Nature Bulletin No. 638-A April 23, 1977
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
Mold is the common name for those cottony, cobwebby, or powdery
growths that appear on almost any food, leather, cloth or paper stored in
a dark, damp place. Soil, however, is the natural habitat for most of
them. There they break down dead plant and animal materials and
maintain the soil's fertility. From our standpoint, some are good, some
Molds, along with bacteria, yeasts, mildews, blights, rusts, smuts and
mushrooms make up that great subdivision of the plant kingdom called
the Fungi. All of them lack the chlorophyll by which common green
plants use the energy from sunlight to manufacture their own food.
Instead, they get their nourishment from dead plant and animal remains,
or as parasites on other living things.
Dry, dust-like mold spores -- of many different kinds and by the
millions -- are carried by the wind and everything else that moves. They
are on the ground, on trees, and on almost every square inch of our
homes. A colony covering a whole slice of fresh bread can grow in a
few days from a single microscopic spore. Under favorable conditions
the spore swells, bursts its wall and sends out a short slender thread.
This grows longer and branches into many threads. Some turn down
like roots to absorb food. The tips of others turn upward to form tiny
white globules which darken as they ripen. Then, each pops open to
release thousands of new spores. In blue mold, chains of spores push
out in clusters that resemble tiny tassels. Under a lens these mold
colonies are exquisite fairy gardens.
Certain kinds of blue mold have long been used in making cheese to
give distinctive qualities and flavors. The famous Roquefort cheese, so-
named after a town in France where it is ripened in caves, is a white
cheese made from the milk of sheep in which there are blue-green
streaks due to sifting powdered bread mold into the curd. Gorgonzola
cheese from Italy, and Stilton from England, are also mold-ripened. Our
brown, salty soy sauce borrowed from China is prepared by a long slow
fermentation of soy beans and rice with a mold.
Of the multitude of species of mold-like fungi, some cause infections
and diseases in animals and man. Two of our skin diseases, more
aggravating than dangerous, are ringworm and athlete's foot. Chickens
eating moldy grain get a mold infection of their air sacs. In winter, fish
are often killed by a water mold that produces patches of gray fuzz on
their skins or gills.
One of the most revolutionary medical discoveries of all time was made
in 1938 by Dr. Alexander Fleming of England. It started when one of
the culture plates on which he was growing pathogenic bacteria was
accidentally contaminated with a spot of blue mold. He noticed that the
mold had created a bacteria-free ring around itself and was shrewd
enough to realize what it meant. That was the origin of the antibiotic
drug, penicillin. Since then, hundreds of other antibiotics, most of them
produced by as many different molds, have their special uses in the
control of bacterial infections in man and domestic animals.
About this same time, Dr. George W. Beadle, of the University of
Chicago, used different strains of red bread mold which had been
crippled by radiation to learn how the hereditary materials -- genes --
controlled growth. He showed that each gene produces its own enzyme
or catalyst to do its work. Both he and Dr. Fleming were awarded Nobel
prizes for their outstanding contributions to science.
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Update: June 2012