Spatial patterns of nitrogen-transforming processes in the Southern Ocean: Potential role of Dissimilatory Nitrate Reduction (DNR)

Spatial patterns of nitrogen-transforming processes in the Southern Ocean: Potential role of Dissimilatory Nitrate Reduction (DNR) | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Spatial patterns of nitrogen-transforming processes in the Southern Ocean: Potential role of Dissimilatory Nitrate Reduction (DNR) Sharvari Sunil Gadegaonkar, Rui Zhang, Hélène Planquette, Antoine Ringard, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8021359/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The nitrogen cycle is crucial for aquatic systems, as it governs the availability of this essential nutrient and thereby supports the productivity of marine ecosystems. While most research in the oxygenated ocean has thus far focused on nitrogen fixation and nitrification, the potential role of dissimilatory processes remains poorly investigated. The objectives of the present study were to determine the spatial patterns of DNR processes [denitrification and dissimilatory nitrate reduction to ammonium], their associations with trace metals that are cofactors, and to identify the involved microbial taxa. We analyzed metagenomes collected along a latitudinal gradient and diverse water masses in the Indian sector of the Southern Ocean during the South West Indian GEOTRACERS section cruise. Genes involved in DNR dominated over those of other nitrogen-transforming processes across all water masses, with a notable preference for enzymes requiring copper over iron, indicating alternative trace metal adaptation. Metagenome-assembled genomes associated with DNR possessed inorganic carbon fixing pathways suggesting mixotrophic strategies. Our observations show the metagenomic potential of DNR as an alternative or additional source of energy for the microbial community in the carbon limited deep ocean. Biological sciences/Ecology/Biogeochemistry/Element cycles Biological sciences/Computational biology and bioinformatics denitrification dissimilatory nitrate reduction to ammonium (DNRA) metagenomics chemolithotrophy mixotrophy Southern Ocean Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementaryFiguresRGB.pdf Supplementary Figures in RGB SupplementaryMethodsNitrogenSWINGS.pdf Supplementary Methods SuppTablesfiles.xlsx RS1255.pdf Reporting Summary Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8021359","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":544184146,"identity":"5757a571-a04a-4a52-ae27-89f0019ac88e","order_by":0,"name":"Sharvari Sunil 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