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Nostoc

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Nostoc
Photo of N. azollae
Scientific classification
Kingdom:
Bacteria
Division:
Cyanobacteria
Class:
see taxonomic note
Order:
Nostocales
Family:
Nostocaceae
Genus:
Nostoc
Species

See text.

Nostoc is a genus of fresh water cyanobacteria that forms spherical colonies composed of filaments of moniliform cells in a gelatinous sheath. When 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, whence the popular names, fallen star and star jelly. It is also called witches' butter (not to be confused with the fungus Tremella mesenterica). Michael Quinion of the World Wide Words newsletter says that it is known in Welsh as pwdre sêr, or rot of the stars.[1]

Nostoc can be found on moist rocks, at the bottom of lakes and springs, and rarely in marine habitats. It may also grow symbiotically within the tissues of plants, such as the aquatic fern Azolla (mosquito fern) or hornworts, providing nitrogen to its host. 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:

Culinary use

Containing protein and vitamin C,[citation needed] 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.[2]

References

  1. ^ Weird Words: Nostoc on World Wide Words
  2. ^ The standard.com.hk
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