Molds are eukaryotic microorganisms in the kingdom of fungi that grow as multicellular filaments called
hyphae, collectively called a mycelium. Hyphae are cylindrical, thread-like structures 2-1 μm in diameter and up to several centimeters. Molds are often seen as fuzzy or fluffy masses on bread and other food products, especially acidic products.
The molds often assume vivid colors from the pigments they produce in spores for reproductive purposes. Molds are the second most common microbial contaminants in the clean room, and under certain circumstances they can become a serious threat. Their nutritional requirements are generally simpler than those of bacteria and they can grow in the absence of significant amounts of moisture.
They resemble microscopic roots and like roots can anchor to ground or tissue, penetrate it and branch and grow unnoticed underneath it. People are most familiar with molds because of their association with food spoilage and the deterioration of materials and equipment through mildew and dry rot.
Aspergillus and
Penicillium species tend to be saprophytic and often attack commodities, such as cereal grains and nuts while in storage, although some aspergili can invade in the field.
Fusarium species may be plant pathogenic as well as saprophytic types.
Multicellular filaments: molds
