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

Screening of strains of lactococci isolated from Egyptian dairy products for their proteolytic activity

International audienceA collection of cocci isolates (293) obtained from traditional Egyptian dairy products collected from four Egyptian regions yielded 151 Lactic Acid Bacteria (LAB) cocci isolates. Among them, 24 isolates were characterized as highly proteolytic. SDS-PAGE showed that 6 isolates were the most proteolytically active, which were classified into Enterococcus faecalis HH22 (4 isolates) and Enterococcus faecium DO623 (2 isolates). The proteolytic activity of Ent. faecalis was higher than that of Ent. faecium (particularly on [beta]-casein). The maximal degradation of milk proteins was achieved at pH 6.5-7.2 (Ent. faecalis) or pH 6.5 (Ent. faecium) and at 42 °C for both strains. The proteolytic activities of the two strains were inhibited mostly by the presence of EDTA, showing that their proteases belong mainly to metalloproteases. A slight inhibition of proteolysis by PMSF in the case of Ent. faecalis HH22 suggests a limited inclusion of serine proteases in its protease system

Bacteriocin production and safety evaluation of non-starter Enterococcus faecium IM1 and Enterococcus hirae IM1 strains isolated from homemade Egyptian dairy products

International audienceThis study presents the characterization of some strains of lactic acid bacteria (LAB) from traditional Egyptian dairy products. Isolated L(623 isolates) were studied for their antimicrobial activity against taxonomically related microorganisms. Selected Lwere identified by PCR method as Enterococcus faecium IM1 and Enterococcus hirae IM1. Partially purified enterocins showed antimicrobial activity against Lactobacillus bulgaricus 340, Lb. brevis F104 and F145, Lb. sakei, Brochothrix thermosphacta DSMZ20171(T) and DSMZ20599, Carnobacterium maltaromaticum CIP103135(T), C. piscicola S4312, E. faecalis JH2-2 and JH2-2rr04, E. faecium CTC492/t1362 and P13, Listeria grayi CLIP12518, L. innocua 1, CIP80.11(T), F and P, L. ivanovii ATCC and CIP78.42T, L. monocytogenes CIP78.35, DSM12464, EGDe, RF124, RF125, RF131, RF132, RF133, RF142, RF151 and RF152, and Vagococcus penaei CIP 109914(T) but have no effect against Bacillus subtilis 168T, Moellerella wisconsensis MIP2451, Morganella psychrotolerans MIP2488, Pseudomonas fluorescens 10, Salmonella enterica, Sal. montevideo, Sal. typhimurium and Serratia liquefaciens CIP103238(T). The inhibitory activity was not due to hydrogen peroxide for E. hirae IM1, but strain E. faecium IM1 may excrete diverse antimicrobial compounds such as hydrogen peroxide and bacteriocins. Antimicrobial activity of E. faecium IM1 was initially detected during exponential phase of growth, and the maximal level (1,300 AU/mL) was observed at 12 h and remained stable till the end of incubation time (48 h). Maximum of activity of E. hirae IM1 was observed during the logarithmic phase (6 h) and then decreased after 12 h. Bacteriocins produced by E. faecium IM1 and E. hirae IM1 were stable between pH 5 and pH 8 and stable also until 100 A degrees C/20 min. Tested strains were free from virulence determinant genes as well as hemolytic and gelatinase activities. E. faecium IM1 was sensitive to penicillin, kanamycin, vancomycin, gentamicin and tetracycline but resistant to ampicillin. Otherwise, E. hirae IM1 was sensitive to penicillin, kanamycin, vancomycin and tetracycline but resistant to ampicillin and gentamicin. The isolated cultures with antimicrobial activities may be used as safe and useful starter cultures or co-cultures

Characterization of a new isolate of Lactobacillus fermentum IFO 3956 from Egyptian Ras cheese with proteolytic activity

International audienceMore than 200 isolates were obtained from 15 Egyptian traditional dairy products (Domiatti cheese, Ras cheese and Rayeb milk) collected from local markets of Alexandria, Tanta and Kafr El-Sheikh. Examination with optical microscope of these dairy samples allowed to classify 92 bacilli, 64 of which were identified as lactobacilli. The proteolytic activity of lactobacilli isolates was tested on skim milk agar. Eight isolates showing a high proteolytic activity were further tested on UHT skim milk. The strain showing the highest proteolytic activity was purified and identified as Lactobacillus fermentum IFO 3656. The specific proteolytic activity of this strain and the factors affecting it (pH, temperature and presence of inhibitors) were studied. The proteolysis targeted mainly caseins (73% of whole casein), especially beta-casein (85%). Smaller portions of whey proteins were proteolyzed (20%) essentially beta-lactoglobulin. The proteolysis process gave rise to medium-sized peptide populations. The optimum conditions for the proteolysis activity of the studied strains were pH 6.5 and 37 A degrees C. Proteolytic activities were very slightly affected by the increase of the temperature to 42 A degrees C or the pH to 8.2. The protease system of Lactobacillus fermentum IFO 3956 is most probably composed from a high amount of metalloproteases and small amount of cysteine and serine protease

Bacteriocin-producing <em>Enterococcus faecalis</em> KT2W2G isolated from mangrove forests in southern Thailand: Purification, characterization and safety evaluation

International audienceThe aim of this work was to purify and characterize the bacteriocin produced by Enterococcus faecalis KT2W2G isolated from the mangrove forest in southern Thailand, in order to evaluate its potential as a new food protective agent. The active peptide from the cell-free supernatant of Ent. faecalis KT2W2G was purified in 4 steps: (i) precipitation with 70% saturated ammonium sulfate, (ii) elution on a reversed phase cartridge (Sep-Pak C8) using different concentrations of acetonitrile, (iii) cation-exchange chromatography and (iv) final purification by reversed phase-HPLC on a C8 column. Each purification step increased the specific activity and reduced the amount of contaminating non-bacteriocin proteins. The specific activity of purified bacteriocin was 13,470.53 AU/mg of protein, which corresponded to a 48.10- fold increase. TricineeSDS-PAGE of the purified bacteriocin gave molecular weight ranging between 3.5 and 6.5 kDa. The activity of the partially purified bacteriocin was unaffected by pH (2.0e12.0) and thermostable, but was sensitive to proteolytic enzymes. This bacteriocin maintained full stability after storage at 20, 4 and 37 C for 2 months. It was stable when incubated for 1 month at 4 C in 0e30% NaCl. Inhibitory spectrum of this bacteriocin showed a wide range of activities against other LAB, foodspoilage and food-borne pathogens. Ent. faecalis KT2W2G was sensitive to kanamycin, tetracycline and vancomycin but resistant to ampicillin, gentamicin and penicillin. PCR amplification demonstrated that Ent. faecalis KT2W2G does not harbor virulence genes cylA, cylB and esp but has virulence genes ace, asa1and efaAfs. The bacteriocin and its producing strain may find application as bio-preservatives for reduction of food-spoilage and food-borne pathogens in food products

Potential use of lactic acid bacteria for reduction of allergenicity and for longer conservation of fermented foods

The interest of consumers for diverse fermented foods has increased in recent years thanks to the positive perception of their impact on consumer health considered as beneficial. Hence, there is an evident need for search of novel ways and for new food preservation agents of natural origins. In this aspect, lactic acid bacteria are very good candidates. It should be highlighted also that the onset of food allergies is rising significantly in recent years. The reduction of the immunoreactivity of food proteins could be achieved thanks to pre-prandial proteolysis occurring in fermented dairy (and other food) systems changing the allergen presentation or cleaving the allergenic protein epitopes, and produce hypoallergenic products.Fil: El-Ghaish, Shady. Institut National de la Recherche Agronomique; FranciaFil: Ahmadova, Aynur. Institut National de la Recherche Agronomique; FranciaFil: Hadji-Sfaxi, Imen. Institut National de la Recherche Agronomique; FranciaFil: El Merchefi, Kamel Eddine. Institut National de la Recherche Agronomique; Francia. Université d’Oran. Département de biologie. Laboratoire de Physiologie de la Nutrition et sécurité Alimentaire; ArgeliaFil: Bazukyan, Inga. Yerevan State University. Faculty of Biology; ArmeniaFil: Choiset, Yvan. Institut National de la Recherche Agronomique; FranciaFil: Rabesona, Hanitra. Institut National de la Recherche Agronomique; FranciaFil: Sitohy, Mahmoud. Institut National de la Recherche Agronomique; Francia. Zagazig University. Faculty of Agriculture. Biochemistry Department; EgiptoFil: Popov, Yuri G.. Yerevan State University. Faculty of Biology; ArmeniaFil: Kuliev, Akif A.. Baku State University. Biotechnical and Biochemistry Chair; AzerbaiyánFil: Mozzi, Fernanda Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Chobert, Jean-Marc. Institut National de la Recherche Agronomique; FranciaFil: Haertle, Thomas. Institut National de la Recherche Agronomique; Franci