Unprecedented N 2 O production by nitrate-ammonifying Geobacteraceae with distinctive N 2 O isotopocule signatures.

Autor: Xu Z; Marine College, Shandong University, Weihai, China.; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan., Hattori S; International Center for Isotope Effects Research (ICIER), Nanjing University, Nanjing, China.; Frontiers Science Center for Critical Earth Material Cycling, State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China., Masuda Y; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan., Toyoda S; School of Materials and Chemical Technology, Institute of Science Tokyo, Yokohama, Japan., Koba K; Center for Ecological Research, Kyoto University, Shiga, Japan., Yu P; SDU-ANU Joint Science College, Shandong University, Weihai, China., Yoshida N; Earth-Life Science Institute, Institute of Science Tokyo, Tokyo, Japan.; National Institute of Information and Communications Technology, Tokyo, Japan., Du Z-J; Marine College, Shandong University, Weihai, China., Senoo K; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Tokyo, Japan.
Jazyk: angličtina
Zdroj: MBio [mBio] 2024 Dec 11; Vol. 15 (12), pp. e0254024. Date of Electronic Publication: 2024 Oct 30.
DOI: 10.1128/mbio.02540-24
Abstrakt: Dissimilatory nitrate reduction to ammonium (DNRA), driven by nitrate-ammonifying bacteria, is an increasingly appreciated nitrogen-cycling pathway in terrestrial ecosystems. This process reportedly generates nitrous oxide (N 2 O), a strong greenhouse gas with ozone-depleting effects. However, it remains poorly understood how N 2 O is produced by environmental nitrate-ammonifiers and how to identify DNRA-derived N 2 O. In this study, we characterize two novel enzymatic pathways responsible for N 2 O production in Geobacteraceae strains, which are predominant nitrate-ammonifying bacteria in paddy soils. The first pathway involves a membrane-bound nitrate reductase (Nar) and a hybrid cluster protein complex (Hcp-Hcr) that catalyzes the conversion of NO 2 - to NO and subsequently to N 2 O. The second pathway is observed in Nar-deficient bacteria, where the nitrite reductase (NrfA) generates NO, which is then reduced to N 2 O by Hcp-Hcr. These enzyme combinations are prevalent across the domain Bacteria. Moreover, we observe distinctive isotopocule signatures of DNRA-derived N 2 O from other established N 2 O production pathways, especially through the highest 15 N-site preference (SP) values (43.0‰-49.9‰) reported so far, indicating a robust means for N 2 O source partitioning. Our findings demonstrate two novel N 2 O production pathways in DNRA that can be isotopically distinguished from other pathways.IMPORTANCEStimulation of DNRA is a promising strategy to improve fertilizer efficiency and reduce N 2 O emission in agriculture soils. This process converts water-leachable NO 3 - and NO 2 - into soil-adsorbable NH 4 + , thereby alleviating nitrogen loss and N 2 O emission resulting from denitrification. However, several studies have noted that DNRA can also be a source of N 2 O, contributing to global warming. This contribution is often masked by other N 2 O generation processes, leading to a limited understanding of DNRA as an N 2 O source. Our study reveals two widespread yet overlooked N 2 O production pathways in Geobacteraceae , the predominant DNRA bacteria in paddy soils, along with their distinctive isotopocule signatures. These findings offer novel insights into the role of the DNRA bacteria in N 2 O production and underscore the significance of N 2 O isotopocule signatures in microbial N 2 O source tracking.
Competing Interests: The authors declare no conflict of interest.
Databáze: MEDLINE
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