Genetics, Molecular and Cell Biology of Yeast - Roger Schneiter

"The most well-known and commercially significant yeasts are the related
species and strains of Saccharomyces cerevisiae. These organisms have long been
utilized to ferment the sugars of rice, wheat, barley, and corn to produce alcoholic
beverages and in the baking industry to expand, or raise, dough. Saccharomyces
cerevisiae is commonly used as baker's yeast and for some types of fermentation.
Yeast is often taken as a vitamin supplement because it is 50 percent protein and is a
rich source of B vitamins, niacin, and folic acid.

In brewing, Saccharomyces carlsbergensis, named after the Carlsberg
Brewery in Copenhagen, where it was first isolated in pure culture by Dr. Emile
Christian Hansen around 1888, is used in the production of several types of beers
including lagers. S. carlsbergensis is used for bottom fermentation. S. cerevisiae used
for the production of ales and conducts top fermentation, in which the yeast rise to the
surface of the brewing vessel. In modern brewing many of the original top
fermentation strains have been modified to be bottom fermenters. Currently the S.
carlsbergensis designation is not used, the S. cerevisiae classification is used instead."

- Roger Schneiter, 2004

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