Iron availability modulates bacteria carbon cycling in the mesopelagic

Iron availability modulates bacteria carbon cycling in the mesopelagic | 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 Iron availability modulates bacteria carbon cycling in the mesopelagic Travis Mellett, Patrick Monreal, Korinna Kunde, Lauren Manck, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6890920/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The mesopelagic ocean is an important boundary between the surface and deep sea and is a key region for carbon cycling. Heterotrophic bacteria in this region dominate organic carbon (Corg) degradation and its conversion back to CO2. While iron (Fe) is known to limit primary production in the surface ocean, its impact on mesopelagic heterotrophic bacteria growth and Corg consumption is less understood. This study demonstrates serial Fe-limitation and Fe-Corg colimitation of bacteria within mesopelagic waters across oligotrophic and productive oceanic regimes. Without added Fe, bacteria increased siderophore production, reducing growth efficiencies. Mesopelagic bacteria exhibited Fe inventories much higher than those previously characterized in surface waters, which indicates luxury uptake and storage of Fe. In the presence of added Corg these cellular Fe quotas demonstrated high plasticity with bacterial growth and provide insights into how bacteria may cope with low Fe availability and transitory Corg availability in the mesopelagic ocean. Earth and environmental sciences/Biogeochemistry/Carbon cycle Earth and environmental sciences/Ocean sciences/Marine biology Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SuppMesopelagicFeBacteria.pdf Supplemental Information Cite Share Download PDF Status: Posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-6890920","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":473256920,"identity":"6212f440-601b-4a12-bc97-7bf7c5e6090f","order_by":0,"name":"Travis Mellett","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAsklEQVRIiWNgGAWjYHACxgMPgCQ/mM1GhHoeID6QwGAgIdlAshaDA8RqsRc7fOBAQsWfOuMbOQYMH8oOE2GLdFrCgYQzBhJmQC2MM84RpSXH4EBiG0hL7gZm3jaitOR/OJD4z0DCeAZQy1/itOQwHEhsAHpfAqiFkSgtt9MMDiQcM5acceb9h4M959IJa2GfnfzwwYcaOX7+9rTEBz/KrAlrQQEHSFQ/CkbBKBgFowAXAABLgzvetjlgtgAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0001-6314-0113","institution":"University of Washington","correspondingAuthor":true,"prefix":"","firstName":"Travis","middleName":"","lastName":"Mellett","suffix":""},{"id":473256921,"identity":"3951a2e0-e76c-472e-b416-1d70dc07bda7","order_by":1,"name":"Patrick Monreal","email":"","orcid":"https://orcid.org/0000-0001-5343-4142","institution":"University of Washington","correspondingAuthor":false,"prefix":"","firstName":"Patrick","middleName":"","lastName":"Monreal","suffix":""},{"id":473256922,"identity":"b90ddc9b-32bd-4b88-b490-46056242052f","order_by":2,"name":"Korinna Kunde","email":"","orcid":"","institution":"University of Washington","correspondingAuthor":false,"prefix":"","firstName":"Korinna","middleName":"","lastName":"Kunde","suffix":""},{"id":473256923,"identity":"6f660131-064a-44cc-aa2f-890dc2027126","order_by":3,"name":"Lauren Manck","email":"","orcid":"","institution":"University of Montana","correspondingAuthor":false,"prefix":"","firstName":"Lauren","middleName":"","lastName":"Manck","suffix":""},{"id":473256924,"identity":"664bcc3c-c120-43b5-8050-aff9ba4c5e84","order_by":4,"name":"Kelsy Cain","email":"","orcid":"","institution":"University of Washington","correspondingAuthor":false,"prefix":"","firstName":"Kelsy","middleName":"","lastName":"Cain","suffix":""},{"id":473256925,"identity":"63613ff5-737c-4ee8-a26c-856a48696fa5","order_by":5,"name":"François Ribalet","email":"","orcid":"https://orcid.org/0000-0002-7431-0234","institution":"University of Washington","correspondingAuthor":false,"prefix":"","firstName":"François","middleName":"","lastName":"Ribalet","suffix":""},{"id":473256926,"identity":"b470f872-00c2-4313-8c3d-0409daaba888","order_by":6,"name":"Matthew Church","email":"","orcid":"","institution":"University of Montana","correspondingAuthor":false,"prefix":"","firstName":"Matthew","middleName":"","lastName":"Church","suffix":""},{"id":473256927,"identity":"dc4237ba-d7a8-4404-ac82-b7aa70a070d0","order_by":7,"name":"E. 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Heterotrophic bacteria in this region dominate organic carbon (Corg) degradation and its conversion back to CO2. While iron (Fe) is known to limit primary production in the surface ocean, its impact on mesopelagic heterotrophic bacteria growth and Corg consumption is less understood. This study demonstrates serial Fe-limitation and Fe-Corg colimitation of bacteria within mesopelagic waters across oligotrophic and productive oceanic regimes. Without added Fe, bacteria increased siderophore production, reducing growth efficiencies. Mesopelagic bacteria exhibited Fe inventories much higher than those previously characterized in surface waters, which indicates luxury uptake and storage of Fe. 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