Saccharomyces is a genus of budding yeast. Yeasts are also part of the residual microbial system of the intestinal microbiota. Saccharomyces cerevisiae is widespread in nature and can be found in plants, fruit and soil. S. cerevisiae is included in foods and beverages for its key role in fermentation processes and in health foods. Strain known as S. boulardii was isolated from the skin of lychees grown in Indochina. This species does not have a taxonomic status and it is considered a biotype of S. cerevisiae ( van der Aa Kühle and Jespersen, 2003). S. boulardii is used as probiotic especially in ruminants and pig feeding.