|MadSci Network: General Biology|
Mold is the word we use for several types of fungi which grow on food (fungi is the plural of fungus; the kingdom Fungi includes molds, mildews, mushrooms, yeasts, and several other similar organisms). Fungi have very similar metabolisms to animals, so they eat the same stuff we do: cheese, bread, my wife's chicken casserole, etc. Some fungi can get all of the nutrition they need to grow big and healthy from eating cheese, especially members of the genus Penicillium, all of which produce blue-green spores that give the mold its color. Some of the species of Penicillium are harmless and, in fact, are used to give the Blue Cheeses their color and flavor.
Cheese is a very good food, it's full of protein, fats, vitamins, and minerals. Since fat content isn't too important for mold growth, most cheeses will support mold. However, cheeses that are full of preservatives, or cheeses that are very hard (i.e. dry), will often take longer for molds to grow on. So remember, the next time you see cheese that has gotten moldy, it's just some fortunate fungus trying to eat its dinner.
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