Nostoc

Nostoc are a genus of Gram-negative photosynthetic cyanobacteria. Some species within the genus also have nitrogen-fixing 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 allow them to survive and thrive in a variety of conditions and habitats including 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 and 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. 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. 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. as well as all essential amino acids. It has been suggested to be anti-inflammatory and an antioxidant as well. Because of this, Nostoc has also been considered to be a strong candidate for extraterrestrial agriculture. == Human impact and management ==

'' overtaking a footbridge 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 of the order Nostocales. 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 (Linnaeus) Vaucher ex Bornet et Flahault • 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 thermotolerans • Nostoc verrucosum Vaucher ex Bornet et Flahault ==References==