Avaliação in vitro e in vivo da capacidade de ligação de bactérias patogênicas e não patogênicas em sítios específicos das leveduras Saccharomyces Boulardii e Saccharomyces Cerevisiae UFMG A-905

Abstract

Recently, most attention has been given to the modulation of the intestinal microbiota by using living microbial adjuvants called probiotics. The great advantage of therapy with probiotics is the lack of side effects, such as selection of resistant bacteria when antibiotics are used. The only yeast available in the market for probiotic use in humans is Saccharomyces boulardii. Studies by Martins et al. showed that the strain Saccharomyces cerevisiae UFMG 905 was able to colonize and survive in the gastrointestinal tract of conventional and germ-free mice, and to protect these animals against experimental infection with Salmonella Typhimurium and Clostridium difficile. The alternative adhesion of these pathogenic bacteria onto the surface of S. cerevisiae UFMG 905 instead on their intestinal receptors could explain the protective effect of the yeast. In this sense, the present study evaluates the adhesion of pathogenic bacteria on the cell wall of S. boulardii, S. cerevisiae UFMG 905, S. cerevisiae W303 and S. cerevisiae BY 4741 mating a. To understand the mechanism of adhesion of pathogens to yeast, we used cell wall mutants of the parental strain of S. cerevisiae BY 4741 mating a due to the difficulty of mutate polyploid yeast, as is the case for S. cerevisiae and S. boulardii. Tests of sedimentation, flocculation and adherence showed that among 10 enterobacteria tested, only Escherichia coli and S. Typhimurium adhered to the surface of S. boulardii, S. cerevisiae UFMG 905, and S. cerevisiae BY 4741 mating a. The presence of mannose inhibited this adhesion. Within 49 cell wall mutants of S. cerevisiae BY 4741 mating a, five of them lost the ability to fix the bacteria. Electron microscopy showed that the phenomenon of yeast-bacteria adhesion occurred both in vitro and in vivo (digestive tract of dixenic mice). These partial results show that some pathogenic bacteria were captured on the surface of S. boulardii, S. cerevisiae UFMG 905, and S. cerevisiae BY 4741 mating a, thus preventing its adhesion to specific receptors on the intestinal epithelium and its subsequent invasion of the host.