Starch biotransformation by Lactococcus lactis: three strategies for process optimization

Starch biotransformation by Lactococcus lactis: three strategies for process optimization | 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 Research Article Starch biotransformation by Lactococcus lactis: three strategies for process optimization Valérie Laroute, Nathalie Aubry, Pauline Goodwin, Arthur Raymond, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9031201/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 Microbial fermentation is increasingly used in the biotransformation of starch for sustainable production of chemicals and natural products. Lactococci have a rich array of metabolic pathways for the degradation of various carbohydrate sources but very few secrete α-amylase, which hydrolyzes starch into oligosaccharides. Here, the model strain Lactococcus lactis IL1403 was engineered to secrete α-amylase from Lactobacillus plantarum A6. This IL1403amy+ strain did not grow on starch and large quantities of unmetabolized maltooligosides accumulated in the growth medium, indicating imperfect starch hydrolysis. Three strategies were evaluated to overcome this bottleneck. First, a hybrid bacterial/enzyme process using added glucoamylase enabled 81% of the starch to be converted into lactic acid. Second, a synthetic consortium designed for labor division, with IL1403amy + and the non-conventional strain L. lactis EIP13A, capable of metabolizing a wide range of oligosaccharides, led to the complete conversion of starch into lactic acid, other organic acids and ethanol. Third, similar conversion efficiencies were obtained with a monoculture of EIP13A engineered to secrete α-amylase. This work demonstrates the potential of L. lactis for the biotransformation of starch into valuable products through different microbial approaches and opens the way to new strategies based on the diversity of natural strains to exploit other by-products. Lactococcus lactis α-amylase starch lactic acid formic acid acetic acid metabolic shift Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementarydataAMB2026.docx 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. 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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-9031201","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":607710157,"identity":"f9d991d7-1147-42b3-bf04-a889ad6ad462","order_by":0,"name":"Valérie Laroute","email":"","orcid":"","institution":"Toulouse Biotechnology Institute","correspondingAuthor":false,"prefix":"","firstName":"Valérie","middleName":"","lastName":"Laroute","suffix":""},{"id":607710158,"identity":"400956ea-acc0-4c7c-ba76-c107f4c23893","order_by":1,"name":"Nathalie Aubry","email":"","orcid":"","institution":"Toulouse Biotechnology 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shift","lastPublishedDoi":"10.21203/rs.3.rs-9031201/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9031201/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMicrobial fermentation is increasingly used in the biotransformation of starch for sustainable production of chemicals and natural products. Lactococci have a rich array of metabolic pathways for the degradation of various carbohydrate sources but very few secrete α-amylase, which hydrolyzes starch into oligosaccharides. Here, the model strain \u003cem\u003eLactococcus lactis\u003c/em\u003e IL1403 was engineered to secrete α-amylase from \u003cem\u003eLactobacillus plantarum\u003c/em\u003e A6. This IL1403amy+ strain did not grow on starch and large quantities of unmetabolized maltooligosides accumulated in the growth medium, indicating imperfect starch hydrolysis. Three strategies were evaluated to overcome this bottleneck. First, a hybrid bacterial/enzyme process using added glucoamylase enabled 81% of the starch to be converted into lactic acid. 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