Vegetative cells sustain the organism by taking in food substances for energy and the production of new cell material. Unlike bacterial spores, mold spores are the source of new mold organisms. Bacterial spores generally form only when environmental conditions are unfavorable. Molds produce a stem consisting of several cells. The fruiting body produces the spores, which detach and are carried by air currents and deposited to start new mold colonies whenever conditions are favorable.
Mold spores are quite abundant in the air.
So, any food allowed to stand in the open soon becomes contaminated with mold if adequate moisture is present. Some types of molds are also psychrophiles and can cause spoilage of refrigerated foods. Molds are important to the food industry. Among their many contributions are the flavor and color they add to cheeses and the making of soy sauce. They also play a role in the making of such chemicals as citric and lactic acid and many enzymes.