Molds (or moulds; see spelling differences) are fungi that grow in the form of multicellular filaments called hyphae.Molds are considered to be microbes but 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.
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.
Biology
There are thousands of known species of molds which include
opportunistic pathogens,
saprotrophs, aquatic species, and
thermophiles. 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,
Food production
Cultured molds are used in the production of foods, including:
cheese (Penicillium spp.)
tempeh (Rhizopus oligosporus)
oncom (Neurospora sitophila)
Quorn (Fusarium venenatum)
some
sausages
soy sauce
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. 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.
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.
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.
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.
See also
Bioaerosol
Decay
Medicinal mushrooms
Mildew
Mold mite
Mycorrhiza
Oomycete
References
External links
The EPA's guide to mold
Category:Fungi
Category:Articles containing video clips
