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Presentation on theme: "NITROGEN FIXATION"— Presentation transcript:


2 Introduction  Most Abundant  Essential Organic Component  Primary Nutrient Green Plants  Fixed Nitrogen ??  Nitrogen Fixing organisms Diazatrophs Prokaryotes

3 Nitrogen Cycle :  What it is ?

4 Relationship b/w Organic & Inorganic N2 Metabolism. I Atmospheric Nitrogen

5  Breaking of N2 bonds Energy  Two Ways : Abiotic Fixation Biological Fixation

6 Abiotic Fixation  Result : Nitrates  Source: Lightening & Cosmic Radiations Nitrogen+ Oxygen Nitrogen Oxides (NO, NO2) Nitrogen Oxides + Water Nitric Acid



9 Biological Fixation Soil  Microrganisms Water Cyanobacteria Green Sulfur Bacteria AzotobacteraceaeRhizobia Frankia

10 Cyanobacteria:  Imp. In Carbon and Nitrogen Cycle  Utilize variety of inorganic and organic sources of combined nitrogen such as nitrate, nitrite, ammonium

11 Rhizobia & Flankia


13 Nitrogen cycle  Series of natural processes by which nitrogen passes through successive stations in air, soil, and organisms.  The atmospheric nitrogen occur in an inert form (N2)/can’t be used by most of the orangnims.  Atmospheric nitrogen is fixed by nitrogen cycle. Which principally invovles:- Nitrogen fixation. Nitrification. Assimilation. Ammonification. Dentrification.

14 Nitrogen fixation:-  Deposits into soil & surface water precipitation.  Once settled; undergo changes Conversion via Microorganisms: Bacteria in symbiotic relation with plants. Free aerobic bacteria/alga. Cyanobactetria

15 Nitrification:-  Two step process; converts NH3/NH4+ to NO3.  In first step:- Nitrosomanas/nitrococcus (soil bacteria) convert NH3 to NO2-.

16  In second step:- Nitrobacter converts NO2- to NO3-.  Bacteria gain energy known as ( nitrifying bacteria).

17 Assimilation:-  Process by which plants/animals take up nitrates and ammonia.  Plants take up NO3- and NH4+ through their roots and integrate them into various plant proteins /nucleic acids.  Animals take up this nitrogen by consuming plant tissues.

18 Ammonification:-  Many bacteria and fungi convert nitrogen into ammoniumNH4+ known as ammonification.  Converted ammmonia become available to take part in other biological processes.

19 Denitrification:-  ‘Reduction of NO3+ N2 (anaerobic bacteria)’  Pseudomonas/Clostridium (anaerobic conditions)


21 Marine nitrogen fixation:-

22 Ecological Implications of Human Alterrations to Nitrogen Cycle:-  Burning fossils fuels.  Primary productivity of many ecosystems.  Alterations in both aquatic/terrestrial ecosystems.  Argicultural systems (leach out of soil)  Haber-bosch process.  Anoxio/hypoxia.  Harmful algal blooms.  Change in boidiversty/overall ecosystem function.  Parasitic/infectious diseases (humans/wildlife).  Increased acidification in freshwater ecosystems.



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