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| Home > Publications database > A new 15N tracer method to determine N turnover and denitrification of Pseudomonas stutzeri |
| Journal Article | PreJuSER-15171 |
; ; ;
2010
Taylor and Francis
London [u.a.]
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Please use a persistent id in citations: doi:10.1080/10256016.2010.528840
Abstract: Although denitrification is one of the key processes of ecosystem N turnover, the understanding of the regulation of the denitrification pathway is still limited due to the lack of feasible methods for the quantification of N₂ formation. Based on the previously developed isotope pairing method, we present a new in vitro ¹⁵N tracer method for the quantification of N₂ released from denitrification by bacterial cultures. The application of the new method was enabled by replacing the background air in the sample flasks with a gas mixture of He and O₂ with an approximately 50-fold reduced N₂ background (1.7% v/v), allowing for a direct and sensitive quantification of N₂ formation with isotope-ratio mass spectrometry after ¹⁵N-labelling on the one hand, but leaving the method relatively insensitive to intrusion of ambient N₂ on the other hand. The method was tested on bacterial cultures of Pseudomonas stutzeri grown at different oxygen levels. Additionally, NO and N₂O formation were determined with a chemoluminescence analyser and a gas chromatograph, respectively. Following labelling with ¹⁵N-ammonium and ¹⁵N-nitrate, it could be shown that P. stutzeri used ammonium preferably for biomass build-up, and nitrate preferably as electron acceptor. Between 84-107% of the total available N could be recovered. Due to the high sensitivity of the new method only low levels of ¹⁵N tracer were necessary, minimising substrate-induced effects and making this method also an appropriate tool for the use on soil cores. By that it offers a new method for studying denitrification in terrestrial ecosystems.
Keyword(s): Denitrification (MeSH) ; Nitrogen Isotopes: metabolism (MeSH) ; Pseudomonas stutzeri: metabolism (MeSH) ; Nitrogen Isotopes ; J ; denitrification (auto) ; isotope pairing (auto) ; Pseudomonas stutzeri (auto) ; nitrogen-15 (auto) ; isotope ecology (auto) ; tracer technique (auto)
; JCR ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection
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