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nitrogen fixation
Hi Folks,
Some thoughts on Nitrogen fixation...
1. Nitogen fixation is a VERY expensive process for bacteria to
perform. They would rather get their nitrogen from urea or ammonia
rather than fromt he air. The primary organisms on the planet that go
through nitrogen fixation are the cyanobacteria (the pretty blue-green
buddies in our tanks) and the ones that make root-nodules on plants.
Bacteria cannot fix nitrogen unless they are able to complete seperate
themselves from their outside environment. Cyanobacteria have to make
modifications of their cell walls to prevent ANY O2 from getting into
the cell. Bacteria (Rhizobium) in the root nodules of bean plants have
to produce chemicals that remove all O2 and they have to live in
specialized tissues made by the plants and the bacteria! As you can
see, this is not a process that is easy. Besides theys spturcutres many
different enymes need to be produced by the bacteria and alot of energy
must be expended for the process to work.
2. Free amino acids have always been present. Someone pointed out that
there has been amino acids around for a long time. Lightning is able to
convert free N2 into NH3 and NH4 within the atmosphere and this was
probably some of the first amine groups created. These compounds are
rarely COMPLETELY broken down by cells. Amino acids are usually broken
down to urea or ammonia...but no further..the amine is too expensive to
destroy!
That is all....I am sure that you now know more that you ever wanted to
know about nitrogen fixation :)
John
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jdavis at bio_tamu.edu
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