Hybrid Nitrous Oxide Production from a Partial Nitrifying Bioreactor: Hydroxylamine Interactions with Nitrite.
The goal of this study was to elucidate the mechanisms of nitrous oxide (N2O) production from a bioreactor for partial nitrification (PN). Ammonia-oxidizing bacteria (AOB) enriched from a sequencing batch reactor (SBR) were subjected to N2O production pathway tests. The N2O pathway test was initiated by supplying an inorganic medium to ensure an initial NH4+-N concentration of 160 mg-N/L, followed by15NO2-(20 mg-N/L) and dual15NH2OH (each 17 mg-N/L) spikings to quantify isotopologs of gaseous N2O (44N2O,45N2O, and46N2O). N2O production was boosted by15NH2OH spiking, causing exponential increases in mRNA transcription levels of AOB functional genes encoding hydroxylamine oxidoreductase (haoA), nitrite reductase (nirK), and nitric oxide reductase (norB) genes. Predominant production of45N2O among N2O isotopologs (46% of total produced N2O) indicated that coupling of15NH2OH with14NO2-produced N2O via N-nitrosation hybrid reaction as a predominant pathway. Abiotic hybrid N2O production was also observed in the absence of the AOB-enriched biomass, indicating multiple pathways for N2O production in a PN bioreactor. The additional N2O pathway test, where15NH4+was spiked into 400 mg-N/L of NO2-concentration, confirmed that the hybrid N2O production was a dominant pathway, accounting for approximately 51% of the total N2O production.
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Akihiko
0000-0002-9258-6912
A
Terada
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Sho
S
Sugawara
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Keisuke
K
Hojo
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Yuki
Y
Takeuchi
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Shohei
S
Riya
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.|Department of Systems Engineering and Management, Air Force Institute of Technology , Dayton, Ohio, United States.
Willie F
WF
Harper
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Tomoko
T
Yamamoto
Department of Environmental and Natural Resource Sciences, Tokyo University of Agriculture and Technology , Saiwai-cho Fuchu, Tokyo, Japan.|Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Yayoi, Bunkyo, Tokyo, Japan.|Department of Biological Sciences, Faculty of Science and Engineering, Chuo University , Bunkyo, Tokyo, Japan.
Megumi
M
Kuroiwa
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo , Yayoi, Bunkyo, Tokyo, Japan.
Kazuo
K
Isobe
Department of Biological Sciences, Faculty of Science and Engineering, Chuo University , Bunkyo, Tokyo, Japan.
Chie
C
Katsuyama
Department of Biological Sciences, Faculty of Science and Engineering, Chuo University , Bunkyo, Tokyo, Japan.
Yuichi
Y
Suwa
Department of Environmental and Natural Resource Sciences, Tokyo University of Agriculture and Technology , Saiwai-cho Fuchu, Tokyo, Japan.
Keisuke
K
Koba
Department of Chemical Engineering, Tokyo University of Agriculture and Technology , 2-24-16 Naka, Koganei, Tokyo 184-8588 Japan.
Masaaki
M
Hosomi
D000641:Ammonia / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology; D019811:Hydroxylamine; D006898:Hydroxylamines; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction
D006898:Hydroxylamines; D009573:Nitrites; D019811:Hydroxylamine; D000641:Ammonia; D009609:Nitrous Oxide