Microbiology of anaerobic ammonium oxidation (anammox)

minerbendBiotechnology

Feb 12, 2013 (4 years and 6 months ago)

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Microbiology of anaerobic ammonium oxidation (anammox)

Contact: prof.dr. J. Gijs Kuenen
Julianalaan 67, 2628 BC Delft
+31-15-278 5308
J.G.Kuenen@tnw.tudelft.nl
Institute: Delft University of Technology,
Department of Biotechnology,
Environmental Biotechnology Group



Description

The oxidation of
ammonium has long been
considered only possible
with oxygen: yielding nitrite
or nitrate as the final
product. The finding in the
nineties of the
disappearance of
ammonium in the absence
of oxygen in a reactor in
Delft therefore was an
indication for an unknown process. The process turned out to be biological and performed by
a bacteria from the rare order of the planctomycetes. In this reaction ammonium is combined
with nitrite to give nitrogen gas. A common characteristic of the anammox bacteria is the
presence of an extra membrane-surrounded intracellular compartment. In anammox, in this
organelle the energy generation takes place (see figure). Amongst the intermediates
surprisingly is hydrazine (N
2
H
4
), normally only known as a rocket fuel, and highly toxic to
most bacteria.
anammoxozome
cytoplasm
4e
NO
2
-
NH
2
OH
NH
4
+
N
2
H
4
N
2
C
atabolic reactions take place near the anammoxozome membrane
anammoxozome
cytoplasm
4e
NO
2
-
NH
2
OH
NH
4
+
N
2
H
4
N
2
C
atabolic reactions take place near the anammoxozome membrane

The cell wall of the anammoxosome is extremely dense, and contains ladderanes:
concatenated cyclobutane rings, that pack closely together.
The synthesis of these lipids remains unresolved and their
function speculatory.

The anammox process is wide distributed over the whole world
and plays an important role in the global nitrogen cycle. A
significant part of the denitrifying capacity of the seas comes to
the account of anaerobic ammonium oxidizers. It was detected
-amongst others- in the Black Sea, in the Golfo dulce (Mexico),
in the Skagerak, but also in arctic ice. Also the genetic diversity
is large. Up till now three mayor species can be distinguished:
Brocadia, Kuenenia and Scalindua.

Research at Delft University now focuses on the
application of
the anammox process in wastewater treatment
, whereas the
basic microbiological and biochemical anammox research is done in close collaboration with
the Radboud University Nijmegen.
Ladderane lipids in the
anammox membrane


References
Strous M, Fuerst JA, Kramer, EHM., Logemann S, Muyzer G., Van de Pas-Schoonen KT,
Webb,R, Kuenen JG & Jetten MSM (1999). Missing lithotroph identified as new
planctomycete. Nature (London) 400(6743) p446-449.

Sinninghe Damsté JS, Strous M, Rijpstra WIC, Hopmans EC, Geenevasen JAJ, van Duin
ACT, Van Niftrik, LA & Jetten MSM. (2002). Linearly concatenated cyclobutane lipids form a
dense bacterial membrane. Nature (London) 419(6908) p708-712.

Kuypers MMM, Sliekers AO, Lavik G, Schmid M., Jorgensen BB, Kuenen JG, Sinninghe
Damste JS, Strous M. & Jetten MSM. (2003). Anaerobic ammonium oxidation by anammox
bacteria in the Black Sea. Nature (London) 422(6932) p608-611.

Other webresources:

The Anammox online resource
Anammox research at R.U. Nijmegen