Evaluation of probiotic properties associated with the cell surface in bifidobacterium for application in poultry

Abstract

Currently, consumers seek to include in their diet minimally processed products that are organic in origin. In this context, the poultry industry has reviewed its production practices and focused on the use of strategies, such as the introduction of probiotic microorganisms, to promote animal health and welfare. Probiotics are able to competitively exclude pathogens that cause food transmitted diseases and eliminate antinutritional factors present in feed, such as lectins, but these properties are strain dependent and should be thoroughly studied to select effective probiotics. The objective of this work was to analyse the ability of 15 Bifidobacterium strains isolated from poultry to self-aggregate, co-aggregate with pathogens, and capture lectins on their surface. Most of the bifidobacteria presented autoaggregation percentages between 9.4 and 25%, and co-aggregated with 3 different serotypes of Salmonella and Escherichia coli. Some bifidobacteria co-aggregated with one or more pathogenic strains, standing out B. boum LET 413 that co-aggregated with all the pathogens evaluated, followed by B. boum LET 414 that only failed to co-aggregate with Salmonella enteritidis, and B. pseudolongum subsp. pseudolongum LET 404, which did not co-aggregate with E. coli. The rest of the strains interacted with at least one pathogen. In addition, the capture of different FITC-labelled dietary lectins was studied. All the strains captured wheat lectin (WGA) on their entire surface, but showed varied binding to the lectins PNA (peanut lectin) and PHA?P (bean lectin) in specific regions of their surface. B. thermacidophilum LET 406, B. boum LET 413, B. pseudolongum subsp. globosum LET 403, and B. pseudolongum subsp. pseudolongum LET 405 and LET 412, bound PNA only in specific regions. B. boum LET 414 was the only strain that could capture PNA in its entire surface. Because capsular polysaccharides were not detected for these strains, their affinity to certain lectins was directly linked to glycoproteins or glycolipids bound to the cell wall. Based on the results, we can conclude that the studied strains showed good aggregation and interaction with Salmonella and E. coli, which could contribute to the elimination of pathogenic bacteria during digestion. The study of capture of antinutritional factors such as lectins, on the bacterial surface, makes it possible to estimate the ability to capture soy lectin (SBA), this cytotoxic phytoagglutinin, present in poultry feed, through binding to lectins of similar affinity, such as PNA and PHA-P.