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Encyclopedia

Molds (or moulds; see spelling differences) are fungi that grow in the form of multicellular filaments called hyphae.[1] In contrast, microscopic fungi that grow as single cells are called yeasts. A connected network of these tubular branching hyphae has multiple, genetically identical nuclei and is considered a single organism, referred to as a colony or in more technical terms a mycelium.

Molds do not form a specific taxonomic or phylogenetic grouping, but can be found in the divisions Zygomycota, Deuteromycota and Ascomycota. Some molds cause disease or food spoilage, others play an important role in biodegradation or in the production of various foods, beverages, antibiotics and enzymes.

Contents

Biology

There are thousands of known species of molds which include opportunistic pathogens, saprotrophs, aquatic species, and thermophiles.[2] Like all fungi, molds derive energy not through photosynthesis but from the organic matter in which they live. Typically, molds secrete hydrolytic enzymes, mainly from the hyphal tips. These enzymes degrade complex biopolymers such as starch, cellulose and lignin into simpler substances which can be absorbed by the hyphae. In this way, molds play a major role in causing decomposition of organic material, enabling the recycling of nutrients throughout ecosystems. Many molds also secrete mycotoxins which, together with hydrolytic enzymes, inhibit the growth of competing microorganisms.

Molds reproduce through small spores,[2] which may contain a single nucleus or be multinucleate. Mold spores can be asexual (the products of mitosis) or sexual (the products of meiosis); many species can produce both types. Mold spores may remain airborne indefinitely, may cling to clothing or fur, or may be able to survive extremes of temperature and pressure.

Although molds grow on dead organic matter everywhere in nature, their presence is only visible to the unaided eye when mold colonies grow. A mold colony does not comprise discrete organisms, but an interconnected network of hyphae called a mycelium. Nutrients and in some cases organelles may be transported throughout the mycelium. In artificial environments like buildings, humidity and temperature are often stable enough to foster the growth of mold colonies, commonly seen as a downy or furry coating growing on food or other surfaces.

Many molds can begin growing at

  1. REDIRECT Template:Convert/°C, the temperature within a typical refrigerator, or less. When conditions do not enable growth, molds may remain alive in a dormant state depending on the species, within a large range of temperatures before they die. The many different mold species vary enormously in their tolerance to temperature and humidity extremes. Certain molds can survive harsh conditions such as the snow-covered soils of Antarctica, refrigeration, highly acidic solvents, and even petroleum products such as jet fuel.

Xerophilic molds use the humidity in the air as their only water source; other molds need more moisture. Mold has a musty odor.

Common molds

Uses

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Food production

Cultured molds are used in the production of foods, including:

The koji molds are a group of Aspergillus species, notably Aspergillus oryzae, that have been cultured in eastern Asia for many centuries. They are used to ferment a soybean and wheat mixture to make soybean paste and soy sauce. They are also used to break down the starch in rice (saccharification) in the production of sake and other distilled spirits.

Red rice yeast is a product of the mold Monascus purpureus grown on rice, and is common in Asian diets. The yeast contains several compounds collectively known as monacolins, which are known to inhibit cholesterol synthesis.[4] According to a study published in the journal Mayo Clinic Proceedings by Dr. David Becker, red rice yeast used as a dietary supplement, combined with fish oil and healthy lifestyle changes, may help reduce "bad" cholesterol as effectively as certain commercial statin drugs.[5]

Drug creation

Alexander Fleming's famous discovery of the antibiotic penicillin involved the mold Penicillium chrysogenum.

Several cholesterol-lowering drugs (such as Lovastatin, from Aspergillus terreus) are derived from molds.

The immunosuppressant drug cyclosporine, used to suppress the rejection of transplanted organs, is derived from the mold Tolypocladium inflatum.

Health effects

Molds are ubiquitous in nature, and mold spores are a common component of household and workplace dust. However, when mold spores are present in large quantities, they can present a health hazard to humans, potentially causing allergic reactions and respiratory problems.

Some molds also produce mycotoxins that can pose serious health risks to humans and animals. Some studies claim that exposure to high levels of mycotoxins can lead to neurological problems and in some cases death. Prolonged exposure, e.g. daily workplace exposure, may be particularly harmful. Research on the health effects of mold has not been conclusive. The term "toxic mold" refers to molds that produce mycotoxins, such as Stachybotrys chartarum, and not to all molds in general.[6]

Mold in the home can usually be found in damp, dark or steam filled areas e.g. bathroom or kitchen, cluttered storage areas, recently flooded areas, basement areas, plumbing spaces, areas with poor ventilation and outdoors in humid environments. Symptoms caused by mold allergy are watery, itchy eyes, a chronic cough, headaches or migraines, difficulty breathing, rashes, tiredness, sinus problems, nasal blockage and frequent sneezing. In extremely rare cases, over-exposure to mold may result in bucal mold growth leading to death by asphyxiation.[citation needed]

Growth in buildings and homes

Mold growth in buildings can lead to a variety of health issues. Various practices can be followed to mitigate mold issues in buildings, the most important of which is to reduce moisture levels that can facilitate mold growth.[6] Removal of affected materials after the source of moisture has been reduced and/or eliminated may be necessary for remediation.

Gallery

See also

File:Karl Johanssvamp, Fungi portal

References

External links


Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

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Contents

English

Cast and mold

Alternative spellings

Pronunciation

mŏld, mōld

Etymology 1

Via Middle English and Old French from Latin modulus

Noun

Singular
mold

Plural
molds

mold (plural molds)

  1. A hollow form or matrix for shaping a fluid or plastic substance.W
  2. A frame or model around or on which something is formed or shaped.
  3. Something that is made in or shaped on a mold.
  4. The shape or pattern of a mold.
  5. General shape or form.
    the oval mold of her face
  6. Distinctive character or type.
    a leader in the mold of her predecessors
  7. A fixed or restrictive pattern or form
    His method of scientific investigation broke the mold and led to a new discovery.
  8. (architecture) See molding.
Derived terms
  • (archaeology) post mold
  • (paleontology) fossil mold
Translations
The translations below need to be checked and inserted above into the appropriate translation tables, removing any numbers. Numbers do not necessarily match those in definitions. See instructions at Help:How to check translations.

Verb

Infinitive
to mold

Third person singular
molds

Simple past
molded

Past participle
molded

Present participle
molding

to mold (third-person singular simple present molds, present participle molding, simple past and past participle molded)

  1. (transitive) To shape in or on a mold.
  2. (transitive) To form into a particular shape; to give shape to.
    • Job 10:8-9, Old Testament, New International Version:
      Your hands shaped me and made me....Remember that you molded me like clay.
  3. (transitive) To guide or determine the growth or development of; influence; as, a teacher who helps to mold the minds of his students
  4. (transitive) To fit closely by following the contours of.
  5. (transitive) To make a mold of or from (molten metal, for example) before casting.
  6. (transitive) To ornament with moldings.
  7. (intransitive) To be shaped in or as if in a mold.
    These shoes gradually molded to my feet.
Translations

Etymology 2

Penicillium mold on mandarin oranges

Via Middle English from Old Norse mygla

Noun

Singular
mold

Plural
molds

mold (plural molds)

  1. A natural substance in the form of a woolly or furry growth of tiny fungi that appears when organic material lies for a long time exposed to (usually warm and moist) air.
Derived terms
See also
Translations

Etymology 3

From Old English molde

Noun

Singular
mold

Plural
molds

mold (plural molds)

  1. Loose friable soil, rich in humus and fit for planting.
Derived terms
Translations

Faroese

Pronunciation

Noun

mold f. sg.

  1. (agriculture) earth, humus soil, humus layer

Declension

f2s Singular
Indefinite Definite
Nominative mold moldin
Accusative mold moldina
Dative mold moldini
Genitive moldar moldarinnar

Icelandic

Noun

mold f.

  1. dirt, mould, humus, ground, earth

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