AIMS: The yeast Saccharomyces boulardii is used as a probiotic for the prevention and treatment of diarrhoea. In this study, the quality of 15 probiotic products containing S. boulardii was verified. METHODS AND RESULTS: Using microsatellite typing, the identity of all Saccharomyces strains in the products was confirmed as S. boulardii. Additionally, solid-phase cytometry (SPC) and a plate method were used to enumerate S. boulardii cells. SPC was not only able to produce results more rapidly than plating (4h compared to 48h) but the cell counts obtained with SPC were significantly higher than the plate counts. Finally, we found that <1% of the S. boulardii cells survived 120min in gastric conditions and storage for 3months at 40°C with 75% relative humidity. CONCLUSIONS: We developed a SPC method for the quantification of viable S. boulardii cells in probiotics. Additionally, we demonstrated that gastric conditions and storage have a marked effect on the viability of the yeast cells. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first time SPC is used for the quality control of probiotics with S. boulardii. Additionally, we demonstrated the need for gastric protection and accurate storage.
AIMS: The yeastSaccharomyces boulardii is used as a probiotic for the prevention and treatment of diarrhoea. In this study, the quality of 15 probiotic products containing S. boulardii was verified. METHODS AND RESULTS: Using microsatellite typing, the identity of all Saccharomyces strains in the products was confirmed as S. boulardii. Additionally, solid-phase cytometry (SPC) and a plate method were used to enumerate S. boulardii cells. SPC was not only able to produce results more rapidly than plating (4h compared to 48h) but the cell counts obtained with SPC were significantly higher than the plate counts. Finally, we found that <1% of the S. boulardii cells survived 120min in gastric conditions and storage for 3months at 40°C with 75% relative humidity. CONCLUSIONS: We developed a SPC method for the quantification of viable S. boulardii cells in probiotics. Additionally, we demonstrated that gastric conditions and storage have a marked effect on the viability of the yeast cells. SIGNIFICANCE AND IMPACT OF THE STUDY: To our knowledge, this is the first time SPC is used for the quality control of probiotics with S. boulardii. Additionally, we demonstrated the need for gastric protection and accurate storage.