Survival and Goat Milk Acidifying Activity of Lactobacillus rhamnosus GG Encapsulated with Agave Fructans in a Buttermilk Protein Matrix.

Lactobacillus rhamnosus GG (L. rhamnosus GG) cells were encapsulated in buttermilk proteins by spray drying, alone (E), or with Agave tequilana fructans (CEF). Buttermilk proteins acted as a thermo-protector for the probiotic cells undergoing the spray-dried process. The addition of Agave fructans in CEF microcapsules significantly enhanced storage stability and survival to in vitro simulated gastrointestinal conditions, compared to E capsules. After 14 days storage at - 20 °C, the number of living cells in CEF microcapsules was in the order of 7.7 log CFU • mL-1 and the survivability in simulated gastrointestinal environment was 73.23%. Spray-dried microparticles were cultured in goat milk to study biomass production. Agave fructans offered a favorable microenvironment and better growth substrate. The population of CEF viable cells reached 1.08 ± 0.02 × 1010 CFU • mL-1 after 18 h of fermentation. In contrast, the population of E viable cells were 3.0 ± 0.01 × 109 CFU • mL-1. The generation time of CEF, L. rhamnosus GG was 15% faster than E, L. rhamnosus GG. Encapsulation with buttermilk proteins in the presence of Agave fructans by spray drying could be suitable for preservation of probiotic powders and may be for a more effective application of probiotics in goat dairy products.

Maillard neoglycans as inhibitors for in vitro adhesion of F4+ enterotoxigenic Escherichia coli to piglet intestinal cells.

Adhesion of enterotoxigenic (ETEC) E. coli to host intestinal cells is mediated by lectin-like fimbriae that bind to specific glycan moieties on the surfaces of enterocytes. To prevent in vitro binding of E. coli F4 fimbriae (F4 ETEC+) to piglet enterocytes, neoglycans were synthesized by the Maillard reaction conjugating lactose (Lac), galacto-oligosaccharides (GOS) or chitin oligosaccharides (Ochit) to porcine serum albumin (PSA). Neoglycans were characterized by SDS-PAGE, intrinsic tryptophan fluorescence and recognition by plant lectins, as well as by F4 ETEC variants. Electrophoretic patterns suggested the binding to PSA of 63, 13 and 2 molecules of Lac, GOS and Ochit, respectively. All neoglycans displayed quenching of tryptophan fluorescence consistent with the degree of glycation estimated by SDS-PAGE. Plant lectins recognized the neoglycans according to their specificity, whereas antigenic variants of F4 ETEC (ab, ac and ad) recognized PSA-Ochit and PSA-Lac with higher affinity than that for GOS. Neoglycans partially hindered the in vitro binding of F4+ ETEC to piglet enterocytes in a dose-dependent manner. The most effective blocking was observed with PSA-Lac that partially inhibited the adhesion of bacteria to enterocytes in a dose dependent manner, as quantified by flow cytometry. Increased production of the cytokines IL-6 and TNF-α was observed in response to F4+ ETEC infection of enterocytes and production was reduced in the presence of PSA-Ochit and PSA-GOS. These results suggest that neoglycans synthesized by the Maillard reaction could be useful in the prophylaxis of diarrhea in piglets.

Novel Synthesis of Core-Shell Silica Nanoparticles for the Capture of Low Molecular Weight Proteins and Peptides.

Silica nanoparticles were functionalized with immobilized molecular bait, Cibacron Blue, and a porous polymeric bis-acrylamide shell. These nanoparticles represent a new alternative to capture low molecular weight (LMW) proteins/peptides, that might be potential biomarkers. Functionalized core-shell silica nanoparticles (FCSNP) presented a size distribution of 243.9 ± 11.6 nm and an estimated surface charge of -38.1 ± 0.9 mV. The successful attachment of compounds at every stage of synthesis was evidenced by ATR-FTIR. The capture of model peptides was determined by mass spectrometry, indicating that only the peptide with a long sequence of hydrophobic amino acids (alpha zein 34-mer) interacted with the molecular bait. FCSNP excluded the high molecular weight protein (HMW), BSA, and captured LMW proteins (myoglobin and aprotinin), as evidenced by SDS-PAGE. Functionalization of nanoparticles with Cibacron Blue was crucial to capture these molecules. FCSNP were stable after twelve months of storage and maintained a capacity of 3.1-3.4 µg/mg.

K88 Fimbrial Adhesin Targeting of Microspheres Containing Gentamicin Made with Albumin Glycated with Lactose.

The formulation and characterization of gentamicin-loaded microspheres as a delivery system targeting enterotoxigenic Escherichia coli K88 (E. coli K88) was investigated. Glycated albumin with lactose (BSA-glucose-ß (4-1) galactose) was used as the microsphere matrix (MS-Lac) and gentamicin included as the transported antibiotic. The proposed target strategy was that exposed galactoses of MS-Lac could be specifically recognized by E. coli K88 adhesins, and the delivery of gentamicin would inhibit bacterial growth. Lactosylated microspheres (MS-Lac1, MS-Lac2 and MS-Lac3) were obtained using a water-in-oil emulsion, containing gentamicin, followed by crosslinking with different concentrations of glutaraldehyde. Electron microscopy displayed spherical particles with a mean size of 10-17 µm. In vitro release of gentamicin from MS-Lac was best fitted to a first order model, and the antibacterial activity of encapsulated and free gentamicin was comparable. MS-Lac treatments were recognized by plant galactose-specific lectins from Ricinus communis and Sophora japonica and by E. coli K88 adhesins. Results indicate MS-Lac1, produced with 4.2 mg/mL of crosslinker, as the best treatment and that lactosylated microsphere are promising platforms to obtain an active, targeted system against E. coli K88 infections.

[Role of prebiotic oligosaccharides in prevention of gastrointestinal infections: a review]. / Revisión del papel de los oligosacáridos prebióticos en la prevención de infecciones gastrointestinales.

Gastrointestinal disorders are still a main world public health problem. Scientific progress shows that and inadequate balance in intestinal microbiota (IM) plays a crucial role in its pathogenesis. Evidence indicates that one way to modulate the IM is through the use of prebiotics. These oligosaccharides stimulate the growth of benefic bacteria and increase the resistance to invading pathogens. Research using animals show that the consumption of prebiotics could be implicated in prevention and treatment of diarrhea. Studies in healthy infants also indicate that the consumption of prebiotic mixtures (galactooligosaccharides/fructooligosaccharides, inulin/galactooligosaccharides) decreases the incidence of fever, infections and pathogens. These results represent a great potential for functional foods that contain prebiotics, mainly the infant formulas. However, results of other clinical studies for prebiotics effects on diarrhea are not conclusive. Specially those studies that include patients with an altered IM (like the elderly), patients with chronic intestinal inflammation and with diarrhea associated to antibiotic treatments. There is a need for more biochemical and microbiological studies in humans at different ages and intestinal health conditions, in order to determine when prebiotics may effectively function on infections.