Hydrazine synthase from anammox is inhibited by linear and aromatic alkynes

Maryan, Cerys, Nuijten, Guylaine H. L., Crombie, Andrew T., Lücker, Sebastian, Gibson, Victoria, Hernández, Marcela, Murrell, J. Colin and Lehtovirta-Morley, Laura E. (2026) Hydrazine synthase from anammox is inhibited by linear and aromatic alkynes. Environmental Microbiology, 28 (3). ISSN 1462-2912

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Abstract

N 2O emissions by nitrifiers are often estimated using selective inhibitors, such as 1-alkynes. However, the effects of these inhibitors on anaerobic ammonium-oxidising (anammox) bacteria are largely unknown. In this study, we assessed the inhibitory effect of linear and aromatic alkynes on anammox activity and identified their target enzyme. ‘Candidatus Kuenenia stuttgartiensis’ biomass and constructed wetland soil samples were incubated with 10 μM of C 2–C₈ linear alkynes or phenylacetylene for 10 days. Anammox activity was determined using the isotopic tracer 15N-nitrite and 29N 2 production. Anammox activity was suppressed by C 2–C 5 alkynes, whereas the larger or aromatic alkynes caused no inhibition. However, hydrazine oxidation activity was not affected, indicating that C 2–C 5 alkynes inactivated enzymes upstream of hydrazine dehydrogenase. In incubations using an NO donor and 15N-ammonium, 29N 2 production stopped, suggesting that hydrazine synthase was the target of these alkynes. A comparable trend was observed in the wetland samples, but with a less pronounced reduction in 29N 2 production. Since alkynes >C 5 did not affect anammox, these findings demonstrate the suitability of using 1-octyne as a selective inhibitor to quantify N 2O contributions from ammonia-oxidising bacteria (AOB) versus ammonia-oxidising archaea (AOA) in oxic/anoxic interface environments.

Item Type:	Article
Additional Information:	Data Availability Statement: The 16S rRNA gene sequencing data have been deposited in the NCBI Sequence Read Archive (SRA) under the BioProject accession number PRJNA1290922.
Faculty \ School:	Faculty of Science > School of Biological Sciences Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA
UEA Research Groups:	Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Groups > Wolfson Centre for Advanced Environmental Microbiology Faculty of Science > Research Groups > Environmental Biology
Related URLs:	https://www.scopus.com/pages/publication...
Depositing User:	LivePure Connector
Date Deposited:	14 May 2026 15:15
Last Modified:	14 May 2026 15:15
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103024
DOI:	10.1111/1462-2920.70261

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