Get access
Advertisement

Importance of denitrifiers lacking the genes encoding the nitrous oxide reductase for N2O emissions from soil

Authors

  • LAURENT PHILIPPOT,

    1. INRA, Department of Soil and Environmental Microbiology, UMR 1229, F-21000 Dijon, France
    2. Department of Soil and Environmental Microbiology, University of Burgundy, UMR 1229, F-21000 Dijon, France
    Search for more papers by this author
  • JANET ANDERT,

    1. Uppsala BioCenter, Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
    Search for more papers by this author
  • CHRISTOPHER M. JONES,

    1. Uppsala BioCenter, Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
    Search for more papers by this author
  • DAVID BRU,

    1. INRA, Department of Soil and Environmental Microbiology, UMR 1229, F-21000 Dijon, France
    2. Department of Soil and Environmental Microbiology, University of Burgundy, UMR 1229, F-21000 Dijon, France
    Search for more papers by this author
  • SARA HALLIN

    1. Uppsala BioCenter, Department of Microbiology, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
    Search for more papers by this author

Sara Hallin, tel. +46 18 67 32 09, fax +46 18 67 33 99, e-mail: Sara.Hallin@mikrob.slu.se

Abstract

Analyses of the complete genomes of sequenced denitrifying bacteria revealed that approximately 1/3 have a truncated denitrification pathway, lacking the nosZ gene encoding the nitrous oxide reductase. We investigated whether the number of denitrifiers lacking the genetic ability to synthesize the nitrous oxide reductase in soils is important for the proportion of N2O emitted by denitrification. Serial dilutions of the denitrifying strain Agrobacterium tumefaciens C58 lacking the nosZ gene were inoculated into three different soils to modify the proportion of denitrifiers having the nitrous oxide reductase genes. The potential denitrification and N2O emissions increased when the size of inoculated C58 population in the soils was in the same range as the indigenous nosZ community. However, in two of the three soils, the increase in potential denitrification in inoculated microcosms compared with the noninoculated microcosms was higher than the increase in N2O emissions. This suggests that the indigenous denitrifier community was capable of acting as a sink for the N2O produced by A. tumefaciens. The relative amount of N2O emitted also increased in two soils with the number of inoculated C58 cells, establishing a direct causal link between the denitrifier community composition and potential N2O emissions by manipulating the proportion of denitrifiers having the nosZ gene. However, the number of denitrifiers which do not possess a nitrous oxide reductase might not be as important for N2O emissions in soils having a high N2O uptake capacity compared with those with lower. In conclusion, we provide a proof of principle that the inability of some denitrifiers to synthesize the nitrous oxide reductase can influence the nature of the denitrification end products, indicating that the extent of the reduction of N2O to N2 by the denitrifying community can have a genetic basis.

Get access to the full text of this article

Ancillary