Nitrogen

N-fixation

N2 to organic nitrogen

Ammonification

Organic-N to NH4+

Assimilation

NH4+ to Orgnaic -N

Anammox

NH4+ to N2 anaerobic oxidation

Nitrification

NH4 to NO3 aerobic oxidatio

Nitrate reduction

NO3- to NO@

Denitrification

NO3- to N2 (No.N2O) First step anaerobic respiration (Dissimilatory reduction of nitrate to ammonia. 

Major natural Nitrogen fixation

mostly biological fixation and a little lightning

Major  human nitrogen fixation source

Nitrogen fertilizer, nitrogen fixing crops, Fossil fuels in that order

What organisms are capable of nitrogen fixation 

cyanobacteria (aquatic) , Rhizobis (Land), Azobacter (Free living)

Positive factors of N2-fixation

PO4 and organic P,

Fe and Mo,

CH2O,

ATP,

LIght

Negatice factors of N2-Fixation

NH4+

Oxygen

Assimilation 

ammonia (NH3) to organic N in biota and detritus 

Step one of nitrification

One set of microorganism (Bacteria and Archaea) oxidize ammonia to nitrite. The ammonis is provided by bacteria that fix nitrogen gas N2

Step two of nitrification process

Nitrite is then oxydized to nitrate (NO3) by other bacteria

Denitrification 

Produces N2, NO, or N2O

Major bacteria responible for denitrification

Pseudomonas

Denitrification is affected by

organic carbon and nitrate concentrations

Why is sulfure based autotrophic denitrification most beneficial? 

Autotrophic denitirification (No organic carbon) 

Inorganic electron source: sulfure 

cost friendly 

byproduct is coal scrubbing and oil refinment 

Thiobacillus denitrification

gram neg

rod chape

anaerobic

pH 6-7

Chemolithotrophic

autotrophic denitrification