L34 nitrogen fixation

Question 1

Ammonium assimilation
input, output, catalyst, describe

Answer 1

NH4 => R-NH2

catalysed by GS/GOAT glutamine-glutamine oxoglucante aminoTransferase
input: ATP + NADPH
output: glutamate
very sensitive process functions at [low]

Question 2

What is nitrogen fixation
give an example and discuss the importance of nitrogen

Answer 2

• rN2 => NH4+ catalysed by nitrogenase
  examples:
  Rhizobium is symbiotic
  Rlebsiella is free living
• 79% of the atmosphere, we need it but only bacteria and archea can fix it
• high energy + high reduction power requiring 24ATP because we need to break the triple bond
• nitrogen fixation is balanced by denitrification

Question 3

Ammonification

Answer 3

R-NH2 => NH4
reverse ammonia assimilation, organic matter decomposition
many enzymes of plants, microbes, animals

Question 4

What is nitrification conditions and examples of bacteria and archaea that participate

Answer 4

turning nitrogen into different compounds
conditions: aerobic, anaerobic, micoaeorbic, autotrophic

Bacteria:
AOB, NOB, anammox, commamox

Archea: AOA like Nitrosphaertata thaumarcheota

Question 5

Draw the three graphs and explain upwelling

Answer 5

PN => NH4 => Nitrite NO2 => Nitrate NO3
oxidation = nitrification

nitrate upwelling in the deep oceans
decomposition => ammonium => nitrate

graph 1: temperature and oxygen
graph 2: dentri, amo, nitro in water space and microbial activity
graph 3: nitrate, nitrite, nitrogen, ammonium

Question 6

List types of nitrification

Answer 6

1. Ammonia oxidation
2. Nitrite oxidation
3. commanox => complete ammonia oxidation

Question 7

What is ammonium oxidation

Answer 7

NH4 => NO2- [ 274kj/ml]
catalyst: ammonium monooxygenase, there are similar monooxygenase
who: Nitrosomonas, Nitrosococcus, Nitrososphaerota (Thaumarchaeota)

Question 8

What is nitrite oxidation

Answer 8

NO2 => NO3- [-74]
using nitrite oxireductase
who: nitrospira, nitrospina

Question 9

complete ammonium oxidation

Answer 9

NH4+ => => NO3- [74 + 274]

noted in Nitrospira species in low O2 and low NH4+, before it was thought they only did NOB
*the key gene is amoA, that amoA of comommox is different and it cannot be amplified by regular amoA primers

Question 10

assimilatory nitrogen reduction

Answer 10

assimilatory nitrate reduction: NO3 => NO2
*inhibited by NH4 which is end product inhibition
*cells only need a little bit of N

assimilatory nitrite: NO2 => NH4
* GS/GOAT

Question 11

dissimilatory nitrogen reduction

Answer 11

anaerobic
dissimilatory nitrate reduction: NO3- => NO2-
* no end product inhibition because cells must continue to respirate even in presence of NH4+
*use NO3- as TEA when there is no O2 meaning facultaltive anaerobes

from that point denitrification will lead to N2 or N2O
otherwise end product can be NH4+ via DNRA

Question 12

Denitrification where, who, measureable

Answer 12

NO2 => N2O or N2
where: soil or water
who: anaerobic done by facultrive ana in special circumstances like floods

measure: measure N2O gas with a chromatograph and expose to C2H2 so that N2O doesn’t become N2 because that is undetectable

Question 13

What is DNRA what, conditions

Answer 13

type of ammoniaification it is dissimilatory nitrate reduction followed by nitrite ammonification
* highly polluted zones with high NO3-
*soil and water
*aerobic and anaerobic

Question 14

Anammox

Answer 14

NH4+ + NO2 => N2 or NO3 maybe
oxidation of NH4 oxidation with NO2
*anaeorbic waste water conditions, sedimenta
*mostly slow growing archea