Yeast and Fermentation
Date: December 2004
Why does yeast preform fermentation?
when yeast is used to ferment a solution containing a lot of sugar,
fermentation usually stops although sugar and yeast are still present. why?
Yeast have evolved what some consider a "primitive" form of metabolism to
use sugar for an energy source. In alcohol fermentation, yeasts that
produce carbon dioxide and alcohol and energy as end products, when the
alcohol reaches a certain level it will inhibit the yeast from fermenting
any more sugar.
Yeast cells ferment sugar because they can! When there is no Oxygen available,
only organism that can ferment are able to synthesize and reproduce. The alcohol
and CO2 that is produced in fermentation, eventually inhibits the cells even
though there is still sugar available.
Ron Baker, Ph.D..
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Update: June 2012