Unveiling the Molecular Characteristics and In Vitro Probiotic Potential of Isolated Lactic Acid Bacteria from Intestine of Freshwater Channa punctata (Taki) and Anabas cobojius (Koi) in Bangladesh 

Unveiling the Molecular Characteristics and In Vitro Probiotic Potential of Isolated Lactic Acid Bacteria from Intestine of Freshwater Channa punctata (Taki) and Anabas cobojius (Koi) in Bangladesh | 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 Unveiling the Molecular Characteristics and In Vitro Probiotic Potential of Isolated Lactic Acid Bacteria from Intestine of Freshwater Channa punctata (Taki) and Anabas cobojius (Koi) in Bangladesh Md. Asik Rabbani, Motahara Farhan Anjum, Sharmin Akter, Md Mehadi Hasan Sohag, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7580244/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 This study investigated the probiotic potential of lactic acid bacteria (LAB) isolated from the intestines of wild freshwater fishes, Channa punctata (Taki) and Anabas cobojius (Koi), collected from Benai Beel of Tangail district, Bangladesh. A total of 24 LAB isolates were obtained and characterized using morphological, biochemical, and molecular approaches, including 16S rRNA gene sequencing. Among these, Lactococcus garvieae (KA6) demonstrated promising probiotic traits. The strain exhibited robust tolerance to acidic pH (as low as pH 3), high bile salt concentration (1%), and elevated NaCl levels (up to 9%), indicating strong survivability in gastrointestinal conditions. KA6 also showed high cell surface hydrophobicity (36%), strong auto-aggregation (85%), and co-aggregation (78% with Staphylococcus aureus ), supporting its potential for intestinal adhesion and pathogen exclusion. Enzymatic assays revealed cellulase activity, suggesting a role in enhancing host digestion and nutrient utilization. The isolate was non-hemolytic, indicating safety, and displayed susceptibility to most tested antibiotics, though antimicrobial activity against selected pathogens ( Staphylococcus aureus , Escherichia coli , or Salmonella typhi ) was absent. These findings highlight Lactococcus garvieae as a potential probiotic candidate for aquaculture, capable of surviving gastrointestinal stress, adhering to intestinal surfaces, and contributing to host nutrition without exhibiting hemolytic activity. So, the survival capacity, adhesion properties, enzymatic activity, and non-hemolytic activity suggest that KA6 can be a strong candidate for probiotic enriched feed development in aquaculture. However, further studies on virulence factors, in vivo efficacy, and safety are recommended to validate its applications in different sectors for sustainable development. Biological sciences/Biotechnology Biological sciences/Microbiology Indigenous Fish Probiotic 16S rRNA gene Lactococcus garvieae Intestinal Adhesion and Non-hemolytic Full Text Additional Declarations No competing interests reported. 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-7580244","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":533275681,"identity":"9cc9ddcc-e95e-4774-9d19-845e7a0bc752","order_by":0,"name":"Md. 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","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Indigenous Fish, Probiotic, 16S rRNA gene, Lactococcus garvieae, Intestinal Adhesion, and Non-hemolytic","lastPublishedDoi":"10.21203/rs.3.rs-7580244/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7580244/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study investigated the probiotic potential of lactic acid bacteria (LAB) isolated from the intestines of wild freshwater fishes, \u003cem\u003eChanna punctata\u003c/em\u003e (Taki) and \u003cem\u003eAnabas cobojius\u003c/em\u003e (Koi), collected from Benai Beel of Tangail district, Bangladesh. A total of 24 LAB isolates were obtained and characterized using morphological, biochemical, and molecular approaches, including 16S rRNA gene sequencing. Among these, \u003cem\u003eLactococcus garvieae\u003c/em\u003e (KA6) demonstrated promising probiotic traits. The strain exhibited robust tolerance to acidic pH (as low as pH 3), high bile salt concentration (1%), and elevated NaCl levels (up to 9%), indicating strong survivability in gastrointestinal conditions. KA6 also showed high cell surface hydrophobicity (36%), strong auto-aggregation (85%), and co-aggregation (78% with \u003cem\u003eStaphylococcus aureus\u003c/em\u003e), supporting its potential for intestinal adhesion and pathogen exclusion. Enzymatic assays revealed cellulase activity, suggesting a role in enhancing host digestion and nutrient utilization. The isolate was non-hemolytic, indicating safety, and displayed susceptibility to most tested antibiotics, though antimicrobial activity against selected pathogens (\u003cem\u003eStaphylococcus aureus\u003c/em\u003e, \u003cem\u003eEscherichia coli\u003c/em\u003e, or \u003cem\u003eSalmonella typhi\u003c/em\u003e) was absent. These findings highlight \u003cem\u003eLactococcus garvieae\u003c/em\u003e as a potential probiotic candidate for aquaculture, capable of surviving gastrointestinal stress, adhering to intestinal surfaces, and contributing to host nutrition without exhibiting hemolytic activity. So, the survival capacity, adhesion properties, enzymatic activity, and non-hemolytic activity suggest that KA6 can be a strong candidate for probiotic enriched feed development in aquaculture. However, further studies on virulence factors, in vivo efficacy, and safety are recommended to validate its applications in different sectors for sustainable development.\u003c/p\u003e","manuscriptTitle":"Unveiling the Molecular Characteristics and In Vitro Probiotic Potential of Isolated Lactic Acid Bacteria from Intestine of Freshwater Channa punctata (Taki) and Anabas cobojius (Koi) in Bangladesh ","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-28 20:10:42","doi":"10.21203/rs.3.rs-7580244/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"76e0944b-e3f0-4528-81ab-a4cc58a8fa6f","owner":[],"postedDate":"October 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":56691493,"name":"Biological sciences/Biotechnology"},{"id":56691494,"name":"Biological sciences/Microbiology"}],"tags":[],"updatedAt":"2026-04-30T10:41:02+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-28 20:10:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7580244","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7580244","identity":"rs-7580244","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}