo e alla tetraciclina. Al contrario, uno dei ceppi si è mostrato sensibile alla vancomicina, considerata invece una resistenza intrinseca dei Lactobacillus.
L’analisi critica della letteratura e dei dati acquisiti mostra come sia indispensabile un approfondimento di questa tematica, data l’importanza industriale di questa specie.
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Jebava, Ondrackova Iva. "Système autolytique de Lactobacillus helveticus". Rennes, Agrocampus Ouest, 2011. http://www.theses.fr/2011NSARI060.
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L´autolyse est une dégradation du peptidoglycan par des enzymes bactériennes endogènes appelées hydrolases du peptidoglycane ou autolysines. Grâce à cette réaction enzymatique, la cellule bactérienne peut éclater et le contenu intracellulaire est libéré. Chez Lactobacillus helveticus, le ferment protéolytique fromager, les enzymes libérées lors de l´autolyse jouent un rôle important dans le développement de l´arôme et la texture des fromages au cours de l´affinage. Il apparait également que l´autolyse accélère l´affinage de fromage, un processus long et coûteux. Il a été démontré que l´aptitude à l´autolyse était un facteur souche dépendant mais les mécanismes à l´origine de cette diversité n´ont pas été élucidés. L´objectif de ce travail est de comprendre pourquoi les souches de L. Helveticus s´autolysent de manière différente. Nous avons élaboré la stratégie suivante : (i) construire une collection de L. Helveticus la plus diverse possible, (ii) rechercher l´origine de la diversité autolytique au niveau génétique et (iii) déterminer le rôle de la paroi cellulaire. Une collection de référence composée de 26 souches de L. Helveticus a été constituée de manière à offrir la plus large diversité possible en termes d´origine géographique et de biotope. La diversité des souches au niveau génomique a été confirmée par électrophorèse en champ pulsé. Le suivi de l´autolyse réalisé en tampon, par microscopie électronique, coloration de Gram et cytometrie en flux, et en milieu fromager modèle ont montré que les souches se distinguent pour leur capacité autolytique. Pour étudier la diversité génétique dans la collection de référence nous nous sommes appuyé sur le génome séquencé de la souche autolytique L. Helveticus DPC 4571. Neuf couple d´amorces, correspondant aux neuf gènes codant pour les autolysines prédits chez la souche DPC 4571, ont été dessinés et validés. La présence des gènes codant pour les autolysines ainsi que leur transcription ont été recherchées par PCR et RT-PCR chez les 26 souches. La technique de zymogramme a été utilisée d´une part pour rechercher l´activité enzymatique des autolysines et d´autre part pour rechercher la diversité des parois cellulaires. Puis la diversité des parois cellulaires parmi les souches de L. Helveticus a été étudiée par analyse des acides teïchoiques et par analyse d´activité enzymatique sur différents substrats par zymogramme. Les travaux réalisés au cours de cette thèse ont permis de comprendre que la diversité autolytique n´est pas due à une variabilité du nombre des gènes codant pour les autolysines ni à leur transcription. Nous montrons ainsi que ce sont des étapes de traduction et/ou modification post-traductionnelle qui peuvent jouer un rôle dans la diversité autolytique. La composition de l´acide teïchoique varie d´une souche à l´autre ce qui montre une diversité parmi les souches au niveau de la paroi cellulaire. De plus, il a été montré que la cytométrie en flux peut être utilisée pour la mesure de l´autolyse in vitroAutolysis results from peptidoglycan degradation, by so called endogenous peptidoglycan hydrolases or autolysins, leading to disintegration of the bacterial cell which causes release of intracellular content. In case of L. Helveticus, a dairy starter culture uses for cheesemaking, released enzymes by autolysis involves a development of sensory properties and accelerates cheese ripening. It was shown that L. Helveticus autolysis is a strain-dependant phenomenon. The aim of this work was to determine the origin of autolytic diversity of L. Helveticus. Following strategy was elaborated: (i) construction of a collection of L. Helveticus strains, (ii) evaluation of the diversity for autolytic genes, and (iii) determination of the role of the cell wall. A collection of 26 stains of L. Helveticus, diverse in terms of origin and biotope, was assembled. Pulsed field gel electrophoresis was applied to assess the genomic diversity of all tested strains. Autolytic capacity was evaluated in vitro in buffers (by electron microscopy, Gram staining, flow cytometry) and in situ in a model cheese. Nine genes coding PGHs were previously annotated in the genome of the high autolytic strain L. Helveticus DPC 4571. Nine pairs of primers, corresponding to the nine PGHs genes, were designed and validated against DPC 4571. Distribution of the genes coding for autolysins were tested in 26 strains by PCR and RT-PCR. Zymogram was used to detect enzymatic activity of autolysins and also for observed the diversity of the cell wall. The difference in composition of the cell wall among six selected strains was accomplished by analysis of teichoic acid and by zymogram using different substrates. The nine PGHs genes are ubiquitous and transcribed early during growth. Zymograms were similar in terms of molecular size of the bands, but exhibited strain to strain variations in the number of bands revealing from 2 to 5 lytic bands per strain. Composition of teichoic acid varied from strain to strain. The work realized during this thesis permitted to understand that the autolytic diversity does not depend on the distribution of autolysins, not even to their transcription. These results indicate that the origin of the autolytic diversity could be due to post-translation steps or to the regulation of peptidoglycan hydrolases, or to the composition of the cell wall. In addition, it was shown that flow cytometry could be used for the determination of autolysis in vitro
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McCracken, Andrea. "Heterologous gene expression in Lactobacillus". Thesis, Queensland University of Technology, 1998.
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Goldberg, Marc. "Entwicklung und Einsatz von 16S rRNA Gensonden zur Identifizierung biotechnologisch genutzter Laktobazillen-Stämme der L. acidophilus- und der L. casei-Gruppe". [S.l. : s.n.], 2002. http://www.diss.fu-berlin.de/2002/94/index.html.
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Fuochi, Virginia. "Amensalistic activity of Lactobacillus spp., isolated from human samples". Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3878.
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Lactobacillus is a bacterial genus belonging to LAB (Lactic Acid Bacteria) and they are among the most common probiotics. Recent guidelines on probiotics, issued by the Italian Ministry of Health, state that, on the basis of the available literature, the amount sufficient to obtain a temporary colonization of the intestine by a probiotic strain is at least 10^9 living cells.
A microorganism can be defined as a probiotic strain if it is of human origin, if it survive to the gastrointestinal tract, resisting the acidity of the stomach and the action of bile, and it should have immunostimulant activity.
In addition, the strain should be able to adhere to the mucosa causing no toxicity, and to produce substances with antibacterial activity against some pathogens.
The aim of the work was the isolation and identification of lactobacilli of human origin. It was also deepened the study of their amensalistic properties, with particular attention to the resistance to gastrointestinal transit and their antagonism against pathogenic microorganisms.
Three hundred fifty-nine lactobacilli strains were isolated from swabs of healthy people and identified using molecular techniques based on the study of 16S rDNA. The identification of some strains was confirmed by further analysis DHPLC V1 and V3 of 16S rDNA. The strains were subjected to the evaluation of the resistance to bile salts and low pH, to the production of hydrogen peroxide and more particularly, it has been evaluated the ability to produce substances with antibacterial activity.
Finally, the attention was focused on the characterization of an active supernatant produced by an oral strain. The isolation of the substance provided chromatographic procedures such as SEC (Size Exclusion Chromatography using Sephadex 50) and SPE (Reverse Phase Chromatography using C18 column). The results were shown that the active fraction has a low molecular weight and for its chemical-physical characteristics is not a common bacteriocin, for this reason are on going further chromatographic studies using columns with increasing polarity (C4, phenyl, cyano, and amino) .
Future outlooks are focused on the identification of the molecule in question, by MALDI-TOF and ESI-TOF and then optimizing the whole process to standardize the entire method. In this way, the opportunity to bring to light new molecules will be possible, with the ultimate goal of being able to take advantage from these antibacterial substances.
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Eifert, Andrea. "Substratspezifität und Thermostabilität der D-2-Hydroxyisocaproat-Dehydrogenase aus Lactobacillus casei sowie strukturelle Untersuchungen von Phytochrom A aus Hafer". [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=963192698.
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Chaves, Maria Manoela Barata de Castro. "Estudo da microbiota vaginal de éguas com ênfase na pesquisa de lactobacilos /". Botucatu : [s.n.], 2011. http://hdl.handle.net/11449/98256.
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Orientador: Marco Antonio AlvarengaBanca: Alexandre Secorun Borges
Banca: Eliane Melo Brolazo
Resumo: Na égua o ambiente uterino saudável não apresenta microflora, diferente da vagina onde se sabe existir uma flora vaginal rica em microrganismos não patogênicos. Muitas bactérias da flora vaginal normal podem ser deslocadas para o interior do útero, podendo ser esta a causa principal de endometrites em éguas doadoras de embriões. A presença de Lactobacillus spp é considerada importante na flora vaginal de mulheres e tem sido pouco investigada em éguas. O presente trabalho tem como objetivo estudar a flora vaginal de éguas, doadoras de embriões, determinar os principais microrganismos presentes, relacionar os achados microbiológicos vaginais e uterinos, assim como determinar a prevalência de Lactobacillus. No experimento 1 foram utilizadas 77 éguas doadoras de embrião, 33 foram coletadas amostras vaginais e uterinas e 77 apenas vaginais. O experimento 2 contou com dois grupos (36 éguas e 10 mulheres) de swabs vaginais sendo um para cultivo e isolamento de Lactobacillus e outro para extração do DNA e PCR. As bactérias predominantes na vagina foram: Streptococcus zooepidemicus (42%), Escherichia coli (25%), Streptococcus alfa hemolítico (15%) Candida (6%), Enterobacter spp (3%), Bacillus spp (3%), Streptococcus beta hemolítico (3%) e Pseudomonas (3%).. Das 33 amostras coletadas do útero de éguas somente 39% (n=12) não apresentaram crescimento bacteriano ou fúngico. Tendo sido Streptococcus zooepidemicus o mais frequentemente encontrado (26%), seguido de Escherichia coli (15%), Candida spp (9%), Streptococcus alfa hemolítico (6%) e Enterobacter (3%). Os microrganismos isolados da vagina e que estavam concomitantemente presentes no útero de éguas foram: Streptococcus zooepidemicus (21%), Escherichia coli (12%), Candida spp (9%) e Streptococcus alfa hemolítico (6%). Em 83,3% houve concordância entre as amostras negativas na vagina e no útero (p <0,05). Em 73,7% ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Different from the vagina, were a rich microflora is present, the uterine environment is considered free of microorganisms. One possibility for the installation of endometritis in mares is the ascendent contamination from the vagina.The presence of Lactobacillus on vaginal flora is considered important in woman however there is few information on mares. The present experiment aimed to study the vaginal microflora of embryo donnor mares, to correlate the vaginal and uterine finds and also to determine the prevalence of Lactobacillus on vaginal envirioment. On experiment 1 a total of 77 mares were used and vaginal samples collected from 33 of these mares both vaginal and uterine samples were collected. On experiment 2 vaginal swabs from 36 mares and 10 women were collected for culture and isolation of Lactobacillus, DNA extration and PCR. The predominate bacteria isolated from the vagina were: Streptococcus zooepidemicus (42%), Escherichia coli (25%), Streptococcus alfa hemolítico (15%) Candida (6%), Enterobacter spp (3%), Bacillus spp (3%), Streptococcus beta hemolítico (3%) e Pseudomonas (3%). From 33 samples collected from the uterus only 39% (n= 12) did not show any microorganism on culture. Streptococcus zooepidemicus was the most frequent isolated microorganism (26%), followed by Escherichia coli (15%), Candida spp (9%), Streptococcus alfa hemolítico (6%) e Enterobacter (3%). When evaluated the microorganisms isolated from both vaginal and uterine samples Streptococcus zooepidemicus (21%), Escherichia coli (12%), Candida spp (9%) e Streptococcus alfa hemolytic (6%) were the most frequent isolated bacteria. The agreement between swabs taken from both uterus and vagina was 83.3% (p <0,05) for negative cultures and 73,7% for positive cultures (p <0,05). From 35 samples collected on group I Lactobacillus spp was isolated in only two (5,7%) eight (20%) samples showed positive ... (Complete abstract click electronic access below)
Mestre
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Schoug, Åsa. "A dry phase of life : freeze-drying and storage stability of Lactobacillus coryniformis Si3 in sucrose-based formulations /". Uppsala : Swedish University of Agricultural Sciences, 2009. http://diss-epsilon.slu.se/archive/00002000/01/Schoug_a_20090507.pdf.
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Moody, Karen J. "Characterisation of Lactobacillus acidophilus L44 fimbriae". Thesis, Glasgow Caledonian University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395791.
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Lynn, Miriam Elen. "Enterocyte maturity influences adhesion by lactobacillus". Thesis, University of Newcastle Upon Tyne, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481471.
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Bates, Elizabeth E. M. "The genetic manipulation of Lactobacillus plantarum". Thesis, University of Newcastle Upon Tyne, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254478.
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Nahaisi, Mohamed Hadi. "Growth and survival of Lactobacillus acidophilus". Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242433.
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Santos, Rocha Clarissa. "Immuno-Modulation Properties of Lactobacillus delbrueckii". Thesis, Paris 11, 2011. http://www.theses.fr/2011PA112353.
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Lactobacillus delbrueckii est une bactérie laitière non commensale qui transite dans notre tractus gastro-intestinal du fait de son utilisation dans les produits laitiers fermentés, notamment les yaourts. Nous avons cherché à déterminer les profils immuno-modulateurs de 59 souches de L. delbrueckii subsp. lactis et subsp. bulgaricus. Nous avons d'abord criblé notre panel de souches sur leur capacités à inhiber l'activation de NF-kB par le TNF-α dans des cellules HT-29. Nous avons ainsi pu mettre en évidence une variabilité des capacités immuno-modulatrices chez ces souches en repérant des souches aux capacités anti- ou pro-inflammatoires. Nous avons retenu les deux souches les plus anti-inflammatoires (L. delbrueckii subsp. lactis CNRZ327 et 333) et avons observé qu'elles perdaient leurs effets après traitement à la trypsine suggérant que les effecteurs inhibant l'activation de NF-kB soient de nature protéique. Nous avons pu aussi déterminer que cette inhibition passait par la réduction de la phosphorylation d'IkB affectant la translocation de NF-kB dans le noyau. Nous avons ensuite testé ces deux souches dans un modèle murin de colite induite au DSS. La souche CNRZ327 a amélioré de façon significative les dommages induits par le DSS confirmant ainsi ses effets anti-inflammatoires in vivo. Nous avons ensuite tenté de déterminer les mécanismes des effets anti-inflammatoires de la CNRZ327. Cette souche i) augmente les taux d'IgA sécrétoires; ii) module la production de TGF-β dans le colon et de l'IL-6 et de l'IL-10 dans la rate; iii) augmente les cellules T régultrices CD4+Foxp3+ dans la rate et les ganglions cécaux et iv) module la fréquence des cellules dendritiques TLR2+2 and TLR4+. Nos travaux constituent la première démonstration d'effets immuno-modulateurs d'une souche de lactobacille laitier. Les lactobacilles laitiers très présents dans nos aliments laitiers fermentés peuvent ainsi moduler notre réponse immune et influencer ainsi notre santéThe work presented in this thesis aims to review the present knowledge on bacteria-host interactions in the GI tract, and to demonstrate the immune modulatory effects of Lactobacillus delbrueckii, a non-commensal dairy bacterium that is in constant transit in our GI tract through the ingestion of fermented food products, like milk and cheese.The main results presented in this thesis can be divided into two parts. In the first part we revisited the anti-inflammatory properties of L. delbrueckii by screening a collection of different strains for their ability to inhibit TNF-α-induced NF-kB activation in an IEC cell line. Our results demonstrated the existence of inter strain variation for immune modulation properties in the L. delbrueckii species. Two of the most effective strains completely lost their ability to suppress NF-kB after trypsin treatment, indicating that the bacterial effectors involved in the NF-kB modulation are proteinaceous in nature. We also showed that L. delbrueckii inhibits NF-kB activation by reducing the phosphorylation of IkB, which would affect translocation of NF-kB to the nucleus. Based on our in vitro results, we selected three strains for tests in a DSS model of experimental colitis. One of the strains tested, L. delbrueckii subsp.Lactis CNRZ327 (Lb CNRZ327) consistently improved the DSS-induced damage, thus confirming its anti-inflammatory properties in vivo. The second part of my thesis was dedicated to the study of the mechanisms involved in the anti-inflammatory effects of L. delbrueckii in the DSS-model of colitis. Lb CNRZ327 showed a tendency to increases s-IgA levels, modulates the production of TGF-β in colonic tissue, and of IL-6 and IL-10 in the spleen, expands the frequency of CD4+Foxp3+ regulatory T cells in the spleen and CLN during colitis and modulates the frequencies of TLR2 and TLR4 expressing dendritic cells in the cecal lymph nodes. TLR2 appears to be involved in Lb CNRZ327 recognition and affect IL-12 production in BMDM. This is the first demonstration of systemic immune modulation effects exerted by a dairy Lactobacillus. The results of this study show that dairy lactobacilli that often are part of a regular diet can modulate innate immune responses and may thus affect health more than generally thought
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Sedano, Bautista José Luis. "Selección de cepas nativas de Lactobacillus con actividad inhibitoria y tolerantes al etanol aisladas de "masato"". Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2006. https://hdl.handle.net/20.500.12672/1424.
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La conservación de alimentos por fermentación natural es ampliamente practicada por diversas comunidades nativas. El “masato” es producto de este proceso y constituye parte importante de la alimentación de los pobladores de la amazonía peruana. La masa de yuca, mandioca o cassava (Manihot esculenta, Crantz) utilizada en la preparación de esta bebida tradicional, constituye el substrato principal para el establecimiento de una microflora mixta ambiental, incluyendo las bacterias lácticas como responsables de la fermentación maloláctica, láctica y otras propiedades de interés industrial.
La búsqueda de nuevas cepas nativas de bacterias lácticas productoras de sustancias antimicrobianas, adaptadas a las condiciones ambientales y materias primas regionales, es sumamente importante, para mejorar la calidad sensorial y sanitaria del “masato”.
Para detectar cepas lácticas con propiedades antimicrobianas, se procesaron 11 muestras de “masato” procedentes de Pucallpa – Ucayali, las cuales fueron sembradas en agar Man Rogosa Sharpe (MRS) pH 6.5 e incubadas a 30° C por 72 horas en condiciones de microaerofilia. La caracterización morfológica, cultural, bioquímica y la actividad antimicrobiana se realizaron según Kandler Weiss (1986) y Tagg McGiven, (1971) respectivamente.
De un total de 81 cepas de Lactobacillus aisladas, se identificaron 33 (41%) de Lactobacillus plantarum, 13 (16%) de Lactobacillus alimentarius, 12 (15%) de Lactobacillus acidophilus, 9 (11%) de Lactobacillus casei y en menores porcentajes Lactobacillus brevis, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus amylophilus y Lactobacillus coryniformis. Se encontró además, 64 (78.9%) de Lactobacillus heterofermentativos y 17 (21.1%) de Lactobacillus homofermentativos. En todas las muestras de “masato” evaluadas, predominó Lactobacillus plantarum, seguido de Lactobacillus acidophilus y Lactobacillus alimentarius.
De 8 cepas lácticas productoras evaluadas, Lactobacillus plantarum M4 fue la única cepa productora de una sustancia antimicrobiana que no es ácido orgánico ni agua oxigenada. Se demostró además, que la sustancia antimicrobiana neutralizada a pH 6,5 posee un reducido espectro antimicrobiano y es estable en un amplio rango de temperatura y pH.
Asimismo, las cepas de Lactobacillus muestran un alto nivel de tolerancia a concentraciones de etanol agregadas al medio de cultivo, siendo mas del 80% de cepas aisladas tolerantes a 10% de etanol, mientras que 6% tolera concentraciones de hasta 12% v/v de etanol.
Se proponen las cepas Lactobacillus plantarum 4M0.2, Lactobacillus plantarum M9.5, Lactobacillus acidophilus M2.9, Lactobacillus alimentarius 5M1.2 como una selección de cepas de interés biotecnológico, así como a Lactobacillus plantarum M4, cepa del estudio con mayor espectro antimicrobiano tolerante hasta una concentración de 8% v/v de etanol en el medio de cultivo.The food preservation by natural fermentation is practiced by diverse native communities. The "masato" is product of this process and constitutes important part of the feeding of the population of peruvian amazonia. The mass of yucca, mandioca or cassava (Manihot esculenta, Crantz) used in the preparation of this traditional drink, constitutes the main substrate for the establishment of an environmental mixed microflora, including the lactic acid bacteria which are responsible for the malolactic and lactic fermentation and other properties of industrial interest. The search of new native strains of antimicrobial substances producing lactic bacteria, adapted to the environmental conditions and regional raw materials, is extremely important, to improve the sensorial and sanitary quality of the "masato". In order to detect lactic strains with antimicrobial properties, 11 samples of "masato" coming from Pucallpa - Ucayali were processed, which were seeded in agar Man Rogosa Sharpe (MRS) pH 6,5 and incubated to 30° C by 72 hours in microaerophilic conditions. The morphologic, cultural, biochemical characterization and the antimicrobial activity were made according to Kandler Weiss (1986) and Tagg McGiven, (1971) respectively. Of a total of 81 isolated strains of Lactobacillus, 33 (41%) of Lactobacillus were identified like Lactobacillus plantarum, 13 (16%) like Lactobacillus alimentarius, 12 (15%) like Lactobacillus acidophilus, 9 (11%) like Lactobacillus casei and in smaller percentage like Lactobacillus brevis, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus amylophilus and Lactobacillus coryniformis. In addition, 64 (78.9%) and 17 (21.1%) of Lactobacillus were detected homofermenters and heterofermenters respectively. In all the evaluated samples of "masato", predominated Lactobacillus plantarum, followed of Lactobacillus acidophilus and Lactobacillus alimentarius. Of 8 evaluated antimicrobial substance producing lactic acid bacteria strains, Lactobacillus plantarum M4 was the only producing strain of a antimicrobial substance that is not acid organic nor oxygenated water. In addition, it was shown that the neutralized antimicrobial substance to pH 6.5 has a reduced antimicrobial spectrum and is stable in a wide range of temperature and pH. Also, the strains of Lactobacillus showed a high level of tolerance to concentrations of ethanol added to culture means, being but of 80% of tolerant isolated strains to 10% of ethanol, whereas 6% tolerated concentrations of up to 12% v/v of ethanol. We propose to Lactobacillus plantarum 4M0.2, Lactobacillus plantarum M9.5, Lactobacillus acidophilus M2.9, Lactobacillus alimentarius 5M1.2 like a selection of strains of biotechnological interest, as well as to Lactobacillus plantarum M4, strain of the study with greater antimicrobial spectrum and tolerance until 8% v/v concentration of ethanol added in culture mean.
Tesis
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Soeryapranata, Elly. "Characterization of aminopeptidase N and endopeptidases E, O, O2, O3 from Lactobacillus helveticus WSU19, a Lactobacilli with industrial significance". Online access for everyone, 2005. http://www.dissertations.wsu.edu/Dissertations/Summer2005/e%5Fsoeryapranata%5F071205.pdf.
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Indelicato, Claire-Emmanuelle. "Caractérisation des mécanismes impliqués dans la promotion de croissance de la Drosophile par Lactobacillus plantarum". Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN094/document.
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Le microbiote intestinal affecte la plupart des processus physiologiques de l’hôte, et plus particulièrement la digestion et le métabolisme. Cependant, les mécanismes moléculaires en jeu restent encore peu connus. Pour répondre à cette question, nous utilisons un modèle gnotobiotique simple : la larve de Drosophile monoassociée à un de ces symbiont naturel : Lactobacillus plantarum. Notre groupe a montré que L. plantarum promeut la croissance larvaire d’individus soumis à une carence en protéines. En effet, les larves monoassociées à L. plantarum se développent bien plus rapidement que des individus axéniques. Ainsi, L. plantarum tempère l’effet délétère de la carence nutritionnelle. Cette amélioration de la croissance repose en partie sur la hausse du niveau d’expression des protéases digestives de l’hôte ainsi que sur la modulation de la voie de signalisation TOR (Target Of Rapamycin) de la Drosophile par les bactéries symbiotiques. Notre travail s’est focalisé sur la recherche d’autres mécanismes génétiques impliqués dans l’interaction entre la Drosophile et L. plantarum au cours de la croissance larvaire. Nos résultats montrent que les variations génomiques naturelles de la Drosophile affectent l’intensité du bénéfice de croissance conféré par L. plantarum. En outre, les bases de notre étude ont permis de mettre en évidence que le microbiote intestinal a la capacité d'agir comme "tampon génétique" en compensant les défauts de croissance causés par le fond génétique des mouches. De plus, L. plantarum permet de diminuer la variation phénotypique de plusieurs caractères de la mouche tels que la croissance, la taille de certains organes et la durée du cycle larvaire. Nous avons également identifié le gène dawdle, codant un ligand de la voie TGF-β, comme acteur de l’interaction Drosophile-L. plantarum. De plus nous avons montré que Dawdle régule les protéases digestives de la Drosophile dans un contexte nutritionnel de carence en protéine, et cette régulation peut-être activatrice ou bien inhibitrice selon l’environnement microbienIntestinal microbiota can modulate virtually all aspects of their host physiology, and particularly, digestion and metabolism. However, the molecular mechanisms at play remain largely unknown. To tackle this question, we use a simple gnotobiotic model: Drosophila larvae monoassociated with one of its major natural symbiont, Lactobacillus plantarum. Previous work from our group showed that L. plantarum promotes the juvenile growth of larvae facing a protein scarcity, thereby dampening the deleterious effect of the nutrient deficiency on larval growth. This growth enhancement partially relies on the upregulation of intestinal proteases, as well as on the modulation of the host TOR (Target Of Rapamycin) pathway by the symbionts. My thesis work aimed at unraveling other host genetic mechanisms involved in the interaction between Drosophila and L. plantarum during growth. Our work showed that host natural genomic variations affect the fly physiologic response to L. plantarum. Furthermore, the bases of our work enabled to unveil a novel role of intestinal bacteria, revealing their ability to act as a genetic buffer to compensate the growth impairments due to the fly genetic background. In addition, L. plantarum decreases the phenotypic variations in various host fitness traits (growth, organ size, timing to pupariation) and it also confers robustness to organ patterning. Finally, we showed that the TGF-β ligand, Dawdle plays an important regulatory role on digestive enzymes in a protein-deficient nutritional context, and that this regulation can be inhibitory or activating depending on the microbial environment
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Turpin, Williams. "Vers une évaluation des potentialités probiotique et nutritionnelle des bactéries lactiques constitutives du microbiote d’un aliment fermenté traditionnel à base de mil par une approche moléculaire". Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20093/document.
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La relation de la microflore lactique avec l'homme n'a été que très peu étudiée dans le contexte des aliments amylacés fermentés tropicaux. La plupart des recherches dans ce domaine sont réalisées par des combinaisons de tests phénotypiques (modèles cellulaires et animaux) et des essais cliniques. Cependant, la disponibilité des données génomiques permettent d'envisager de nouvelles stratégies. L'objectif de ce travail est de rechercher la présence d'une cinquantaine de gènes impliqués dans des fonctions probiotiques dans une collection de 152 bactéries lactiques isolées d'un aliment fermenté africain à base de mil, le ben-saalga, ainsi que dans le métagénome de différents aliments amylacés fermentés. Plusieurs couples d'amorces ont été dessinés par nos soins et ont permis de détecter par PCR la présence de ces gènes. Le criblage génétique est efficace pour déterminer le potentiel lié à certaines fonctions « simples » (synthèse de vitamines B et caroténoïdes, métabolisme de l'amidon, etc.), puisqu'il permet le plus souvent de réduire le nombre de tests phénotypiques à réaliser aux souches porteuses des gènes d'intérêt. Au contraire, des tests in vitro complémentaires (résistance au pH acide et aux sels biliaires, adhésion sur des modèles cellulaires, imagerie à résonnance plasmonique de surface) montrent les limites de l'approche moléculaire appliquée à la détection de fonctions plus complexes que sont l'adhésion et la survie des bactéries. Par ailleurs, les profils d'expression des gènes impliqués dans la fonction d'adhésion par PCR en temps réel sont fonction du modèle utilisé (cellules ou rats). Nous avons montré qu'un mélange des trois souches les plus prometteuses modifie le profil de protéines impliquées dans la maturation de l'épithélium intestinal de rats initialement axéniques. Nous pouvons conclure que le criblage génétique des métagénomes d'aliments amylacés fermentés tropicaux permet de mettre en évidence un potentiel probiotique et nutritionnel prometteurThe relationship between the lactic acid bacteria composing the microbiota of tropical starchy fermented foods and humans has been poorly investigated. Most of the studies focus on a combination of phenotypical (cells models, animals) and clinical trials. However the increasing numbers of genomic data allow new strategies. The objective of this work was to screen the presence of around 50 genes involved in probiotic functions in a collection of 152 lactic acid bacteria isolated from an African fermented cereal based food called ben-saalga, and in the metagenome of various starchy fermented foods. In this study, several primers have been designed allowing the detection of genes of interest by PCR. The genetic screening is efficient for determining the potential linked to simple functions (B vitamins and carotenoids synthesis, starch metabolism, tannin degradation) as in most cases it allows to limit the number of phenotypical tests to the strain harbouring the genes of interest. On the opposite, more complex functions such as cell binding or bacterial survival, estimated in vitro (low pH, bile salts, cell models, surface plasmonic resonance imagery) revealed the limit of the approach. The expression of genes involved in cell adhesion measured by real time PCR vary depending on the model used (cells or animal).We showed that a cocktail of three potentially probiotic strains modifies the profile of proteins involved in the maturation of the intestinal epithelium of initially germ free rats. The genetic screening of the metagenomes shows that the traditional starchy fermented foods harbour a promising probiotic and nutritional potential
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Heumann, Arnaud. "Etude de la survie et de la fonctionnalité de probiotiques dans des formulations sous forme de biofilm en gel de polyoside comestible". Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCK014.
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L’objectif de cette thèse est d’encapsuler dans une matrice polyosidique des probiotiques sous forme de biofilm en utilisant comme modèle Lactobacillus paracasei ATCC334. La matrice d’encapsulation (billes) est obtenue par gélification ionique d’une pectine amidée et faiblement méthylée en présence d’ions calcium. Nous avons remarqué que le réseau de pectine dans ces billes d’un diamètre d’environ 500 µm permet la formation de microcolonies sphériques (biofilm-like) avec une taille de 25 µm de diamètre. Une augmentation de la concentration bactérienne de L. paracasei ATCC334 de 3 Log d’UFC après 24 h de croissance des bactéries immobilisées est observée pour atteindre au sein de ces billes une concentration supérieure à 10 Log d’UFC/g humide. Nous avons également noté une distribution homogène des microcolonies dans les billes et une organisation structurée des bactéries au sein des microcolonies. En effet, une adhésion des bactéries à la matrice pectine est observée ainsi que la présence de substances polymériques permettant de lier les bactéries les unes aux autres. Les résultats suggèrent donc des phénomènes d’interaction entre le réseau formé par la pectine et les bactéries dans les billes. Nous avons montré que L. paracasei ATCC334 formulée en biofilm dans ces billes de pectine présente une résistance accrue à un stress gastrique (pH 2) et au séchage par lyophilisation. La capacité d’adhésion des bactéries formulées à des cellules épithéliales est conservée et la pectine semble stimuler cette adhésion aux cellules de l’hôte. Des résultats in-vivo utilisant un modèle murin d’inflammation intestinale montrent que les biofilms de L. paracasei ATCC334 sont libérés au niveau intestinal où ils s’implantent notamment dans le côlon. Des microcolonies de tailles approchant les 20 µm sont retrouvées au niveau du côlon suggérant que les billes de pectine ont libéré les bactéries sous forme de biofilm. Par ailleurs, l’administration aux souris de la formulation à base de pectine avec des biofilms de probiotiques a entrainé chez les souris ayant reçu un traitement DSS (une molécule capable de déclencher une inflammation intestinale) : une perte de poids moindre, un état de santé général amélioré, une muqueuse colique moins altérée ainsi qu’une diminution de la réponse inflammatoireThe aim of this thesis is to encapsulate biofilm probiotics in a polysaccharide matrix using Lactobacillus paracasei ATCC334 as a model. The encapsulation matrix (beads) is obtained by the ionotropic gelation of amidated low-methoxylated pectin with calcium ions. We noticed that the pectin network in these beads with a diameter of approximately 500 microns, allow the formation of spherical microcolonies (biofilm-like) with a diameter of 25 microns. An increase of 3 Log CFU in the bacterial concentration of L. paracasei ATCC334 is observed after 24 hours of growth of the immobilized bacteria, while the observed concentration in these beads reaches more than 10 Log of CFU/g wet. We also noticed that the microcolonies within the beads are homogeneously distributed and the bacteria within the microcolonies are well structured. Moreover, a bacterial adhesion to the pectin matrix is observed as well as the presence of polymeric substances that bind the bacteria to each other. Our results suggest that interaction phenomenon may take place between pectin network and bacteria within beads. We also showed that biofilms of L. paracasei ATCC334 formulated in these pectin beads exhibit increased resistance to the gastric stress (pH 2) and to the freeze-drying process. In addition, the adhesion capacity of the formulated bacteria to epithelial cells is conserved and pectin seems to stimulate this adhesion to host cells. In-vivo results using a murine model presenting intestinal inflammation showed that L. paracasei ATCC334 biofilms are released in the intestinal level and are specifically implanted in the colon. Moreover, microcolonies of sizes approaching 20 μm are found in the colon suggesting that the bacteria are released in their biofilm form. In addition, the administration of pectinate beads containing probiotic biofilms to mice which have received a DSS treatment (inducing intestinal inflammation) resulted in: less weight loss of mice, improved their overall health status, less injured colonic mucosa and a decrease in the inflammatory response
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Sanchez, Alzuria Nuria. "Evaluación del efecto probiótico de las cepas Lactobacillus reuteri CECT7266 y Lactobacillus fermentum CECT7265 en perros sanos". Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/367686.
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Roos, Stefan. "Adhesion and autoaggregation of Lactobacillus reuteri and description of a new lactobacillus species with mucus binding properties /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5457-3.pdf.
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Matsubara, Victor Haruo. "Colonização oral experimental por Candida albicans em camundongos imunossuprimidos e tratados com Lactobacillus acidophilus e Lactobacillus rhamnosus". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/23/23150/tde-11062013-194541/.
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Bactérias probióticas, como Lactobacillus sp, são conhecidas como inibidoras do crescimento de microrganismos patogênicos, têm a capacidade de modificar o equilíbrio microbiológico do hospedeiro e reduzir o crescimento de patógenos, como o microoganismo Candida albicans. Para avaliar a colonização oral experimental e o seu tratamento com probióticos, 152 camundongos DBA/2 imunossuprimidos foram inoculados oralmente com uma suspensão (108 células viáveis) de C. albicans. Os animais foram divididos em 4 grupos: controle positivo (sem tratamento), tratados oralmente com nistatina, com Lactobacillus acidophilus e Lactobacillus rhamnosus. No grupo que recebeu nistatina, o tratamento foi iniciado um dia após a inoculação por Candida, já nos grupos que receberam as bactérias probióticas, os tratamentos foram iniciados 14 dias antes da inoculação. Tratamentos com nistatina e probióticos foram diários e duraram 13 dias. As avaliações foram realizadas 1, 3, 5, 7, 9, 11 e 13 dias após a inoculação inicial e feitas através de análises microbiológicas da mucosa oral dos animais. A colonização por C. albicans iniciou-se um dia após a inoculação, sendo o aumento das unidades formadoras de colônia progressivo e significante até o sétimo dia. Após este período, observou-se uma redução significativa no isolamento de leveduras. Todos os tratamentos probióticos reduziram significativamente a colonização de C. albicans na mucosa oral dos animais, comparada com a do grupo de animais não tratados. No grupo tratado com L. rhamnosus, a redução da colonização de levedura foi significativamente maior comparado ao grupo nistatina. Concluiu-se que o modelo animal DBA/2 imunossuprimidos é um bom modelo experimental para o estudo da colonização oral e o tratamento com probióticos, no presente modelo, pode ser uma alternativa eficaz para a redução da Candida na cavidade oral.To evaluate experimental oral candidiasis and the treatment using probiotics, 152 DBA/2 mice after being immunosuppressed were orally inoculated with a suspension of C. albicans containing 108 viable cells of yeast. The animals were devided into four groups: positive control (untreated), trated oraly with nystatin, with Lactobacillus acidophilus and with Lactobacillus rhamnosus. In the group that received nystatin, the treatment was initiated one day after Candida inoculation, and in the groups that received the probiotic bacteria, the treatment began fourteen days before inoculation. Treatments with nystatin and probiotics were daily and lasted 13 days. Evaluations were performed at 1, 3, 5, 7, 9, 11 and 13 days (after the initial inoculation) and made by microbiological analysis of the oral mucosa of these animals. The colonization of C. albicans in the oral mucosa animals began one day after the initial challenge and it was progressive and significant until the seventh day, when there was a significant reduction in the isolation of yeast. All treatments with probiotic bacteria significantly reduced the colonization of C. albicans in oral mucosa of the animals, compared to the untreated animal group. In group treated with L. rhamnosus the reduction of colonization of yeast was significantly higher compared to the group receiving nystatin. Based on the findings of this study we suggest that animal model DBA/2 immunosuppressed is a good model for experimental oral candidiasis and the treatment with probiotics in this model may be an effective alternative to the treatment of oral candidiasis.
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Oberauskas, Vaidas. "Laktobacilų padermių probiotikų savybių bei įtakos veršelių virškinimo trakto mikroflorai ir jų sveikatingumui tyrimai". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2004~D_20050314_161335-17375.
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1. Ištirtos registruotos Lactobacillus plantarum U-14, kuri išskirta iš sveikos karvės makšties ir Lactobacillus fermentum U-5, kuri išskirta iš sveiko veršelių fekalijų, padermės, nustatytos jų optimalios kultivavimo temperatūros, įvertintos jų probiotinės savybės, nustatytas antagonistinis aktyvumas, atsparumas antibiotikams bei įvertinta liofilizacijos įtaka šioms laktobacilų padermėms. 2. Liofilizacijos būdu pagamintas probiotikas, sudarytas iš Lactobacillus plantarum U-14 ir Lactobacillus fermentum U-5 padermių, nustatytas laktobacilų gyvybingumas preparate laikant vienus metus +4oC temperatūroje. 3. Nustatyta probiotiko profilaktinė dozė naujagimiams veršeliams girdant su krekenomis arba pienu pirmas 10 gyvenimo dienų, stebint veršelių klinikinius požymius, įvertinant paros priesvorį, įtaką bendram enterobakterijų ir laktobacilų kiekiui bei nustatant laktobacilų rūšinę sudėtį fekalijose įvertinant kraujo morfologinius ir biocheminius parametrus.4. Nustatyta probiotiko profilaktinė dozė veršeliams, kuri buvo – 4g/d. ir ji palyginta su probiotiko Yeasture profilaktine doze.1.The registered strains of Lactobacillus plantarum U-14 isolated from the vagina of healthy cow and Lactobacillus fermentum U-5 isolated from the faeces of healthy calve were studied, the optimal temperature for the cultivation was defined, were evaluated their probiotic properties, the antagonistic activity, resistance to antibiotics and the effect of lyophilization on these strains of lactobacillus were studied. 2.The probiotic preparation, consisting of Lactobacillus plantarum U-14 and Lactobacillus fermentum U-5 strains was produced by the method of lyophilization and the viability of lactobacillus during the period of 1 year storage at +4oC temperature was defined. 3.The preventive dose of probiotic preparation for neonate calves given with colostrum or milk was defined during the first 10 days, the clinical signs of calves, daily weight gain, effect on the total number of enterobacteria and lactobacillus were studied and the lactobacillus species composition in the faeces together evaluating morphological and biochemical indicators of blood was investigated. 4.The defined dose of probiotic preparation for calves was – 4g/d. and it was compared to the preventive dose of the preparation Yeasture.
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Rönnqvist, Daniel. "Urogenital probiotics : potential role of Lactobacillus in the prevention of urogenital infections in women /". Umeå : Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1400.
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Duarte, Priscila Filgueiras. "Avaliação de cepas de microrganismos probióticos a base de Lactobacillus sobre o sistema imunológico de camundongos Swiss". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/97/97132/tde-24102012-124214/.
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A procura por suplementos alimentares cresce a cada ano, pois o seu uso contínuo promove a melhora e manutenção da qualidade de vida do hospedeiro. Sustentado neste princípio, a ingestão de produtos probióticos, principalmente leites fermentados, passa a ser uma alternativa neste segmento do mercado. Os probióticos são suplementos alimentares que contem microrganismos vivos que trazem benefícios à saúde do consumidor pela manutenção e melhora do balanço microbiano do trato gastrintestinal. Existem vários gêneros de microrganismos que apresentam propriedades probióticas, destacando-se o gênero Lactobacillus; que exercem várias funções benéficas ao hospedeiro como a diminuição dos níveis de colesterol sangüíneo, efeito anticarcinogênico, adesão ao epitélio intestinal, melhora do sistema imune e a exclusão competitiva, conhecida também como efeito barreira. Dentro deste contexto, o presente trabalho teve como objetivo avaliar o efeito de inibição exercido por cinco cepas de Lactobacillus isoladas de fezes humanas: denominadas L. plantrum (Lac-01), L. plantarum (Lac-02), L. fermentum (Lac-03), L. fermentum (Lac-04) e L. fermentum (Lac-05) sobre o crescimento de E. coli O157:H7, Listeria spp., P. aeruginosa ATCC 27853, Salmonella typhi e Shigella spp , por meio da técnica de co-cultura. Os resultados revelaram que as cepas Lac-01, Lac-02 e Lac-03 foram capazes de inibir, em diferentes níveis, o crescimento das cepas patogênicas avaliadas, sendo este efeito mais acentuado para S. typhi e Shigella spp. Observou-se ainda que a cepa Lac-04 não apresentou efeito de inibição sobre E. coli O157:H7 e P. aeruginosa, ao passo que a cepa Lac-05 inibiu o crescimento de P. aeruginosa, S. typhi e Shigella spp., sendo incapaz de inibir E. coli O157:H7 e Listeria spp, nas condições estudadas. Posteriormente ao se verificar a produção de substâncias antimicrobianas por meio do método \"spot-test\", observou-se o efeito positivo de inibição exercida pelas cepas de Lactobacillus sobre o crescimento dos respectivos patógenos. Verificou-se também, por meio de testes enzimáticos específicos, que as substâncias antimicrobianas produzidas pelas cepas de Lactobacillus não foram sensíveis às enzimas utilizadas, não podendo afirmar, desta forma, que estas substâncias são bacteriocinas. Os testes de co-agregação demonstraram que as cepas Lac-04 e Lac-05 exerceram melhor efeito sobre os patógenos, quando comparadas com as cepas Lac-01 e Lac-02. A cepa Lac-03 não exerceu efeito de coagregação com nenhum dos patógenos avaliados. Os testes de autoagregação revelaram que as cepas Lac-01, Lac-02, Lac-04 e Lac-05 exerceram efeito de autoagregação acentuado. Observou-se ainda que nenhum dos patógenos estudados foi capaz de autoagregar.The probiotics are special food that contain live microorganisms that promote beneficits to consumer health through maintenance and improvement of microbial balance of gut tract. There are many microorganisms species used in probiotics products, standing out Lactobacillus species that produce many beneficies to consumer like decrease of blood cholesterol level, anti-carcinogenic effect, adhrence to intestinal epithelium, immune system stimulation and the competitive exclusion, also known as barrier effect. In this regard, the present work aimed to evaluate the inhibition effect exerted by five Lactobacillus strains, isolated from humam faeces: denominate, L. plantarum Lac-01, L. plantarum Lac-02, L. fermentum Lac-03, L. fermentum Lac-04 e L. fermentum Lac-05 on the gowth of E. coli O157:H7, Listeria spp., Pseudomonas aeruginosa ATCC 27853, Salmonella typhi and Shigella spp., by means of coculture technique. The results showed that the strains Lac-01, Lac-02 and Lac-03, were able to inhibit, at different levels, the growth of pathogenic strains, and this effect was more accentuated on S. typhi and Shigella spp. It was also observed that the strain Lac-04 did not present inhibition effect on E. coli O157:H7 and P. aeruginosa ATCC 27853, and the Lac-05 inhibited the growth of P. aeruginosa, S. tyhpi and Shigella spp., and showed no effect on E. coli O157:H7 and Listeria spp. Afterwards, the production of antimicrobial substance was verified by means of \"spot-test\" method, showing the positive inhibition effect exerted by all Lactobacillus strains on the growth of the respective pathogens. By means of specific enzymatic test, the antimicrobial substances produced by lactobacillus strains were not sensible to the action of enzymes proteinase-K, papain and pepsin, but this is not enough to affirm that this substances are bacteriocins. The coaggregation test demonstrated that the strains Lac-04 and Lac-05 exerted better effect on the pathogens, when compared to strains Lac-01 and Lac-02. The strain Lac-03 did not coaggregate with any pathogenic strains. The autoaggregation test showed that the strain Lac-01, Lac-02, Lac-04 and Lac-05 exerted accentuated auto-aggregation effect. The studied pathogen was not able to autoaggregate.
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Bianchi, Fernanda. "Desenvolvimento e avaliação em simulador do ecossistema microbiano humano de uma bebida simbiótica à base de extratos aquosos de quinoa (chenopodium quinoa willd) e de soja /". Araraquara, 2013. http://hdl.handle.net/11449/88333.
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Orientador: Katia SivieriBanca: Raquel Gutierres Gomes
Banca: Ana Lúcia Barreto Penna
Resumo: O conhecimento da população, em relação a uma alimentação mais saudável e nutritiva, tem levado o aumento da procura por alimentos funcionais e que proporcionem uma melhor qualidade de vida. Em função deste interesse, pesquisas que comprovem os benefícios do consumo desses novos produtos tornam-se essenciais. O objetivo do trabalho foi desenvolver uma nova bebida fermentada, potencialmente simbiótica, fermentada com Lactobacillus casei Lc-01 e adicionado de fruto-oligossacarídeo à base de extratos aquosos de quinoa e de soja e avaliar sua ação sob a microbiota intestinal por meio de sistema in vitro. O trabalho foi dividido em duas fazes, na Fase I, cinco formulações com diferentes proporções de extrato aquoso de soja e de quinoa foram testadas. A viabilidade do micro-organismo nas bebidas, assim como os valores de pH e de acidez foram monitorados até o 28º dia de estocagem a 5ºC. Foram também analisadas a composição química dos extratos e das bebidas elaboradas, bem como as propriedades reológicas e sensoriais dos produtos finais. Embora tenha ocorrido um aumento na acidez e um declínio no pH durante os 28 dias de armazenamento das bebidas, o micro-organismo probiótico manteve uma população de 108 UFC.mL-1 para todas as bebidas durante o período experimental. Houve um aumento na viscosidade e na consistência nas bebidas com maior proporção de extrato de quinoa (F1 e F2). A formulação F4 (com 70% extrato de soja- 30% extrato de quinoa) mostrou a menor curva de histerese. As formulações F4 e F5 (com 100% extrato de soja) obtiveram melhor aceitação sensorial e F4 maior intenção de compra. Com relação a composição físico-química, a formulação F3 (com 50% extrato de soja- 50% extrato de quinoa) e F4 mostraram resultados mais próximos aos das bebidas fermentadas à base de soja encontradas na literatura... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The conscience of the population, regarding to a healthier diet, has led to an increase in the demand for functional foods, providing, this way, a better quality of life. Because of this interest, researches demonstrating the benefic consumption of these new products become essential. The aim of this study was to develop a new potentially synbiotic beverage, fermented with Lactobacillus casei Lc-01 and with added fructo-oligosaccharide, based on aqueous extracts of quinoa and soy and to assess its influence on the intestinal microbiota through an in vitro system. The project was divided into two phases, in phase I, five formulations with different proportions of aqueous extract of soy and quinoa were tested. The viability of the microorganism in beverages, as well as the pH and acidity were monitored during 28 days of storage at 5◦C. It was also analyzed the chemical composition of the extracts and beverages as well as the rheological and sensorial properties of the final products. Although there was an increase in acidity and a decline in pH during the 28 days of storage, the probiotic microorganism maintained a population of 108 UFC/mL for all beverage during the experimental period. There was an increase in viscosity and consistency in beverages with higher proportion of quinoa extract (F1 and F2). The formulation F4 (70% soy extract- 30% quinoa extract) showed the lowest hysteresis curve. The formulations F4 and F5 (100% soy extract) obtained the best sensory acceptance, and F4, the higher intention to purchase. Regarding to physical and chemical composition, formulation F3 (with 50% soy extract-50% quinoa extract) and F4 showed the best results compared to similar fermented beverages. Beverage F4 was considered the best beverage developed and, therefore, had its efficacy analyzed from the Simulator Human Microbial Ecosystem (SHIME), phase II of the project... (Complete abstract click electronic access below)
Mestre
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Estrêla, Renata Pereira. "Atividade antimicrobiana da carbodiimida (EDC) sobre microorganismos presentes em lesões cariosas /". Araraquara, 2014. http://hdl.handle.net/11449/110811.
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Orientador: Josimeri HeblingBanca: Débora Lopes Salles Scheffel
Banca: Daniela Prócida Raggio
Resumo: Tem sido demonstrado que a carbodiimida (EDC) apresenta notável potencial inibidor de proteases (MMPs) e de melhorar as propriedades mecânicas do colágeno quando aplicada sobre a dentina desmineralizada. Entretanto, não existem informações a respeito de sua ação antimicrobiana sobre microrganismos comumente encontrados em lesões de cárie ou mesmo após a sua remoção. Objetivo: Investigar a atividade antimicrobiana do EDC em diferentes concentrações sobre microrganismos presentes em cavidades cariosas. Métodos: Soluções de EDC foram preparadas e testadas contra S. mutans e sobrinus, L. acidophilus e Candida albicans. Inicialmente, foi utilizado o teste de difusão em ágar, no qual discos de papel filtro foram impregnados com EDC 2, 1, 0,5, 0,3 ou 0,1 mol/L, clorexidina 0,12%, nistatina 1% ou tampão Sorensen pH 6,2 (n=6). Em seguida, foi determinada a concentração inibitória mínima (CIM) e bactericida mínima (CBM) do EDC sobre L. acidophilus em suspensão planctônica (n=9), por meio de turvamento. Por fim, a atividade do EDC (de 0,01 à 2 mol/L) sobre L. acidophilus em biofilme monoespécie foi definida por meio do ensaio de XTT (n=6). Os dados foram submetidos aos testes estatísticos de ANOVA e Tukey ou Mann-Whitney (p<0,05). Resultados: No teste de difusão em ágar, nenhuma atividade antimicrobiana foi observada para EDC nas concentrações de 0,1 e 0,3 mol/L, assim como para o grupo controle. EDC 0,5, 1 e 2 mol/L exerceu efeito antimicrobiano apenas sobre L. acidophilus. A CIM do EDC foi de 0,01 mol/L e a CBM foi de 0,03 mol/L. Todas as concentrações de EDC igual ou superiores a 0,05 mol/L foram capazes de reduzir significantemente o metabolismo do biofilme formado por L. acidophilus. Essa redução variou de 84,2 para 0,05 mol/L até 93,4% para 2 mol/L. Conclusão: O EDC apresentou atividade antimicrobiana apenas contra L. acidophilus reduzindo significantemente o crescimento deste microrganismo quando em suspensão...
Abstract: It has been demonstrated that carbodiimide (EDC) is a potent protease inhibitor (MMPs) and is able to improve the mechanical properties of collagen when applied on the demineralized dentin. However, there is no information about its antimicrobial effect on microorganisms commonly found in caries lesions or even after its removal. Objective: To investigate the antimicrobial activity of different concentrations of EDC against microorganisms present in caries lesions. Methods: EDC solutions were prepared and tested against S. mutans and sobrinus, L. acidophilus and Candida albicans. Initially, the agar diffusion test was used, where paper discs were impregnated with 2, 1, 0.5, 0.3 or 0.1 mol/L EDC, 0.12% chlorhexidine, nistatin 1% or Sorensen's buffer pH 6.2 (control) (n=6). Then, the minimum inhibitory (MIC) and bactericide concentrations (MBC) of EDC were determined against L. acidophilus using turbidity. Finally, the growth inhibitory activity of EDC (from 0.01 to 2 mol/L) against L. acidophilus in monoespecies biofilm was defined using the XTT assay (n=6). Data were submitted to ANOVA and Tukey tests or Mann-Whitney (p<0.05). Results: For the agar diffusion test, lack of antimicrobial activity was seen for EDC at 0.1 and 0.3 mol/L, as well as for the control group. 0.5, 1 and 2 mol/L EDC exerted a growth inhibitory effect only against L. acidophilus. The MIC for EDC was set as 0.01 mol/L and the MBC as 0.03 mol/L. Concentrations equal to or greater than 0.05 mol/L were capable of significantly reducing the metabolism of L. acidophilus when in monospecies biofilm. This reduction ranged from 84.2% for 0.05 mol/L to 93.4% for 2 mol/L. Conclusion: EDC exerted antibacterial activity only against L. acidophilus significantly reducing its growth in planktonic suspension and its metabolism in biofilms in the concentration of 0.05 mol/L or higher.
Mestre
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Sohier-Pérennes, Danièle. "Systématique des espèces Lactobacillus hilgardii et Lactobacillus brevis : Application à la détection des bactéries lactiques d'altération des vins". Bordeaux 2, 1998. http://www.theses.fr/1998BOR20612.
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En vinification, les bactéries lactiques conduisent la fermentation malolactique, processus de désacidification du vin. Cependant, certaines d’entre elles peuvent être à l’origine d’altérations. Le contrôle de la flore microbienne est donc souhaitable à toutes les étapes de la vinification, grâce à la mise en œuvre de méthodes d’identification de plus en plus efficaces. L’identification moléculaire des bactéries lactiques est désormais réalisée par une méthode d’hybridation ADN/ADN. Mais, des hybridations croisées sont observées entre plusieurs souches L. Hilgardii et L. Brevis, différenciées au préalable d’après leur profils API. Les souches fermentant ce pentose sont classées au sein de l’espèce L. Brevis, les autres au sein de l’espèce L. Hilgardii. La caractérisation moléculaire des espèces L. Hilgardii et L. Brevis constitue donc l’essentiel de ce travail. Des sondes et tests PCR spécifiques de l’espèce L. Hilgardii ont été élaborés. Par contre, dans le cas de L. Brevis, les polymorphismes génomiques observés laissent supposer que le regroupement de souches effectué sur la base de profil fermentaire ne correspond pas véritablement à une espèce. Ainsi, trois souches fermentant l’arabinose, mais possédant toutes les caractéristiques génomiques requises, ont été reclassés au sein de l’espèce L. Hilgardii, remettant ainsi en cause la validité du test biochimique. Une étude métabolique et génétique de l’assimilation de l’arabinose a donc été abordée chez différentes souches L. Hilgardii et L. Brevis. Les différences phénotyques observées entre les souches L. Hilgardii ne porteraient pas forcément sur la capacité ou non à fermenter l’arabinose. Enfin, dans le but de réaliser un contrôle de qualité efficace des vins, une méthode d’hybridation in situ a été adaptée au contrôle de la flore lactique avec les sondes d’ores et déjà utilisées pour des méthodes d’hybridation en tache ou sur colonie.
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Richard, Béatrice. "Le genre Lactobacillus et la carie dentinaire : utilisation de méthodes génotypiques pour l'identification de l'espèce L. Rhamnosus". Bordeaux 2, 2000. http://www.theses.fr/2000BOR20797.
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Les capacités de survie des lactobacilles en milieu acide en font le genre prédominant dans la carie dentinaire profonde. Le suivi des espèces associées à la carie au sein de l'écosystème buccal est indispensable à une meilleure compréhension du déroulement du processus carieux et à sa prévention. Il nécessite le développement d'outils permettant la caractérisation précise de ces bactéries, indépendamment de leur phénotype qui peut être instable. Des méthodes génotypiques ont donc été appliquées aux principales espèces retrouvées dans le milieu salivaire (souches de référence de l'ATCC) ainsi qu'à des souches sauvages d'origine buccale pour permettre leur identification. Le travail a été plus particulièrement orienté vers l'espèce Lactobacillus rhamnosus qui prédomine dans les prélèvements issus de dentine cariée. Un profil d'amplification par réaction de polymérisation en chaine (PCR) permettant une première discrimination de cette espèce par rapport aux autres espèces de lactobacilles salivaires a été obtenu. Une sonde spécifique a également été développée et testée en hybridation sur taches. Elle permet d'identifier cette espèce et de suivre son implantation dans la lésion carieuse, mais aussi de surveiller son évolution dans la salive et dans la plaque dentaire. A partir d'un prélèvement de salive, de plaque dentaire ou de dentine cariée, la détection de l'espèce L. Rhamnosus peut se faire par amplification sur cellules entières après incubation du prélèvement sur milieu MRS gélosé. Les profils PCR obtenus en RAPD comme en REP permettent également le typage des souches. Ils pourront autoriser le suivi de leur évolution dans un écosystème particulier, leur transmission à l'intérieur d'un groupe familial, ou aider à mieux comprendre la résistance de certains individus à la carie malgré des charges microbiennes élevées, certains biotypes pouvant être spécifiquement associées à la carie. La détermination du biotype d'une souche est indissociable de celle de son milieu d'origine ou de ses capacités métaboliques. La taxonomie modernes (taxonomie polyphasique) à côté des informations génotypiques ou phylogéniques, doit intégrer des informations phénotypiques sur les micro-organismesThe Lactobacillus genus is involved in the progression of dental decay. The high acid tolerance of these bacteria make them predominant in dentinal caries. Conventional methods often lead to ambigous results or even to misidentifications. However, very few taxonomic tools have been developed to allow accurate identification of oral lactobacilli. This work develops reliable genotypic methods for identification and detection of the species relative to caries, and particularly of the Lactobacillus rhamnosus species, which dominate in samples from carious dentine, with the aim to monitor its development in this particular ecosystem. Methods based on hybridization with DNA probes and DNA amplification by PCR were used. The dominant salivary Lactobacillus species (reference strains from the ATCC) were selected for this purpose as well as some oral wild strains. DNA profiling using random polymorphic DNA amplification (RAPD) generated specific patterns for L. Rhamnosus ATCC 7469. A species-specific probe was developed and used on dot blots ; it may help to locate this species within its ecological niche and elucidate the progression of the carious process. The detection of L. Rhamnosus from oral samples was obtained after growth in nutritive medium and direct PCR on cells. Moreover, DNA profiles obtained by rep- or RAPD-PCR allow strain typing. This may help to elucidate the progression of the carious process, the transmission within familygroups, or some unexplained resistance to caries that could be related to a particular biotype. Typing do not exclude the description of the metabolic specifities of a strain. Modern taxonomy (polyphasic taxonomy) must include phenotypic characteristics besides genotypic and phylogenetic informations
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Trahan, Caitlin Elizabeth. "Lactobacillus acidophilus NCFM Survival in Acidified Yogurts". NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-11072008-084635/.
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Lactobacillus acidophilus NCFM is a probiotic culture widely added to dairy products and dietary supplements. The bacterium has been linked with immune modulation, cold prevention in humans, and relief of gut pain via a morphine like mechanism in animals. Industrially, the target for delivery of viable cells in a 6 oz. serving of yogurt at the end of a 52 day shelf-life is 2 x 106 CFU/g. Survival studies with an industrial yogurt formulation showed that counts of NCFM fell to less than 102 CFU/g at the end of shelf-life. The objective of this study was to investigate the reasons for the dramatic loss of viability during shelf-life, and define a solution that could maintain viability throughout shelf-life. Levels of NCFM were followed in fermented yogurts at pH 4.1, 4.7 and 5.0. Results showed that with inoculation levels of 108 CFU/ml, NCFM added at the outset of fermentation maintained survival in yogurts acidified at pH 4.7 and 5.0. NCFM showed poor survival in yogurts acidified to pH 4.1, exhibiting a 3 log loss after 48 days. The possible effects of cell injury in lyophilized Lb. acidophilus NCFM cells were also investigated. Cells subjected to a 60 minute resuscitation period in MRS media, prior to addition to acidified yogurt base at pH 4.1, showed only a ~1.5 log loss after 42 days. Survival of NCFM in yogurt was compromised at acidic conditions below pH 4.7 and a recovery period of the lyophilized cells can greatly improve survival.
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Habibi-Najafi, Mohammad B. (Mohammad Bagher). "Proline-specific peptidases from Lactobacillus casei subspecies". Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28455.
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The objectives of this study were (l) to screen out active proline-specific peptidases from Lactobacillus casei subspecies, (2) to study growth kinetic and enzyme production from enriched medium (MRS) and cheese whey medium, (3) to purify and characterize two active proline-specific enzymes, and (4) to investigate the action of purified enzyme on bitter tryptic digests of $ beta$-casein as well as bitter enzyme-modified cheese. Lactobacillus casei subsp. casei LLG and Lactobacillus casei subsp. rhamnosus S93 were examined for extra- and intra-cellular proline-specific peptidase activities. Both strains showed strong activity for x-prolyl dipeptidyl peptidase and proline iminopeptidase but had weak activities for prolidase, prolinase, and post proline endopeptidase. Histochemical staining of crude enzyme extract from Lactobacillus casei ssp. casei LLG with different substrates revealed a distinct protein band for x-prolyl dipeptidyl peptidase as well as for proline iminopeptidase. The growth kinetics showed that the intracellular proline-specific peptidases increased gradually at the beginning of the exponential phase and reached a maximum at the beginning of stationary phase.Storage stability of x-prolyl dipeptidyl peptidase and proline iminopeptidase in crude extract, with and without stabilizers showed no significant loss in activity of these two enzymes at 4$ sp circ$C for 9 days without adding any stabilizers. The levels of x-prolyl dipeptidyl peptidase, proline iminopeptidase, and post proline endopeptidase activities of cells grown in whey did not vary markedly from cells grown in MRS broth. X-prolyl dipeptidyl peptidase and proline iminopeptidase were purified from crude cell-free extract of Lactobacillus casei ssp. casei LLG by Fast Protein Liquid Chromatography (FPLC) equipped with ion-exchange and gel-filtration columns. X-prolyl dipeptidyl peptidase was found to be a serine-dependent enzyme with molecular mass of 79 kDa. The pH and the temperature optima by the purified enzyme were 7.0 and 50$ sp circ$C, respectively. Proline iminopeptidase was sulfhydryl enzyme with molecular mass of 46 kDa. The maximum enzyme activity was observed at pH 7.5 and 40$ sp circ$C. This is the first report describing the purification and characterization of x-prolyl dipeptidyl peptidase and proline iminopeptidase from Lactobacillus casei to homogeneity.
The debittering of tryptic digests from $ beta$-casein by x-prolyl dipeptidyl peptidase was studied by reversed phase high performance liquid chromatography (RP-HPLC) and liquid chromatography/mass spectrometry. The results showed that two bitter peptides (f53-97 and f03-209) containing X-Pro-Y-Pro in their amino acid residues were completely hydrolyzed and many other peptides with high hydrophobicity were decreased in peak area. The addition of purified x-prolyl dipeptidyl peptidase on bitter enzyme-modified cheese (EMC) also showed that at least one bitter peptide with X-Pro-Y derived from $ alpha$-casein hydrolysis was removed.
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Hickey, Eileen. "Speciation of Lactobacillus isolates by molecular methods". Thesis, University of East London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242149.
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Gjertz, Marcus. "Ångsterilisering av morötter. Infekterade med Lactobacillus plantarum". Thesis, Högskolan i Borås, Institutionen Ingenjörshögskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-18924.
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The purpose of the project was to exam steams ability to sterilize carrots infected withLactobacillus plantarum. The project was a cowork with Brämhults Juice AB. They hadobserved an increase of Lactobacillus in the production of carrot juice during the summer. Tokeep the flavour of fresh fruits, the juice is treated carefully with heat. This means that thejuice only stays fresh for a few days, around two weeks for an unopened package and threedays for an opened package.In an attempt to remove the remaining Lactobacillus of the carrots, steam is tested as an extrastep in the production of juice. During the project it was found that it is difficult to reach thewanted temperature of above 100°C, when the steam is generated under pressure. When thesteam was released in normal pressure, a decrease in temperature occurred that were so largethat the steam had a temperature of only 40°C. At the second treatment the steam wasgenerated at 1,8 bar pressure and 130°C, the steam then decreased to 80°C.At the third and last treatment the steam was generated under normal pressure and atemperature of 90°C was reached. At this temperature an 96,5% sterilization occurred after 15seconds of steam treatment. This is not enough for Brämhults Juice, since they need only afew percent surviving Lactobacills after 6 seconds.Uppsatsnivå: C
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Variane, Suzy Fernandes. "Caracterização molecular de linhagens de lactobacillus fermentum". [s.n.], 1996. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255726.
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Orientador: Vanderlei Perez CanhosDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-07-21T19:52:26Z (GMT). No. of bitstreams: 1 Variane_SuzyFernandes_M.pdf: 3085153 bytes, checksum: 4e630a2f16c0fbf342ef24a0167e8ff1 (MD5) Previous issue date: 1996
Resumo: O gênero Lactobacillus é encontrado no trato intestinal de humanos saudáveis e animais, como também em vegetais fermentados, produtos cámeos, vinhos e cervejas. Por outro lado, são largamente utilizados na preparação de uma variedade de alimentos como culturas "starter" em queijos e outros laticínios (BOTIAZZI, 1988). Além disso, linhagens de Lactobacillus têm sido isoladas como contaminantes em usinas de álcool. O gênero Lactobacillus é o que contém o maior número de espécies de bactérias ácido-lácticas; é também o mais heterogêneo compreendendo espécies com uma grande variedade de propriedades bioquímicas e fisiológicas. A heterogeneidade se reflete pela extensão do teor de mol% de G+C das espécies incluídas no gênero que é de 32-53 mol%. Linhagens de Lactobacillus fermentum, isoladas de usinas de álcool do estado de São Paulo foram caracterizadas através de técnicas bioquímica e molecular, através dos perfis de fermentação de carboidratos e da técnica de RAPO (Randomly Amplified Polymorphic ONA). A partir da amplificação de fragmentos de ONA, utilizando-se "primers" arbitrários, foi possível gerar "fingerprintings" através da técnica de RAPD, capazes de discriminar entre linhagens da mesma espécie, permitindo o enquadramento em grupos distintos com características em comum. Através da análise dos perfis de fermentação de carboidratos, observou-se a formação de grupos com características próprias e que foram os mesmos grupos obtidos através da técnica de RAPO, indicando portanto a existência de grupos bem definidos de linhagens pertencentes ao gênero Lactobacillus que estão presentes como contaminantes de fermentação alcoólica
Abstract: The Lactobacillus genus is found mainly in the intestinal tract of healthy humans and animals, as well as in fermented vegetables, fleshy products, wines and beers. Nevertheless, it is largely used in several food preparations, for instance, as starter cultures for cheeses and other dairy products (BOTI AZ'ZJ, 1988). Strains of Lactobacillus genus have been isolated from alcohol industries. The Lactobillus genus is the biggest one in the lactic-acidic bacteria group; it is also the most heterogeneous group, which comprises species with a large variety of biochemical and physiological properties. The heterogeneity is due to the high G+C content of species from this genus, 32 to 53 mol%. Lactobacillus fermentum strains isolated from alcohol industries from São Paulo State were characterized by biochemical and molecular techniques, such as carbohydrate fermentation profiles and RAPO technique (Randomly Amplified Polymorphic ONA). Based on amplification of ONA fragments, using random primers, the RAPO technique provides fingerprintings, enabling to discriminate between strains from the same species, besides it allows the formation of different groups with the same characteristics. Through analysis of carbohydrate fermentation profiles, it was possible to observe the formation of groups with their own features, which were the same group obtained through RAPO technique, showing, therefore, the existence of well defined groups of Lactobacillus strains which are present as alcoholic fermentation contaminants
Mestrado
Mestre em Ciência de Alimentos
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Lehri, Burhan. "Lactobacillus fermentum 3872 genome sequencing and analysis". Thesis, Kingston University, 2017. http://eprints.kingston.ac.uk/40907/.
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In recent years, there has been a rise in antimicrobial-resistant bacteria caused by overdependence on, and misuse of, antibiotics. This has led to an increase in research for identifying alternatives to combat pathogens. One promising means of combating pathogenic bacteria, particularly for those residing in the gastrointestinal tract (GIT), is the use of probiotics. This thesis focuses on a potential probiotic strain Lactobacillus fermentum 3872, the genome sequence of which was circularised during the study, identifying genes that may contribute to probiotic activity. Several genes involved in GIT survival, such as acid symporters were discovered, along with genes that encode adhesion proteins such as those involved in mucus, fibronectin and collagen binding. The genes mentioned above may contribute to L. fermentum 3872 survivability within the GIT and have an antagonistic effect on enteric pathogens via competitive exclusion. Other interesting genes identified in L. fermentum 3872 were potentially involved in bacterial aggregation, exopolysaccharide and vitamin synthesis, along with four prophage encoding regions. Genes that encode a class III bacteriocin was also identified. An additional gene encoding a collagen binding protein (CBP) of a newly discovered plasmid pLF3872, was recognised. The chromosomal sequence also had a partial CBP encoding gene. pLF3872 has a toxin-antitoxin gene pair that ensures stable maintenance of the plasmid, along with conjugation-related genes. Functional analysis of the recombinant CBP via ELISA experiments found that the protein had the ability to bind to collagen I, a protein present on the epithelial lining of cells of the GIT. ELISA experiments also demonstrated that a common gastrointestinal pathogen, Campylobacter jejuni, can bind to collagen I in a concentration-dependent manner. In addition, mass spectrometry analysis identified that C. jejuni strains 11168H and 81-176 may utilise flagellar components (FlaA and FlaB) for adhesion. Furthermore, C. jejuni 11168H and 81-176 binding to collagen I was inhibited in the presence of either L. fermentum 3872 or CBP, thus reducing C. jejuni adherence via competitive exclusion. Using an in vitro assay, it was also demonstrated that L. fermentum 3872 cell-free supernatant could inhibit the growth of C. jejuni, due to the acidic environment brought about by L. fermentum 3872. During the completion of the genome sequence of L. fermentum 3872, comparison of various sequence assembly techniques which focused on the quality of the genome assembly was conducted. The results showed that further extension of the genome sequence during sequence assembly may lead to assembly errors when over-relying on a commonly-used sequence quality indicator, referred to as read mapping. It is suggested that care must also be taken when using long read technology to complete the genome sequence of a bacteria, as this may result in nucleotide sequence redundancies.
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Lyle, Keenan Harris. "Comparison of plasmids from clinical Lactobacillus strains". University of the Western Cape, 2018. http://hdl.handle.net/11394/6397.
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Magister Scientiae - MSc (Biotechnology)The vaginal mucosa is dominated by Gram positive, rod shaped lactobacilli which serve as a natural barrier against infection. In both healthy and BV infected women Lactobacillus crispatus and Lactobacillus jensennii has been found to be the predominant Lactobacillus species. Many studies have been conducted to assess factors influencing lactobacilli dominance in the vaginal microbiome. However, no study has evaluated the impact of plasmids on the vaginal lactobacilli. In the present study two plasmids, pLc17 and pLc4, isolated from vaginal Lactobacillus species of both healthy and BV infected women were characterized. pLc4 was present in both Lactobacillus crispatus and Lactobacillus jensennii while pLc17 was only present in Lactobacillus crispatus. pLc17 (16663 bp in size) encoded a ribonucleotide diphosphate reductase (RNR), a filamentation induced by cAMP-like (FIC-like) protein and numerous mobile elements. The FIC-like protein may assist pLc17 to persist within the bacterial population, while RNR is commonly associated with phages and may indicate phage infection. pLc4 (4224 bp in size) encodes for a replication initiator protein and a plasmid partitioning protein. The replication protein on pLc4 shows 44% identity with the replication initiation protein of pSMQ173b_03. On further phylogenetic and sequence analysis with other Rolling Circle Replication (RCR) plasmids, pLc4 appears to be novel as the plasmid shows a low degree of similarity to these RCR plasmids. pLc17 appears to carry both a RCR replicon as well as a theta replicon, similar to pIP501, the broad-host-range plasmid from Bacillus subtilis. The relative Plasmid Copy Number (PCN) for pLc4 and pLc17 was analysed using quantitative polymerase chain reaction (qPCR) for the healthy state relative to the disease state from twentyeight vaginal swab samples obtained from the National Institute for Communicable Diseases (NICD). The relative PCN for pLc4 and pLc17 had a fold increase of ~2.803 and ~1.693, respectively in the healthy patient samples relative to BV infected patient samples. However, there were not found to be significant differences when taking the standard error into account Due to the novelty of these plasmids further analysis and characterisation is required for both plasmids, to establish what role they may play in the health of the vaginal milieu.