Ostrom, N.E., A.J. Pitt, R. Sutka, P.H. Ostrom, T.T. Bergsma, H. Gandhi, M. Jinuntuya, and J. Breznak
Presented at the ASM in Seattle (2003-09-18 to 2017-12-05 )
Nitrous oxide is well known as a greenhouse gas that has been increasing in concentration in the atmosphere over the past 150 years in a manner similar to carbon dioxide and methane. Microbial nitrification and denitrification are the predominant sources of nitrous oxide to the atmosphere, however, the relative importance of these two processes in the flux of this gas have proven elusive. Such information will be particularly valuable in agricultural environments that can be managed to foster one process or the other. Our laboratory has investigated the use of isotopomers as a potential indicator of the relative importance of nitrification and denitrification in nitrous oxide production. The term “isotopomer” refers to not only the isotopic abundance of nitrous oxide (d15N and15N andd18O) but also to the 15N abundance within each of the nitrogen atoms comprising this molecule. Recently we demonstrated that the isotopomer composition of nitrous oxide can be used to understand pathways of production by the nitrifying bacteria Nitrosomonas europaea and Methylococcus capsulatus Bath (Sutka et al., 2003). We combine these results with experiments using laboratory cultures of whole soil microbes and pure cultures of an N2O-producing denitrifier, Pseudomonas chlororaphis (ATCC #43928) to demonstrate that the isotopomer fingerprint of N2O derived from denitrification is unique from other that of nitrification. Furthermore, we have demonstrated that in agricultural soils the consumption of N2O during denitrification has no affect on site preference. With these results we are now poised to begin to apply isotopomers to apportion the relative contribution of N2O derived from nitrification and denitrification in agricultural soils and other environments. 18O) but also to the 15N abundance within each of the nitrogen atoms comprising this molecule. Recently we demonstrated that the isotopomer composition of nitrous oxide can be used to understand pathways of production by the nitrifying bacteria Nitrosomonas europaea and Methylococcus capsulatus Bath (Sutka et al., 2003). We combine these results with experiments using laboratory cultures of whole soil microbes and pure cultures of an N2O-producing denitrifier, Pseudomonas chlororaphis (ATCC #43928) to demonstrate that the isotopomer fingerprint of N2O derived from denitrification is unique from other that of nitrification. Furthermore, we have demonstrated that in agricultural soils the consumption of N2O during denitrification has no affect on site preference. With these results we are now poised to begin to apply isotopomers to apportion the relative contribution of N2O derived from nitrification and denitrification in agricultural soils and other environments.
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