Disentangling the Sources of Spectral Induced Polarization of Microbial Systems: Experiments in Non-Geological Media

Disentangling the Sources of Spectral Induced Polarization of Microbial Systems: Experiments in Non-Geological Media | 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 Disentangling the Sources of Spectral Induced Polarization of Microbial Systems: Experiments in Non-Geological Media Satoshi Izumoto, Frank Delvine, Frédéric Nguyen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8899213/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract This study investigates the origin of spectral induced polarization (SIP) signals associated with microbial systems, aiming to distinguish direct microbial electrical effects from indirect geochemical processes. Although SIP has been proposed for detecting subsurface microbial activity, its interpretation is complicated by overlapping polarization mechanisms. We therefore performed controlled experiments in simplified, non-geological environments to isolate the roles of microbial presence, attachment, and activity. Using a custom millifluidic chip, SIP measurements were conducted with \textit{Pseudomonas putida} KT2440 under three configurations: bacteria suspended in solution, bacteria attached to metal surfaces, and bacteria affecting SIP through redox reactions.Bacterial cells in suspension did not produce a measurable SIP response: phase shifts were indistinguishable from those of the background medium, despite small increases in bulk conductivity. Reanalysis of previous studies indicates that interpretations based solely on imaginary conductivity can be misleading, and that phase shift is the more reliable indicator. Likewise, bacterial attachment to metal surfaces did not modify the SIP response, even though microscopy confirmed surface colonization.In contrast, strong and time-dependent SIP signals were observed when iron was immersed in oxygenated media, closely tracking oxygen consumption and attributable to surface oxidation. When oxygen was removed—by microbial respiration or chemical scavenging—the change in SIP response was significantly reduced, and systems with and without bacteria behaved similarly. Numerical simulations with redox-modified boundary conditions reproduced these trends and linked SIP evolution to changes in surface capacitance and electron transfer. Overall, SIP is sensitive not to microbial cells themselves, but to microbially mediated redox processes involving conductive materials. Earth and environmental sciences/Environmental sciences Biological sciences/Microbiology Earth and environmental sciences/Solid earth sciences Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 06 Apr, 2026 Reviewers invited by journal 26 Feb, 2026 Editor assigned by journal 26 Feb, 2026 Editor invited by journal 26 Feb, 2026 Submission checks completed at journal 22 Feb, 2026 First submitted to journal 22 Feb, 2026 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. 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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-8899213","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":598316998,"identity":"9162e2e1-fb39-41f4-91c5-628826b6ff14","order_by":0,"name":"Satoshi Izumoto","email":"data:image/png;base64,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","orcid":"","institution":"University of Liège","correspondingAuthor":true,"prefix":"","firstName":"Satoshi","middleName":"","lastName":"Izumoto","suffix":""},{"id":598316999,"identity":"643f28a2-a9b1-4f2a-b109-738c98e80df9","order_by":1,"name":"Frank Delvine","email":"","orcid":"","institution":"Gembloux Agro-Bio Tech","correspondingAuthor":false,"prefix":"","firstName":"Frank","middleName":"","lastName":"Delvine","suffix":""},{"id":598317000,"identity":"246e81be-2a21-4b38-a7c8-110ea363f273","order_by":2,"name":"Frédéric Nguyen","email":"","orcid":"","institution":"University of Liège","correspondingAuthor":false,"prefix":"","firstName":"Frédéric","middleName":"","lastName":"Nguyen","suffix":""}],"badges":[],"createdAt":"2026-02-17 08:53:26","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8899213/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8899213/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104401172,"identity":"b0b8a724-b191-43f6-9136-3528cb74e59e","added_by":"auto","created_at":"2026-03-11 12:12:02","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2533546,"visible":true,"origin":"","legend":"","description":"","filename":"jsrgdnvshjrshjctfpzcndwhrvxbtrwb.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8899213/v1_covered_2dcf6e65-cf84-4842-af2b-554f276d04fe.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Disentangling the Sources of Spectral Induced Polarization of Microbial Systems: Experiments in Non-Geological Media","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8899213/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8899213/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"This study investigates the origin of spectral induced polarization (SIP) signals associated with microbial systems, aiming to distinguish direct microbial electrical effects from indirect geochemical processes. Although SIP has been proposed for detecting subsurface microbial activity, its interpretation is complicated by overlapping polarization mechanisms. We therefore performed controlled experiments in simplified, non-geological environments to isolate the roles of microbial presence, attachment, and activity. Using a custom millifluidic chip, SIP measurements were conducted with \\textit{Pseudomonas putida} KT2440 under three configurations: bacteria suspended in solution, bacteria attached to metal surfaces, and bacteria affecting SIP through redox reactions.Bacterial cells in suspension did not produce a measurable SIP response: phase shifts were indistinguishable from those of the background medium, despite small increases in bulk conductivity. Reanalysis of previous studies indicates that interpretations based solely on imaginary conductivity can be misleading, and that phase shift is the more reliable indicator. Likewise, bacterial attachment to metal surfaces did not modify the SIP response, even though microscopy confirmed surface colonization.In contrast, strong and time-dependent SIP signals were observed when iron was immersed in oxygenated media, closely tracking oxygen consumption and attributable to surface oxidation. When oxygen was removed—by microbial respiration or chemical scavenging—the change in SIP response was significantly reduced, and systems with and without bacteria behaved similarly. Numerical simulations with redox-modified boundary conditions reproduced these trends and linked SIP evolution to changes in surface capacitance and electron transfer. 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