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{{short description|Wooly, dust-like fungal structure or substance}}
{{About|true fungi| non-fungal 'molds'|Slime mold|and|Water mold|the manufacturing tool|Mold (manufacturing)|other uses}}

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{{Use American English|date=September 2019}}
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[[File:Mold on a strawberry.jpg|thumb|Close up of mold on a strawberry]]
[[File:Mouldy Clementine.jpg|thumb|''[[Penicillium]]'' mold growing on a [[clementine]]]]
A '''mold''' ({{small|[[American English|US]], [[Philippine English|PH]]}}) or '''mould''' ({{small|[[British English|UK]], [[Commonwealth English|CW]]}}) is one of the structures that certain [[fungus|fungi]] can form. The dust-like, colored appearance of molds is due to the formation of [[Spore#Fungi|spores]] containing [[Secondary metabolite#Fungal secondary metabolites|fungal secondary metabolites]]. The spores are the dispersal units of the fungi.<ref name=Moore>{{cite book |veditors=Moore D, Robson GD, Trinci AP |title=21st Century Guidebook to Fungi |edition=1st |publisher=[[Cambridge University Press]] |year=2011 |isbn=978-0521186957}}</ref><ref name=Brock>{{cite book |veditors=Madigan M, Martinko J |title=Brock Biology of Microorganisms |edition=11th |publisher=[[Prentice Hall]] |year=2005 |isbn=978-0-13-144329-7 |oclc=57001814}}</ref> Not all fungi form molds. Some fungi form [[mushrooms]]; others grow as [[unicellular organism|single cells]]  and are called [[microfungi]] (for example, [[yeast]]s).

A large and [[taxonomy (biology)|taxonomically]] diverse number of fungal species form molds. The growth of [[hypha]]e results in discoloration and a fuzzy appearance, especially on food.<ref>{{cite web |last=Morgan |first=Mike |title=Moulds |url=http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjan99/mmould.html |publisher=Microscopy UK |access-date=26 June 2012 |archive-date=28 March 2019 |archive-url=https://web.archive.org/web/20190328192228/http://www.microscopy-uk.org.uk/mag/indexmag.html?http%3A%2F%2Fwww.microscopy-uk.org.uk%2Fmag%2Fartjan99%2Fmmould.html |url-status=live }}</ref> The network of these tubular branching hyphae, called a [[mycelium]], is considered a single [[organism]]. The hyphae are generally transparent, so the mycelium appears like very fine, fluffy white threads over the surface. Cross-walls (septa) may delimit connected compartments along the hyphae, each containing one or multiple, genetically identical [[Cell nucleus|nuclei]]. The dusty texture of many molds is caused by profuse production of asexual spores ([[conidia]]) formed by differentiation at the ends of hyphae. The mode of formation and shape of these spores is traditionally used to classify molds.<ref>{{cite web|last=Chiba University, Japan|title=Fungus and Actinomycetes Gallery|url=http://www.pf.chiba-u.ac.jp/english/gallery.html|publisher=Chiba University Medical Mycology Research Center|access-date=26 June 2012|archive-date=19 July 2012|archive-url=https://web.archive.org/web/20120719085908/http://www.pf.chiba-u.ac.jp/english/gallery.html|url-status=live}}</ref> Many of these spores are colored, making the fungus much more obvious to the human eye at this stage in its life-cycle.

Molds are [[microorganism|microbes]] that do not form a specific [[Taxonomy (biology)|taxonomic]] or [[phylogeny|phylogenetic]] grouping, but can be found in the divisions [[Zygomycota]] and [[Ascomycota]]. In the past, most molds were classified within the [[Deuteromycota]].<ref name=Hibbett2007>{{cite journal |vauthors=Hibbett DS, Binder M, Bischoff JF, Blackwell M, Cannon PF, Eriksson OE, etal |year=2007 |title=A higher level phylogenetic classification of the ''Fungi'' |journal=Mycological Research |pmid=17572334 |volume=111 |issue=5 |pages=509–547 |doi=10.1016/j.mycres.2007.03.004 |url=http://www.clarku.edu/faculty/dhibbett/AFTOL/documents/AFTOL%20class%20mss%2023,%2024/AFTOL%20CLASS%20MS%20resub.pdf |url-status=dead |archive-url=https://web.archive.org/web/20090326135053/http://www.clarku.edu/faculty/dhibbett/AFTOL/documents/AFTOL%20class%20mss%2023%2C%2024/AFTOL%20CLASS%20MS%20resub.pdf |archive-date=2009-03-26 |citeseerx=10.1.1.626.9582 |s2cid=4686378 }}</ref> Mold was the common name for [[water molds]] or [[slime molds]], which were formerly classified as fungi.<ref>{{cite web |title=Slime Molds |url=https://herbarium.usu.edu/fun-with-fungi/slime-molds |website=herbarium.usu.edu |publisher=Utah State University |access-date=21 April 2020 |language=en |archive-date=20 February 2020 |archive-url=https://web.archive.org/web/20200220205614/http://herbarium.usu.edu/fun-with-fungi/slime-molds |url-status=live }}</ref><ref>{{cite web |title=Slime Molds: Myxomycetes |url=https://plantclinic.cornell.edu/factsheets/slimemolds.pdf |publisher=Cornell University |access-date=21 April 2020}}</ref><ref>{{cite web |title=Introduction to the Oomycota |url=https://ucmp.berkeley.edu/chromista/oomycota.html |website=ucmp.berkeley.edu |publisher=UC Berkeley |access-date=21 April 2020 |archive-date=6 May 2020 |archive-url=https://web.archive.org/web/20200506035535/https://ucmp.berkeley.edu/chromista/oomycota.html |url-status=live }}</ref>

Molds cause [[biodegradation]] of natural materials, which can be unwanted when it becomes [[decomposition|food spoilage]] or damage to property. They also play important roles in biotechnology and food science in the production of various pigments, foods, beverages, [[antibiotic]]s, pharmaceuticals and [[enzyme]]s.<ref>{{Cite journal|last1=Toma|first1=Maria Afroz|last2=Nazir|first2=K. H. M. Nazmul Hussain|last3=Mahmud|first3=Md Muket|last4=Mishra|first4=Pravin|last5=Ali|first5=Md Kowser|last6=Kabir|first6=Ajran|last7=Shahid|first7=Md Ahosanul Haque|last8=Siddique|first8=Mahbubul Pratik|last9=Alim|first9=Md Abdul|title=Isolation and Identification of Natural Colorant Producing Soil-Borne Aspergillus niger from Bangladesh and Extraction of the Pigment|journal=Foods|year=2021|language=en|volume=10|issue=6|pages=1280| pmid=34205202| doi=10.3390/foods10061280|pmc=8227025|doi-access=free}}</ref> Some diseases of animals and humans can be caused by certain molds: disease may result from allergic sensitivity to mold spores, from growth of [[pathogen]]ic molds within the body, or from the effects of ingested or inhaled toxic compounds ([[mycotoxin]]s) produced by molds.<ref name="Moore"/>

==Biology==
[[File:Spinellus fusiger 51504.jpg|thumb|left|''[[Spinellus fusiger]]'' growing on the mushroom ''[[Mycena haematopus]]'']]
There are thousands of known species of mold fungi with diverse life-styles including [[saprotroph]]s, [[mesophile]]s, [[psychrophile]]s and [[thermophile]]s, and a very few [[opportunistic pathogen]]s of humans.<ref name=Sherris>{{cite book | veditors= Ryan KJ, Ray CG | title = Sherris Medical Microbiology | url= https://archive.org/details/sherrismedicalmi00ryan | url-access= limited | pages= [https://archive.org/details/sherrismedicalmi00ryan/page/n650 633]–8 | edition = 4th | publisher = McGraw Hill | year = 2004 | isbn = 978-0-8385-8529-0 }}</ref> They all require moisture for growth and some live in aquatic environments. Like all fungi, molds derive energy not through [[photosynthesis]] but from the [[Organic material|organic]] matter on which they live, utilizing [[heterotroph]]y. Typically, molds secrete hydrolytic [[enzymes]], mainly from the hyphal tips. These enzymes degrade complex [[biopolymers]] such as [[starch]], [[cellulose]], and [[lignin]] into simpler substances that can be absorbed by the hyphae. In this way, molds play a major role in the [[decomposition]] of organic material, enabling the recycling of nutrients throughout [[ecosystem]]s. Many molds also synthesize [[mycotoxin]]s and [[siderophore]]s that, together with [[lysis|lytic]] enzymes, inhibit the growth of competing [[microorganism]]s. Molds can also grow on stored food for animals and humans, making the food unpalatable or toxic, and are thus a major source of food losses and illness.<ref>{{cite web|last=Wareing|first=Peter|title=The Fungal Infection of Agricultural Produce and the Production of Mycotoxins|url=http://services.leatherheadfood.com/eman/FactSheet.aspx?ID=78|work=European Mycotoxins Awareness Network|access-date=3 August 2013|archive-url=https://web.archive.org/web/20131019053128/http://services.leatherheadfood.com/eman/FactSheet.aspx?ID=78|archive-date=19 October 2013|url-status=dead}}</ref>  Many strategies for [[food preservation]] (salting, pickling, jams, bottling, freezing, drying) are intended to prevent or slow mold growth as well as the growth of other microbes.

Molds reproduce by producing large numbers of small [[spores]],<ref name=Sherris /> that may contain a single [[cell nucleus|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. Some molds produce small, [[Hydrophobe|hydrophobic]] spores that are adapted for wind dispersal and may remain airborne for long periods; in some the cell walls are darkly pigmented, providing resistance to damage by [[Ultraviolet|ultraviolet radiation]]. Other mold spores have slimy sheaths and are more suited to water dispersal. Mold spores are often spherical or ovoid single cells, but can be multicellular and variously shaped. Spores may cling to clothing or fur; some are able to survive extremes of temperature and pressure.

Although molds can grow on dead organic matter everywhere in nature, their presence is visible to the unaided eye only when they form large [[Colony (biology)|colonies]]. A mold colony does not consist of discrete organisms but is an interconnected network of hyphae called a [[mycelium]]. All growth occurs at hyphal tips, with [[cytoplasm]] and organelles flowing forwards as the hyphae advance over or through new food sources. Nutrients are absorbed at the hyphal tip. In artificial environments such as buildings, humidity and temperature are often stable enough to foster the growth of mold colonies, which are often visible as a downy or furry coating growing on food or other surfaces.

Few molds can begin growing at temperatures of {{convert|4|C|F}} or below, so food is typically [[refrigeration|refrigerated]] to this temperature. When conditions do not enable growth to take place, molds can remain alive in a dormant state within a large range of temperatures that depends on the species. The many different mold species vary enormously in their tolerance for temperature and humidity extremes. Certain molds can survive harsh conditions such as the snow-covered soils of Antarctica, refrigeration, highly acidic solvents, anti-bacterial soap, and even petroleum products such as jet fuel.<ref name=malloch1981/>{{rp|22}}

[[Xerophile|Xerophilic]] molds are able to grow in relatively dry, salty, or sugary environments, where [[water activity]] (a<sub>w</sub>) is less than 0.85; other molds need more moisture.<ref name=Pitt2009>{{cite book |vauthors=Pitt JI, Hocking AD | year=2009 | title=Fungi and Food Spoilage |url=https://archive.org/details/fungifoodspoilag00pitt_565 |url-access=limited | pages=[https://archive.org/details/fungifoodspoilag00pitt_565/page/n347 339]–355 | publisher=Springer | location=London | doi= 10.1007/978-0-387-92207-2_9| chapter=Xerophiles | isbn=978-0-387-92206-5 }}</ref>

==Common molds==
[[File:Ojmold1000xa.jpg|thumbnail|Spores from green mold growing on an orange, 1000× wet mount]]
Common [[genera]] of molds include:
{{Div col|colwidth=22em}}
* ''[[Acremonium]]''
* ''[[Alternaria]]''
* ''[[Aspergillus]]''
* ''[[Cladosporium]]''
* ''[[Fusarium]]''
* ''[[Mucor]]''
* ''[[Penicillium]]''
* ''[[Rhizopus]]''
* ''[[Stachybotrys]]''
* ''[[Trichoderma]]''
* ''[[Trichophyton]]''
{{div col end}}

==Food production==
The [[Kōji mold]]s are a group of ''[[Aspergillus]]'' species, notably ''[[Aspergillus oryzae]]'', and secondarily ''[[Aspergillus sojae|A. sojae]]'', that have been cultured in eastern Asia for many centuries. They are used to ferment a soybean and wheat mixture to make [[miso|soybean paste]] and [[shoyu|soy sauce]]. ''Koji'' molds break down the [[starch]] in rice, barley, sweet potatoes, etc., a process called [[Hydrolysis#saccharification|saccharification]], in the production of ''[[sake]]'', ''[[shōchū]]'' and other distilled spirits.  ''Koji'' molds are also used in the preparation of [[Katsuobushi]].

[[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 [[monacolin]]s, which are known to inhibit cholesterol synthesis.<ref>{{cite web |url=http://www.mayoclinic.com/health/red-yeast-rice/NS_patient-redyeast |title=Red yeast rice (Monascus purpureus) |publisher=[[Mayo Clinic]] |date=2009-09-01 |access-date=2010-02-01 |archive-date=2010-02-06 |archive-url=https://web.archive.org/web/20100206021521/http://www.mayoclinic.com/health/red-yeast-rice/ns_patient-redyeast |url-status=live }}</ref> A study has shown that 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.<ref>{{cite web |url=https://www.npr.org/templates/story/story.php?storyId=92103272 |title=Study: Red Rice Yeast Helps Cut Bad Cholesterol |publisher=[[National Public Radio]] |date=2008-07-01 |access-date=2010-02-01 |archive-date=2010-02-12 |archive-url=https://web.archive.org/web/20100212154906/http://www.npr.org/templates/story/story.php?storyId=92103272 |url-status=live }}</ref> Nonetheless, other work has shown it may not be reliable (perhaps due to non-standardization) and even toxic to liver and kidneys.<ref>Red Yeast Rice Preparations: Are They Suitable Substitutions for Statins?, Dujovne, CA, Am J Med. 2017 Oct;130(10):1148-1150. doi: 10.1016/j.amjmed.2017.05.013. Epub 2017 Jun 7.</ref>

Some [[sausage]]s, such as [[salami]], incorporate starter cultures of molds <ref>{{cite journal|title=Mould starter cultures for dry sausages—selection, application and effects|journal=Meat Science |date=November 2003|vauthors=Sunesen LO, Stahnke LH|volume=65|issue=3|pages=935–948|doi= 10.1016/S0309-1740(02)00281-4|pmid=22063673 }}</ref> to improve flavor and reduce bacterial spoilage during curing. ''[[Penicillium nalgiovense]]'', for example, may appear as a powdery white coating on some varieties of dry-cured sausage.

Other molds that have been used in food production include:
* ''[[Fusarium venenatum]]'' – [[quorn]]
* ''[[Geotrichum candidum]]'' – [[cheese]]
* ''[[Neurospora sitophila]]'' – [[oncom]]
* ''[[Penicillium]]'' spp. – various cheeses including [[Brie]] and [[Blue cheese]]
* ''[[Rhizomucor miehei]]'' – microbial [[rennet]] for making vegetarian and other cheeses
* ''[[Rhizopus oligosporus]]'' – [[tempeh]]
* ''[[Rhizopus oryzae]]'' – tempeh, [[jiuqu]] for [[jiuniang]] or precursor for making [[Mijiu|Chinese rice wine]]

==Pharmaceuticals from molds==
[[File:Mold(плесень).jpg|thumb|left|Molds on a [[Petri dish]]]]
[[Alexander Fleming]]'s accidental discovery of the antibiotic [[penicillin]] involved a ''[[Penicillium]]'' mold then called ''Penicillium rubrum'' (although the species was later established to be ''[[Penicillium rubens]]'').<ref name="The Nobel Prize website">{{cite web|title=The Nobel Prize website|url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1945/|access-date=27 June 2012|archive-date=19 May 2012|archive-url=https://web.archive.org/web/20120519161518/http://www.nobelprize.org/nobel_prizes/medicine/laureates/1945/|url-status=live}}</ref><ref name=":1">{{Cite journal|last1=Houbraken|first1=Jos|last2=Frisvad|first2=Jens C.|last3=Samson|first3=Robert A.|date=2011|title=Fleming's penicillin producing strain is not Penicillium chrysogenum but P. rubens|url= |journal=IMA Fungus|language=en|volume=2|issue=1|pages=87–95|doi=10.5598/imafungus.2011.02.01.12|pmc=3317369|pmid=22679592}}</ref><ref>{{Cite journal|last1=Houbraken|first1=J.|last2=Frisvad|first2=J.C.|last3=Seifert|first3=K.A.|last4=Overy|first4=D.P.|last5=Tuthill|first5=D.M.|last6=Valdez|first6=J.G.|last7=Samson|first7=R.A.|date=2012-12-31|title=New penicillin-producing Penicillium species and an overview of section Chrysogena|url= |journal=Persoonia - Molecular Phylogeny and Evolution of Fungi|language=en|volume=29|issue=1|pages=78–100|doi=10.3767/003158512X660571|pmc=3589797|pmid=23606767}}</ref> Fleming continued to investigate penicillin, showing that it could inhibit various types of bacteria found in infections and other ailments, but he was unable to produce the compound in amounts large enough for the production of a medicine.<ref name=TNPM>{{cite web|title=Award Ceremony Speech|url=https://www.nobelprize.org/nobel_prizes/medicine/laureates/1945/press.html|work=Nobel Prizes and Laureates|publisher=Nobel Media|access-date=26 May 2014|archive-date=27 May 2014|archive-url=https://web.archive.org/web/20140527212423/http://www.nobelprize.org/nobel_prizes/medicine/laureates/1945/press.html|url-status=live}}</ref> His work was expanded by a team at Oxford University: Clutterbuck, Lovell, and Raistrick, who began to work on the problem in 1931. This team was also unable to produce the pure compound in large amounts, and found that the purification process diminished its effectiveness and negated its anti-bacterial properties.<ref name=TNPM/>

[[Howard Florey]], [[Ernst Chain]], [[Norman Heatley]], [[Edward Abraham]], also all at Oxford, continued the work.<ref name=TNPM/> They enhanced and developed the concentration technique by using organic solutions rather than water, and created the "Oxford Unit" to measure penicillin concentration within a solution. They managed to purify the solution, increasing its concentration by 45–50 times, and found that a higher concentration was possible. Experiments were conducted and the results published in 1941, though the quantities of penicillin produced were not always high enough for the treatments required.<ref name=TNPM/> As this was during the Second World War, Florey sought US government involvement. With research teams in the UK and some in the US, industrial-scale production of crystallized penicillin was developed during 1941–1944 by the [[USDA]] and by Pfizer.<ref name="The Nobel Prize website"/><ref>{{cite web | url =https://www.acs.org/content/acs/en/pressroom/newsreleases/2008/june/pfizers-work-on-penicillin-for-world-war-ii-becomes-a-national-historic-chemical-landmark.html | date =June 12, 2008 | title =Pfizer's work on penicillin for World War II becomes a National Historic Chemical Landmark | publisher =[[American Chemical Society]] | access-date =June 14, 2016 | archive-date =August 8, 2016 | archive-url =https://web.archive.org/web/20160808032624/https://www.acs.org/content/acs/en/pressroom/newsreleases/2008/june/pfizers-work-on-penicillin-for-world-war-ii-becomes-a-national-historic-chemical-landmark.html | url-status =live }}</ref>

Several [[statin]] cholesterol-lowering drugs (such as [[lovastatin]], from ''Aspergillus terreus'') are derived from molds.<ref name="CoxSimpson2010">{{cite book |last1=Cox |first1=Russell J. |title=Comprehensive Natural Products II |last2=Simpson |first2=Thomas J. |chapter=Fungal Type I Polyketides |year=2010 |page=355 |doi=10.1016/B978-008045382-8.00017-4 |quote=Lovastatin (also known as mevinolin) is produced by Aspergillus terreus|isbn=9780080453828 }}</ref>

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

==Health effects==
{{Main|Mold health issues}}

<!--WAIT: DON'T ADD INFORMATION HERE. SEE ARTICLE [[Mold health issues]] instead-->
Molds are [[Wiktionary:ubiquitous#Adjective|ubiquitous]], 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.<ref>{{Cite journal|last1=Gent|first1=Janneane F|last2=Ren|first2=Ping|last3=Belanger|first3=Kathleen|last4=Triche|first4=Elizabeth|last5=Bracken|first5=Michael B|last6=Holford|first6=Theodore R|last7=Leaderer|first7=Brian P|date=December 2002|title=Levels of household mold associated with respiratory symptoms in the first year of life in a cohort at risk for asthma.|journal=Environmental Health Perspectives|volume=110|issue=12|pages=A781–6|doi=10.1289/ehp.021100781|pmid=12460818|pmc=1241132|issn=0091-6765}}</ref>

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.<ref name="Toxicol Ind Health">{{Cite journal
| pmid = 19854819
| year = 2009
| last1 = Empting
| first1 = L. D.
| title = Neurologic and neuropsychiatric syndrome features of mold and mycotoxin exposure
| journal = Toxicology and Industrial Health
| volume = 25
| issue = 9–10
| pages = 577–81
| doi = 10.1177/0748233709348393
| bibcode = 2009ToxIH..25..577E
| s2cid = 27769836
}}</ref> Prolonged exposure, e.g., daily home exposure, may be particularly harmful. Research on the health impacts of mold has not been conclusive.<ref>{{cite book|last=Money|first=Nicholas|title=Carpet Monsters and Killer Spores: A Natural History of Toxic Mold|url=https://archive.org/details/monsterskillersp00mone|url-access=limited|year=2004|publisher=Oxford University Press|location=Oxford, UK|isbn=978-0-19-517227-0|pages=[https://archive.org/details/monsterskillersp00mone/page/n190 178]}}</ref> The term "toxic mold" refers to molds that produce mycotoxins, such as ''[[Stachybotrys chartarum]]'', and not to all molds in general.<ref name=niosh>[https://www.cdc.gov/niosh/topics/indoorenv/mold.html Indoor Environmental Quality: Dampness and Mold in Buildings] {{Webarchive|url=https://web.archive.org/web/20200507222501/https://www.cdc.gov/niosh/topics/indoorenv/mold.html |date=2020-05-07 }}. National Institute for Occupational Safety and Health. August 1, 2008.</ref>
[[File:Mold from a grapefruit.jpg|thumb|Mold on a grapefruit under the microscope]]Molds can also pose a hazard to human and animal health when they are consumed following the growth of certain mold species in stored food. Some species produce toxic secondary metabolites, collectively termed [[mycotoxin]]s, including [[aflatoxin]]s, [[ochratoxin]]s, [[fumonisin]]s, [[trichothecene]]s, [[citrinin]], and [[patulin]]. These toxic properties may be used for the benefit of humans when the toxicity is directed against other organisms; for example, [[penicillin]] adversely affects the growth of Gram-positive bacteria (e.g. [[Clostridium]] species), certain [[spirochetes]] and certain [[fungi]].<ref>Saunders Comprehensive Veterinary Dictionary, Blood and Studdert, 1999</ref>

==Growth in buildings and homes==
{{Main|Indoor mold|Indoor air quality}}
<!--WAIT: DON'T ADD INFORMATION HERE. SEE ARTICLE [[Indoor mold]] instead-->
[[File:Moldy Housecorner both Sides.jpg|thumb|upright=1.35|Moldy housecorner from outside and inside]]
Mold growth in buildings generally occurs as fungi colonize porous building materials, such as wood.<ref>{{cite web |last1=Fairey |first1=Philip |last2=Chandra |first2=Subrato |last3=Moyer |first3=Neil |title=Mold Growth |url=http://www.fsec.ucf.edu/en/consumer/buildings/basics/moldgrowth.htm |website=Florida Solar Energy Center |publisher=University of Central Florida |access-date=19 August 2019 |archive-date=27 August 2019 |archive-url=https://web.archive.org/web/20190827183935/http://www.fsec.ucf.edu/en/consumer/buildings/basics/moldgrowth.htm |url-status=live }}</ref> Many building products commonly incorporate paper, wood products, or solid wood members, such as paper-covered drywall, wood cabinets, and insulation. Interior mold colonization can lead to a variety of health problems as microscopic airborne reproductive spores, analogous to tree pollen, are inhaled by building occupants. High quantities of indoor airborne spores as compared to exterior conditions are strongly suggestive of indoor mold growth.<ref>IICRC S500 Standard and Reference Guide for Professional Water Damage Restoration</ref> Determination of airborne spore counts is accomplished by way of an air sample, in which a specialized pump with a known flow rate is operated for a known period of time. To account for background levels, air samples should be drawn from the affected area, a control area, and the exterior.

The air sampler pump draws in air and deposits microscopic airborne particles on a culture medium. The medium is cultured in a laboratory and the fungal genus and species are determined by visual microscopic observation. Laboratory results also quantify fungal growth by way of a spore count for comparison among samples. The pump operation time is recorded and when multiplied by pump flow rate results in a specific volume of air obtained. Although a small volume of air is actually analyzed, common laboratory reports extrapolate the spore count data to estimate spores that would be present in a cubic meter of air.<ref>{{Cite web|url=http://prestige-em.com/tech/AirborneFungalSporesByCulture.htm|title=Prestige EnviroMicrobiology, Inc.|website=prestige-em.com|language=en|access-date=2018-03-26|archive-date=2017-03-01|archive-url=https://web.archive.org/web/20170301233659/http://prestige-em.com/tech/AirborneFungalSporesByCulture.htm|url-status=live}}</ref>

Mold spores are drawn to specific environments, making it easier for them to grow. These spores will usually only turn into a full-blown outbreak if certain conditions are met.<ref>{{Cite web|url=https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home|title=A Brief Guide to Mold, Moisture and Your Home|website=EPA|date=13 August 2014 }}</ref> 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.<ref name=niosh /> Air filtration reduces the number of spores available for germination, especially when a High Efficiency Particulate Air (HEPA) filter is used. A properly functioning AC unit also reduces the relative humidity in rooms.<ref>{{Cite web|url=https://www.aiha.org/publications-and-resources/TopicsofInterest/Hazards/Pages/Facts-About-Mold.aspx|title=Facts About Mold|website=www.aiha.org|language=en-us|access-date=2018-03-26}}</ref> The United States Environmental Protection Agency (EPA) currently recommends that relative humidity be maintained below 60%, ideally between 30% and 50%, to inhibit mold growth.<ref>{{Cite web|url=https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home|archive-date=January 6, 2020|archive-url=https://web.archive.org/web/20200106221435/https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home|title=A Brief Guide to Mold, Moisture and Your Home|website=US EPA|date=13 August 2014 }} Click on "Moisture and Mold Prevention and Control Tips".</ref>

Eliminating the moisture source is the first step at fungal remediation. Removal of affected materials may also be necessary for remediation, if materials are easily replaceable and not part of the load-bearing structure. Professional drying of concealed wall cavities and enclosed spaces such as cabinet toekick spaces may be required. Post-remediation verification of moisture content and fungal growth is required for successful remediation. Many contractors perform post-remediation verification themselves, but property owners may benefit from independent verification. Left untreated, mold can potentially cause serious cosmetic and structural damage to a property.<ref>{{Cite web|url=https://www.gtamoldremoval.com/mississauga.html|title=What is Mold?|website=gtamoldremoval.com|date=14 September 2024 }}</ref>

==Use in art==
{{See also|Fungi in art}}
Various artists have used mold in various artistic fashions. Daniele Del Nero, for example, constructs scale models of houses and office buildings and then induces mold to grow on them, giving them an unsettling, reclaimed-by-nature look.<ref>{{cite magazine |last1=Solon |first1=Olivia |title=Artist uses mould to create decayed architectural models |url=https://www.wired.co.uk/article/mould-art |magazine=Wired UK |access-date=19 August 2019 |date=30 November 2010 |archive-date=19 August 2019 |archive-url=https://web.archive.org/web/20190819232102/https://www.wired.co.uk/article/mould-art |url-status=live }}</ref> [[Stacy Levy]] sandblasts enlarged images of mold onto glass, then allows mold to grow in the crevasses she has made, creating a macro-micro portrait.<ref>{{cite web|title=The Art of Mould |url=http://discardstudies.com/2012/01/02/the-art-of-mould/ |website=Discard Studies |date=2 January 2012 |access-date=May 11, 2015}}</ref> [[Sam Taylor-Johnson]] has made a number of time-lapse films capturing the gradual decay of classically arranged still lifes.<ref>{{Cite web |title=Still Life, 2001 |url=http://samtaylorjohnson.com/moving-image/art/still-life-2001 |url-status=dead |archive-url=https://web.archive.org/web/20170324084911/http://samtaylorjohnson.com/moving-image/art/still-life-2001 |archive-date=2017-03-24 |access-date=2017-03-23 |website=Sam Taylor-Johnson}}</ref>

==See also==
{{Portal|Fungi}}
{{Div col}}
* {{annotated link|Bioaerosol}}
* {{annotated link|Decomposition|Decay}}
* {{annotated link|Indoor mold}}
* {{annotated link|Medicinal fungi}}
* {{annotated link|Mildew}}
* {{annotated link|Mold mite}}
* {{annotated link|Mycorrhiza}}
* {{annotated link|Oomycete}}
* [[Slime mold]]
* [[Water mold]]
{{div col end}}
{{Clear}}

==References==
{{Reflist|refs=
<ref name=malloch1981>{{cite book|last=Malloch|first=D.|title=Moulds : their isolation, cultivation and identification|year=1981|publisher=Univ. of Toronto Press|location=Toronto Canada|isbn=978-0-8020-2418-3|url=https://archive.org/details/mouldstheirisola0000mall|url-access=registration}}</ref>
}}

==External links==
{{Commons}}
* [https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home The EPA's guide to mold]

{{Fungus}}
{{Authority control}}

[[Category:Fungus common names]]
[[Category:Articles containing video clips]]