Screening the probiotic potential of food-bourne yeast strains.
Nicolas Pagé, Dominique de Maleprade, Sophie Meier, Olivia Morandi, Fanny Scalfo, Josette Sidoti, Christof Gysler
Food Science, Nestlé Research Centre, Vers-chez-les-blanc, Lausanne 26, CH-1000, Switzerland
A large variety of fermented foods and drinks exist, that contain living yeasts which have either alone, or in combination with other microorganisms, contributed to the fermentation process. The wide majority of these foodstuffs are of artisanal origin and their industrial production with defined starter cultures is the exception. Moreover, the microbial composition of one and the same product, may qualitatively, as well as quantitavely vary depending on the geographic and historic origin. In the present study we analysed some 50 yeast strains from a variety of food fermentation processes upon their potential probiotic characteristics. These include namely, the ability to survive acidic conditions and the resistance to bile acids during transition through the human or animal gastrointestinal tract. Not unexpectedly we found that most of the tested yeast strains were rather tolerant towards the harsh conditions encountered during passage through stomach and jejunum and might in fact fulfill the pre-requisite of a probiotic sensu stricto. In a second assay we investigated the evocation of immune responses within human peripheral blood mononuclear cells (PBMC) upon contact with selected yeast strains. Rather distinct patterns could be observed for the different isolates varying not only between species but as well between representatives of the same species.