Editing Mold (section)

==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 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 [[ecosystem]]s. Many molds also synthesize [[mycotoxin]]s and [[siderophore]]s which, 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 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 /> which 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, commonly seen 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]] at this temperature. When conditions do not enable growth to take place, molds may remain alive in a dormant state depending on the species, within a large range of temperatures. 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, 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>