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| Titel |
The mechanism of oxygen isotopic fractionation during fungal denitrification - A pure culture study |
| VerfasserIn |
Nicole Wrage-Moennig, Lena Rohe, Traute-Heidi Anderson, Gesche Braker, Heinz Flessa, Annette Giesemann, Dominika Lewicka-Szczebak, Reinhard Well |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092843
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| Publikation (Nr.) |
 EGU/EGU2014-7207.pdf |
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| Zusammenfassung |
| Nitrous oxide (N2O) from soil denitrification originates from bacteria and - to an unknown
extent - also from fungi. During fungal denitrification, oxygen (O) exchange takes place
between H2O and intermediates of the denitrification process as in bacterial exchange[1,2].
However, information about enzymes involved in fungal O exchanges and the associated
fractionation effects is lacking.
The objectives of this study were to estimate the O fractionation and O exchange during
the fungal denitrifying steps using a conceptual model[2] adapted from concepts for bacterial
denitrification[3], implementing controls of O exchange proposed by Aerssens, et al.[4] and
using fractionation models by Snider et al.[5]
Six different pure fungal cultures (five Hypocreales, one Sordariales) known to be
capable of denitrification were incubated under anaerobic conditions, either with nitrite or
nitrate. Gas samples were analyzed for N2O concentration and its isotopic signatures (SP,
average δ15N, δ18O). To investigate O exchange, both treatments were also established with
18O-labelled water as a tracer in the medium.
The Hypocreales strains showed O exchange mainly at NO2- reductase (Nir) with NO2-
as electron acceptor and no additional O exchange at NO3- reductase (Nar) with NO3- as
electron acceptor. The only Hypocreales species having higher O exchange with NO3- than
with NO2- also showed O exchange at Nar. The Sordariales species tested seems
capable of O exchange at NO reductase (Nor) additionally to O exchange at Nir with
NO2-. The data will help to better interpret stable isotope values of N2O from
soils.
.[1] D. M. Kool, N. Wrage, O. Oenema, J. Dolfing, J. W. Van Groenigen. Oxygen
exchange between (de)nitrification intermediates and H2O and its implications for source
determination of NO?3- and N2O: a review. Rapid Commun. Mass Spec. 2007, 21,
3569.
[2] L. Rohe, T.-H. Anderson, B. Braker, H. Flessa, A. Giesemann, N. Wrage-Mönnig, R.
Well. Fungal Oxygen Exchange between Denitrification Intermediates and Water. Rapid
Commun. Mass Spec. 2014, 28, 377.
[3] K. L. Casciotti, J. K. Böhlke, M. R. McIlvin, S. J. Mroczkowski, J. E. Hannon.
Oxygen Isotopes in Nitrite: Analysis, Calibration, and Equilibration. Anal. Chem. 2007, 79,
2427.
[4] E. Aerssens, J. M. Tiedje, B. A. Averill. Isotope Labeling Studies on the
Mechanisms of N-bond Formation in Denitrification J. Biol. Chem. 1986, 261,
9652.
[5] D. M. Snider, J. J. Venkiteswaran, S. L. Schiff, J. Spoelstra. Deciphering the oxygen
isotope composition of nitrous oxide produced by nitrification. Glob. Change Biol. 2012, 18,
356. |
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