Nitrogen Metabolism
There is a topic In the 11th Ncert in chapter 12.
* Nitrogen Cycle
1. Nitrification Bacteria -
Nitrosomonas and Nitrococcus both are Chemoautotrophs Bacteria who do nitrification.
Nitrobactor is also a chemoautotroph nitrogen fixer bacteria
2. Denitrification
Pseudomonas And Thiobascillus
These are denitrifying bacteria.
3. Free-living aerobic Nitrogen fixer
Azobacter & Beijernikia
4. Free-living anaerobic Nitrogen fixer
Rhodospirillum and Baciilus
5. Free-living Nitrogen-fixing cynobacteria
Anabaena and Nostoc these are facultative anaerobic Blue green algae.
6. Symbiotic Biological Nitrogen Fixation
Rhizobium in Legume alpha-alpha
Frankia in Alegume plants
Note:- Rhizobium and frankia both are free - living in soil but they are symbiotic nitrogen fixer.
Here is Summary -
* Symbiotic biological nitrogen fixation
Several types of symbiotic biological nitrogen fixing associations are known.
The most prominent among them is the legume-bacteria relationship.
Species of rod-shaped Rhizobium has such relationship with the roots of
several legumes such as alfalfa, sweet clover, sweet pea, lentils, garden pea,
broad bean, clover beans, etc. The most common association on roots is
as nodules. These nodules are small outgrowths on the roots. The microbe,
Frankia, also produces nitrogen-fixing nodules on the roots of non-
leguminous plants (e.g., Alnus). Both Rhizobium and Frankia are free-
living in soil, but as symbionts, can fix atmospheric nitrogen.
Uproot any one plant of a common pulse, just before flowering. You
will see near-spherical outgrowths on the roots. These are nodules. If
you cut through them you will notice that the central portion is red or
pink. What makes the nodules pink? This is due to the presence of
leguminous haemoglobin or leg-haemoglobin.
Posts
