Isotopic signatures of N2O produced by ammonia-oxidizing archaea from soils.
N2O gas is involved in global warming and ozone depletion. The major sources of N2O are soil microbial processes. Anthropogenic inputs into the nitrogen cycle have exacerbated these microbial processes, including nitrification. Ammonia-oxidizing archaea (AOA) are major members of the pool of soil ammonia-oxidizing microorganisms. This study investigated the isotopic signatures of N2O produced by soil AOA and associated N2O production processes. All five AOA strains (I.1a, I.1a-associated and I.1b clades of Thaumarchaeota) from soil produced N2O and their yields were comparable to those of ammonia-oxidizing bacteria (AOB). The levels of site preference (SP), δ(15)N(bulk) and δ(18)O -N2O of soil AOA strains were 13-30%, -13 to -35% and 22-36%, respectively, and strains MY1-3 and other soil AOA strains had distinct isotopic signatures. A (15)N-NH4(+)-labeling experiment indicated that N2O originated from two different production pathways (that is, ammonia oxidation and nitrifier denitrification), which suggests that the isotopic signatures of N2O from AOA may be attributable to the relative contributions of these two processes. The highest N2O production yield and lowest site preference of acidophilic strain CS may be related to enhanced nitrifier denitrification for detoxifying nitrite. Previously, it was not possible to detect N2O from soil AOA because of similarities between its isotopic signatures and those from AOB. Given the predominance of AOA over AOB in most soils, a significant proportion of the total N2O emissions from soil nitrification may be attributable to AOA.
Department of Microbiology, Chungbuk National University, Cheongju, South Korea.
Man-Young
MY
Jung
Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany.
Reinhard
R
Well
Center for Gas Analysis, Korea Research Institute of Standards and Science, Daejeon, South Korea.
Deullae
D
Min
Thünen Institute of Climate-Smart Agriculture, Braunschweig, Germany.
Anette
A
Giesemann
Department of Biology, Jeju National University, Jeju, South Korea.
Soo-Je
SJ
Park
Department of Microbiology, Chungbuk National University, Cheongju, South Korea.
Jong-Geol
JG
Kim
Department of Microbiology, Chungbuk National University, Cheongju, South Korea.
So-Jeong
SJ
Kim
Department of Microbiology, Chungbuk National University, Cheongju, South Korea.
Sung-Keun
SK
Rhee
D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000145:classification* / Q000378:metabolism*; D058465:Nitrification; D058458:Nitrogen Cycle; D009609:Nitrous Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D010802:Phylogeny; D012988:Soil Microbiology
D000641:Ammonia; D009609:Nitrous Oxide