EFFECTS OF ORALLY ADMINISTERED ENTEROCOCCUS FAECIUM ON THE IMMUNE SYSTEMIC RESPONSE AND INTESTINAL EPITHELIAL STRUCTURE IN BALB/C MICE IMMUNIZED BY BOVINE Î’-LACTOGLOBULIN

Objective: Determine the effect of Enterococcus faecium on systemic immune response and its effect on the intestinal epithelial structure in the Balb/c mice. Methods: Thirty Balb/c mice were dispatched in three lots of 10 mice each. During an initial period of 18 days, the animals from the first lot received via an oral way suspension of 0,3 mL containing 108 ufc/mL of Enterococcus faecium,for the second and the third lot received 0,3 mL of a saline solution. In a second period of time, mice from the first and second lots were immunised via parenteral way using β-Lg. Then they were sacrified on the 50th day after the end of the first period (18 days). The level of IgG anti-β-Lg was determined in the sera by the ELISA, and histologic studies were conducted on the jejunum fragments. Results: Our results show that anti β-Lactoglobulin IgG titers were significantly reduced in immunized mice that received the Enterococcus faecium (1/280th) (***p<0,001). The histological studies of the intestinal epithelium shows long intestinal villi (53,88 ± 1,38µm) with diminished intra-epithelial lymphocytes. Conclusion: The study shows that Enterococcus faecium PC4.1 may help protect the intestinal epithelium integrity by maintaining the structure of the villi and has the ability to decrease the systemic immune response to β-lactoglobulin

Phenotypic and genotypic characterization of lactic acid bacteria isolated from Azerbaijani traditional dairy products

Studied lactic acid bacteria (LAB) were isolated from two types of final ready-to-eat artisanal dairy products (cheeses-Agdas, Sheki and yogurts-Karabakh, Ganja and Baku) manufactured in Azerbaijan. The Agdas cheese belongs to the group of semi hard cheeses whilst the Sheki cheese belongs to hard cheeses. Both of cheeses were produced from cow's milk without the addition of the starter cultures. The Karabakh and Baku yogurts were produced from bovine's milk and the Ganja yogurt from buffalo's milk. Overall 378 isolates were collected from these dairy products and 296 of them were Gram-positive and catalase-negative. It was determined using biochemical tests and molecular methods that four species of LAB were mostly present in these cheeses: Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus paraplantarum and Enterococcus faecium while in yogurts, Lactobacillus delbrueckii subsp. lactis, Lactobacillus delbrueckii subsp. bulgaricus, Streptococcus thermophilus and Enterococcus faecium dominated. Five enterococci were producers of antimicrobial compounds

Milk protein tailoring to improve functional and biological properties

Proteins are involved in every aspects of life: structure, motion, catalysis, recognition and regulation. Today's highly sophisticated science of the modifications of proteins has ancient roots. The tailoring of proteins for food and medical uses precedes the beginning of what is called biochemistry. Chemical modification of proteins was pursued early in the twentieth century as an analytical procedure for side-chain amino acids. Later, methods were developed for specific inactivation of biologically active proteins and titration of their essential groups. Enzymatic modifications were mainly developed in the seventies when many more enzymes became economically available. Protein engineering has become a valuable tool for creating or improving proteins for practical use and has provided new insights into protein structure and function. The actual and potential use of milk proteins as food ingredients has been a popular topic for research over the past 40 years. With today's sophisticated analytical, biochemical and biological research tools, the presence of compounds with biological activity has been demonstrated. Improvements in separation techniques and enzyme technology have enabled efficient and economic isolation and modification of milk proteins, which has made possible their use as functional foods, dietary supplements, nutraceuticals and medical foods. In this review, some chemical and enzymatic modifications of milk proteins are described, with particular focus on their functional and biological properties

Les produits laitiers mongols, source de bactéries lactiques aux propriétés antimicrobiennes (identification, purification, caractérisation et application)

Deux souches de bactéries lactiques productrices d'agents antimicrobiens ont été isolées à partir de produits laitiers mongols. Elles montrent une forte activité antimicrobienne contre des bactéries pathogènes. Elles ont été identifiées sur la base de leurs caractéristiques morphologiques, biochimiques et moléculaires. Enterococcus durans A5-11 a été isolé à partir d'airag mongol. Un procédé de purification en 3 étapes a permis de séparer deux bactériocines de masse moléculaire respective de 5206 et 5218 Da qui sont thermostables et actives dans une large gamme de pH. Enterococcus durans A5-11 présente des propriétés antifongiques quand on la fait croître sur des tourteaux de tournesol. Une souche de Lactobacillus delbrueckii subsp. lactis T31, productrice de 5 mM/l d'H2O2 a été isolée à partir de yaourt mongol. Dans des co-cultures de L. delbrueckii subsp. lactis T31 réalisées en présence d'E. coli ou de L. innocua, une diminution du nombre de bactéries pathogènes était observée.Two lactic acid bacteria were isolated from mongolian traditional fermented dairy products. They show a strong antimicrobial activity against some food-born pathogens. They were identified on the basis of their morphological, biochemical and molecular biological characteristics. Enterococcus durans A5-11 was isolated from mongolian airag. A three-step purification procedure was developed to separate two bacteriocins with molecular mass of 5206 and 5218 Da, respectively. They are thermostable and not sensitive to acid and alkaline conditions. E. durans A5-11 shows antifungal properties during its growth on defatted sunflower meal. Lactobacillus delbrueckii subsp. lactis T31 producing 5 mM/l H2O2 was isolated from mongolian yoghurt. A significant decrease of pathogens was observed in mixed cultures of L. delbrueckii subsp. lactis T31 with either E. coli or L. innocua.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Glycation leads to polymerization and tryptic resistance of beta-lactoglobulin

International audienceThe Maillard reaction also named “non-enzymatic browning” is a chemical reaction involving reducing sugars and the amino groups of amino acids and proteins. Despite its great importance in culinary art thanks to generation of flavors this reaction may be also deleterious because of uncontrolled deterioration of foods during storage and processing. The aim of this work was to determine how the time of heating of ßlactoglobulin, at 60°C, in the presence of glucose, could influence the modification of this most important whey protein.Upon heating, glycation induced the polymerization of b-lactoglobulin via non S-S bond; molecular masses of about 18, 36 and 55 kDa could be observed in SDS-PAGE. The grafting of glucose on lysine and arginine (the most modified amino acids on the protein) led to a shift of the pHi of the modified proteins toward acidic pH (IEF) and to a resistance to tryptic attack (RP-HPLC).The Maillard reaction between b-lactoglobulin and glucose makes modified proteins resistant to trypsinolysis. Consequently, glycation may affect the nutritional properties of this whey protein. However, since the amino acids involved in ligand binding are not glycated, this implies their shielding by spatial factors and/or possible internalized ligands

Glycation leads to polymerization and tryptic resistance of beta-lactoglobulin

International audienceThe Maillard reaction also named “non-enzymatic browning” is a chemical reaction involving reducing sugars and the amino groups of amino acids and proteins. Despite its great importance in culinary art thanks to generation of flavors this reaction may be also deleterious because of uncontrolled deterioration of foods during storage and processing. The aim of this work was to determine how the time of heating of ßlactoglobulin, at 60°C, in the presence of glucose, could influence the modification of this most important whey protein.Upon heating, glycation induced the polymerization of b-lactoglobulin via non S-S bond; molecular masses of about 18, 36 and 55 kDa could be observed in SDS-PAGE. The grafting of glucose on lysine and arginine (the most modified amino acids on the protein) led to a shift of the pHi of the modified proteins toward acidic pH (IEF) and to a resistance to tryptic attack (RP-HPLC).The Maillard reaction between b-lactoglobulin and glucose makes modified proteins resistant to trypsinolysis. Consequently, glycation may affect the nutritional properties of this whey protein. However, since the amino acids involved in ligand binding are not glycated, this implies their shielding by spatial factors and/or possible internalized ligands

Étude des protéines du système laitier ovin et de leurs transformations par hydrolyse et par fermentation lors de la fabrication des yaourts

Quatre types de levains ont été utilisés pour la fabrication de yaourts à partir de laits de brebis ayant subi un pré-traitement thermique différent. Le degré d'hydrolyse des caséines et des protéines du lactosérum dépendait des ferments lactiques utilisés. Au cours de la fermentation, la caséine est davantage dégradée que les caséines S ; l' -lactalbumine (ALA) est davantage dégradée que la -lactoglobuline (BLG). L' -lactalbumine et la -lactoglobuline ont été obtenues pures par chromatographie sur résine échangeuse d'anions. La -lactoglobuline était un mélange des deux variants A et B tandis que l' -lactalbumine n'était composée que d'une seule fraction. La -lactoglobuline existe sous une forme monomérique à pH acide et à faible force ionique mais se dimérise à pH neutre. Contrairement à son homologue bovin, la -lactoglobuline ovine est sensible à l'action de la pepsine. Des hydrolysats pepsiques des protéines du lactosérum ont montré une activité antimicrobienne contre Escherichia coli, Bacillus subtilis et Staphylococcus aureus.Four set of starters have been used for the fabrication of yoghurts from ovine milk pre-heated in different conditions. The degree of hydrolysis of caseins and whey proteins depended on the starter used. During fermentation, -casein was more hydrolysed than S-caseins; -lactalbumin (ALA) was more degraded than -lactoglobulin (BLG). -lactalbumin and -lactoglobulin have been obtained in a pure form by anion-exchange chromatography. -lactoglobulin was a mixture of A and B variants. -lactalbumin was obtained as an unique variant. -lactoglobulin was monomeric at acid pH and low ionic strength but became dimeric at neutral pH. At the opposite of its bovine counterpart, ovine -lactoglobulin was susceptible to pepsinolysis. Peptic hydrolysates of whey proteins showed an antibacterial activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus.NANTES-BU Sciences (441092104) / SudocSudocFranceF

Bacteriocin-producing lactic acid bacteria isolated from mangrove forests in southern Thailand as potential bio-control agents in food: Isolation, screening and optimization

International audienceA total of 386 isolates of lactic acid bacteria isolated from mangrove forests (soil, water, leaf, twig and fruit) in southern Thailand were screened for bacteriocin production. Only 4 strains that produced bacteriocin-like inhibitory substance (BUS) in MRS broth, named KT2W2G, KT2W2L, TS9S17 and TS9S19 showed an inhibition zone against Lactobacillus sakei subsp. sakei JCM 1157, Listeria monocytogenes DMST 17303 and Brochothrix thermosphacta DSM 20171 as indicators by using agar well diffusion assay. None of the inhibitory activities were related to the production of either organic acids or hydrogen peroxide. The BLISs produced by these strains were not affected by heating but were sensitive to proteolytic enzymes. The isolate KT2W2L was identified as Lactococcus lactis subsp. lactis while the isolates KT2W2G, T59S17 and TS9S19 were identified as Enterococcus faecalis. These BLISs showed a wide range of antibacterial activity against similar bacterial strains, food-spoilage and food-borne pathogens, but were inactive against the Gram-negative bacteria tested. Statistical experimental designs, based on the Plackett-Burman protocol, were applied to optimize the bacteriocin production by Ent faecalis KT2W2G in flask cultures. By using Plackett-Burman protocol, lactose and temperature were found to be the most important factors for bacteriocin production. The effects of the two main factors on bacteriocin activity were further investigated using a central composite design (CCD) and the optimum composition was found to be lactose 14.85 g/I and temperature 25.59 degrees C. Optimum conditions were validated by experiment in which bacteriocin activity (Arbitrary Unit/ml) was increased 8-fold (640 AU/ml) in 18 h fermentation

Phosphorylation of β-lactoglobulin using amino acids as the sole base and nucleophile of the reaction

International audienceβ-Lactoglobulin was phosphorylated with 20, 40, and 80 mol of POCl3/mol protein in the presence of 4, 5, and 6 molar excess of basic amino acid per mol POCl3. Maximal phosphorylation yields of 5 and 3 mol P/mol protein were achieved when the highest stoichiometries of POCl3/arginine and lysine were used. Proportional high amounts of basic amino acids were also grafted to the protein molecule during its phosphorylation through the phosphoamide bond. Modified proteins displayed increased negative charges and reduced isoelectric points and were monomeric. The phosphorylated and phosphoamidatedβ-lactoglobulin showed improved functional properties