TY - JOUR
T1 - Denitrification kinetics indicates nitrous oxide uptake is unaffected by electron competition in Accumulibacter
AU - Roy, Samarpita
AU - PRADHAN, Nirakar
AU - Yong, N. G.How
AU - Stefan, Wuertz
N1 - Funding Information:
This research was supported by the Ministry of Education, Singapore under the Research Centre of Excellence Programme. We acknowledge Dr. Daniela Drautz-Moses for performing 16S rRNA gene amplicon sequencing. Many thanks go to Dr. Rohan Williams for his inputs on interpretation of the sequencing data and for proofreading the manuscript. We also extend our gratitude to James Jun, Muhamad Danial Bin Suthree, Ahmadul Hafiz Ain Azman Jun, Eganathan Kaliyamoorthy and Sara Swa Thi for performing nutrient tests during the course of this study. The authors thank the four anonymous reviewers for helpful suggestions to improve our manuscript.
Funding Information:
This research was supported by the Ministry of Education, Singapore under the Research Centre of Excellence Programme. We acknowledge Dr. Daniela Drautz-Moses for performing 16S rRNA gene amplicon sequencing. Many thanks go to Dr. Rohan Williams for his inputs on interpretation of the sequencing data and for proofreading the manuscript. We also extend our gratitude to James Jun, Muhamad Danial Bin Suthree, Ahmadul Hafiz Ain Azman Jun, Eganathan Kaliyamoorthy and Sara Swa Thi for performing nutrient tests during the course of this study. The authors thank the four anonymous reviewers for helpful suggestions to improve our manuscript.
Copyright © 2020. Published by Elsevier Ltd.
PY - 2021/2/1
Y1 - 2021/2/1
N2 - Denitrifying phosphorus removal is a cost and energy efficient treatment technology that relies on polyphosphate accumulating organisms (DPAOs) utilizing nitrate or nitrite as terminal electron acceptor. Denitrification is a multistep process, but many organisms do not possess the complete pathway, leading to the accumulation of intermediates such as nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance. Candidatus Accumulibacter organisms are prevalent in denitrifying phosphorus removal processes and, according to genomic analyses, appear to vary in their denitrification abilities based on their lineage. Denitrification kinetics and nitrous oxide accumulation in the absence of inhibition from free nitrous acid is a strong indicator of denitrification capabilities of Accumulibacter exposed long-term to nitrate or nitrite as electron acceptor. Thus, we investigated the preferential use of the nitrogen oxides involved in denitrification and nitrous oxide accumulation in two enrichments of Accumulibacter and a competitor – the glycogen accumulating organism Candidatus Competibacter. We modified a metabolic model to predict phosphorus removal and denitrification rates when nitrate, nitrite or N2O were added as electron acceptors in different combinations. Unlike previous studies, no N2O accumulation was observed for Accumulibacter in the presence of multiple electron acceptors. Electron competition did not limit denitrification kinetics or lead to N2O accumulation in Accumulibacter or Competibacter. Despite the presence of sufficient internal storage polymers (polyhydroxyalkanoates, or PHA) as energy source for each denitrification step, the extent of denitrification observed was dependent on the dominant organism in the enrichment. Accumulibacter showed complete denitrification, whereas Competibacter denitrification was limited to reduction of nitrate to nitrite. These findings indicate that DPAOs can contribute to lowering N2O emissions in the presence of multiple electron acceptors under partial nitritation conditions.
AB - Denitrifying phosphorus removal is a cost and energy efficient treatment technology that relies on polyphosphate accumulating organisms (DPAOs) utilizing nitrate or nitrite as terminal electron acceptor. Denitrification is a multistep process, but many organisms do not possess the complete pathway, leading to the accumulation of intermediates such as nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance. Candidatus Accumulibacter organisms are prevalent in denitrifying phosphorus removal processes and, according to genomic analyses, appear to vary in their denitrification abilities based on their lineage. Denitrification kinetics and nitrous oxide accumulation in the absence of inhibition from free nitrous acid is a strong indicator of denitrification capabilities of Accumulibacter exposed long-term to nitrate or nitrite as electron acceptor. Thus, we investigated the preferential use of the nitrogen oxides involved in denitrification and nitrous oxide accumulation in two enrichments of Accumulibacter and a competitor – the glycogen accumulating organism Candidatus Competibacter. We modified a metabolic model to predict phosphorus removal and denitrification rates when nitrate, nitrite or N2O were added as electron acceptors in different combinations. Unlike previous studies, no N2O accumulation was observed for Accumulibacter in the presence of multiple electron acceptors. Electron competition did not limit denitrification kinetics or lead to N2O accumulation in Accumulibacter or Competibacter. Despite the presence of sufficient internal storage polymers (polyhydroxyalkanoates, or PHA) as energy source for each denitrification step, the extent of denitrification observed was dependent on the dominant organism in the enrichment. Accumulibacter showed complete denitrification, whereas Competibacter denitrification was limited to reduction of nitrate to nitrite. These findings indicate that DPAOs can contribute to lowering N2O emissions in the presence of multiple electron acceptors under partial nitritation conditions.
KW - Accumulibacter
KW - Electron competition
KW - Free nitrous acid
KW - Nitrous oxide (NO) emission
KW - Polyhydroxyalkanoates
UR - http://www.scopus.com/inward/record.url?scp=85096711178&partnerID=8YFLogxK
U2 - 10.1016/j.watres.2020.116557
DO - 10.1016/j.watres.2020.116557
M3 - Journal article
C2 - 33220610
AN - SCOPUS:85096711178
SN - 0043-1354
VL - 189
JO - Water Research
JF - Water Research
M1 - 116557
ER -
