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Identification of key nitrous oxide production pathways in aerobic partial nitrifying granules
Author(s) -
Ishii Satoshi,
Song Yanjun,
Rathnayake Lashitha,
Tumendelger Azzaya,
Satoh Hisashi,
Toyoda Sakae,
Yoshida Naohiro,
Okabe Satoshi
Publication year - 2014
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12458
Subject(s) - denitrification , aerobic denitrification , nitrous oxide , heterotroph , nitrification , hydroxylamine , denitrifying bacteria , biology , environmental chemistry , autotroph , nitrogen , ecology , bacteria , chemistry , biochemistry , genetics , organic chemistry
Summary The identification of the key nitrous oxide ( N 2 O ) production pathways is important to establish a strategy to mitigate N 2 O emission. In this study, we combined real‐time gas‐monitoring analysis, 15 N stable isotope analysis, denitrification functional gene transcriptome analysis and microscale N 2 O concentration measurements to identify the main N 2 O producers in a partial nitrification ( PN ) aerobic granule reactor, which was fed with ammonium and acetate. Our results suggest that heterotrophic denitrification was the main contributor to N 2 O production in our PN aerobic granule reactor. The heterotrophic denitrifiers were probably related to R hodocyclales bacteria, although different types of bacteria were active in the initial and latter stages of the PN reaction cycles, most likely in response to the presence of acetate. Hydroxylamine oxidation and nitrifier denitrification occurred, but their contribution to N 2 O emission was relatively small (20–30%) compared with heterotrophic denitrification. Our approach can be useful to quantitatively examine the relative contributions of the three pathways (hydroxylamine oxidation, nitrifier denitrification and heterotrophic denitrification) to N 2 O emission in mixed microbial populations.