Q&A: What is saccharomyces? Why is it in products?

In the August Q&A, Brian asked: It’s the saccharomyces ingredient that seems new or unusual in both these products. Maybe a yeast of some kind. Rare? How to preserve? Effective for what? Brian referenced these two products, which will lead into another question about what it means for something to be an “essence”. Fresh, Black Tea Kombucha…