Nostoc

Nostoc
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Photo of N. azollae
Scientific classification
Kingdom:	Bacteria
Phylum:	Cyanobacteria
Class:	see taxonomic note
Order:	Nostocales
Family:	Nostocaceae
Genus:	Nostoc
Species
N. azollae N. caeruleum N. carneum N. comminutum N. commune N. ellipsosporum N. flagelliforme N. linckia N. longstaffi N. microscopicum N. muscorum N. paludosum N. pruniforme N. punctiforme N. sphaericum N. sphaeroides N. spongiaeforme N. verrucosum

Nostoc is a genus of cyanobacteria found in a variety of environmental niches that forms colonies composed of filaments of moniliform cells in a gelatinous sheath.

The name Nostoc was coined by Paracelsus. It derives from the ancient Greek word "nόsos" (νόσος, "disease" or "sickness").

Nostoc can be found in soil, on moist rocks, at the bottom of lakes and springs (both fresh- and saltwater), and rarely in marine habitats. It may also grow symbiotically within the tissues of plants, such as the evolutionarily ancient angiosperm Gunnera and the hornworts (a group of bryophytes), providing nitrogen to its host through the action of terminally differentiated cells known as heterocysts. These bacteria contain photosynthetic pigments in their cytoplasm to perform photosynthesis.

Species

Nostoc pruniforme

Nostoc is a member of the family Nostocaceae of the order Hormogonales. Species include:

• N. azollae
• N. caeruleum
• N. carneum
• N. comminutum
• N. commune, Koxianmi (Chinese)
• N. ellipsosporum
• N. flagelliforme
• N. linckia
• N. longstaffi
• N. microscopicum
• N. muscorum
• N. paludosum
• N. pruniforme
• N. punctiforme
• N. sphaericum
• N. sphaeroides
• N. spongiaeforme
• N. verrucosum

Non-scientific nomenclature

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, star jelly, troll’s butter, witch's butter (not to be confused with the fungus Tremella mesenterica), and witch’s jelly.

Michael Quinion of the "World Wide Words" newsletter says that it is known in Welsh as pwdre sêr (rot of the stars). It is also known as pydredd sêr (star-slime).

Culinary use

Containing protein and vitamin C, Nostoc species are cultivated and consumed as a foodstuff, primarily in Asia. The N. flagelliforme and N. commune varieties are consumed in China, Japan and Java, N. commune is also consumed in the Andes. The preferred variety in Central Asia is N. ellipsosporum.

A research team from the biochemistry department of the Chinese University of Hong Kong said that international research has shown that fat choy (Nostoc flagelliforme), besides having no nutritional value, has also been found to contain Beta-methylamino L-alanine (BMAA), a toxic amino acid that could affect the normal functions of nerve cells. Professor Chan King-ming of the team told the media that eating fat choy could lead to degenerative diseases such as Alzheimer's, Parkinson's, and dementia. While all cyanobacteria produce BMAA, the beneficial compounds may override any toxic effects.

References

• http://www.microscopyu.com/galleries/confocal/nostoc.html
• http://www.yourdictionary.com/ahd/n/n0171000.html
• http://www.glerl.noaa.gov/seagrant/GLWL/Algae/Cyanophyta/Cyanophyta.html
• http://machaut.uchicago.edu/cgi-bin/WEBSTER.sh?WORD=nostoc 1913 Webster's Dictionary
• Davidson, Alan. Oxford Companion to Food (1999), "Nostoc". ISBN 0-19-211579-0

External links

• Nostoc spec. in lichens