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| Titel |
Isotope effects and O-exchange with water during N2O production by denitrifying fungi |
| VerfasserIn |
Lena Rohe, Gesche Braker, Reinhard Well, Anette Giesemann, Traute-Heidi Anderson, Nicole Wrage-Mönnig, Heinz Flessa |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250081349
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| Zusammenfassung |
| N2O from soil denitrification originates from bacteria and - to an unknown extent - also from
fungi. In pure culture studies, bacterial and fungal denitrification showed differences in
isotopomer ratios of N2O. Isotopomer ratios of N2O can be expressed as 15N site preference
(SP), i.e. the difference between δ15N of the central and terminal N-position of the
asymmetric N2O molecule and might be suitable to distinguish between bacterial and fungal
N2O under denitrifying soil conditions.
Oxygen exchange takes place between H2O and intermediates during the denitrification
process. Several studies showed that O-exchange of bacterial denitrifiers varies, but
information about fungal O-exchanges is lacking.
The objectives of the study presented are i) to verify SP of fungal N2O reported for two
strains from pure culture studies and ii) to analyze the oxygen exchange between
intermediates and H2O during denitrification in fungal pure cultures. Six different fungal pure
cultures known to be capable of denitrification were incubated under anaerobic conditions,
either with nitrite or nitrate. Gas samples were analysed for concentration and isotopic
signatures (SP, average δ15N, δ18O) of N2O. To investigate the oxygen exchange, both
treatments were also established in a tracer experiment where 18O-labelled water was used in
the medium.
The fungal strains evaluated so far indicate similar SP as reported previously. Concerning
the amount of N2O produced, the nitrite led to a higher yield than nitrate.
O-exchange with 18O-labelled water during fungal denitrification was visible. Using
nitrite, the exchange ranged amounted from 39% to full exchange while nitrate led to
exchange rates between 13% and full exchange. Detailed results will be presented. |
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