Molds

Molds are a type of microscopic multicellular fungi. They have essentially the same growth requirements as bacteria, but they ordinarily grow much more slowly. The molds are also distinguished by their capacity to grow on materials that would seem to offer only small supplies of nutrients, for example, linen, cotton cloth, and tanned leather. Thus, molds are found growing in surprising situations. Over 200 different kinds of molds have been described from mildewed fabrics; they grow in patches that often are brightly colored. Molds like mushrooms reproduce by spores. Airborne spores fall upon organic materials and begin growing, especially in warm and humid environments.

Molds growing from spores collected from the surface of a pillow case.

A common bread mold, Neurospora, forms red spores which give the characteristic color to moldy bread, though its relative, Aspergillus, is often present, too. The gray bread mold is Mucor. Bread molds viewed under a stereo microscope appear similar to miniature mushrooms: small balls on on tiny stalks. They have thread-like structure that cover the surface of the food and extend below the surface. We ingest penicillin, a chemical defense against bacteria first made by the green bread and fruit mold Penicillium long ago. The drug penicillin prevents infectious bacteria from making cell walls. Thus this fungus, by saving itself, has also saved millions of human lives. Although not always poisonous, some molds make food taste bad. On the other hand, humans eat some types of molds as food.

Of the 100,000 known fungi only a small percentage is associated with the indoor environment. Indoor molds comprise a group of fungi that are pathogens of humans and cause a variety of allergies and respiratory illnesses. These molds produce abundant amounts of microscopic spores called conidia. All indoor environments have some mold spores, with the possible exception of strictest clean rooms. The molds get indoors by hitching a ride on shoes, pets, or wind currents through open windows and doors. Homes that are consistently cleaned, dusted, and vacuumed have a lot less molds compared to those homes that are cleaned infrequently.

References: Ref file BFM-12-345