Denitrification and Anammox Flashcards
Describe the history of the discovery of anammox
1965- scientists can’t explain the disappearing ammonium in an anoxic Norwegian fjord study
1995- similar in lab bioreactor using undefined mixed population of microbes
1999- first anammox bacteria is finally enriched enough to be studied at the molecular level
What does anammox stand for?
Anaerobic ammonia oxidation
What is the first reaction anammox does?
NO2- + e- + 2H+ —-> NO + H2O
Nitrite reductase
What is the second reaction anammox does?
NO + NH4 + 2H+ + 3e- —–> N2H4 + H2O
Hydrazine hydrolase/synthase
What is the third reaction anammox does?
N2H4 —-> N2 + 4H+ + 4e-
Hydrazine octoreductase/dehydrogenase
Describe anammox’s cell wall
Proteinaceous ‘S layer’
Outer membrane
A very thin layer of peptidoglycan
Periplasm/paryphoplasm
Describe anammox’s riboplasm
Basically a cytoplasm Contains ribosomes Contains nucleoid 3.9 Mbp genome Carbon is store as glycogen
Describe anammox’s anammoxosome
Large membrane-bound organelle
Contains anammox enzymes
Protects riboplasm from NO and N2H4
Describe hydrazine dehydrogenase
Haem cofactors carrying and storing e-
24 identical subunits with 8 haem each
12 extra subunits
Hydrazine enters the central cavity
What is the first reaction P. stutzeri does?
NO3- + 2e- + 2H+ —-> NO2- + H2O
Nitrate reductase
What is the second reaction P. stutzeri does?
NO2- + e- + 2H+ —-> NO + H2O
Nitrite reductase
What is the third reaction P. stutzeri does?
2NO + 2e- + 2H+ —-> N2O + H2O
Nitric oxide reductase
What is the fourth reaction P. stutzeri does?
N2O + 2e- + 2H+ —-> N2 + H2O
Nitrous oxide reductase
Describe nitrous oxide reductase
2 copper cofactors (CuA and CuZ)
e- are moved from A to Z
Homodimerisation allows fast intermolecular e- transfer
What does nitric oxide dismutase do?
2NO—-> N2 + O2
