Search results
Results from the WOW.Com Content Network
In 1998, Jonathan Zehr, an ocean ecologist at the University of California, Santa Cruz, found an unknown DNA sequence that appeared to be for an unknown nitrogen-fixing cyanobacterium in the Pacific Ocean, which they called UCYN-A (unicellular cyanobacterial group A). [3]
Biological productivity (photosynthesis) in marine ecosystems is often limited by the bioavailability of nitrogen. [6]The amount of bioavailable nitrogen (nitrate (NO 3 −), nitrite (NO 2 −), and ammonium (NH 4 +)) depends on the inputs from nitrogen fixation and losses from denitrification and anammox as dinitrogen gas (N 2), a compound only accessible to nitrogen-fixing bacteria.
The ability to fix nitrogen in nodules is present in actinorhizal plants such as alder and bayberry, with the help of Frankia bacteria. They are found in 25 genera in the orders Cucurbitales, Fagales and Rosales, which together with the Fabales form a nitrogen-fixing clade of eurosids. The ability to fix nitrogen is not universally present in ...
Nitrogen enters the ocean through precipitation, runoff, or as N 2 from the atmosphere. Nitrogen cannot be utilized by phytoplankton as N 2 so it must undergo nitrogen fixation which is performed predominantly by cyanobacteria. [82] Without supplies of fixed nitrogen entering the marine cycle, the fixed nitrogen would be used up in about 2000 ...
Deep ocean water contains the largest reservoir of nitrogen available to hydrothermal vents, with around 0.59 mM of dissolved nitrogen gas. [24] [25] Ammonium is the dominant species of dissolved inorganic nitrogen, and can be produced by water mass mixing below hydrothermal vents and discharged in vent fluids. [25]
Trichodesmium is the only known diazotroph able to fix nitrogen in daylight under aerobic conditions without the use of heterocysts. [ 2 ] Trichodesmium can live as individual filaments, with tens to hundreds of cells strung together, or in colonies consisting of tens to hundreds of filaments clustered together. [ 3 ]
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc, Cylindrospermum, and Anabaena. [1] They fix nitrogen from dinitrogen (N 2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis. [2]