Dissertations / Theses: 'Lactobacillu'

1

LONGO, STEFANO. "Lactobacillus crispatus M247: azioni immuno - modulanti e interazioni molecolari con l' epitelio intestinale." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/405.

Full text

Abstract:

Con il primo lavoro è stato identificato un tratto fenotipico di un ceppo di L.crispatus associato alla capacità di persistere e colonizzare il colon dell’ospite e di modificarene la composizione microbica, tale L.crispatus M247 è in grado di modificare, nell’epitelio del colon, il livello di espressione dei TLR2 dei TLR4 sia in vitro che in vivo. Con il secondo studio si identifica un meccanismo antinfiammatorio, prima sconosciuto, indotto da un ceppo probiotico che coinvolge l’attivazione di PPAR-γ e fornisce una nuova visuale sui meccanismi molecolari coinvolti nel dialogo tra epitelio intestinale e microbiota simbionte.
The colonic microbiota is a major modulator of the mucosal immune system; therefore, its manipulation through supplementation with probiotics may significantly affect the host’s immune responses. Since different probiotics seem to exert various effects in vivo, we tested the relevance of the autoaggregation phenotype on the intestinal persistence of lactobacilli and their ability to modulate the host’s innate immune responses. After 14 days of diet supplementation, the aggregating strain Lactobacillus crispatus M247 but not aggregation-deficient isogenic mutant MU5 was recovered from the feces and colonic mucosa of mice. This observation was confirmed by strain-specific PCR amplification and by Lactobacillus-specific denaturing gradient gel electrophoresis analysis. Indeed, L. crispatus M247 increased Toll-like receptor 2 (TLR2) mRNA levels, while it reduced TLR4 mRNA and protein levels in the colonic mucosa, whereas MU5 was ineffective. In colonic epithelial cells (CMT-93 cells) L. crispatus M247 but not MU5 induced time-dependent extracellular signal-regulated kinase-1 (ERK1) tyrosine phosphorylation and TLR modulation, which were abolished in the presence of PD98059 (an ERK1 inhibitor). To assess the functional relevance of probiotic-induced TLR modulation, we determined the consequences of L. crispatus preexposure on TLR4 (lipopolysaccharide [LPS]) and TLR2 [Pam3Cys-Ser-(Lys)4] ligand-mediated effects in intestinal epithelial cells. Preexposure to L. crispatus M247 blunted LPS-induced interleukin-6 (IL-6) release and inhibition of CMT-93 migration over a wound edge, whereas it enhanced TLR2-mediated IL-10 up-regulation. In summary, the aggregation phenotype is required for L. crispatus persistence in the colon and for modulation of TLR2/TLR4 expression through an ERK-dependent pathway. We speculate that the aggregation phenotype in L. crispatus M247 is required to temper epithelial cell responsiveness to bacterial endotoxins, which thus affects the evolution of intestinal inflammatory processes. Accumulating evidence indicates that the peroxisome proliferator activated receptor (PPAR)- is a major player in maintaining intestinal mucosa homeostasis, but whether PPAR- is directly involved in probiotic-mediated effects and the molecular events involved in its activation are not known. Methods: We investigated the role of PPAR- in the immunomodulatory effects of Lactobacillus crispatus M247 on intestinal epithelial cells (IEC) and the role of probiotic-derived H2O2 on PPAR- activity. Results: L crispatus M247 supplementation in mice significantly increased PPAR- levels and transcriptional activity in the colonic mucosa. L crispatus M247 induced PPAR- nuclear translocation and enhanced transcriptional activity in epithelial (CMT-93) cells, as demonstrated by the increased luciferase activity of a PPAR- –responsive element, PPAR- – responsive gene up-regulation, and reduced activity of an nuclear factor- B–responsive element. Pharmacologic PPAR- inhibition or silencing by small interfering RNA cancelled the L crispatus M247–mediated effects in CMT-93 cells. Because Lactobacillus strains producing little H2O2 failed to activate PPAR- , we investigated the role of L crispatus M247– derived H2O2 in PPAR- activation. L crispatus M247 induced a transient rise in intracellular H2O2 and PPAR- transcriptional activity was cancelled by antioxidant or H2O2 scavenger. Toll-like receptor (TLR)-2 was not required for PPAR- up-regulation mediated by L crispatus M247 in mice, although the protective effects of L crispatus M247 on dextran sodium sulfate-induced colitis were less pronounced in TLR-2 / mice. Conclusions: L crispatus M247 uses H2O2 as a signal transducing molecule to induce PPAR- activation in IEC, directly modulating epithelial cell responsiveness to inflammatory stimuli.

APA, Harvard, Vancouver, ISO, and other styles

2

LONGO, STEFANO. "Lactobacillus crispatus M247: azioni immuno - modulanti e interazioni molecolari con l' epitelio intestinale." Doctoral thesis, Università Cattolica del Sacro Cuore, 2009. http://hdl.handle.net/10280/405.

Full text

Abstract:

Con il primo lavoro è stato identificato un tratto fenotipico di un ceppo di L.crispatus associato alla capacità di persistere e colonizzare il colon dell’ospite e di modificarene la composizione microbica, tale L.crispatus M247 è in grado di modificare, nell’epitelio del colon, il livello di espressione dei TLR2 dei TLR4 sia in vitro che in vivo. Con il secondo studio si identifica un meccanismo antinfiammatorio, prima sconosciuto, indotto da un ceppo probiotico che coinvolge l’attivazione di PPAR-γ e fornisce una nuova visuale sui meccanismi molecolari coinvolti nel dialogo tra epitelio intestinale e microbiota simbionte.
The colonic microbiota is a major modulator of the mucosal immune system; therefore, its manipulation through supplementation with probiotics may significantly affect the host’s immune responses. Since different probiotics seem to exert various effects in vivo, we tested the relevance of the autoaggregation phenotype on the intestinal persistence of lactobacilli and their ability to modulate the host’s innate immune responses. After 14 days of diet supplementation, the aggregating strain Lactobacillus crispatus M247 but not aggregation-deficient isogenic mutant MU5 was recovered from the feces and colonic mucosa of mice. This observation was confirmed by strain-specific PCR amplification and by Lactobacillus-specific denaturing gradient gel electrophoresis analysis. Indeed, L. crispatus M247 increased Toll-like receptor 2 (TLR2) mRNA levels, while it reduced TLR4 mRNA and protein levels in the colonic mucosa, whereas MU5 was ineffective. In colonic epithelial cells (CMT-93 cells) L. crispatus M247 but not MU5 induced time-dependent extracellular signal-regulated kinase-1 (ERK1) tyrosine phosphorylation and TLR modulation, which were abolished in the presence of PD98059 (an ERK1 inhibitor). To assess the functional relevance of probiotic-induced TLR modulation, we determined the consequences of L. crispatus preexposure on TLR4 (lipopolysaccharide [LPS]) and TLR2 [Pam3Cys-Ser-(Lys)4] ligand-mediated effects in intestinal epithelial cells. Preexposure to L. crispatus M247 blunted LPS-induced interleukin-6 (IL-6) release and inhibition of CMT-93 migration over a wound edge, whereas it enhanced TLR2-mediated IL-10 up-regulation. In summary, the aggregation phenotype is required for L. crispatus persistence in the colon and for modulation of TLR2/TLR4 expression through an ERK-dependent pathway. We speculate that the aggregation phenotype in L. crispatus M247 is required to temper epithelial cell responsiveness to bacterial endotoxins, which thus affects the evolution of intestinal inflammatory processes. Accumulating evidence indicates that the peroxisome proliferator activated receptor (PPAR)- is a major player in maintaining intestinal mucosa homeostasis, but whether PPAR- is directly involved in probiotic-mediated effects and the molecular events involved in its activation are not known. Methods: We investigated the role of PPAR- in the immunomodulatory effects of Lactobacillus crispatus M247 on intestinal epithelial cells (IEC) and the role of probiotic-derived H2O2 on PPAR- activity. Results: L crispatus M247 supplementation in mice significantly increased PPAR- levels and transcriptional activity in the colonic mucosa. L crispatus M247 induced PPAR- nuclear translocation and enhanced transcriptional activity in epithelial (CMT-93) cells, as demonstrated by the increased luciferase activity of a PPAR- –responsive element, PPAR- – responsive gene up-regulation, and reduced activity of an nuclear factor- B–responsive element. Pharmacologic PPAR- inhibition or silencing by small interfering RNA cancelled the L crispatus M247–mediated effects in CMT-93 cells. Because Lactobacillus strains producing little H2O2 failed to activate PPAR- , we investigated the role of L crispatus M247– derived H2O2 in PPAR- activation. L crispatus M247 induced a transient rise in intracellular H2O2 and PPAR- transcriptional activity was cancelled by antioxidant or H2O2 scavenger. Toll-like receptor (TLR)-2 was not required for PPAR- up-regulation mediated by L crispatus M247 in mice, although the protective effects of L crispatus M247 on dextran sodium sulfate-induced colitis were less pronounced in TLR-2 / mice. Conclusions: L crispatus M247 uses H2O2 as a signal transducing molecule to induce PPAR- activation in IEC, directly modulating epithelial cell responsiveness to inflammatory stimuli.

APA, Harvard, Vancouver, ISO, and other styles

3

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.

Full text

Abstract:

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 thérapeutiques
Giardia 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

APA, Harvard, Vancouver, ISO, and other styles

4

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

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.

Full text

Abstract:

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 fermentés
Two 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

APA, Harvard, Vancouver, ISO, and other styles

6

Chaves, Maria Manoela Barata de Castro [UNESP]. "Estudo da microbiota vaginal de éguas com ênfase na pesquisa de lactobacilos." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/98256.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:29:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-12Bitstream added on 2014-06-13T19:17:45Z : No. of bitstreams: 1 chaves_mmbc_me_botfmvz.pdf: 1213419 bytes, checksum: c6618d188eefb02feaf360154f766257 (MD5)
Universidade Estadual Paulista (UNESP)
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%...
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)

APA, Harvard, Vancouver, ISO, and other styles

7

Regulski, Krzysztof. "Influence of peptidoglycan metabolism on immunomodulatory properties of Lactobacillus casei." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112313.

Full text

Abstract:

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 mutants
Peptidoglycan (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

APA, Harvard, Vancouver, ISO, and other styles

8

Polizzi, Andrea. "Studio sulla valorizzazione della crusca di canapa come sottoprodotto industriale, analisi della capacità prebiotica." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

Find full text

Abstract:

In questo lavoro di tesi è stata studiata l’idrolisi batterica del sottoprodotto crusca della farina di semi di canapa ottenuta dalla lavorazione industriale della canapa da fibra e/o alimentare (Cannabis sativa L.), con lo scopo di valorizzarne i componenti bioattivi rilasciati, per un loro impiego nell’industria alimentare o cosmetica. In particolare, oltre alla capacità di idrolizzare e rendere maggiormente bio-accessibili le proteine vegetali della canapa, si è voluto studiarne le capacità prebiotiche sui batteri benefici del tratto gastro-intestinale umano. Dopo aver messo a punto un protocollo che comprendeva sia un trattamento termico che la diluizione ottimale della sospensione della crusca, questa è stata fermentata con differenti specie di Lactobacillus spp.: L. casei, L. rhamnosus, L. plantarum e L. fermentum. L’inoculo batterico iniziale è stato di 6 Log10 CFU/ml e l’idrolisi è stata condotta prima in una fase di screening per 24 ore e poi in una fase in tempi prolungati fino a 72 ore, utilizzando solo le combinazioni e le specie batteriche più promettenti. Le performance di crescita sono state studiate con la quantificazione del carico microbico e la valutazione del pH del mezzo. La quantificazione è stata eseguita sia con tecnica coltura-dipendente, che con coltura-indipendente, tramite qPCR. Inoltre, su differenti campioni di crusca di canapa è stato condotto il saggio di attività prebiotica, anch’esso per via molecolare, confrontandone le performances con farina di semi di canapa e con Frutto-oligosaccaridi di cicoria (FOS). I risultati hanno mostrato che il campione con l’attività prebiotica maggiore verso Lactobacillus probiotico è quella idrolizzata da un pool di tre specie di lattobacilli differenti; mentre verso Bifidobacterium probiotico è quella della crusca che ha subito solo trattamento termico. Nel primo caso, l’attività prebiotica aveva valori simili al FOS, che ad oggi è l'unico composto con l'indicazione prebiotica accettata dall'EFSA

APA, Harvard, Vancouver, ISO, and other styles

9

Harris, Lyle Keenan. "Comparison of plasmids from clinical Lactobacillus strains." University of the Western Cape, 2018. http://hdl.handle.net/11394/6439.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

10

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.

Full text

Abstract:

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 nutritionnels
Symbiotic 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

APA, Harvard, Vancouver, ISO, and other styles

11

Bianchi, Fernanda [UNESP]. "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." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/88333.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:23:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-09-23Bitstream added on 2014-06-13T20:10:48Z : No. of bitstreams: 1 bianchi_f_me_arafcf.pdf: 1595850 bytes, checksum: b0b3350af531af9844bc98a774d86718 (MD5)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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...
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)

APA, Harvard, Vancouver, ISO, and other styles

12

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

13

Brolazo, Eliane Melo. "Prevalencia e caracterização de especies de lactobacilos vaginais em mulheres saudaveis em idade reprodutiva." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310509.

Full text

Abstract:

Orientador: Luis Guillermo Bahamondes
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
Made available in DSpace on 2018-08-13T11:58:54Z (GMT). No. of bitstreams: 1 Brolazo_ElianeMelo_D.pdf: 580434 bytes, checksum: 24b8356368950df00b8a139f02ad0fef (MD5) Previous issue date: 2009
Resumo: A microflora vaginal de mulheres saudáveis em idade reprodutiva é composta por uma variedade de bactérias aeróbias e anaeróbias, mas as espécies dominantes são os lactobacilos (bacilos de Döderlein), que exercem significante influência sobre a microbiota local. Além de restringir o crescimento de patógenos competindo pelo espaço e nutrientes, os lactobacilos produzem substâncias antimicrobianas como ácidos orgânicos, peróxido de hidrogênio (H2O2) e bacteriocinas. Esta atividade antagonista é importante na proteção contra várias infecções, principalmente a vaginose bacteriana (VB). Objetivos: Identificar as espécies de lactobacilos isolados do conteúdo vaginal de mulheres saudáveis e assintomáticas e determinar as espécies mais prevalentes e caracterizá-las quanto à produção de ácido láctico, peróxido de hidrogênio (H2O2) e sua capacidade de adesão às células do epitélio vaginal. Métodos: Foram isoladas 83 linhagens de lactobacilos de amostras de conteúdo vaginal de 135 mulheres, sem queixa de corrimento e com diagnóstico laboratorial negativo para infecções vaginais, acompanhadas no ambulatório de Planejamento Familiar da Faculdade de Ciências Médicas - UNICAMP. As linhagens isoladas foram identificadas por PCR multiplex e, quando necessário, submetidas ao sequenciamento do gene RNAr 16S. Foram então avaliadas quanto à produção de ácido láctico, de H2O2, bacteriocinas e a capacidade de adesão às células epiteliais. Resultados: A espécie predominante foi L. crispatus presente em 30,1% das mulheres, seguida de L. jensenii (26,5%), L. gasseri (22,9%) e L. vaginalis (8,4%). As outras espécies isoladas foram L. delbrueckii, L fermentum, L reuteri e L rhamnosus, com duas linhagens cada uma, e L. mucosae e L. salivarius com uma cepa cada. Das 83 linhagens de lactobacilos analisadas, apenas 20 não apresentaram produção de H2O2 detectável pela técnica de cultivo em agar MRS com TMB. Foram selecionadas 37 linhagens para teste de adesão às células epiteliais. Destas, 12 tiveram adesão entre 50% e 69% e 10 igual ou maior a 70%. As linhagens restantes apresentaram pouca capacidade de aderir às células epiteliais. Nenhuma das linhagens testadas produziu bacteriocinas. Conclusões: As espécies de lactobacilos mais prevalentes em mulheres sem vulvovaginites, isoladas em meio de cultura seletivo e identificadas por métodos moleculares, foram L. crispatus, L. jensenii e L. gasseri. Dentre as linhagens analisadas, além de mais frequentes, estas também foram as que atingiram menores valores de pH em meio de cultura e apresentaram melhor produção de H2O2
Abstract: The vaginal microflora of healthy women is composed of a large variety of aerobic and anaerobic bacteria. The dominant species is a group of lactobacilli (Doderlein's bacillus), which has a significant effect on vaginal microbiota, curtailing the growth of pathogens competing for space and nutrients. The lactobacilli specie produces various antimicrobial substances that include organic acids, hydrogen peroxide (H202) and bacteriocins. Objectives: Identify the prevalence of the different species of lactobacilli isolated from the vagina of healthy asymptomatic women, determine the most prevalent species and characterize them regarding the production of lactic acid, hydrogen peroxide (H2O2) and their capacity to adhere to vaginal epithelial cells. Methods: Eightythree strains of lactobacilli were isolated from the vagina of 135 women, with no complaints of vaginal discharge and negative laboratory diagnosis for vaginal infection, who were being followed up at the Family Planning clinic of the Medical school, Unicamp. The isolates were identified using multiplex polymerase chain reaction (PCR) and, when necessary, 16S rRNA gene sequencing. They were then evaluated with regards to the production of lactic acid, H2O2, bacteriocins, and their capacity to adhere to epithelial cells. Results: The predominant species found were L. crispatus (in 30.1% of the women), followed by L. jensenii (26.5%), L. gasseri (22.9%) and L. vaginalis (8.4%). The other species isolated were L. delbrueckii, L fermentum, L reuteri and L rhamnosus (two strains) and L. mucosae and L. salivarius (one strain). Only 20 out of 83 lactobacilli analyzed using the plate technique (in MRS agar with TMB) were found to be non-producers of H2O2. Thirty-seven lineages were selected and tested for their capacity to adhere to epithelial cells. Of these, 12 had an adhesion between 50% and 69% and 10 equal or superior to 70%. The remainder had little capacity to adhere to epithelial cells. None of the strains tested produced bacteriocins. Conclusions: L. crispatus, L. jensenii and L. gasseri were the most prevalent species isolated in selective culture media and identified through molecular techniques. Besides their frequencies, they also presented best H2O2 production and lowest pH in culture media
Doutorado
Ciencias Biomedicas
Doutor em Tocoginecologia

APA, Harvard, Vancouver, ISO, and other styles

14

Badet, Cécile. "Etude quantitative, par pHmétrie libre et stabilisée, de la production acide de trois lactobacilles d'origine buccale." Bordeaux 2, 1993. http://www.theses.fr/1993BOR2OND2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

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.

Full text

Abstract:

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 biofilm
An 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

APA, Harvard, Vancouver, ISO, and other styles

16

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.

Full text

Abstract:

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/virus
The 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

APA, Harvard, Vancouver, ISO, and other styles

17

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.

Full text

Abstract:

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 microbien
Intestinal 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

APA, Harvard, Vancouver, ISO, and other styles

18

Lagrafeuille, Rosyne. "Activités anti-biofilm de Lactobacillus vis-à-vis de Klebsiella Pneumoniae." Thesis, Clermont-Ferrand 1, 2016. http://www.theses.fr/2016CLF1PP03/document.

Full text

Abstract:

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 utilisation
In 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

APA, Harvard, Vancouver, ISO, and other styles

19

Kocaoglu-Vurma, Nurdan A. "Isolation and characterization of nonstarter Lactobacillus spp. in Swiss cheese and assessment of their role on Swiss cheese quality." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124129870.

Full text

Abstract:

Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xiv, 111 p.; also includes graphics (some col.). Includes bibliographical references (p. 104-111). Available online via OhioLINK's ETD Center.

APA, Harvard, Vancouver, ISO, and other styles

20

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Teixeira, Renato da Silva. "Avaliação do efeito de micro-organismos probiótics sobre Haemonchus contortus em ovinos." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/97/97132/tde-22082013-162216/.

Full text

Abstract:

A infecção por Haemonchus contortus é a principal parasitose que afeta a ovinocultura, provocando consideráveis perdas econômicas. Sua patogenia é caracterizada por uma intensa anemia, além de hipoproteinemia e reduções nos níveis séricos de ferro. Devido ao aumento da resistência desse parasito aos anti-helmínticos comumente encontrados no mercado, surge a necessidade de tratamentos alternativos, como por exemplo, o uso de produtos probióticos. Probióticos são alimentos funcionais que contém micro-organismos vivos, que ingeridos, com frequência e em doses adequadas trazem benefícios aos hospedeiros por meio de diferentes mecanismos de ação. Desta forma, o presente trabalho teve como objetivo avaliar o efeito de uma preparação probiótica constituída de diferentes espécies de Lactobacillus (L. casei ATCC 7469, L. plantarum ATCC 8014, L. fermentum ATCC 9338 e L. acidophilus ATCC 4536) na forma de \"pool\" sobre H. contortus em ovinos. Para tanto foram estudados 40 animais naturalmente infectados e distribuídos em 4 grupos e por 90 dias submetidos a diferentes tratamentos, a saber: Grupo A (controle): os animais não receberam nenhum tratamento, Grupo B os animais receberam em 3 dias por semana (2ª, 4ª e 6ª feiras) uma dose de 10 mL da preparação probiótica, Grupo C os animais receberam, no dia 0 dose única de Diantel® (1 mL para cada 10 Kg de PV) e Grupo D os animais receberam, no dia 0, dose única de Diantel® (1 mL para cada 10 Kg de PV) e após 30 dias passaram a receber em 3 dias por semana 10 mL da preparação probiótica, sendo interrompido no 60° dia. A cada 15 dias foram realizados exames parasitológicos para quantificação de OPG de fezes, hemograma completo, dosagem de proteínas e ferro. Os resultados demonstraram que os animais do Grupo B (probiótico) apresentaram uma eliminação de OPG de fezes significativamente menor (p<0,05) em relação aos demais grupos com uma eficácia de ação máxima de 66,3%, além dos animais se apresentarem em melhores condições fisiológicas. Maiores concentrações de hemoglobina, hematócrito e ferro também foram observadas nesse grupo, que podem ser explicadas pela ação imunomoduladora apresentada pelas espécies de Lactobacillus avaliadas, além de facilitar a absorção de nutrientes pelo animal hospedeiro. Em relação aos animais do Grupo C (Diantel®), após 45 dias ocorreu um aumento significativo (p<0,05) na contagem de OPG de fezes indicando uma maior atividade parasitária, levando a redução dos valores de hemoglobina e hematócrito. O uso do anti-helmíntico no Grupo D apresentou eficácia máxima de 90,3% após 15 dias. A inclusão da preparação probiótica, na dieta dos animais deste grupo após 30 dias, não contribuiu para se evitar a reinfecção, possivelmente devido a sensibilidade das cepas utilizadas ao princípio ativo closantel, tendo sido evidenciada a necessidade de uma nova dosagem do anti-helmíntico após 60 dias, como indicado pelo fabricante.
The infestation by Haemonchus contortus is the main parasitize that affects the ovine farms, causing a significantly economic loss. Its pathogenesis is characterized through an intense anemia, besides hypoproteinemia and blood iron level reduction. Due to the parasite resistance increasing to anti-helmintics usually found in the market, a need of an alternative treatment is evident, as example, the use of probiotics microorganisms. Probiotics are functional food that contains live microorganisms that when ingested in appropriate amount bring benefits to the hosts through different action mechanisms. Thus, this research had as purpose to study the effect of a probiotic preparation formed by a pool of Lactobacillus species (L. casei ATCC 7469, L. plantarum ATCC 8014, L. fermentum ATCC 9338 e L. acidophilus ATCC 4536) on H. contortus in ovines. Therefore, 40 naturally infected animals were distributed in 4 groups and during 90 days they were submitted to different treatments: Group A (control): the animals did not receive any treatment, Group B: The animals received 3 times a week (2º, 4º, 6º) a 10 ml dose of the probiotic preparation, Group C: the animals received on 0 day, a Diantel single dose (1 ml /10 kg of LW) and in group D: the animals received on 0 day, a Diantel single dose (1 ml /10 kg of LW) and after 30 days they started receiving 3 times a week 10 ml of the probiotic preparation, ending at the 60th day. In each fifteen days parasitological exams were realized to check the amount of EPG of feces, complete blood exam, protein and blood iron analysis. The results showed that the animals in group B (probiotic) had \"EPG\" of feces elimination significantly minor (p 0,05) related to the other groups with a efficacy of 66,3% besides, the animals presented better physiological conditions. An increasing of hemoglobin, hematocrit and blood iron level were also observed in this group, which can be explained by the immunemodulator action presented by the Lactobacillus species, which contribute to the nutrients absorption by the host animal. In relation to group C animals (Diantel), is was observed, after 45 days, a significantly increasing (p 0,05) in the EPG counting, resulting in a major parasitary activity, decreasing the hemoglobin and hematocrit values. The usage of anti-helmintic in group D showed a efficacy of 90,3% after 15 days. The probiotic preparation administered to the animals of group D did not contribute to avoid the re-infestation, probably due to the strains sensibility regarding to the active principle (closantel) of Diantel, being necessary another anti-helmintic dose administration after 60 days as indicated by the manufacturer.

APA, Harvard, Vancouver, ISO, and other styles

22

Trautwetter, Annie. "Caractérisation physique et génétique du phage LL-H." Lyon, INSA, 1986. http://www.theses.fr/1986ISAL0029.

Full text

Abstract:

Les bactéries lactiques jouent un rôle très important dans les industries agroalimentaires et en particulier dans l'industrie laitière. Le problème des bactériophages reste l'un des plus importants à résoudre pour cette industrie. Nous avons étudié l'organisation physique du bactériophage LL-H virulent pour Lactobacillus lactis LL-23. L'information génétique de ce phage est contenue dans la capside sous la forme d'une molécule linéaire d'ADN bicaténaire de 34 Kb. La carte de restriction de l'ADN phagique, réalisée pour les endonucléases EcoRI, Sali, Pstl et BamHI, apparaît circulaire. Les gènes phagiques sont donc permutés circulairement. La réalisation d'une banque de gènes de LL-H dans des vecteurs plasmidiques d'Escherichia coli a permis de détecter par "immunoblotting" l'expression des gènes codant 5 des 7 principales protéines structurales phagiques. Le gène impliqué dans la production de l'endolysine phagique a également été localisé. Le gène de la protéine structurale de 34 KD est fortement exprimé chez Escherichia coli, à partir de son propre promoteur. De même, nous avons montré que les génomes des phages mv4 (tempéré pour L. Bulgaricus) et c3, c5 et 1b4 (virulents sur cette même souche) sont constitués par un ADN bicaténaire linéaire à extrémités S'P protubérantes. Par hybridation ADN-ADN entre les ADN des phages virulents LL-H, 1v (de L. Lactis) c3, c5, 1b4 (de L. Bulgaricus) et tempérés mvl et mv4 (de L. Bulgaricus) on peut distinguer 2 familles : d'une part LL-H, 1v, mv1 et mv4, d'autre part c3, c5 et 1b4. Il existe donc une certaine parenté entre des phages tempérés et virulents de Lactobacilles. De plus, il a été montré que les fragments génomiques de LL-H codant la protéine structurale de 34 KD et l'endolysine hybrident avec des fragments de restriction des phages 1v, mv1 et mv4. Il est donc probable que la protéine structurale de 34 KD commune à ces 4 phages soit codée par une séquence d'ADN très similaire à celle de LL-H. Il en est peut être de même pour le gène de l'endolysine de ces phages
Lactobacilli, as well as lactic streptococci, play a central role in various food fermentation processes. The primary cause of slow acid production by lactic bacteria during industrial fermentation is lysis by bacteriophages. Since an improvement in the prevention of acidification perturbation resides in part in a better knowledge of the phage we have begun molecular biology studies on several phages of Lactobacilli. The first one, LL-H, is a virulent phage of strain Lactobacillus lactis LL 23. A restriction map of the phage genome was constructed, using EcoRI, Sali, Pstl and BamHI. This chromosome has a size of 34 kb and seems to be circularly permuted. A bank of LL-H restriction fragments was constituted using Escherichiacoli vectors such as pBR322 or pBR32S. The expression of S among the 7 main phage particle proteins in E. Coli by immunoblotting experiments, which allowed the mapping on the chromosome of genes coding for phage particule proteins. We have also shown that the gene of the main capsid protein is expressed from its own promoter in Escherichia coli strain. A similar study conducted on phages mv4 (temperate for L. Bulgaricus) and C3, CS and lb4 (virulent on this same strain) has shown that all the phage genomes were constituted by double stranded DNA molecules with 5'P protruding ends. DNA-DNA hybridization experiments led to the distinction of 2 families, on the one hand LL-H, 1v, mv1, and mv4, on the other 1b4 , C3 and CS. There is no DNA sequence homology between the two families, but on the contrary, the members of one family shown homologies between themselves. So, these results suggest that these virulent and temperate phages may have a common phage ancestor. Moreover, temperate phages may ac t as a source of lytic phages in cheese plants

APA, Harvard, Vancouver, ISO, and other styles

23

Zacarchenco, Patricia Blumer. "Leites fermentados por streptococcus thermophilus adicionados de lactobacillus acidophilus e bifidobacterium longum : isolamento diferencial dos microrganismos, multiplicação em diferentes condições e efeitos nas caracteristicas sensoriais dos leites fermentados naturais ou modificados." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255590.

Full text

Abstract:

Orientador: Salvador Massaguer Roig
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-03T20:56:04Z (GMT). No. of bitstreams: 1 Zacarchenco_PatriciaBlumer_D.pdf: 905521 bytes, checksum: 6d2849e2b69ed715dda0573bad474ece (MD5) Previous issue date: 2004
Doutorado
Doutor em Tecnologia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

24

Botelho, Lidiane. "Isolamento e identificação de lactobacilos e bifidobacterias em alimentos probioticos disponiveis no mercado brasileiro." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256187.

Full text

Abstract:

Orientador: Edir Nepomuceno da Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-05T01:10:55Z (GMT). No. of bitstreams: 1 Botelho_Lidiane_D.pdf: 2674428 bytes, checksum: 87e73a9d73408a767f62587a3afcade5 (MD5) Previous issue date: 2005
Resumo: No período de março a maio de 2001, várias culturas lácticas foram isoladas de 11 marcas de produtos contendo microrganismos vivos, comercializados na região de Campinas (SP). A amostragem incluiu 3 iogurtes, 5 leites fermentados, 2 bebidas lácteas e 1 mistura simbiótica em pó. As culturas foram identificadas por características fenotípicas e genotípicas. Foram também submetidas a testes para verificação do cumprimento dos pré-requisitos mínimos exigidos para culturas probióticas, que são resistência ao pH, resistência à bile e a produção de bacteriocinas. Os resultados da identificação por características fenotípicas (36 culturas), feita utilizando-se o Kit de identificação API 50CHL (BioMérieux), mostraram as seguintes espécies: 1o) Lactobacillus paracasei subsp. paracasei ¿ isolado de 6 produtos, 2o) Streptococcus thermophilus ¿ isolado de 4 produtos, 3o) Leuconostoc mesenteroides subsp.cremoris ¿ isolados de 3 produtos, 4o) Lactobacillus rhamnosus, Lactobacillus acidophilus e Lactococcus lactis subsp.lactis ¿ isolados de 2 produtos cada, 5o) Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus delbrueckii subsp. lactis, Leuconostoc lactis e Lactobacillus curvatus subsp. curvatus ¿ isolados de 1 produto cada. Os resultados da identificação por características genotípicas (41 culturas, 36 de produtos e 5 padrão de coleção de culturas), feita utilizando a técnica de ribotipagem automática Riboprinter (Dupont/Qualicon), mostraram os seguintes resultados: duas culturas não se mostraram tipáveis pelo Riboprinter (Leuconostoc mesenteroides subsp. cremoris pelo API 50CHL). Cinco foram tipadas mas não identificadas pelo Riboprinter (Leuconostoc mesenteroides subsp. cremoris e Lactobacillus acidophilus pelo API 50CHL). Três foram identificadas como Lactobacillus apenas até o nível de gênero (Lactobacillus delbrueckii subsp. lactis e Lactobacillus acidophilus pelo API 50CHL). As demais foram identificadas até o nível de espécie, 63% com o mesmo resultado do API 50CHL e 37% com resultados discordantes. A discordância concentrou-se nas culturas identificadas pelo API 50CHL como Leuconostoc mesenteroides (subsp. cremoris e lactis), Streptococcus thermophilus, Lactobacillus acidophilus e Lactobacillus delbrueckii subsp. bulgaricus. As culturas com resultados concordantes concentraram-se naquelas identificadas pelo API 50CHL como Lactobacillus rhamnosus e Lactobacillus paracasei subsp. paracasei., enquanto os discordantes concentraram-se naquelas identificadas pelo API 50CHL como Leuconostoc, Streptococcus thermophilus, Lactobacillus acidophilus e Lactobacillus delbrueckii subsp. lactis. Uma cepa de Bifidobacterium bifidum (KCTC 3440) foi corretamente identificada pelo Riboprinter e 1 cepa de Bifidobacterium subtile (ATCC 27537) foi erroneamente identificada como Enterococcus faecium. Na avaliação da resistência ao pH, 36 culturas foram avaliadas e a maioria apresentou completa perda da viabilidade após 1 a 3 hora em pH 1,0 (25 culturas ou seja 69,4%) ou 2,0 (16 culturas ou seja 44,4%). Em pH 3,0 a taxa de sobrevivência foi maior. Dois critérios foram utilizados para a conclusão. De acordo com o primeiro, são consideradas como potencialmente probióticas as culturas que apresentam 80% de sobrevivência (menos de 0,1 reduções) após 3 horas de permanência em pH 3 ou 1% de bile. De acordo com esse critério, nenhuma das culturas isoladas pode ser considerada probiótica. De acordo com o segundo critério, a resistência em pH 3 por 90 minutos e na presença de 0,1% de bile (24h), sem redução na contagem de viáveis, indica culturas potencialmente probióticas. De acordo com esse critério, duas culturas se mostraram potencialmente probióticas, uma de Lactobacillus rhamnosus e uma de Lactobacillus acidophilus. Na avaliação da resistência à bile, 29 culturas foram avaliadas e dois critérios utilizados para a conclusão. De acordo com o primeiro, culturas que apresentam taxa de 80% de sobrevivência (redução menor do que 0,1 log) na presença de 1,0% w/v de bile e pH 3,0 por 3 horas são resistentes. Segundo esse critério, nenhuma das 29 culturas isoladas de produtos mostrou resistência à bile. De acordo com o segundo, culturas que apresentem crescimento em presença de 1% de Oxgall, igual ou superior a 20% daquele obtido no controle, é considerada resistente (redução menor do que 0,7 log). Segundo esse critério, 24% ou seja, 7 das 29 culturas isoladas de produtos mostraram-se resistentes: uma cepa de L.acidophilus, uma de L.rhamnosus, uma de L.paracasei subsp. paracasei, uma de Streptococcus thermophilus, uma de Lactococcus lactis subsp. lactis e duas de Leuconostoc mesenteroides subsp cremoris. Na avaliação da produção de bacteriocinas, 32 culturas foram testadas, todas com resultados negativos. Na avaliação do antagonismo contra algumas espécies de bactérias patogênicas Gram negativas e Gram positivas, uma cepa de L.rhamnosus promoveu a inibição de Listeria e outra cepa de L.rhamnosus promoveu a inibição de Listeria e S. aureus. Não se observou inibição das bactérias Gram-negativas (E. coli e Salmonella)
Abstract: In the period between March and May 2001, a series of lactic cultures were isolated from 11 different brand products purchased from regular retail outlets located in Campinas (SP, Brazil). The sample types collected included 3 yogurts, 5 fermented milks, 2 dairy beverages and 1 symbiotic dry mix. The strains were identified by phenotypic and genotypic characteristics, in addition to being submitted to tests to investigate whether they fulfill the minimum prerequisites for microorganisms to be considered probiotic, i.e. resistance to pH, resistance to bile and bacteriocin production. Phenotypic identification (36 strains) using the API 50CHL Identification Kit (BioMérieux) evidenced the presence of the following species: 1o) Lactobacillus paracasei subsp. paracasei - isolated from 6 products, 2o) Streptococcus thermophilus - isolated from 4 products, 3o) Leuconostoc mesenteroides subsp.cremoris - isolated from 3 products, 4o) Lactobacillus rhamnosus, Lactobacillus acidophilus and Lactococcus lactis subsp.lactis - isolated from 2 products each, 5o) Lactobacillus delbrueckii subsp.bulgaricus, Lactobacillus delbrueckii subsp. lactis, Leuconostoc lactis and Lactobacillus curvatus subsp. curvatus - isolated from 1 product each. Identification on the basis of genotypic characteristics (41 strains, 36 of which isolated from products and 5 standard strains from a culture collection) using an automated ribotyping method RiboPrinter® microbial characterization system, (Dupont/Qualicon) produced the following results: two strains could not be typed by the Riboprinter method (identified as Leuconostoc mesenteroides subsp. cremoris by API 50CHL). Five strains were typed but not identified by the Riboprinter system (identified as Leuconostoc mesenteroides subsp. cremoris and Lactobacillus acidophilus by API 50CHL). Three strains were identified as Lactobacillus only to the genus level (identified as Lactobacillus delbrueckii subsp. lactis and Lactobacillus acidophilus by API 50CHL). The remaining strains were identified to the species level, 63% with the same results as those obtained with API 50CHL and 37% with discordant results. Most of the discordant results between the two identification methods were generated by the strains identified by API 50CHL as Leuconostoc mesenteroides (subsp. cremoris and lactis), Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus delbrueckii subsp. bulgaricus. The strains with concordant results were predominantly those identified by API 50CHL as Lactobacillus rhamnosus and Lactobacillus paracasei subsp. paracasei, while the strains producing discordant results were mainly those identified by API 50CHL as Leuconostoc, Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus delbrueckii subsp. lactis. One strain of Bifidobacterium bifidum (KCTC 3440) was correctly identified by the Riboprinter system, whereas 1 strain of Bifidobacterium subtile (ATCC 27537) was incorrectly identified as Enterococcus faecium. Most of the 36 strains evaluated for resistance to pH showed complete loss of viability after 1 to 3 hours at pH 1,0 or 2,0. At pH 3,0 the survival rate was considerably greater. Two criteria were used for drawing conclusions relative to the probiotic potential of the strains. According to the first criterion, strains exhibiting an 80% survival rate (reduction factor smaller than 0.1 log) after exposure for 3 hours to pH 3 or 1% bile. Based on this criterion, none of the strains isolated could be considered probiotic. According to the second criterion, resistance to pH 3 for 90 minutes and in the presence of 0,1% bile (24h), without reduction in viable counts, indicates potentially probiotic strains. Based on this latter criterion, two strains were found to exhibit probiotic potential, one strain of Lactobacillus rhamnosus and another of Lactobacillus acidophilus. A total of 29 strains were evaluated for bile resistance and the conclusions of the test results produced were based on two different criteria. According to the first, strains presenting an 80% survival rate (reduction factor smaller than 0,1 log) after 3 hours exposure to 1,0% w/v bile and pH 3,0 are considered resistant. Based on this criterion, none of the 29 strains isolated was found to be resistant to bile. According to the second criterion, cultures presenting growth in the presence of 1% Oxgall, equal or greater than 20% of that produced by the control, are considered resistant (reduction factor smaller than 0,7 log). Based on this criterion, 7 (24%) of the 29 strains isolated from products were found to be resistant: one strain of L.acidophilus, one of L.rhamnosus, one of L.paracasei subsp. paracasei, one of Streptococcus thermophilus, one of Lactococcus lactis subsp. lactis and two strains of Leuconostoc mesenteroides subsp cremoris. Thirty-two strains were tested for bacteriocin production, all of which gave negative results. The results of the test performed to evaluate antagonism against some species of Gram-negative and Gram-positive pathogenic bacteria showed that one strain of L.rhamnosus inhibited Listeria, while another strain of L.rhamnosus inhibited both Listeria and S. aureus. No inhibition of Gram-negative bacteria (E. coli e Salmonella) was found
Doutorado
Tecnologia de Alimentos
Doutor em Tecnologia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

25

Bernard, Elvis. "Etude du rôle fonctionnel de l'O-acétylation et de l'amidation du peptidoglycane chez les lactobacilles." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112084.

Full text

Abstract:

Le peptidoglycane (PG) est le composé majeur de la paroi des bactéries à Gram positif. Il est constitué de chaines de sucres, formées de l’alternance de N-acétyl-glucosamine (GlcNAc) et d’acide N-acétyl-muramique (MurNAc) et reliées entre elles par des chaines peptidiques. Cette structure confère à la bactérie une grande résistance mais aussi une certaine flexibilité qui lui permettent de grandir et de se diviser tout en gardant sa forme. Cette dualité entre rigidité et flexibilité est assurée par un équilibre entre l’activité des enzymes qui polymérisent le PG, les protéines liant la pénicilline (PBP), et de celles qui l’hydrolysent, les hydrolases du PG (PGH). Pendant ou après sa synthèse, la structure du PG peut subir différentes modifications, qui vont moduler l’activité des enzymes de synthèse et dégradation du PG. Au cours de ce travail, nous avons caractérisé les modifications structurales du PG chez deux espèces de lactobacilles et étudié leur rôle fonctionnel. Nous avons identifié la première amidotransférase responsable de l’amidation de l’acide méso-diaminopimélique et montré l’influence de cette modification sur l’activité d’une PGH, la L,D-carboxypeptidase DacB, ainsi que sur la synthèse du PG septal par les PBPs chez Lactobacillus plantarum. Nous avons ensuite mis en évidence pour la première fois une O-acétylation des GlcNAc en plus de l’O-acétylation des MurNAc, ces deux modifications étant réalisées par deux O-acétyl-transférases distinctes, OatA et OatB, qui jouent des rôles antagonistes dans le contrôle de l’activité des PGHs chez L. plantarum. Nous avons aussi révélé l’implication de l’O-acétyl-transférase OatA dans le contrôle de la septation. Enfin, nous avons montré l’influence de l’O-acétylation des MurNAc du PG sur les propriétés anti-inflammatoires d’une souche de Lactobacillus casei
Peptidoglycan (PG) is the major component of the gram positive cell wall. It is composed of glycan chains formed by the polymerization of the N-acetylglucosamine-N-acetyl muramic acid heterodimer, and cross-linked by peptidic stem. This structure confers high resistance to the bacterial cell wall but also some flexibility allowing growth and shape maintenance. This duality between rigidity and flexibility is the result of a steady-state between the PG polymerizing enzymes, the penicillin binding protein (PBP) and the PG hydrolases (PGH). More or less concomitantly with its synthesis, certain modifications can occur on PG structure that will modulate the activity of PG synthesis and degradation enzymes.During this work, we have characterized the PG structural modifications in two lactobacilli species and studied their functional role. We have identified the first amidotransferase involved in meso-diaminopimelic acid amidation and shown the influence of this modification on the activity of the L,D-carboxypeptidase, DacB, and also on the septal PG synthesis by the PBP in Lactobacillus plantarum. Then, we have highlighted for the first time, the presence of O-acetylation on GlcNAc in addition to O-acetylation on MurNAc. These two modifications are catalyzed by two dedicated O-acetyltransferases, OatB and OatA respectively, that control PGH activity in an antagonistic way. We have also demonstrated the implication of the OatA O-acetyltransferase in septation control. Finally, we have shown the influence of PG MurNAc O-acetylation on the anti-inflammatory properties of a Lactobacillus casei strain

APA, Harvard, Vancouver, ISO, and other styles

26

Dal, Bello Fabio. "Ecological studies of the Lactobacillus biota in the human digestive tract and adaptation of intestinal lactobacilli to the sourdough ecosystem." [S.l.] : [s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB12046167.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Samot, Johan. "Evaluation du potentiel probiotique de lactobacilles buccaux." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR21970/document.

Full text

Abstract:

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'Homme
The 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

APA, Harvard, Vancouver, ISO, and other styles

28

Fuochi, Virginia. "Amensalistic activity of Lactobacillus spp., isolated from human samples." Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3878.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

29

Hochwind, Kerstin. "Untersuchungen zum Genom und dem immunologisch aktiven D-Tryptophan im probiotischen Lactobacillus casei W56 im Vergleich mit anderen probiotischen Lactobacillen." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-170248.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Junior, Fernando Eustáquio de Matos. "Avaliação da viabilidade e funcionalidade de microrganismos probióticos microencapsulados em partículas lipídicas recobertas por interação eletrostática de polímeros." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/74/74132/tde-23022018-110245/.

Full text

Abstract:

A microencapsulação tem sido utilizada promissoramente para melhorar a viabilidade de probióticos. Porém, pouco se sabe sobre o impacto desta na manutenção da funcionalidade do probiótico in vivo. Este trabalho teve como objetivo avaliar duas cepas de lactobacilos, encapsular essas cepas por um sistema envolvendo partículas lipídicas recobertas por interação eletrostática de polímeros e avaliar o efeito da encapsulação na manutenção da capacidade imunomoduladora das cepas. Na primeira etapa do estudo L. rhamnosus 64 e L. paracasei BGP1 foram avaliados quanto à resistência à lisozima e aos fluidos gastrointestinais simulados, perfil de hidrofobicidade da parede celular, susceptibilidade a antibióticos, atividade antagonista contra patógenos e capacidade de utilização de prebióticos. Em etapa seguinte as cepas foram encapsuladas e as microcápsulas avaliadas quanto à morfologia, tamanho e distribuição de partículas, umidade, atividade de água e efeito do pH e temperatura em sua estabilidade. Para avaliar a susceptibilidade dos microrganismos ao processo de encapsulação e estresse tecnológico, investigou-se o impacto do efeito da homogeneização com Ultra-Turrax, tolerância à temperatura, salinidade, diferentes pH e fluidos gastrointestinais simulados na viabilidade das bactérias. A viabilidade dos microrganismos durante a estocagem também foi estudada. Por fim, avaliou-se a manutenção da capacidade imunomoduladora dos microrganismos microencapsulados por meio da dosagem de citocinas pró e anti-inflamatórias e determinação da capacidade protetora contra infecção de Salmonella entérica sorovar Typhimurium em modelo animal. Os microrganismos demonstraram resistência à lisozima, com taxas de sobrevivência superiores a 80%. O perfil de hidrofobicidade da parede celular, foi baixo, entre 8,47 e 19,19%. Demonstraram resistência apenas à vancomicina (35 µg) e eritromicina (15 µg). As duas cepas foram capazes de antagonizar o crescimento de Escherichia coli V517, Salmonella enteritidis OMS-Ca, Staphylococcus aureus 76 e Listeria monocytogenes ATCC 15313. Quanto à capacidade de utilização de prebióticos, os microrganismos apresentaram comportamentos inversos, utilizaram preferencialmente inulina, raftilose 95 e lactulose. Nos testes de resistência aos fluidos gastrointestinais simulados constatou-se declínio significativo de células viáveis, com subtração de até 3,37 log UFC/mL. As cápsulas obtidas apresentaram formato típico e tamanhos médios de 80,12 ± 1,89 e 83,92 ± 1,70 µm. Condições de pH extremos (1,5 e 9,0) e temperatura superior a 50 °C comprometeram a estabilidade das cápsulas. A encapsulação melhorou significativamente a tolerância dos microrganismos à altas concentrações de sal e elevação de temperatura. Além disso, favoreceu a resistência dos microrganismos frente aos fluidos gastrointestinais simulados. A estabilidade dos microrganismos durante o período de estocagem também foi favorecida, após 120 dias de estocagem a 7 e 25 °C a concentração de microrganismos viáveis permaneceu superior a 7,0 log UFC/g. Nos testes in vivo para avaliação da manutenção da capacidade de imunomodulação constatou-se através de dosagem de citocinas (IL-2, IL-6, IL-10 e TNF-α) e IgA secretora, que a encapsulação não alterou a resposta imunológica provocada pelas cepas estudas. Concluiu-se que os microrganismos apresentaram comportamento in vitro de acordo com o desejado para candidatos ao uso de probióticos. A microencapsulação foi bem-sucedida, proporcionando as duas cepas maior resistência frente às condições adversas e de estresse tecnológico.
Microencapsulation has been used successfully to improve the viability of probiotics microorganisms. The aim of this work was to evaluate two strains of lactobacilli, to encapsulate these strains by a system involving lipid particles coated by electrostatic interaction of polymers and to evaluate the effect of encapsulation in the maintenance of immunomodulatory capacity of these strains. In the first stage of the study L. rhamnosus 64 and L. paracasei BGP1 were evaluated for resistance to lysozyme and simulated gastrointestinal fluids, cell wall hydrophobicity profile, susceptibility to antibiotics, antagonist activity against pathogens and prebiotic utilization capacity. In the next step, the strains were encapsulated and the microcapsules evaluated regarding morphology, particle size and distribution, moisture, water activity and pH and temperature. The tolerance to temperature, salinity, different pH and simulated gastrointestinal fluids in the viability of the bacteria were also evaluated. The probiotics viability during the storage period was also studied. Finally, the maintenance of the immunomodulatory capacity of the encapsulated microorganisms was evaluated by means of the dosage of pro and anti-inflammatory cytokines and IgA. L. rhamnosus 64 and L. paracasei BGP1 demonstrated resistance to lysozyme, with survival rates above 80%. The hydrophobicity profiles of the cell wall were from 8.47 to 19.19%. Susceptibility to antibiotics also corroborated the literature, demonstrating resistance only to vancomycin (35 µg) and erythromycin (15 µg). The two strains were able to antagonize the growth of Escherichia coli V517, Salmonella enteritidis OMS-Ca, Staphylococcus aureus 76 and Listeria monocytogenes ATCC 15313. As far as the capacity of using prebiotics the two strains of lactobacilli presented inverse behaviors, they used preferably inulin, raftilose 95 and lactulose. In the tests of resistance to the simulated gastrointestinal fluids it was verified a significant decline of viable cells, with subtraction of up to 3.37 log CFU / mL, justifying the application of encapsulation technology. In the encapsulation step the capsules were produced with gum arabic, porcine gelatin and vegetable fat. The obtained capsules presented a typical format and average sizes of 80.12 ± 1.89 and 83.92 ± 1.70 µm. Extreme pH conditions (1.5 and 9.0) and temperature above 50 ° C compromised the stability of the capsules. The encapsulation significantly improved the tolerance of microorganisms to high salt concentrations and elevation of temperature. In addition, it favored the resistance of the microorganisms to the simulated gastrointestinal fluids. The stability of the microorganisms during the storage period was also favored, after 120 days of storage at 7 and 25 ° C the concentration of viable microorganisms remained higher than 7.0 log CFU / g. In the in vivo tests for evaluation of the maintenance of the immunomodulation capacity, the cytokines (IL-2, IL-6, IL-10 and TNF-α) and secretory IgA were determined, that encapsulation did not alter the immunological response by the strains of lactobacilli studied. It was concluded that the microorganisms presented in vitro behavior in accordance with the one desired for probiotic candidates. Microencapsulation was successful, giving both strains greater resistance to adverse conditions and technological stress.

APA, Harvard, Vancouver, ISO, and other styles

31

Souza, Aline Francisca de. "Estudo da viabilidade de microrganismos probióticos encapsulados em matriz polimérica natural contendo ingredientes prebióticos e fibras alimentares." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/97/97132/tde-03122015-154309/.

Full text

Abstract:

A saúde e o bem estar estão diretamente relacionados com a alimentação saudável. O consumo de alimentos funcionais como fibras, ingredientes prebióticos e probióticos pode promover diversos benefícios para a saúde, como a melhoria do funcionamento do organismo e a prevenção de diversas doenças. Neste contexto, o presente trabalho teve como objetivo estudar o encapsulamento de Lactobacillus delbrueckii UFV H2B20 em matriz polimérica natural constituída por alginato e farinhas de banana verde, maracujá, feijão branco, maçã e laranja. Para tanto, foi realizado planejamento fatorial 24 completo visando a identificação dos parâmetros que influenciam na eficiência do encapsulamento em diferentes matrizes poliméricas e na viabilidade celular do micro-organismo probiótico estudado. As variáveis independentes estudadas foram velocidade de agitação, volume de tween 80, alginato e farinhas funcionais. Os resultados demonstraram que a técnica de emulsificação utilizada apresentou alta eficiência de encapsulamento (acima de 80 %) das células de L. delbrueckii UFV H2B20 nas diferentes matrizes poliméricas estudadas. A análise dos resultados mostrou que os principais parâmetros que afetaram a microencapsulação de L. delbrueckii UFV H2B20 foram a velocidade de agitação e a concentração de alginato. Em condições de fluido gástrico simulado (FGS), somente as microcápsulas constituídas de alginato e farinha de banana verde ou maracujá apresentaram sobrevivência média de 60,5 % e 41,0 %, respectivamente, após 30 minutos de exposição ao FGS, sendo selecionadas para os estudos posteriores. A adição de inulina à matriz polimérica contendo alginato e farinha de banana verde ou maracujá apresentou eficiência de encapsulamento acima de 80 %, porém não conferiu proteção às células quando expostas a condições de FGS. Verificou-se também que após 28 dias de armazenamento, a 4°C ou em sorvete a -18°C, a sobrevivência das células de L. delbrueckii UFV H2B20 microencapsuladas em matriz contendo farinha de banana verde ou maracujá foi superior a 90 %. A adição de sacarose ou leite desnatado reconstituído na referida matriz não interferiu significativamente na proteção das células microencapsuladas quando armazenadas a 4° C ou em sorvete a -18°C. Estes resultados revelaram que as farinhas de banana verde e maracujá, quando associadas ao alginato de sódio, são promissoras para a microencapsulação de bactérias probióticas, nas condições do presente trabalho.
Health and wellness are directly related to the consumption of healthy foods containing functional ingredients such as fibers, pre- and probiotics, which promote many health benefits, regarding body functions and prevention of several diseases. Therefore, this work aimed to study the encapsulation of Lactobacillus delbrueckii UFV H2B20, by emulsification technique, in natural polymeric matrices composed of alginate and flours of pulp of unripe banana, passion fruit husk, integral white beans, bagasse of apple and orange. The experiments were undertaken based on a 24 factorial design in order to identify the parameters that affect the encapsulation efficiency in different polymer matrices and microorganisms viability, as well. It was studied the effect of stirring speed, and concentrations of Tween 80, sodium alginate and the mentioned functional flours. The results showed that the emulsification technique showed high encapsulation efficiency (> 80%) of the Lactobacillus cells in the different polymer matrices evaluated. In addition, the main parameters that affected microencapsulation of L. delbrueckii UFV H2B20 included stirring speed and alginate concentration. Regarding the \"simulated gastric fluid\" (SGF) assays, microcapsules made of alginate, and flours of pulp of unripe banana or husk of passion fruit showed cell survival average than 60,5 % and 41,0 %, respectively, after 30 minutes of exposure to SGF, being selected for further studies. Although the addition of inulin to the polymeric matrix containing alginate and flour of unripe banana pulp or husk of passionfruit presented encapsulation efficiency higher than 80%, they did not show any protection effect to the cells when exposed to SGF. It was also showed, after 28 days of storage at 4 °C or in ice cream at -18 °C, that the cell survival of L. delbrueckii UFV H2B20 microencapsulated in matrices containing flours of unripe banana pulp or husk of passion fruit was higher than 90%. The addition of sucrose or reconstituted skim milk in these matrixes, as thermoprotector, did not interfere significantly in the protection of microencapsulated cells when stored at 4 °C or -18 °C. These results revealed that flours made of unripe banana pulp and husk of passion fruit, when combined with sodium alginate, represent a promising alternative for microencapsulation of probiotic bacteria under the conditions evaluated in this work.

APA, Harvard, Vancouver, ISO, and other styles

32

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.

Full text

Abstract:

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-organismes
The 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

APA, Harvard, Vancouver, ISO, and other styles

33

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

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.

Full text

Abstract:

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 prometteur
The 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

APA, Harvard, Vancouver, ISO, and other styles

36

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.

Full text

Abstract:

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

APA, Harvard, Vancouver, ISO, and other styles

37

Fangous, Marie-Sarah. "Nouvelle thérapeutique anti-Pseudomonas aeruginosa dans la mucoviscidose : les Lactobacillus spp. Lactobacilli intra-tracheal administration protects from Pseudomonas aeruginosa pulmonary infection in mice – a proof of concept, in Beneficial Microbes 10 (8), December 2019 Prevalence and dynamics of Lactobacillus sp. in the lower respiratory tract of patients with cystic fibrosis, in Research in Microbiology 169 (4-5), May-June 2018." Thesis, Brest, 2019. http://www.theses.fr/2019BRES0056.

Full text

Abstract:

L’augmentation préoccupante de la résistance aux antibiotiques de Pseudomonas aeruginosa (PA) nécessite la recherche de thérapies alternatives telles que les Lactobacillus. Dans cette thèse, différents travaux ont été réalisés :1) Sur un modèle murin de pneumonie aigüe à PA, nous avons démontré l’effet bénéfique de l’administration intratrachéale d’un mélange de 3 souches de Lactobacillus provenant de lait ou de la cavité orale de patients sains.2) Nous avons ensuite prospectivement étudié la population en Lactobacillus des expectorations de patients atteints de mucoviscidose (CF). La prévalence moyenne de portage était de 61%.3) Parmi ces Lactobacillus issus de l’écosystème respiratoire des patients CF, nous avons constitué deux mélanges de 3 souches de Lactobacillus, sélectionnées pour leur activité anti-élastolytique et antipyocyanine in vitro. L’administration intranasale de ces mélanges à des souris C57Bl/6, 18h avant leur infection par PAO1, améliore significativement la survie à 7 jours des souris, ainsi que la clairance pulmonaire en PAO1 à 24h post-infection. Une diminution significative du recrutement pulmonaire des neutrophiles et des cytokines proinflammatoires était observée, associée à une augmentation de celle en IL-10.Ainsi, cette thèse démontre les effets bénéfiques de l’administration prophylactique des Lactobacillus par voie respiratoire sur la pneumonie aigue à PA. Ce résultat serait lié à l’immunomodulation de ces bactéries.Enfin, les propriétés contre l’élastase et la pyocyanine de ces souches in vitro ne présagent pas de leur activité in vivo, avec le mélange L. paracasei 9N, L. brevis 24C et L. salivarius 20C présentant seulement in vivo la meilleure activité (Brevet BIO17555)
The alarming increase in antibiotic resistance of Pseudomonas aeruginosa (PA) requires studying alternative therapies, such as Lactobacillus. In this thesis, several studies were carried out:1) In a murine model of acute PA pneumonia, we have demonstrated the beneficial effect of intratracheal administration of a mixture of three Lactobacillus strains from milk or the oral cavity of healthy patients.2) We then prospectively studied the Lactobacillus population in sputum of patients with cystic fibrosis (CF). The average prevalence of carry was 61%.3) Lactobacillus from the respiratory ecosystem of CF patients were used to establish two mixtures of 3 Lactobacillus strains. Strains were selected for their antielastolytic and anti-pyocyanin effects in vitro.Intranasal administration of these mixtures to C57Bl / 6 mice, 18h prior to PAO1 infection significantly improves 7-day survival and pulmonary clearance of PAO1 24h postinfection.A significant decrease in lung neutrophil recruitment and pro-inflammatory cytokines was observed, while the production of IL-10 increased.This thesis demonstrates the beneficial effects of prophylactic respiratory administration of Lactobacillus on acute PA pneumonia. Anti-PA properties in vitro are not an indication of the in vivo activity. The mixture containing L. paracasei 9N, L. brevis 24C, and L. salivarius 20C show the best anti-PA activity (Patent BIO17555). This result is likely related to an immunomodulating effect of these bacteria

APA, Harvard, Vancouver, ISO, and other styles

38

Xavier, Michelle da Cunha Abreu 1985. "Bioconversão de xilose em ácido lático." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266847.

Full text

Abstract:

Orientadores: Telma Teixeira Franco, Saartje Hernalsteens
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-18T17:32:59Z (GMT). No. of bitstreams: 1 Xavier_MichelledaCunhaAbreu_M.pdf: 1925082 bytes, checksum: 338a42bb30c7bb7e769283f5557ba4e4 (MD5) Previous issue date: 2011
Resumo: A produção do ácido lático vem recentemente aumentando devido à sua importância como precursor na fabricação de plásticos biodegradáveis, o polilactato (PLA). Devido à preocupação com a redução do custo da matéria-prima, o uso de materiais lignocelulósicos como fonte de carbono barata para a produção de ácido lático é bastante atraente. O bagaço de cana-de-açúcar, disponível em abundância no Brasil, representa grande potencial como matéria prima para fermentação, por ser fonte renovável de carbono para obtenção de blocos construtores de interesse industrial, tais como o ácido lático (AL). O Neste contexto, o presente trabalho foi delineado para estudar a produção de ácido lático a partir da xilose, principal constituinte da fração hemicelulósica presente no bagaço de cana-de-açúcar. Nosso estudo explorou o uso de duas preparações distintas de biomassa antes de seu uso no processo fermentativo: a água de lavagem de bagaço de cana (MRS) e do hidrolisado do bagaço de cana (MRSHBC). Para a bioconversão de interesse, foram selecionadas 9 cepas de Lactobacillus capazes de assimilar xilose, identificadas através de um teste screening para acidificação em placas de Agar sólido e ensaios de fermentação em incubador rotativo. O Lactobacillus pentosus ATCC 8041 foi a cepa que apresentou maior produtividade, sendo selecionado para estudos posteriores. As fermentações dos meios MRSxilose e MRS na ausência de xilose mostraram que o microrganismo produz ácido acético a partir dos componentes presentes no meio (tais como, peptona A, extrato de levedura e peptona de soja). Os resultados da fermentação em batelada em meio MRSALB indicaram que o Lactobacillus pentosus ATCC 8041 fermentou eficientemente pentoses (xilose e arabinose) também na presença de glicose, atingindo 2,37 g/L de ácido lático e 0,99 g/L de ácido acético, que representa um rendimento (YP/S) de 0,65 g/g e (YP/S) de 0,27 g/g, respectivamente. O B. coagulans 162 apresentou melhor rendimento de ácido lático (YP/S = 0,85 g/g) e produtividade (QP = 0,35 g/[L.h]) em relação ao L. pentosus ATCC 8041 quando o meio MRSALB foi utilizado como meio de fermentação. Resultados da fermentação em batelada em meio MRSHBC revelaram que a glicose foi o primeiro açúcar a ser esgotado, seguido de xilose. Nestas condições de fermentação, o L. pentosus ATCC 8041 produziu 28,99 g/L de ácido lático (YP/S = 0,78 g/g), enquanto que o ácido acético alcançou uma concentração final de 8,19 g/L (YP/S = 0,21 g/g). O D(-)-ácido lático foi a forma isomérica produzida, representando de 53 a 66% do ácido lático total sintetizado pelo L. pentosus ATCC 8041. A maior assimilação de xilose foi observada quando a peptona A foi substituída por uréia na fermentação do meio MRSxilose pelo L. pentosus ATCC 8041. Assim, a fração hemicelulósica do bagaço de cana-de-açúcar, mais difícil de ser metabolizada que a fração celulósica pode ser considerada matéria-prima promissora para processos de bioconversão, como a produção de ácido lático, representando uma fonte de menor custo, renovável e rica em açúcares fermentescíveis
Abstract: The demands for lactic acid production are increasing in the last few years due to its use as precursor for the synthesis of biodegradable plastics, also known as polylactic acid (PLA) bioplastics. In order to reduce the production costs, which are mainly dependent on the raw material employed for PLA synthesis, the use of lignocellulosic biomass as carbon source is a promising alternative, since it constitutes a large scale byproduct in several industrial sectors. Among the available biomass substrates, the sugarcane bagasse represents an attractive candidate to feed PLA demands, since it constitute a cheap and abundant raw material in Brazil. In this context, the present work was delineated to study the lactic acid production from xylose, the main constituent of the hemicellulose fraction present in sugarcane bagasse. Our study explored the use of two distinct preparations of the biomass prior its use in the fermentative process: the bagasse wash water (MRSALB) and the bagasse hydrolyzate (MRSHBC). For the bioconversion of interest, we selected 9 Lactobacillus strains ferment xylose were indentified for the acid production by screening tests for acidification on solid agar plates and fermentation assays in rotary incubator. Lactobacillus pentosus ATCC 8041 was the strain displaying the highest productivity, being selected for further studies. Fermentations using synthetic media (MRS) in the presence or absence of xylose revealed that Lactobacillus pentosus ATCC 8041 produces acetic acid from other carbon sources present in the media, such as peptone A, yeast extract and soy peptone. Results from batch fermentation in MRSALB media indicated that Lactobacillus pentosus ATCC 8041 fermented efficiently pentoses (xylose and arabinose) in the presence of glucose, reaching 2.37 gl-1 of lactic acid and 0.99 gl-1 of acetic acid, which represents a yield (YP/S) of 0.65 g/g and 0.27 g/g, respectively. This productivity was slightly minor than the observed for other lactic acid-producing strain, Bacillus coagulans 162, in similar fermentation conditions (YP/S = 0.85 g/g). Results from batch fermentation in MRSHBC media revealed that glucose was the first sugar to be depleted, followed by xylose. In this fermentation conditions, Lactobacillus pentosus ATCC 8041 produced 28.99 gl-1 of lactic acid, (YP/S = 0.78 g/g), whereas the acetic acid reached a final concentration of 8.19 gl-1 (YP/S= 0.22 g/g). D(-)- lactic acid was produced isomeric form, representing 53-66% of total lactic acid synthesized by Lactobacillus pentosus ATCC 8041, which is important since it presents the ideal characteristics for PLA production. The highest xylose assimilation was observed when the peptone A was replaced by urea. In summary, our study confirm that, despite the hemicellulose fraction of sugarcane bagasse be more difficult to be assimilated than the cellulosic fraction, it can be considered an adequate raw material for the production of polylactic acid bioplastics, representing a low cost, renewable and abundant source of fermentable sugars. The strain Lactobacillus pentosus ATCC 8041 displayed a good fermentative performance, being considered a very attractive candidate for the biosynthesis of lactic acid from sugarcane bagasse
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química

APA, Harvard, Vancouver, ISO, and other styles

39

Menezes, Francisca Nayara Dantas Duarte. "Avaliação in vitro do potencial prebiótico do subproduto do do processamento do pedúnculo do caju(Anacardium occidentale L.) frente à Lactobacillus spp." Universidade Federal da Paraíba, 2016. http://tede.biblioteca.ufpb.br:8080/handle/tede/8800.

Full text

Abstract:

Submitted by Maike Costa (maiksebas@gmail.com) on 2017-01-30T12:24:19Z No. of bitstreams: 1 arquivo total.pdf: 605461 bytes, checksum: e147ffe79147860c37a2b571b23b9cbc (MD5)
Made available in DSpace on 2017-01-30T12:24:20Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 605461 bytes, checksum: e147ffe79147860c37a2b571b23b9cbc (MD5) Previous issue date: 2016-03-29
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
The cashew (Anacardium occidentale L.) is a tropical, popular and well accepted fruit, due its nutritional characteristics and sensory attributes. The processing of the cashew pseudo-fruit (also called peduncle) generates the main byproduct which represent up to 20% of the total weight of the pseudo-fruit. In the last years, studies verifying the prebiotic potential of the byproducts from the processing of the cashew peduncle are scarce or nonexistent. In this context, the present study aimed to evaluate in vitro the prebiotic effects of a lyophilized powder obtained from the byproduct of the cashew peduncle (named CAP) against different probiotic strains of Lactobacillus, such as: L. acidophillus LA-05, L. casei L-26 and L. paracasei L-10. The growth and viable cell numbers of the Lactobacillus strains were monitored in Mann, Rogosa and Sharpe (MRS) broth containing CAP (20 g/L), glucose (20 g/L) and fructooligosaccharides – FOS (20 g/L), during 48 h. Some parameters related to the metabolic activity of the probiotic strains, cultivated in these different culture media, were evaluated, such as pH, production of organic acids and consumption of sugars. Similar viable cell count for each tested Lactobacillus strain in the different culture media were observed, count reached 8.5 - 9.0 log CFU/mL and pH values at approximately 4.0 after 48 h of cultivation. The growth of these Lactobacillus strains in MRS broth containing glucose, FOS or CAP resulted in a decrease of pH, production of organic acids (acetic, citric, malic, formic and lactic) and consumption of sugars (glucose, fructose and maltose) during the incubation time, indicating an intense bacterial metabolic activity. Overall, the tested Lactobacillus strains showed similar capability to ferment the FOS and the CAP, although some differences related to the production of organic acids and consumption of sugars were detected. The results showed that the CAP possesses a prebiotic potential effect toward Lactobacillus strains. These findings may stimulate the agro-industrial sector to valorize the byproducts from the cashew pseudo-fruit processing as an added-value ingredient to the food industry.
O caju (Anacardium occidentale L.) é uma fruta tropical, amplamente difundida e valorizada, tanto por suas características nutricionais quanto pelos seus atributos sensoriais. O principal subproduto gerado do caju decorre do processamento do seu pedúnculo (pseudofruto), representando até 20% do peso total do pseudofruto. Com base nesse contexto, esse estudo teve por objetivo avaliar in vitro os efeitos prebióticos de um pó liofilizado obtido a partir do subproduto do pedúnculo do caju (denominado CAP) frente a diferentes cepas probióticas de Lactobacillus, a citar: L. acidophillus LA-05, L. casei L-26 e L. paracasei L-10. O crescimento e o número de células viáveis das cepas de Lactobacillus foram monitorados em caldo de Mann, Rogosa e Sharpe (MRS), contendo o CAP (20 g/L), glicose (20 g/L) e frutooligossacarídeos - FOS (20 g/L), durante um período de 48 h. Também foram avaliados alguns parâmetros relacionados à atividade metabólica das cepas probióticas ensaiadas quando cultivadas nos diferentes meios de cultura, como os valores de pH, produção de ácidos orgânicos e o consumo de açúcares. Para cada cepa de Lactobacillus ensaiada, foram observadas contagem similares de células viáveis nos diferentes meios de cultivo, sendo alcançadas contagens entre 8.5 – 9.0 log UFC/mL e valores de pH em torno de 4.0, ao final do cultivo de 48 h. O cultivo de todas as cepas de lactobacilos em MRS contendo glicose, FOS ou CAP resultou em decréscimos de pH, produção de ácidos orgânicos (acético, cítrico, málico, fórmico e lático) e consumo de açúcares (glicose, frutose e maltose) ao longo do tempo de incubação avaliado, indicando intensa atividade metabólica bacteriana. Em geral, todas as cepas de lactobacilos testadas apresentaram capacidade semelhante para fermentar FOS e CAP, embora algumas diferenças quantitativas relacionadas com a produção de ácidos orgânicos e consumo de açúcares tenham sido detectadas. Os resultados deste estudo mostraram que o CAP possui potencial prebiótico frente a cepas de Lactobacillus. Estes resultados podem estimular o setor agro-industrial para valorizar os subprodutos do processamento do pendúnculo do caju como um ingrediente com valor agregado para a indústria de alimentos.

APA, Harvard, Vancouver, ISO, and other styles

40

Barinov, Aleksandr. "An in silico approach to the identification of proteins involved in bacteria-host interactions : a case-study of lactobacillus delbrueckii ssp. bulgaricus and related lactobacilli." Paris 11, 2009. http://www.theses.fr/2009PA112055.

Full text

Abstract:

Les interactions bactéries-hôte constituent un domaine de recherche en pleine expansion. Pendant longtemps, les efforts se sont portés sur les interactions bactéries pathogènes-hôte mais depuis peu, il y a un intérêt grandissant pour le rôle bénéfique joué par les bactéries non-pathogènes dans le tractus digestif. Des études de plus en plus nombreuses décrivent le rôle des bactéries commensales sur la balance énergétique de l’hôte, les réponses immunitaires et l’homéostasie intestinale selon des mécanismes non encore élucidés. Les objectifs de ces travaux de thèse étaient de mieux comprendre ces interactions bactéries commensales avec l’hôte en se basant sur des analyses in silico des donnée issues de programmes de séquençage. Nous avons démontré comment ce type d’analyse pouvait s’appliquer à la détermination des mécanismes moléculaires impliqués dans les interactions microbiote-hôte. Les principaux résultats de ces travaux peuvent être classés en trois parties. La première concerne le développement et la validation de SurfG+, un nouvel outil d’analyse de séquences de protéines pour prédire les protéines potentiellement exposées à la surface de bactéries à Gram positif. La deuxième partie de résultats décrit l’application de l’outil SurfG+ aux protéomes de lactobacilles dont les génomes sont séquencés. Nous avons ainsi mis en évidence des différences significatives au niveau de leurs protéines de surface notamment en terme de nombre de protéines sécrétées et ancrées à la paroi. Enfin, dans la troisième partie, nous avons montré comment ces outils d’analyse in silico peuvent être exploités dans l’analyse fonctionnelle des protéines. Dans cette partie, nous étudions les effets immuno-modulateurs potentiels de protéines de surface de Lactobacillus delbrueckii subsp. Bulgaricus ATCC 11842
Bacteria-host cell interactions is an area of growing interest. While pathogenic bacteria and their interaction with the human host traditionally received much attention, there is a growing interest for the beneficial role that non-pathogenic bacteria play at these interfaces and in the GI tract in particular. Growing number of studies indicate that intestinal bacteria influence host energy balance, immune responses and contribute to gut homeostasis, however the mechanisms underlying this dialogue still remains largely unexplored. The work presented in this thesis aims to review the present knowledge on bacteria-host interactions in the GI tract, and to demonstrate the importance of in silico analyses that are widely used in the modern era of genome sequencing to broaden our knowledge. It also shows how this information can be applied for functional studies aiming to decipher molecular mechanisms involved in bacteria-host interactions. The main results presented in this thesis can be divided into three parts. The first part deals with the development and validation of a new protein sequence analysis method to predict potentially surface exposed (PSE) proteins from Gram-positive bacteria. The second part describes the application of the newly developed prediction method to the proteomes of sequenced lactobacilli revealing important differences in their predicted surface protein content. Finally, in the third part we demonstrated how the application of the in silico tools may be applied for functional protein studies. In this part, we focus on the potential immune modulation effects of surface exposed proteins from Lactobacillus delbrueckii subsp. Bulgaricus ATCC 11842

APA, Harvard, Vancouver, ISO, and other styles

41

Angelakis, Emmanouil. "Evaluation des effets des lactobacillus sur la prise de poids, la flore intestinale et le métabolisme." Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX20660.

Full text

Abstract:

De nos jours, l’obésité est un problème majeur de santé publique dont la prévalence mondiale ne cesse d’augmenter. Ainsi selon la National Health and Nutrition Examination Surveys (NHANES), le pourcentage d’adultes obèses aux Etats-Unis a presque doublé entre 1976-1980 et 1999-2002. De plus, pour la première fois dans l’histoire des Etats-Unis, la longévité de l’actuelle génération d’enfants est estimée à la baisse. Cette augmentation de l’obésité résulte à la fois de prédispositions génétiques et de facteurs environnementaux tels que l’accès à la nourriture, le tissu social, le régime alimentaire ou encore le manque d’activité physique. , Aussi, de récentes études ont suggéré que la flore microbienne intestinale jouait un rôle majeur dans la conversion énergétique des nutriments et son stockage. Bien que très peu d’expériences aient été réalisées, le rôle des Lactobacillus spp. a déjà été évoqué dans la prise de poids chez l’homme. Deux importantes études, l’une menée au Danemark et l’autre au sein même de notre laboratoire, ont montré que les Lactobacillus spp. étaient présents en quantité plus importante chez les sujets obèses par rapport aux contrôles et que leur taux corrélaient à la glycémie chez des patients diabétiques de type II (obèses). L’effet des Lactobacillus spp sur la prise de poids a été beaucoup plus étudié chez les animaux. En effet, l’agriculture représente l’un des domaines majeur d’utilisation des antibiotiques comme « growth promoters », notamment l’avoparcin qui empêche le développement de nombreuses bactéries dont des Gram positives comme les Actinobacteria et les Firmicutes à l’exception toutefois des Lactobacillus spp. Les probiotiques sont aussi utilisés comme « growth promoters » et il a été montré que l’addition de 106 Lactobacillus spp. dans les régimes alimentaires d’animaux permettait de modifier leur flore microbienne intestinale et d’entrainer un gain de poids important. A partir de toutes ces constatations, nous avons émis l’hypothèse que les bactéries pouvaient jouer un rôle dans l’obésité via une modification de la composition de la flore intestinale. Il nous est également apparu essentiel d’évaluer l’effet de l’addition de concentration bactérienne importante dans l’alimentation quotidienne. L’objectif de notre étude est ainsi d’évaluer le rôle des Lactobacillus spp. en tant que facteur de croissance et d’évaluer leur impact sur la prise de poids
The prevalence of obesity is a major world health problem that is rapidly increasing. In the USA, according to the National Health and Nutrition Examination Surveys (NHANES), the percentage of obese adults nearly doubled between NHANES 1976–1980 and NHANES 1999– 2002. Moreover, because of the increase in prevalence of American childhood obesity, the current children generation is predicted to be the first in United States to see a decrease in longevity. Obesity results from a mixture of genetic background and environmental factors including food availability, social networks, diet, and physical activity. Recent evidence suggests that gut microbiota plays a major role in energy intake, conversion and storage. Although very few reports have investigated gut microbiota and its association with obesity, several evidences support a role of Lactobacillus spp. in weight gain within human. Lactobacillus spp. were found at higher levels among obese subjects in two major studies, one conducted by us and one made in Denmark. Moreover, the rate of Lactobacillus spp. was correlated with blood glucose in subjects with type II diabetes (obese). In agriculture avoparcin which is one of the most used antibiotics to cause weight gain in animals, is effective on most bacteria including Gram-positive Actinobacteria and Firmicutes, with the notable exception on some Lactobacillus spp.. In addition, probiotics are also used as growth promoters and the addition of even 106 Lactobacillus spp in the diet of farm animals results in gut microbiota changes and weight gain. As a result, we hypothesized that bacteria could play a role in the obesity pandemic notably with the ingestion of probiotics that modified the gut microbiota structure. In addition, we stressed the necessity for further investigations to assess the effects of routinely adding high amounts of bacteria in food. The objective of our study was to evaluate the putative role of Lactobacillus sp. in growth promotion

APA, Harvard, Vancouver, ISO, and other styles

42

Vera, Annabelle. "Étude de l’écosystème levain de panification : incidence de l’échelle de fermentation sur la composition physico-chimique et microbiologique des levains." Thesis, Lyon 1, 2011. http://www.theses.fr/2011LYO10123.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

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.

Full text

Abstract:

Submitted by Pedro Barros (pedro.silvabarros@ufpe.br) on 2018-07-05T19:43:18Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Thaísa Gabriela Silva de Farias.pdf: 2561092 bytes, checksum: 61dd727f2632e2027d4d11f7e6d52912 (MD5)
Made available in DSpace on 2018-07-05T19:43:18Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) DISSERTAÇÃO Thaísa Gabriela Silva de Farias.pdf: 2561092 bytes, checksum: 61dd727f2632e2027d4d11f7e6d52912 (MD5) Previous issue date: 2017-02-20
CAPES
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.

APA, Harvard, Vancouver, ISO, and other styles

45

Hochwind, Kerstin [Verfasser], and Anton [Akademischer Betreuer] Hartmann. "Untersuchungen zum Genom und dem immunologisch aktiven D-Tryptophan im probiotischen Lactobacillus casei W56 im Vergleich mit anderen probiotischen Lactobacillen / Kerstin Hochwind. Betreuer: Anton Hartmann." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1052015476/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Beaufils, Sophie. "Etude de la réponse aux stress environnementaux chez deux Lactobacilles : identification de régulateurs impliqués dans le stress oxydatif chez Lactobacillus sakei et étude de la relation entre la protéine HPr et les stress froid et acide chez Lactobacillus casei." Caen, 2005. http://www.theses.fr/2005CAEN2056.

Full text

Abstract:

Afin de mieux comprendre l'adaptation de L. Sakei et L. Casei à leur environnement de prédilection, la viande et le lait respectivement, une analyse comparative de leur génome a été entreprise. Elle a permis de cibler les régulateurs de la famille MarR chez L. Sakei. Certains de ces régulateurs seraient impliqués dans la régulation de la production de protéines de surface (LSA178, LSA1724 et LSA1607) et d'autres dans la réponse au stress oxydatif. Parmi ces derniers, la protéine LSA529 jouerait vraisemblablement un rôle dans la réponse aux peroxydes car (i) cette protéine est un homologue d'OhrR de B. Subtilis, (ii) un motif de régulation ohr conservé a été identifié dans le promoteur du gène lsa529 et (iii) l'expression du gène lsa529 est fortement induite en condition de croissance aérobie, en comparaison avec la croissance en anaérobie. L'analyse des génomes n'ayant pas permis de cibler des gènes spécifiques de la croissance de L. Casei dans l'environnement lait, une approche physiologique a été réalisée pour étudier les réponses au choc froid et stress acide chez cette bactérie. Nous avons caractérisé le gène cspA impliqué dans la résistance au stress hypothermique. Une relation entre la réponse au choc froid et la répression catabolique a été mise en évidence. En effet, la protéine CspA est dérégulée dans un mutant de RC et la croissance des mutants pstH1, pstH2, ptsH3, ccpA et hprK est affectée à basse température et les mutants pstH1 et hprK sont plus sensibles lors des cycles de congélation/décongélation. Enfin, la résistance à l'acidité étant un critère de sélection des probiotiques, nous avons également exploré la réponse au stress acide chez cette bactérie. Chez L. Casei, la résistance à l'acidité varie selon la source de carbone utilisée pour la croissance. La tolérance à l'acidité est plus grande lorsque L. Casei est cultivée avec les disaccharides lactose, tréhalose ou cellobiose. De plus, nous avons observé que la résistance à l'acidité semble être dépendante de la forme P-His-HPr.

APA, Harvard, Vancouver, ISO, and other styles

47

Carvalho, Juliane Doering Gasparin. "Caracterização da microbiota latica isolada de queijo de coalho artesanal produzido no Ceara e suas propriedades tecnologicas." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255732.

Full text

Abstract:

Orientador: Arnaldo Yoshiteru Kuaye, Laura Maria Bruno
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-08T22:18:13Z (GMT). No. of bitstreams: 1 Carvalho_JulianeDoeringGasparin_D.pdf: 1954120 bytes, checksum: 4ba23fd784559801ff2b5568f4ba02c0 (MD5) Previous issue date: 2007
Resumo: O conhecimento da microbiota lática dos queijos de Coalho produzidos de forma artesanal a partir de leite cru, e suas propriedades tecnológicas são fundamentais para preservar as características originais do produto tradicional em queijos de Coalho industrializados, elaborados com leite pasteurizado. Para alcançar este conhecimento, foi realizado um trabalho de pesquisa dividido em três etapas: I) caracterização físico-química de queijos de Coalho artesanais produzidos no Ceará e de sua microbiota lática; II) estudo do comportamento das bactérias ácido láticas (BAL) durante o processamento do queijo; III) caracterização de propriedades tecnológicas das culturas láticas isoladas a partir deles. As análises físico-químicas caracterizaram as amostras avaliadas como sendo queijo de médio conteúdo de umidade (42%), baixa acidez (0,24%), com pH de 6,30; elevada atividade de água (0,959) e teor de NaCl de 2,88%. Dentre as BAL (643) isoladas destas amostras, foram encontrados os gêneros Enterococcus (59,6%), Lactobacillus (22%), Streptococcus (12,8%), Lactococcus (1,7%) e Leuconostoc (0,6%). A identificação de gênero não foi conclusiva para 3,3% de isolados. As espécies prevalecentes foram Enterococcus faecium, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus e Lactococcus lactis subsp. lactis. O acompanhamento da evolução da microbiota lática em amostras de leite cru, massa de queijo e do produto final, coletadas em duas unidades produtoras, revelou a presença de Lactococcus no leite e sua ausência no queijo. A presença de Enterococcus aumentou das amostras de matéria-prima para o queijo, indicando a transferência e multiplicação destes microrganismos ao longo do processamento. Estes resultados evidenciaram uma seleção de microrganismos resistentes às temperaturas elevadas no processamento do queijo, durante o cozimento da massa. Quanto às propriedades tecnológicas avaliadas, 15 isolados foram considerados produtores rápidos de ácido, com predominância dos Lactococcus e Streptococcus (40% cada). Os Lactobacillus exibiram maior variabilidade e extensão proteolítica, além de maior produção de aroma. As culturas analisadas mostraram boa tolerância a 3 e 4% de sal. As cepas de Enterococcus faecium apresentaram a maior produção de bacteriocinas ativas contra Listeria spp., com potencial de emprego na produção de queijo de Coalho, como cultura protetora
Abstract: Understanding the lactic microbiota of the artisanal Coalho cheeses produced from raw milk, and its technological properties, is important to preserve the characteristics of the traditional product in the industrialized Coalho cheeses, elaborated with pasteurized milk. In order to achieve such knowledge, a research work was carried out in three stages: I) the physical-chemical characterization of the artisanal Coalho cheeses from Ceara-Brazil and its lactic microbiota, II) the study of the behaviour of the lactic acid bacteria (LAB) along the processing of cheese, III) characterization of technological properties of the lactic cultures isolated from the cheese. The physical-chemical analyses characterized the evaluated cheese samples with medium moisture content (42%), low acidity (0.24%), pH of 6.30, high water activity (0.959) and 2.88% NaCl content. Amongst the 643 LAB isolated from these samples, Enterococcus (59.6%), Lactobacillus (22%), Lactococcus (1.7%), Leuconostoc (0.6%) and Streptococcus (12.8%) genera were found. The identification was not conclusive for 3.3% of the isolates. The main species were Lactococcus latis subsp. latis, Lactobacillus paracasei subsp. paracasei, Streptococcus thermophilus and Enterococcus faecium. Following the evolution of lactic microbiota in raw milk, curd and cheese samples collected in two dairies, Lactococcus was found to be present in the milk, but absent in the cheese. The presence of Enterococcus increased from the raw material to the cheese samples, indicating the transference and multiplication of these microorganisms throughout the cheesemaking. Such results evidenced a selection of high temperature resistant microorganisms at the curd cooking stage of cheesemaking. According to the technological properties evaluated, 15 isolates were considered fast producers of acid, with predominance of the Lactococcus and Streptococcus (40% each). The Lactobacillus showed high variability and provided the widest range of proteolytic activity and production of flavour. The lactic cultures also showed good tolerance to 3 and 4 % of NaCl. Strains of Enterococcus faecium produced active bacteriocins against Listeria spp., with potential use in the production of Coalho cheese like protective culture
Doutorado
Doutor em Tecnologia de Alimentos

APA, Harvard, Vancouver, ISO, and other styles

48

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.

Full text

APA, Harvard, Vancouver, ISO, and other styles

49

Ricci, Luca. "Antibiotico resistenza di Lactobacillus sakei." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/16829/.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

50

Jebava, Ondrackova Iva. "Système autolytique de Lactobacillus helveticus." Rennes, Agrocampus Ouest, 2011. http://www.theses.fr/2011NSARI060.

Full text

Abstract:

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 vitro
Autolysis 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

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Lactobacillu'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles