Nostoc commune Vaucher
Higher order taxa: Bacteria, Cyanobacteria, Nostocaceae.
Nostoc commune Vaucher is the type species of the genus Nostoc belonging to the cyanobacteria (former blue algae). It is a colonial species forming long strings of cells (trichomes) embedded in a protective gelatinous mass including extracellular polysaccharides playing a crucial role in resistance to adverse conditions. At the ends of the strings or inside between the ordinary cells, some larger specialist cells may be found: the heterocysts. They synthesize an enzyme allowing them to fix nitrogen from the atmosphere so that the Nostocs can thrive and survive in very diverse types of locations, including the most extreme. During dry periods, the dessicated colonies usually go unnoticed on the ground or on their substratum and remain dormant. When climatic conditions become favourable, they undergo a rehydration process and adopt a gelatinous aspect. One of the attribute of Nosctocs is their ability to act as photobiont in lichens. In such circumstances they are visible to the naked eyes as small gelatinous masses, cephalodia, or free on or nearby they hosts. Very common on bare grounds, sandy soils in dunes, dirt pathes and tracks, etc. but only distinctly visible in wet conditions.*
Additional information available: TAMARU Y., TAKANI Y. YOSHIDA T., SAKAMOTO T. Crucia Role of Extracellular Polysaccharides in Dessication and Freezing Tolerance in the Terrestrial Cyanobacterium Nostoc commune. Applied and Environnemental Microbiology. 2005. p. 7327-7333.