Probiotics are live microorganisms conferring health benefits when administered in adequate amounts. However, the passage through the gastrointestinal tract represents a challenge due to pH variations, proteases, and bile salts. This study aimed to evaluate the proteomic response of Saccharomyces boulardii to simulated gastrointestinal digestion and the influence of encapsulation on yeast viability. Different pH values and time periods simulating the passage through different sections of the gastrointestinal tract were applied to unencapsulated and encapsulated yeasts. Encapsulation in 0.5% calcium alginate did not improve yeast survival or induce changes in protein patterns whereas protein extracts from control and digested yeasts showed remarkable differences when separated by SDS-PAGE. Protein bands were analyzed by tandem mass spectrometry. Protein identification revealed unique proteins that changed acutely in abundance after simulated digestion. Carbohydrate metabolism, protein processing, and oxide-reduction were the biological processes most affected by simulated gastrointestinal digestion in S. boulardii.
Keywords: Electrophoresis; Probiotic yeast; Stress; Tandem mass spectrometry; Viability.