Glossary
Saccharomyces
The genus of yeast responsible for almost all beer fermentation: S. cerevisiae for ales and S. pastorianus for lagers.
Pronounced sak-a-roh-MY-seez.
Also called sacch, brewers yeast, saccharomyces cerevisiae, saccharomyces pastorianus.
S. pastorianus is a hybrid, and a remarkable one — a cross between S. cerevisiae and the cold-tolerant S. eubayanus, which was not identified in the wild until 2011, in Patagonian forests. Its cold tolerance is what made lager brewing possible in cool Bavarian cellars.
Related
- Top fermentation — What S. cerevisiae does.
- Bottom fermentation — What S. pastorianus does.
- Saccharomyces cerevisiae — The catalogue record for ale yeast.
More vocabulary
Adjunct · Aroma hop · Base malt · Bittering hop · Black malt · Brettanomyces · Candi sugar · Chocolate malt · Crystal malt · Dextrin
See every term on the glossary index.
Last reviewed 2026-08-16.