by Simone Maccaferri
Considering the increase in the consumption of yeasts as human probiotics, the aim of this study was to broadly... more
Considering the increase in the consumption of yeasts as human probiotics, the aim of this study was to broadly investigate the beneficial properties of the lactic yeast K. marxianus fragilis B0399. Several potential probiotic traits of K. marxianus fragilis B0399 were investigated using in vitro assays, including adhesion and immune modulation, as well as the effect of the administration of 10(7) CFU/day of K. marxianus fragilis B0399 on composition and metabolic activity of the human intestinal microbiota in a 3-stage continuous culture system simulating the human colon.We demonstrated that this strain was highly adhesive to the human enterocyte-like Caco-2 cells and modulated the immune response, inducing pro-inflammatory cytokines in peripheral blood mononuclear cells (PBMCs). In presence of inflammatory stimulation with LPS, K. marxianus fragilis B0399 provoked a decrease in the production of pro-inflammatory cytokines in PBMCs and Caco-2 cells, thus ameliorating the inflammatory response.Furthermore, K. marxianus fragilis B0399 impacted on the colonic microbiota, increasing the bifidobacterial concentration in the stages of the colonic model system simulating the proximal and transverse colon. Short chain fatty acids acetate and propionate also increased following the yeast supplementation. Finally, K. marxianus fragilis B0399 was found to induce a decrease of the cytotoxic potential of the cultural supernatant from the first stage of the colonic model system.The effects of K. marxianus fragilis B0399 on adhesion, immune function and colonic microbiota demonstrate that this strain possesses a number of beneficial and strain-specific properties desirable in a microorganism considered for application as a probiotics.
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