RESUMEN
Fruit extracts from different tissues (pulp, seed and peel) have shown antimicrobial and prebiotic activities related to their phenolic profile, although structure-specific evaluations have not been reported yet. The effect of five phenolic compounds (catechin and gallic, vanillic, ferulic and protocatechuic acids) identified in different fruits, particularly in mango, was evaluated on the growth of two probiotic (Lactobacillus rhamnosusGG ATCC 53103 and Lactobacillus acidophilusNRRLB 4495) and two pathogenic (Escherichia coli 0157:H7 ATCC 43890 and Salmonella enterica serovar Typhimurium ATCC 14028) bacteria. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of phenolic acids ranged from 15-20 mmol l-1 and 20-30 mmol l-1 against E. coli and S. Typhimurium, respectively. For catechin, the MIC and MBC were 35 mmol l-1 and >35 mmol l-1 against E. coli and S. Typhimurium, respectively. The presence of catechin and gallic, protocatechuic and vanillic acids in MRS broth without dextrose allowed the growth of lactobacilli. Catechin combined with protocatechuic or vanillic acid mildly allowed the growth of both probiotics. In conclusion, phenolic compounds can selectively inhibit the growth of pathogenic bacteria without affecting the viability of probiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides relevant information about the effects of phenolic compounds commonly present in fruit and vegetables on the growth of probiotic and pathogenic bacteria. The compounds selectively allowed the growth of probiotic lactobacilli (Lactobacillus rhamnosus GG and Lactobacillus acidophilus) and inhibited pathogenic bacteria (Escherichia coli and Salmonella Typhimurium) at the same concentration (20 mmol l-1 ). These findings can contribute to the formulation of nutraceutical products, such as synbiotics, that can restore or maintain an optimal composition of human microbiota, potentially improving the overall health of the consumer.
Asunto(s)
Antibacterianos/farmacología , Escherichia coli/efectos de los fármacos , Lactobacillus/efectos de los fármacos , Fenoles/farmacología , Probióticos/análisis , Salmonella typhimurium/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , Humanos , Hidroxibenzoatos/farmacología , Lactobacillus/crecimiento & desarrollo , Fenoles/química , Salmonella typhimurium/crecimiento & desarrolloRESUMEN
There are very few reports on the self-assembly of peptides derived from proteins of agro industrial byproducts origin. Although it has been claimed that purity is a determining factor in peptide self-assembly, whether proteins extracted using water along with other components also form self-assembled structures is not known. The results of this work prove that albumins from wheat bran, a byproduct obtained from the milling industry, can form tubular nanostructures during their hydrolysis with the V8 protease in the presence of Ca(2+). Electron microscopy of the hydrolysate revealed that under specific conditions, long filaments are formed, which are nanotubes of several microns in length, with inner and outer diameters of 100 and 200 nm, respectively. The infrared analysis of the hydrolysate identified (-)OOC-Ca(2+) interactions and changes in beta sheet content in response to variations in protein/V8/Ca(2+) molar ratios. A model that explains the probable mechanism of the observed self-assembly is discussed.
Asunto(s)
Albúminas/química , Calcio/química , Fibras de la Dieta/análisis , Nanoestructuras/química , Serina Endopeptidasas/química , Nanotubos/química , Péptidos/química , ProteolisisRESUMEN
Adherence to the gastrointestinal tract is a key element desirable for many of the proposed beneficial health effects of probiotic bacteria. The aims of this study were to determine the amounts of adhesion of 3 Lactobacillus salivarius strains (Lb6, Lb9, and Lb10) to porcine small intestinal mucins and to determine whether adhesion is a function of lectin-like activities. Dot and Western blot assays were performed to investigate bacterial adhesion. Several carbohydrates and glycoproteins were evaluated to determine whether they interfered with adhesion of the Lactobacillus strains to intestinal mucins and to determine whether they had lectin-like activities. The Lb9 and Lb10 strains had greater association with piglet mucins than did those from 22- to 24-wk-old finishing pigs (P = 0.021 and 0.037, respectively), whereas the Lb6 strain adhered to both (P = 0.138). Western blot assays showed that bacterial adhesion detected piglet mucosa from the duodenum, jejunum, and ileum. In finishing pigs, the adhesion was variable throughout the gastrointestinal tract. Galactose and mannose diminished the interaction of the Lb9 and Lb10 strains in intestinal mucosa (P = 0.028 and 0.026, respectively), whereas pig gastric mucin reduced the adhesion of the Lb6 strain (P = 0.013). Adhesion of the Lb9 and Lb10 strains to intestinal mucosa was less after protease treatment (P = 0.023 and 0.018, respectively), which indicates that proteins are needed for the Lb9 and Lb10 strains to recognize mucin. The Lb6 strain also demonstrated diminished adhesion after periodate treatment (P = 0.038). From these results, we suggest that the nature of the bacterial lectin-like substance is a surface protein that loosely binds to the bacterial cell surface. All the tested strains adhered to specific targets in the small intestinal mucosa of piglets, and the bacteria had lectin-like proteins involved in this adhesion.