We’ve all seen it. You stick a loaf of bread in your breadbox or pantry, and a few days later you begin to notice blue, green and black fuzz growing on top of it. Bread mold is a common problem, and can actually be the source of many interesting science experiments. But why is a loaf of bread such a desirable source for mold? The answer lies in an understanding of exactly what mold is, where it is found and how it survives.
Mold is a member of the fungi kingdom, which is a separate categorization from plants and animals. Mushrooms also fall into this category. Fungi can be defined as a plant without chlorophyll, so it cannot get energy directly from the sun. This means that fungi must use other plants and animals as its food source. This is why bread mold is so common - because of the ingredients in bread, it is an excellent source of nutrition for many molds to grow and thrive. It also contains limited moisture content, which is why mold can grow so well instead of bacteria or yeast that requires higher moisture levels to survive.
Bread and mold often meet through the mold spores that are in the air. Although you cannot see them, there are probably millions in the air around you. These spores can accumulate in the dust around our home, which is kicked up through cleaning or even someone walking by. The spores can then settle on your bread and the bread molding process will begin. Mold will not only live and feed on bread, it will also reproduce there. This is why you see bread mold spread throughout your loaf if you let it sit there long enough. Mold reproduces as long as it has a nutrient source - sometimes it can double in size in an hour’s time.
Molds grow in every
color imaginable. Look for Rhizopus stolinifera (black bread mold) on old
bread. Look for Penicillium camenbertii on blue cheese--it is what makes
blue cheese blue. The green fuzz on oranges that have been around too long
is also a Penicillium, from the same genera of organisms that gave us
penicillin, that critical antibiotic. Fungi are a great boon to humankind.
Without yeast, there would be no bread or beer. Fungi are used to make
antibiotics, soy sauce, miso, sake, tufu,and many, many more foods. On the
other hand, some of the most devestating plant diseases are caused by mold.
The Irish Famine was caused by the potato blight, Phytophthera infestans.
Most of the great American Chestnut forests where wiped out within 50 years
by a fungus introduced into the U.S. in a tree planted in the New York
Botanical Garden. Fungi are responsible for Trillions of dollars in damage
every year from food spoilage around the world.