Probiotic capability in yeasts: Set-up of a screening method

Microbial probiotic supplements are used to improve the health and wellness of people. For checking this ability (resistance to gastrointestinal conditions, auto-aggregation, cell surface hydrophobicity or biofilm formation abilities), it is crucial to evaluate some kinetics parameters. The objective of the present study was to establish an adequate method for studying the probiotic potential of Saccharomyces and non-Saccharomyces strains isolated from food ecosystems. A new protocol was designed based on kinetics parameters: lag phase (λ), generation time (G) and maximum OD (ODmax). The design was done using a step-by-step approach (up to 10 protocols), focusing on the choice of controls and the conditions to simulate the stomach and intestine. Each decision was made based on multifactorial statistical assay results. A preliminary screening indicates that protocol is adequate, quick and reproducible and that S. cerevisiae strains are more resistant than non-Saccharomyces ones. S. boulardii, (commercial control), was not one of the best yeasts evaluated. Thus, the most relevant results of the work are the setup of a new method for studying the survival/resistance of yeasts to the transit into the gut based on a complex statistical analysis of results and to mark the probiotic character in Saccharomyces yeasts versus non-Saccharomyces.