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Efficient nitrous oxide production and metagenomics-based analysis of microbial communities in denitrifying systems acclimated with different electron acceptors

Zhao, Yingfen, Zeng, Danfei, Wu, Guangxue
International biodeterioration & biodegradation 2019 v.138 pp. 92-98
Acidovorax, Thauera, carbon nitrogen ratio, denitrification, denitrifying microorganisms, electrons, genes, microbial communities, nitrates, nitrites, nitrous acid, nitrous oxide, nitrous oxide production, nitrous-oxide reductase, organic carbon
Effects of electron acceptors and free nitrous acid (FNA) concentrations on the denitrification performance and nitrous oxide (N2O) generation were investigated in denitrifying systems acclimated with nitrate (SBRA) and nitrite (SBRI). Denitrifying genes and functional microbial communities were also analyzed. Under the same influent organic carbon to nitrogen ratio, the nitrate removal percentage in SBRA was 75.2%, while that of nitrite was 99.8% in SBRI. The highest N2O conversion ratio of 89.9% was obtained when nitrite was applied to SBRA due to the insufficient electrons for N2O reductase (Nos). Higher N2O generation was attributed to the severe FNA inhibition on Nos when NO2N was used as the electron acceptor, rather than the relative abundance of gene nos. The dominant denitrifier was Acidovorax with the abundance of 21.9% in SBRA, while Thauera of 11.3% in SBRI.