2.1. Microorganisms

The microorganisms used were Lacticaseibacillus rhamnosus GG ATCC 53103 (LGG), and Saccharomyces cerevisiae CNCM I-3856 (both from Gnosis by Lesaffre, Marcq-en-Baroeul, France). The I-3856 strain of Saccharomyces cerevisiae is a proprietary, well-characterized strain of Lesaffre, registered in the French National Collection of Cultures of Microorganisms (CNCM). Both probiotic cultures were provided by Lesaffre Asia Pacific Pte Ltd. in the freeze-dried form and active dried form for LGG and S. cerevisiae, respectively. LGG was propagated by inoculating the freeze-dried culture into de Man, Rogosa and Sharpe (MRS) broth (Oxoid Ltd., Hampshire, UK) and incubating at 37 °C for 48 h. S. cerevisiae CNCM I-3856 was propagated by inoculating the active-dried culture into yeast-malt (YM) broth comprising of 10 g/L dextrose (Sigma-Aldrich, St. Louis, MO, USA), 3 g/L yeast extract, 3 g/L malt extract, and 5 g/L bacteriological peptone (all from Oxoid Ltd.) and incubating at 30 °C for 48 h. Propagated cultures of LGG and S. cerevisiae CNCM I-3856 were aliquoted into cryovials with 15% (v/v) glycerol (Merck, Darmstadt, Germany), and stored at −80 °C prior to use.