Increased intestinal delivery of viable Saccharomyces boulardii by encapsulation in microspheres

Purpose. Although probiotics are of a major potential therapeutic interest, their efficacy is usually limited by poor bioavailability of viable microorganisms on site. The aim of this study was to protect the probiotic Saccharomyces boulardii from degradation in order to ensure a greater number of viable yeast in the colon. Methods. Alginate microspheres coated with or not with chitosan were used to encapsulate the yeast by an extrusion method. The efficiency of encapsulation was assessed both in vitro and in vivo. Results. In vitro, less than 1% of the non-encapsulated probiotic survived after 120 min at pH 1.1, whereas the majority of encapsulated yeast cells remained entrapped within both types of microspheres. Further exposure to a pH 6.8 allowed the release of about 35% of viable yeasts. In vivo, the percentage of viable yeast excreted over 96 h after a single oral dose of 2x10(8) cfu/100 g in rats was 2.5% for non-encapsulated yeast and reached 13.3 and 9.0% of the dose administered for the uncoated and chitosan-coated microspheres, respectively. Conclusions. Given the dose-dependent efficacy of S. boulardii and the efficiency of microencapsulation in protecting the yeast from degradation, alginate microspheres could be of great interest in therapeutic applications of the yeast.