Yeast and Ethanol
Name: Marissa S.
Why can yeast rarely produce more than 14% ethanol?
The growth of ethanol-producing yeasts is self-limiting because when the
concentration of ethanol reaches about 14% it becomes toxic to the yeast
Just like with all animals, the alcohol is a toxin.
At levels above a certain percentage, this waste
product kills the yeast.
Fortunately, at lesser levels, we can enjoy alcohol
with apparent health benefits. Naturally, if we
consume too much alcohol, the effect on us can be the
same as the yeast.
Thanks for using NEWTON!
Ethanol is a toxic waste product. The yeast are poisoned by it.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
The alcohol concentration eventually becomes simply too toxic for the yeast
Jeff Buzby, Ph.D.
The alcohol concentration inhibits the function of certain enzymes in the
yeast...high alcohol concentration becomes toxic.
Peter Faletra Ph.D.
Office of Science
Department of Energy
You have to remember that the ethanol is a waste product as far as the yeast
is concerned. I believe that the ethanol builds up to a point where the yeast
can no longer actively grow in the culture (or wine or beer bottle). In
effect, they are fouling their own nest.
Paul Mahoney, Ph.D.
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Update: June 2012