''Nostoc'', also known as
star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as
witches' butter), and witch's jelly, is the most common genus of
cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...
found in a variety of both aquatic and terrestrial environments that may form
colonies
A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their '' metropole'' (or "mother country"). This separated rule was often or ...
composed of
filaments of
moniliform cells in a gelatinous sheath of polysaccharides.
It may also grow
symbiotically within the
tissues of
plant
Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
s, providing
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
to its host through the action of terminally differentiated cells known as
heterocysts
Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as ''Nostoc'', ''Cylindrospermum'', and '' Anabaena''. They fix nitrogen from dinitrogen (N2) in the air ...
. ''Nostoc'' is a genus that includes many species that are diverse in morphology, habitat distribution, and ecological function.
''Nostoc'' can be found in
soil
Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
, on moist rocks, at the bottom of
lake
A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...
s and springs, and rarely in marine habitats. It may also be found in terrestrial temperate, desert, tropical, or polar environments.
The name ''Nostoc'' was coined by
Paracelsus
Paracelsus (; ; 1493 – 24 September 1541), born Theophrastus von Hohenheim (full name Philippus Aureolus Theophrastus Bombastus von Hohenheim), was a Swiss physician, alchemist, lay theologian, and philosopher of the German Renaissance.
H ...
and is a combination of the English ''nost''ril and German ''Nasenloch'' "nose hole, nostril", likely due to appearance of many species colonies being similar to nasal mucus. When it is on the ground, a ''Nostoc'' colony is ordinarily not seen, but after a rain, it swells up into a conspicuous, jellylike mass, which was once thought to have fallen from the sky, hence the popular names, like
star jelly, troll's butter, and witch's butter mentioned above.
Morphology
''Nostoc'' are a genus of
Gram-negative
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...
photosynthetic
cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...
.
Many species of ''Nostoc'' possess an outer layer and extensive inner matrix of
polysaccharide
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...
s, giving them their "jelly-like" or gelatinous appearance, and also help to protect them from their environment and can assist in the absorption of moisture. This allows them to survive stressful conditions such as fluctuating temperatures, drought, salt stress, desiccation, UV radiation, and infection by pathogens.
Some species within the genus also have
nitrogen-fixing
Nitrogen fixation is a chemical process by which molecular dinitrogen () is converted into ammonia (). It occurs both biologically and abiological nitrogen fixation, abiologically in chemical industry, chemical industries. Biological nitrogen ...
heterocyst filaments enclosed in this membrane.
Many members of the ''Nostoc'' genus form colonies. These colonies can reach several centimeters in diameter.
These colonies consist of mats or gelatinous masses created by aggregated trichomes that can appear in a range of colors (depending on the species) such as brown, yellow, or green.
Additionally, some species of ''Nostoc'' are able to enter quiescent stages, further aiding in their survival of adverse conditions, and allowing them to resume metabolism when re-hydrated.
Ecology
Habitat and distribution
''Nostoc'' can be found in a variety of environments, both terrestrial and aquatic, depending on the species. Their polysaccharide outer layer and matrix allows them to survive and thrive in a variety of conditions and habits ranging from deserts, semideserts, grasslands, polar, and tropical regions depending on the particular species of ''Nostoc''.
In terms of aquatic environments, ''Nostoc'' has been documented to be naturally found in marine water, fresh water, as well as brackish water.
Interactions with other organisms
Depending on the species, ''Nostoc'' may either be free-living in their environment, or they may form relationships with the other organisms in their environment, such as plants, fungi, or other bacteria.
Because ''Nostoc'' is able to form colonies on the surface of bare minerals, it is able to provide a more stable environment for higher vegetation in its environment.
Some species of ''Nostoc'' also form relationships with plants that lack vascular tissue such as Bryophytes because of their ability to fix nitrogen. ''Nostoc'' has also been found to form
symbiotic associations and other relationships with other bacteria in their environment. Some species of ''Nostoc'' that form colonies in freshwater environments provide a habitat to other freshwater bacteria. Additionally, some species like ''
N. commune'' and ''
N. flageliforme'' form relationships with
heterotrophic bacteria and
actinobacteria present in their environments, likely due to the fact that they are a potential significant player in
nitrogen cycling in aquatic ecosystems.
Usage
Biotechnological usage
''Nostoc'' has been documented to produce many compounds of interest, including those that are antiviral, antitumor, antifungal, and antibacterial.
In addition to the suggested pharmaceutical usage, ''Nostoc'' has also been a suggested
biofertilizer, and source of
fatty acid
In chemistry, in particular in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated and unsaturated compounds#Organic chemistry, saturated or unsaturated. Most naturally occurring fatty acids have an ...
s for
biofuel
Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...
production.
Environmental usage
''Nostoc'' has the unique ability to survive and colonize new and bare mineral surfaces by moss and other higher plants, which then allows for more organic soil and stable vegetation. It has been suggested that ''Nostoc'' be used in environments of retreating glaciers in order to establish new and more stable presences of vegetation on newly exposed mineral surfaces.
Historical and culinary usage
''Nostoc'' has historically been utilized as a healthy food and traditional medicine, most notably in Asia
Historically, the species ''
N. flagelliforme'' and ''
N. commune'' have been consumed in China, where it was used to survive famines and has been used as an ingredient in Chinese medicine since the
Eastern Jin Dynasty.
Additionally, ''Nostoc'' has had documented culinary usage in India, Indonesia, Peru, Bolivia, and Ecuador.
''Nostoc'' is also highly nutritious, containing protein and
vitamin C
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription di ...
,
as well as all
essential amino acid
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life forms ...
s.
It has been suggested to be anti-inflammatory and an
antioxidant
Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...
as well.
Because of this, ''Nostoc'' has also been considered to be a strong candidate for extraterrestrial agriculture.
Human impact and management

Because of human foot traffic, and contaminated gardening tools and irrigation systems, ''Nostoc'' is usually found outside of its natural habitat in plant nurseries and greenhouses. A number of different control methods can be effective in removing unwanted ''Nostoc'' from these environments, including implementing increased drainage in these facilities, physical removal of ''Nostoc'', and flame weeders or solarization.
Taxonomy

''Nostoc'' is a member of the family
Nostocaceae
The Nostocaceae are a family of cyanobacteria that forms filamentation, filament-shaped colony (biology), colonies enclosed in mucus or a gelatinous sheath. Some genera in this family are found primarily in fresh water (such as ''Nostoc''), whil ...
of the order
Nostocales
The Nostocales are an order of cyanobacteria
Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (c ...
. Species include (see collapsed list on the right for full listing) :
*''
Nostoc azollae''
*''
Nostoc caeruleum'' Lyngbye ex Bornet et Flahault
*''
Nostoc carneum''
*''
Nostoc comminutum''
*''
Nostoc commune
''Nostoc commune'' is a species of cyanobacterium in the family Nostocaceae. Common names include star jelly, witch's butter, mare's eggs. It is the type species of the genus ''Nostoc'' and is cosmopolitan in distribution.
Description
''Nosto ...
'' (Linnaeus) Vaucher ex Bornet et Flahault
(
Chinese: ''Koxianmi'')
*''
Nostoc ellipsosporum''
*''
Nostoc flagelliforme''
*''
Nostoc linckia''
*''
Nostoc longstaffi''
*''
Nostoc microscopicum'' (Carmichael ex Harvey) Bornet et Flahault
*''
Nostoc muscorum''
*''
Nostoc paludosum''
*''
Nostoc pruniforme'' (Linnaeus) C. A. Agardh ex Bornet et Flahault
*''
Nostoc punctiforme''
*''
Nostoc sphaericum''
*''
Nostoc sphaeroides''
*''
Nostoc spongiaeforme
''Nostoc'', also known as star jelly, troll's butter, spit of moon, fallen star, witch's butter (not to be confused with the fungi commonly known as witches' butter), and witch's jelly, is the most common genus of cyanobacteria found in a varie ...
''
*''
Nostoc thermotolerans''
*''
Nostoc verrucosum
''Nostoc verrucosum'' is a species of cyanobacteria usually found in colonies and in globose racks. It has a greenish to blackish color. It grows in creek beds, shallow streams, waterfalls, and moist understory in rain forests, in alkaline soil a ...
'' Vaucher ex Bornet et Flahault
References
Citations
General sources
*
*
*Davidson, Alan. Oxford Companion to Food (1999), "Nostoc".
External links
* ''Nostoc'' spec. in lichens
*
{{Authority control
Nostocaceae
Cyanobacteria genera
Lichen photobiont