NITROGEN FIXATION

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Introduction

Most Abundant Essential Organic Component Primary Nutrient Green Plants Fixed Nitrogen ?? Nitrogen Fixing organisms

Diazatrophs

Prokaryotes

Nitrogen Cycle :

What it is ?

Relationship b/w Organic & Inorganic N2 Metabolism.

IAtmospheric Nitrogen

Breaking of N2 bonds Energy Two Ways :

Abiotic Fixation

Biological Fixation

Abiotic Fixation

Result : Nitrates Source: Lightening & Cosmic Radiations

Nitrogen+ Oxygen Nitrogen Oxides

(NO , NO2) Nitrogen Oxides + Water Nitric

Acid

Biological Fixation

Soil Microrganisms Water

Cyanobacteria

Green Sulfur Bacteria

Azotobacteraceae Rhizobia

Cyanobacteria:

Imp. In Carbon and Nitrogen Cycle

Utilize variety of inorganic and organic sources of combined nitrogen such as nitrate, nitrite, ammonium

Rhizobia & Flankia

SEHRISH KHAN

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.

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

Nitrification:-

Two step process; converts NH3/NH4+ to NO3.

In first step:- Nitrosomanas/nitrococcus (soil bacteria)

convert NH3 to NO2-.

In second step:- Nitrobacter converts NO2- to NO3-. Bacteria gain energy known as

( nitrifying bacteria).

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.

Ammonification:-

Many bacteria and fungi convert nitrogen into ammoniumNH4+ known as ammonification.

Converted ammmonia become available to take part in other biological processes.

Denitrification:-

‘Reduction of NO3+ N2 (anaerobic bacteria)’

Pseudomonas/Clostridium (anaerobic conditions)

Marine nitrogen fixation:-

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. 

CONCLUSION