Dictionary > Diazotroph

Diazotroph

Definition
noun, plural: diazotrophs
A microorganism capable of assimilating and fixing atmospheric nitrogen (N2)
Supplement
Nitrogen in the atmosphere cannot be used directly by most organisms except for certain bacteria and archaea. These bacteria and archaea capable of assimilating and fixing atmospheric nitrogen (N2) through natural means are referred to as diazotrophs. They make use of iron-molybdenum or –vanadium nitrogenase systems to fix atmospheric nitrogen and produce new nitrogen compounds that are more readily available for use by other organisms, such as plants.
Some diazotrophs are free-living whereas others are in symbiotic relationship with other organisms. Examples of free-living diazotrophs are as follows:

  • anaerobic diazotrophs such as Clostridium spp.
  • facultative diazotrophs such as Klebsiella pneumoniae, Paenibacillus polymyxa, Bacillus macerans, and Escherichia intermedia
  • aerobic diazotrophs such as Azotobacter vinelandii
  • oxygenic photosynthetic diazotrophs, e.g. Anabaena cylindrica, Nostoc commune
  • anoxygenic photosynthetic diazotrophs, e.g. Rhodobacter sphaeroides, Rhodopseudomonas palustris, Rhodobacter capsulatus

Diazotrophs that are in symbiosis with other organisms are as follows:

  • Rhizobia species in the root nodules of leguminous plants (Fabaceae family)
  • Frankias species in the Actinorhizal nodules
  • Cyanobacteria in symbiosis with lichens, liverworts, ferns, and cycads
  • Word origin: diazo-, from Greek di- (two) + azo (from French azote nitrogen) + -troph, from Greek trophikós (pertaining to food or nourishment)
    See also:


    You will also like...

    Selective Breeding
    Selective Breeding

    Gregor Mendel's studies into Monohybrid and Dihybrid crossing and Charles Darwin's study of evolution and natural select..

    An artistic depiction of Dunkleosteus fish
    Fish

    The sea was teeming with life. Eventually, through reproduction and continued variation, fish came about. There are over..

    green plant cells
    Plant Cells vs. Animal Cells

    Plant cells have plastids essential in photosynthesis. They also have an additional layer called cell wall on their cell..

    Early Mammals on Earth
    Early Mammals on Earth

    The Earth's ecosphere was rapidly changing and throwing up a wide range of ecological niches that new adaptive organisms..

    Hormone Production
    Hormone Production

    Hormones are chemical messengers produced by specialized glands and they were produced by switching on the genes designe..

    "Cronopio dentiacutus", a prehistoric mammal (an illustration)
    Mammalian Ancestors

    Mammals are a diverse group of organisms, where most of them develop their offspring within the uterus of the mother. Ov..

    Related Articles...

    No related articles found

    See all Related Topics