ABSTRACT
Fungi such as molds and yeasts are single-and multi-celled, plant-like organisms that grow on cereals, breads, fruits, vegetables, and cheeses. For years man has used fungi for their beneficial properties. Antibiotics such as penicillin and vitamins such as vitamin C, are derived from molds. Yeasts are used in making wine and bread. They also serve as a protein source in foods. Aside from these beneficial effects, certain fungi possess properties that are harmful to humans. The potato blight in Ireland during the 1800s was caused by the fungus Phytothora infestans. Certain molds, such as Penicillium and Aspergillus, are toxigenic and can produce mycotoxins such as aflatoxin. Mycotoxins are mold metabolites produced on food that cause illness or death when ingested by man or animals. Other molds such as Mucor and Rhizopus species are common spoilage organisms and can also be pathogenic to man. Fungi can grow in conditions in which most bacteria could not survive. Molds can tolerate a pH as low as 2.0 and can thrive in low moisture environments. The majority of molds are aerobes and are therefore found on the surfaces of substrates where oxygen is present. In contrast to this, yeasts are facultative anaerobes which may be found within a substrate, require more moisture than molds, and prefer slightly acidic environments.
