Characterization of the Exopolysaccharide Produced by Salipiger mucosus A3T, a Halophilic Species Belonging to the Alphaproteobacteria, Isolated on the Spanish Mediterranean Seaboard

We have studied the exopolysaccharide produced by the type strain of Salipiger mucosus, a species of halophilic, EPS-producing (exopolysaccharide-producing) bacterium belonging to the Alphaproteobacteria. The strain, isolated on the Mediterranean seaboard, produced a polysaccharide, mainly during its exponential growth phase but also to a lesser extent during the stationary phase. Culture parameters influenced bacterial growth and EPS production. Yield was always directly related to the quantity of biomass in the culture. The polymer is a heteropolysaccharide with a molecular mass of 250 kDa and its components are glucose (19.7%, w/w), mannose (34%, w/w), galactose (32.9%, w/w) and fucose (13.4%, w/w). Fucose and fucose-rich oligosaccharides have applications in the fields of medicine and cosmetics. The chemical or enzymatic hydrolysis of fucose-rich polysaccharides offers a new efficient way to process fucose. The exopolysaccharide in question produces a solution of very low viscosity that shows pseudoplastic behavior and emulsifying activity on several hydrophobic substrates. It also has a high capacity for binding cations and incorporating considerable quantities of sulfates, this latter feature being very unusual in bacterial polysaccharides

Proteolyse des proteines plasmatiques par la thermolysine : optimisation d'un reacteur enzymatique a membrane d'ultrafiltration

CNRS T 56586 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Caractérisation d'entités moléculaires de surface impliquées dans la relation de la bactérie probiotique Lactobacillus plantarum 299v avec l'hôte (approche in vitro)

Les microorganismes probiotiques mis en œuvre dans les aliments fonctionnalisés, sont capables de produire des effets bénéfiques sur la santé du consommateur. Ces effets dépendent entre autres de la capacité d adhésion des probiotiques aux constituants de l épithélium intestinal. L adhésion, est un phénomène complexe dépendant des propriétés physico-chimiques de la surface bactérienne ainsi que de la présence d entités protéiques et/ou non protéiques possédant une affinité pour les constituants de la muqueuse intestinale de l hôte. Au travers de l étude de l hydrophobie/hydrophilie et de la charge électrique de la surface de la souche probiotique Lactobacillus plantarum 299v ainsi que de celles d autres souches adhérentes de L. plantarum, une absence de corrélation entre de telles propriétés et la capacité d adhésion des souches sur les cibles mucine et cellules épithéliales intestinales Caco-2 a été établie. La caractérisation systématique des protéines associées à la paroi de L. plantarum 299v suivie de l estimation de leur affinité pour des cibles de la surface intestinale, ont conduit à l identification de la glyceraldéhyde-3-phosphate déshydrogénase (GAPDH) en tant qu adhésine potentielle. L analyse, par cytométrie en flux, des cellules de L. plantarum 299 v marquées par des anticorps anti-GAPDH et par l iodure de propidium a permis d établir un lien entre la perte d intégrité de la membrane plasmique et la présence de cette anchorless protein associée à la paroi bactérienne. Cette observation conduit à la proposition d un mécanisme original concernant l exportation de l enzyme cytoplasmique à la surface de la bactérie. D autres polymères non protéiques de type acides lipoteichoïques associés à la paroi, ont été caractérisés et leur implication dans l interaction de L. plantarum 299v avec la mucine et les cellules épithéliales intestinales Caco-2 a été démontrée.The probiotic microorganisms implemented in functionalized foods can produce beneficial effects on consumer health. These effects depend on the adhesion ability of probiotics to the constituents of the intestinal tract. The phenomenon of bacterial adhesion is a complex process which is mediated by the physico-chemical properties of the bacterial surface and by a set of proteinaceous and non-proteinaceous molecular entities with specific binding abilities to constituents of the host intestinal mucosa. Through the study of the hydrophobic/hydrophilic character and electric charge of the probiotic strain Lactobacillus plantarum 299v and those of other adherent strains of L. plantarum, no correlation between such properties and their adhesion ability to mucin and Caco-2 epithelial cells was established. The systematic characterization of the cell wall associated proteins of L. plantarum 299v followed by the estimation of their affinities for targets of the intestinal surface, led to the identification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a potential adhesin. Flow cytometry analysis of L. plantarum 299v cells labelled with anti-GAPDH and propidium iodide unambiguously confirmed a relationship between the loss of the plasma membrane integrity and location on cell wall of GAPDH and probably of other "anchorless protein". This observation led to us the proposal of an original mechanism on the export of this cytoplasmic enzyme to the bacterial cell wall surface. Other non-proteinaceous polymers like lipoteichoic acids have been characterized and their involvement in the interaction of L. plantarum 299v to mucin and Caco-2 monolayer cells was demonstrated.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Optimisation de la production d arabinoxylooligosaccharides d intérêt biologique à partir de sons de céréales (approches méthodologiques)

Dans le cadre de la valorisation de sous-produits de l industrie céréalière, des sons de blé et de seigle ont été sélectionnés pour la production d arabinoxylooligosaccharides (AXOS) d intérêt prébiotique. Les prébiotiques sont des ingrédients alimentaires, glucidiques, non digestibles, stimulant sélectivement la croissance et/ou l activité d éléments de la flore colique parmi lesquels les bactéries probiotiques, ingérées vivantes par l ho te produisent des effets bénéfiques sur sa santé. La fraction arabinoxylane des sons, extraite par traitement alcalin après délignification puis purification, est soumise à un traitement de dépolymérisation impliquant deux étapes successives d hydrolyse, chimique (acide) puis enzymatique. L optimisation du processus, par plans d expériences, conduit à l obtention d AXOS avec un rendement de 50% pds/pds. La distribution en tailles des AXOS issus des différents sons est établie par SM/MALDI-TOF et ESI. Leurs propriétés prébiotiques ont été évaluées sur des souches bactériennes probiotiques reconnues, des genres Lactobacillus, Bifidobacterium, Clostridium et Bacillus comparativement à celles de fructooligosaccharides de référence et d AXOS issus de mais.In the context of a valorisation of agricultural by-products, wheat and rye bran have been chosen as substrates for the production of arabinoxylooligosaccharides (AXOS) with prebiotics properties. Prebiotics are non-digestible food ingredients, mainly oligosaccharides, that benefit the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon, named probiotics. Probiotics are live micro-organisms that exert health benefits beyond basic nutrition when ingested in sufficient quantities. After lignin removal and alkali treatment, the arabinoxylan fractions are converted into AXOS (50% w/w) by a two step hydrolytic treatment (chemical then enzymatic) optimized by experimental design approach. The AXOS mass distributions have been established by SM/MALDI-TOF or ESI. Their prebiotic properties have been evaluated on common probiotic bacterial strains, Lactobacillus plantarum, Bifidobacterium longum, Clostridium butyricum and Bacillus cereus, and compared to fructooligosaccharides and AXOS from maize bran.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Exported proteins in probiotic bacteria: adhesion to intestinal surfaces, host immunomodulation and molecular cross-talking with the host.

International audienceThe group of exported proteins of a bacterium are those proteins that are sorted from the cytoplasm to the bacterial surface or to the surroundings of the microorganism. In probiotic bacteria, these proteins are of special relevance because they might determine important traits such as adhesion to intestinal surfaces and molecular cross-talking with the host. Current knowledge about the presence and biological relevance of exported proteins produced by the main genera of probiotic bacteria in the gastrointestinal environment is reviewed in this minireview. As will be seen, some of these proteins are involved in host adhesion or are able to modify certain signalization pathways within host cells, whereas others are important for the physiology of probiotic bacteria in the gastrointestinal tract

Strain- and matrix-dependent adhesion of Lactobacillus plantarum is mediated by proteinaceous bacterial compounds.

International audienceAIMS: The ability of 31 Lactobacillus plantarum strains to adhere to biological matrixes was evaluated, and the molecules involved in adherence were studied. METHODS AND RESULTS: Mucin, basement membrane proteins and Caco-2 cells were used in adhesion tests. These in vitro assays, together with a yeast agglutination test, were found to be discriminative for screening Lact. plantarum strains for adhesion. Some strains, such as 299v, CBE, BMCM12, Col4S and T25, were shown to possess interesting adhesion properties in at least two models. The adhesion of these strains was strongly inhibited when the bacterial cells were pretreated with trypsin. Lithium chloride and methyl-alpha-D-mannoside also inhibited adhesion to a lower extent. CONCLUSIONS: The adhesion of Lact. plantarum depends on both the model and the strain used. The chemical and enzymatic pretreatments applied to the bacterial cells suggested that lectin-like adhesins and other proteinaceous cell-surface structures are involved in adhesion of these strains. SIGNIFICANCE AND IMPACT OF THE STUDY: We found a great diversity in the adhesion properties between Lact. plantarum strains. Based upon the adhesive property of these strains interesting candidates were identified, that will undergo further study as potential probiotics

Separation and Purification Technology

Opuntia ficus indica has been identified for its bioflocculant properties in water treatment; however, its underlying mechanism and active compounds have not been clearly identified. Flocculent molecules of cactus solid material (CSM) under alkaline conditions were extracted at pH 10 and then precipitated under neutral conditions (pH 7). The precipitate was fractionated by ultrafiltration systems and analyzed using inverted phase chromatography and enzymatic treatments. This approach revealed that quercetin and starch constitute the active agents found in the fractionated parts at ≤3,000 and ≥10,000 Da, respectively. The use of quercetin or (potato) starch alone at 18 mg/L yielded 72% ± 2% and 54% ± 3% of turbidity removal, respectively. With a combination of both these components, a higher flocculation activity (84% ± 2%) could be obtained. From these experimental results, a flocculation model based on identified active constituents is being proposed in order to improve process knowledge