Page 178 - The Microworld Miracle

YEASTS THAT PRODUCE FOODSTUFFS THROUGH
FERMENTATION

There are around 600 known species of yeasts, single-celled
fungi that can be spherical, oval or cylindrical in shape, and are 7 to
17 microns in size. One gram of yeast therefore can contain some 15
million independent cells of yeast.
Yeasts feed on sugar, and in an oxygen-free environment can
produce from it ethyl alcohol and carbon dioxide.
This process, called fermentation, is of considerable economic

importance. Yeast is the basic element in the making of various
foods, giving bread its texture and flavor by producing tiny bubbles
of carbon dioxide in the dough. Yeast is also used in fermenting
soya, which produces low-calorie soy sauce. People who consume
soy sauce enjoy vital amino acids provided by the combination of
yeast and soya beans, so long as they do not take in too many calo-
ries. Therefore, yeasts are both nutritional and also serve in the pro-
duction of useful foods.

The bacterium
Staphylococcus
and Alexander
Fleming.
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