Mucilage is a thick gluey substance produced by nearly all
plants and some
microorganisms. These microorganisms include
protists which use it for their locomotion. The direction of their movement is always opposite to that of the secretion of mucilage.[1] It is a
polarglycoprotein and an
exopolysaccharide. Mucilage in plants plays a role in the storage of
water and
food, seed
germination, and thickening membranes. Cacti (and other
succulents) and
flax seeds are especially rich sources of mucilage.[2]
Occurrence
Exopolysaccharides are the most stabilising factor for
microaggregates and are widely distributed in
soils. 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
filamentousgreen algae and
cyanobacteria. Amongst the green algae especially, the group
Volvocales are known to produce exopolysaccharides at a certain point in their
life cycle. It occurs in almost all plants, but usually in small amounts. It is frequently associated with substances like
tannins and
alkaloids.[3]
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.[5]
Mucilage mixed with water has been used as a
glue, especially for bonding paper items such as labels,
postage stamps, and envelope flaps.[7]
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.[8] During the fermentation of
nattōsoybeans, extracellular enzymes produced by the
bacteriumBacillus 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 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.[13][14][15] Some authors have also suggested a role of seed mucilage in protecting
DNA material from
irradiation damage.[16] 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.[17]
^Dawidowsky, Ferdinand (1905). Glue, Gelatine, Animal Charcoal, Phosphorus, Cements, Pastes, and Mucilage. Henry Carey Baird & Co. p. 1.
ISBN978-1-113-00611-0.
^"Drosera L."Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 16 March 2023.
^Östman, Elisabeth (1911).
"Recept på filmjölk, filbunke och långmjölk". Iduns kokbok (in Swedish). Stockholm: Aktiebolaget Ljus, Isaac Marcus' Boktryckeriaktiebolag. p. 161.
Archived from the original on 29 October 2008. Retrieved 18 July 2007.
^Harper, J. L.; Benton, R. A. (1 January 1966). "The Behaviour of Seeds in Soil: II. The Germination of Seeds on the Surface of a Water Supplying Substrate". Journal of Ecology. 54 (1): 151–166.
doi:
10.2307/2257664.
JSTOR2257664.