Mucilage

2025-05-07T13:35:36Z

1.53.74.83: /* Plant sources */

{{short description|Thick, gluey substance produced by nearly all plants and some microorganisms}}
{{Distinguish|mucigel}}
[[File:Drosera anglica ne4.jpg|thumb|upright=1.2|right|A [[sundew]] with a leaf bent around a fly trapped by mucilage]]
{{use dmy dates|date=April 2021}}

'''Mucilage''' is a thick gluey substance produced by nearly all [[plant]]s and some [[microorganism]]s. These microorganisms include [[protist]]s which use it for their locomotion, with the direction of their movement always opposite to that of the secretion of mucilage.<ref>{{cite news|url=http://www.biologydiscussion.com/protists/modes-of-locomotion-in-protists-5-modes/52116|title=Modes of Locomotion in Protists: 5 Modes|date=2016-09-06|work=Biology Discussion|access-date=2017-10-26|language=en-US|url-status=live|archive-url=https://web.archive.org/web/20171224225039/http://www.biologydiscussion.com/protists/modes-of-locomotion-in-protists-5-modes/52116|archive-date=2017-12-24}}</ref> It is a [[chemical polarity|polar]] [[glycoprotein]] and an [[exopolysaccharide]]. Mucilage in plants plays a role in the storage of [[water]] and [[food]], seed [[germination]], and thickening membranes. Cacti (and other [[Succulent plant|succulents]]) and [[flax]] seeds are especially rich sources of mucilage.<ref>{{cite web|url=http://www.sbs.utexas.edu/mauseth/weblab/webchap9secretory/9.1-2.htm|title=Mucilage cell, cactus|website=www.sbs.utexas.edu|access-date=2017-10-26|url-status=live|archive-url=https://web.archive.org/web/20170615085638/http://www.sbs.utexas.edu/mauseth/weblab/webchap9secretory/9.1-2.htm|archive-date=2017-06-15}}</ref>

== Occurrence ==

Exopolysaccharides are the most stabilising factor for [[Soil horizon#Diagnostic surface horizons of mineral soils|microaggregates]] and are widely distributed in [[soil]]s. Therefore, exopolysaccharide-producing "soil [[algae]]" play a vital role in the [[ecology]] of the world's soils. The substance covers the outside of, for example, [[unicellular]] or [[Filamentation|filamentous]] [[green algae]] and [[cyanobacteria]]. Amongst the green algae especially, the group [[Volvocales]] are known to produce exopolysaccharides at a certain point in their [[biological life cycle|life cycle]]. It occurs in almost all plants, but usually in small amounts. It is frequently associated with substances like [[tannin]]s and [[alkaloid]]s.<ref>{{cite book |editor-last=Paul |editor-first=Eldon A. |date=2006 |title=Soil Microbiology, Ecology and Biochemistry |url=https://books.google.com/books?id=gk1KRzYtxfYC |publisher=Academic Press |edition=3rd |page=33 |isbn=9780080475141 |url-status=live |archive-url=https://web.archive.org/web/20171224225039/https://books.google.com/books?id=gk1KRzYtxfYC&printsec=frontcover |archive-date=2017-12-24 }}</ref>

Mucilage has a unique purpose in some [[carnivorous plant]]s. The plant [[Genus|genera]] ''[[Drosera]]'' (sundews), ''[[Pinguicula]]'' (butterworts), and others have leaves studded with mucilage-secreting glands, and use a "[[Carnivorous plant#Flypaper traps|flypaper trap]]" to capture insects.<ref>{{cite web|url=http://www.carnivorousplants.org/cp/TrappingMechanisms.php|title=Carnivorous Plant Trapping Mechanisms|website=International Carnivorous Plant Society|access-date=29 March 2016|url-status=live|archive-url=https://web.archive.org/web/20160406144219/http://www.carnivorousplants.org/cp/TrappingMechanisms.php|archive-date=6 April 2016}}</ref>

== Human uses ==
[[File:MODOMucilage.jpg|thumb|Glass container for mucilage, from the first half of the 20th century]]
Mucilage is edible. It is used in [[medicine]] as it relieves irritation of mucous membranes by forming a protective film. It is known to act as a soluble, or viscous, [[dietary fiber]] that thickens the fecal mass, an example being the consumption of fiber supplements containing [[psyllium]] seed husks.<ref name=IOM>{{cite book |last1=Institute of Medicine |title=Dietary Reference Intakes: Proposed Definition of Dietary Fiber |date=2001 |publisher=National Academy Press| location=Washington, D.C. |isbn=978-0-309-07564-0 |page=19 |url=https://www.nap.edu/catalog/10161/dietary-reference-intakes-proposed-definition-of-dietary-fiber}}</ref>

The [[Bark (botany)|inner bark]] of the [[Ulmus rubra|slippery elm (''Ulmus rubra'')]], a North American tree species, has long been used as a [[demulcent]] and cough medicine, and is still produced commercially for that purpose.<ref>{{cite web |url=https://umm.edu/health/medical/altmed/herb/slippery-elm |title=Slippery Elm |publisher=University of Maryland Medical Center |url-status=live |archive-url=https://web.archive.org/web/20151117025939/https://umm.edu/health/medical/altmed/herb/slippery-elm |archive-date=2015-11-17}}</ref>

Mucilage mixed with water has been used as a [[glue]], especially for bonding paper items such as labels, [[postage stamp]]s, and envelope flaps.<ref>{{cite news |last=Spitzenberger |first=Ray |date=23 August 2007 |title=Glue, Paste or Mucilage: Know the Difference? |url=https://news.google.com/newspapers?nid=2235&dat=20070823&id=yYdWAAAAIBAJ&pg=1895,2656822&hl=en |newspaper=East Bernard Express |location=East Bernard, TX |access-date=29 March 2016}}</ref>
Differing types and varying strengths of mucilage can also be used for other adhesive applications, including gluing labels to metal cans, wood to china, and leather to pasteboard.<ref>{{cite book |last=Dawidowsky |first=Ferdinand |title=Glue, Gelatine, Animal Charcoal, Phosphorus, Cements, Pastes, and Mucilage |year=1905 |publisher=Henry Carey Baird & Co. |isbn=978-1-113-00611-0 |pages=1}}</ref> During the fermentation of [[nattō]] [[soybean]]s, extracellular enzymes produced by the [[bacterium]] ''[[Bacillus natto]]'' react with soybean sugars to produce mucilage. The amount and viscosity of the mucilage are important nattō characteristics, contributing to nattō's unique taste and smell.

The mucilage of two kinds of [[insectivorous plant]]s, [[Drosera|sundew (''Drosera'')]]<ref name=powo>{{cite web |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30001036-2 |work=Plants of the World Online |title=Drosera L. |access-date=2023-03-16 |publisher=Royal Botanic Gardens, Kew |language=English }}</ref> and [[Pinguicula|butterwort (''Pinguicula'')]],<ref>{{cite journal |year=2002 |title=Filmjölk från Linnés tid |journal=Verumjournalen |volume=2002 |pages=10 |url=http://www.verum.se/verumjournalen/Verumjournalen_2002.pdf#page=10 |language=sv |format=PDF |access-date=2007-07-18}} {{dead link|date=December 2017 |bot=KAP03 |fix-attempted=yes}}</ref> is used for the traditional production of a variant of the [[yogurt]]-like [[Sweden|Swedish]] dairy product called [[filmjölk]].<ref>{{cite book |last = Östman |first = Elisabeth |title = Iduns kokbok |chapter-url =https://runeberg.org/idunskok/0165.html |access-date = 2007-07-18 |publisher = Aktiebolaget Ljus, Isaac Marcus' Boktryckeriaktiebolag |location = Stockholm |language = sv |chapter = Recept på filmjölk, filbunke och långmjölk |page = 161 |year = 1911 |url-status = live |archive-url = https://web.archive.org/web/20081029081321/http://runeberg.org/idunskok/0165.html |archive-date = 2008-10-29}}</ref><ref name="jarnriket">
{{cite web |url=http://www.jarnriket.com/bergsman/ramdokument/21-051_mjoelken.htm |title=Vad gjorde man med mjölken? |access-date=2007-08-05 |publisher=Järnriket Gästrikland, Länsmuseet Gävleborg |language=sv |archive-url=https://web.archive.org/web/20070322031437/http://www.jarnriket.com/bergsman/ramdokument/21-051_mjoelken.htm  |archive-date=2007-03-22}}</ref>

== Ecological implications for plants ==
The presence of mucilage in seeds affects important ecological processes in some plant species, such as tolerance of water stress, competition via [[allelopathy]], or facilitation of germination through attachment to soil particles.<ref>{{Cite journal|last1=Harper|first1=J. L.|last2=Benton|first2=R. A.|date=1966-01-01|title=The Behaviour of Seeds in Soil: II. The Germination of Seeds on the Surface of a Water Supplying Substrate|jstor=2257664|journal=Journal of Ecology|volume=54|issue=1|pages=151–166|doi=10.2307/2257664|bibcode=1966JEcol..54..151H }}</ref><ref>{{Cite journal|last1=Hasegawa|first1=K.|last2=Mizutani|first2=J.|last3=Kosemura|first3=S.|last4=Yamamura|first4=S.|date=1992-10-01|title=Isolation and identification of lepidimoide, a new allelopathic substance from mucilage of germinated cress seeds|journal=Plant Physiology|volume=100|issue=2|pages=1059–1061|issn=0032-0889|pmc=1075667|pmid=16653018|doi=10.1104/pp.100.2.1059}}</ref><ref>{{Cite journal|last1=Lu|first1=Juanjuan|last2=Tan|first2=Dunyan|last3=Baskin|first3=Jerry M.|last4=Baskin|first4=Carol C.|date=2010-06-01|title=Fruit and seed heteromorphism in the cold desert annual ephemeral Diptychocarpus strictus (Brassicaceae) and possible adaptive significance|journal=Annals of Botany|volume=105|issue=6|pages=999–1014|doi=10.1093/aob/mcq041|issn=0305-7364|pmc=2876001|pmid=20348559}}</ref> Some authors have also suggested a role of seed mucilage in protecting [[DNA]] material from [[irradiation]] damage.<ref>{{Cite journal|last1=Yang|first1=Xuejun|last2=Zhang|first2=Wenhao|last3=Dong|first3=Ming|last4=Boubriak|first4=Ivan|last5=Huang|first5=Zhenying|date=2011-09-02|title=The Achene Mucilage Hydrated in Desert Dew Assists Seed Cells in Maintaining DNA Integrity: Adaptive Strategy of Desert Plant Artemisia sphaerocephala |journal=PLOS ONE |volume=6 |issue=9 |pages=e24346 |doi=10.1371/journal.pone.0024346 |issn=1932-6203 |pmc=3166310|pmid=21912689 |bibcode=2011PLoSO...624346Y|doi-access=free}}</ref> The amount of mucilage produced per seed has been shown to vary across the [[distribution range]] of a species, in relation with local environmental conditions of the populations.<ref>{{cite journal |last1=Villellas |first1=J. |last2=García |first2=M. B. |date=2013-09-01 |title=The role of the tolerance–fecundity trade-off in maintaining intraspecific seed trait variation in a widespread dimorphic herb |journal=Plant Biology |language=en |volume=15 |issue=5 |pages=899–909 |doi=10.1111/j.1438-8677.2012.00684.x |pmid=23126286 |bibcode=2013PlBio..15..899V |issn=1438-8677 |hdl=10261/87756 |url=https://digital.csic.es/bitstream/10261/87756/1/Villellas%20_Garcia_role%20of%20the%20tolerance-fecundity_PlantBiology2013.pdf|hdl-access=free }}</ref>

A variety of [[maize]] grows [[aerial roots]] that produce a sweet mucus. The [[Sierra Mixe corn|Sierra Mixe]] is a tall variety that survives in poor soils without [[fertilizer]] in [[Oaxaca|Oaxaca, Mexico]], and the mucilage has been shown to support [[nitrogen fixation]] through [[bacteria]] that thrive in its high-[[sugar]], low-[[oxygen]] environment.<ref name="Smithsonian20180810">{{cite magazine |issn=0037-7333 |magazine=[[Smithsonian Magazine]] |title=The Corn of the Future Is Hundreds of Years Old and Makes Its Own Mucus |url=https://www.smithsonianmag.com/science-nature/corn-future-hundreds-years-old-and-makes-its-own-mucus-180969972/ |given=Jason |surname=Daley |date=10 August 2018}}</ref>

== Plant sources ==
The following plant and algae species are known to contain far greater concentrations of mucilage than typical:
{{div col|colwidth=20em}}
* ''[[Aloe vera]]''
* ''[[Watershield]]''
* [[Althaea (plant)|Althaea]]
* ''[[Basella alba]]'' (Malabar spinach)
* [[Cactus]]
* ''[[Chondrus crispus]]'' (Irish moss)
* ''[[Corchorus]]'' (jute plant)
* ''[[Dioscorea polystachya]]'' (nagaimo, Chinese yam)
* ''[[Drosera]]'' (sundews)
* ''[[Drosophyllum lusitanicum]]''
* [[Fenugreek]]
* [[Flax]] seeds
* [[Kelp]]
* [[Liquorice]] root
* [[Malvaceae|Mallow]]
* [[Verbascum|Mullein]]
* [[Okra]]
* [[Nopal]]
* ''[[Parthenium]]''
* ''[[Pinguicula]]'' (butterwort)
* ''[[Plantago major]]'' (greater plantain)
* ''[[Psyllium]]'' seed husks
* ''[[Salvia hispanica]]'' seed (chia)
* ''[[Talinum triangulare]]'' (waterleaf)
* [[Taro]]
* ''[[Ulmus rubra]]'' bark (slippery elm)
{{div col end}}

== See also ==
{{portal|Plants}}
* {{annotated link|Marine mucilage|aka=sea snot}}

== References ==
{{Reflist}}

== External links ==
{{Wiktionary}}
*[https://www.encyclopedia.com/plants-and-animals/botany/botany-general/mucilage#mucilage Mucilage] Columbia Encyclopedia, Sixth Edition (2007).
*{{Cite EB1911|wstitle=Mucilage|volume=18|page=954}}

{{Authority control}}

[[Category:Adhesives]]
[[Category:Carnivorous plants]]
[[Category:Polysaccharides]]

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Mucilage