AZOTO
C, H, N, O compongono 96% del
materiale vivente
78% aria (in peso)
secondo elemento piu’ abbondante nel
corpo umano
Fissazione dell’azoto di tipo biologico
•Batteri simbionti (associati alle radici delle leguminose)
Rhizobium
•Batteri “liberi” nel suolo (Azotobacter)
arricchimento di azoto (NH4+) nel terreno
NITRIFICAZIONE
conversione ammonio  nitrato
“ossidazione” in terreni aerati
Nitrosomonas NH3  NO2Nitrobacter NO2-  NO3-
AMMONIFICAZIONE
conversione nitrato  ammonio
Nitrato: azoto biodisponibile per eterotrofi (aa e acidi
nucleici)
Azione dei funghi decompositori
DENITRIFICAZIONE
conversione nitrato  azoto N2
Pseudomonas
Did you know?
1.That most of the air we breathe is made by anammox bacteria?
2.That anammox bacteria divide only once per two weeks at
maximum speed?
3.That hydrazine (rocket fuel) and nitric oxide are the anammox
intermediates?
4.That these intermediates are turned over in an organelle surrounded
by an impermeable membrane made of ladderane lipids?
5.That anammox bacteria share a common ancestor with the parasitic
chlamydia?
6.That you can download the anammox genome HERE?
Partial nitrification/Anammox® is a new method for nitrogen removal
from wastewater. It targets wastewater streams (or gases) high in
ammonium (>0.2 g/l) and low in organic carbon (C:N ratio lower than
0.15). The two processes proceed as follows:
(partial nitrification) 2NH4+ + 1.5O2 => NH4+ + NO2- + H2O + 2H+
(anammox) NH4+ + NO2- => N2 + 2H2O
(total) 2NH4+ + 1.5O2 =>N2 + 3H2O + 2H+
(the produced acid is balanced by the counter-ion of ammonium, usually
bicarbonate or sulfide)
STECHIOMETRIA:
1 NH4+ + 1.32 NO2- +
0.066 HCO3- + 0.13 H+
=
1.02 N2 + 0.26 NO3- + 0.066 CH2O0.5N0.15 + 2.03 H2O
Optimum:
6°C<T<43°C
6.7<pH<8.3
DO<0.5%
NO2- <20mM
anammox process is based on energy conservation from anoxic
ammonium oxidation with nitrite as the electron acceptor and hydrazine
as the intermediate.
CO2 is used as the main carbon source for growth. Recently we learned
that CO2 fixation is accomplished via the acetyl-CoA pathway.
The necessary electrons are obtained from the anaerobic oxidation of
nitrite to nitrate
anammox mechanism with
hydrazine and nitric oxides as
intermediates;
reversed electron transport to
upgrade electrons from nitrite
oxidation to drive anammox
carbon fixation via the acetyl
CoA pathway
planctomycetes
They lack the otherwise universal
bacterial cell wall polymer
peptidoglycan, they divide by budding,
and they have a differentiated
cytoplasm.. They are separated from
other bacteria and amongst themselves
by large evolutionary distances. Other
species of planctomycetes are aerobic
chemoorganoheterotrophs, very different
from the anammox bacteria
The first full scale anammox reactor,
Rotterdam, the Netherlands. It works
at design load and removes over 500
kg N/day