Molds, or mould, are various fungi that cover surfaces in the form of fluffy mycelia and usually produce masses of spores (most commonly asexual spores but sometimes sexual).

Mold is a growth of these minute fungi forming on vegetable or animal matter, commonly as a downy or furry coating. It is often a sign of decay or dampness. The Molds are not a specific taxonomic or phylogenetic grouping – they can be found in the divisions Zygomycota, Deuteromycota and Ascomycota.

The presence of mold usually implies decay, although some molds are cultivated deliberately; for example in making certain types of cheese, and for the production of antibiotics derived from the organisms' natural defenses against bacteria.

The numerous spores released by mold do not themselves cause significant harm in humans, but the hyphae grown from those spores can attach to cells along the respiratory tract and cause problems in those with weak immunity.

Alexander Fleming's famous discovery of penicillin involved the mold Penicillium notatum. The mold Neurospora crassa is commonly used as a model organism in scientific experiments. Mold is often a problem in damp areas such as basements and bathrooms, and after floods. It can be seen on surfaces of walls, but also grows deep within, and produces a distinctive dusty, slightly pungent smell. It grows on food in closed containers, even in refrigerators.

Mold growth in buildings

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The main problem with the presence of mold in buildings arises from the inhalation of mold spores. Some molds are particularly serious in this respect, because their spores are important causes of allergies (they are allergens); also, the spores of some fungi like Stachybotrys release potent toxins into the lungs when inhaled; Stachybotrys spores can cause very severe symptoms and lung lesions in children. In the home, the presence of mold can mean that something is wrong. Mold doesn’t require sunlight; often, sunlight will kill it. Mold does require moisture and food. In houses and buildings, this food source is usually some form of cellulose such as wood or cardboard.

• If an entire house has problems with mold year-round, there is probably too much moisture in the house, possibly from a dirt basement or a leaking roof.
• If there are mold problems in one specific part of a house year-round, then that part of the house probably needs more sunlight and ventilation. Mold often forms on perimeter walls, because they are coolest, and where ventilation is poorest (in corners, around furniture).

If there are mold problems in a house only during certain times of the year, then it is probably either too air-tight, or too drafty. Mold problems occur in air-tight homes more frequently in the warmer months (when humidity reaches high levels inside the house, and moisture is trapped), and occur in drafty homes more frequently in the colder months (when warm air escapes from the living area into unconditioned space, and condenses). If a house is humidified artificially during the winter, this can create conditions favorable to mold. Also see ventilation issues in houses for tips on preventing different types of mold. ^*

See also

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• Toxic mold, Mycotoxin, Aflatoxin
• Slime mould, water mould
• Yeasts are a family of fungi closely related to molds.
• Foods produced using cultured molds: cheese, tempeh, Quorn, famous black tea Pu-erh and some sausages
• Indoor air quality
• Mildew
• Ergot is a hallucinogenic mold which forms on grains and breads, most commonly rye. Lysergic acid, used to manufacture LSD, is prepared from ergot.
• "Mold of the Earth" (a micro-story that uses mold as metaphor).

External links

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• EPA mold guide
• EPA mold website
• Mold FAQ
• Household mold
• Bread Mold FAQ
• How dangerous is eating moldy bread? (FAQ Farm)
• Mold Guys
• Environix - Indoor Environmental Solutions

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