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Importance of denitrifiers lacking the genes encoding the nitrous oxide reductase for N 2 O emissions from soil
Author(s) -
PHILIPPOT LAURENT,
ANDERT JANET,
JONES CHRISTOPHER M.,
BRU DAVID,
HALLIN SARA
Publication year - 2011
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2010.02334.x
Subject(s) - nitrous oxide reductase , denitrifying bacteria , denitrification , nitrous oxide , microcosm , soil water , aerobic denitrification , biology , environmental chemistry , chemistry , ecology , nitrogen , organic chemistry
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 N 2 O 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 N 2 O 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 N 2 O emissions. This suggests that the indigenous denitrifier community was capable of acting as a sink for the N 2 O produced by A. tumefaciens . The relative amount of N 2 O 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 N 2 O 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 N 2 O emissions in soils having a high N 2 O 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 N 2 O to N 2 by the denitrifying community can have a genetic basis.