{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T01:54:46Z","timestamp":1783994086017,"version":"3.55.0"},"reference-count":44,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,8,22]],"date-time":"2025-08-22T00:00:00Z","timestamp":1755820800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Universidad T\u00e9cnica del Norte","award":["9674\/2024"],"award-info":[{"award-number":["9674\/2024"]}]},{"name":"Universidad T\u00e9cnica del Norte","award":["147\/2025"],"award-info":[{"award-number":["147\/2025"]}]},{"name":"Universidad T\u00e9cnica del Norte","award":["ATN\/RF-21044-RG\/2024"],"award-info":[{"award-number":["ATN\/RF-21044-RG\/2024"]}]},{"name":"Scientific Visitor Fellowship","award":["9674\/2024"],"award-info":[{"award-number":["9674\/2024"]}]},{"name":"Scientific Visitor Fellowship","award":["147\/2025"],"award-info":[{"award-number":["147\/2025"]}]},{"name":"Scientific Visitor Fellowship","award":["ATN\/RF-21044-RG\/2024"],"award-info":[{"award-number":["ATN\/RF-21044-RG\/2024"]}]},{"name":"Regional Fund for Agricultural Technology (FONTAGRO)","award":["9674\/2024"],"award-info":[{"award-number":["9674\/2024"]}]},{"name":"Regional Fund for Agricultural Technology (FONTAGRO)","award":["147\/2025"],"award-info":[{"award-number":["147\/2025"]}]},{"name":"Regional Fund for Agricultural Technology (FONTAGRO)","award":["ATN\/RF-21044-RG\/2024"],"award-info":[{"award-number":["ATN\/RF-21044-RG\/2024"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antibiotics"],"abstract":"<jats:p>Background\/Objectives: The global increase in multidrug-resistant (MDR) bacterial infections underscores the urgent need for effective and sustainable antimicrobial alternatives. This study investigates the antimicrobial activity of exometabolite-based formulations (ExAFs), derived from the cell-free supernatants (CFS) of native lactic acid bacteria (LAB) applied individually or in combination thereof, against MDR-Escherichia coli strain L1PEag1. Methods: Fourteen ExAFs were screened for inhibitory activity using time\u2013kill assays, and structural damage to bacterial cells was assessed via scanning and transmission electron microscopy (SEM\/TEM). The most potent formulation was further characterized by liquid chromatography\u2013tandem mass spectrometry (LC\u2013MS\/MS) employing a Sequential Windowed Acquisition of All Theoretical Fragment Ion Mass Spectra (SWATH) approach for untargeted metabolite profiling. Results: Among the tested formulations, E10, comprising CFS from Weissella cibaria UTNGt21O, exhibited the strongest inhibitory activity (zone of inhibition: 17.12 \u00b1 0.22 mm), followed by E1 (CFS from Lactiplantibacillus plantarum Gt28L and Lactiplantibacillus plantarum Gt2, 3:1 v\/v) and E2 (Gt28L CFS + EPS from Gt2, 3:1 v\/v). Time\u2013kill assays demonstrated rapid, dose-dependent bactericidal activity: E1 and E10 achieved &gt;98% reduction in viable counts within 2\u20133 h, at 1\u00d7 MIC, while E2 sustained 98.24% inhibition over 18 h, at 0.25\u00d7 MIC. SEM and TEM revealed pronounced ultrastructural damage, including membrane disruption, cytoplasmic condensation, and intracellular disintegration, consistent with a membrane-targeting mode of action. Metabolomic profiling of E10 identified 22 bioactive metabolites, including lincomycin, the proline-rich peptide Val\u2013Leu\u2013Pro\u2013Val\u2013Pro\u2013Gln, multiple flavonoids, and loperamide. Several compounds shared structural similarity with ribosomally synthesized and post-translationally modified peptides (RiPPs), including lanthipeptides and lassopeptides, suggesting a multifaceted antimicrobial mechanism. Conclusions: These findings position ExAFs, particularly E10, as promising, peptide-rich, bio-based antimicrobial candidates for food safety or therapeutic applications. The co-occurrence of RiPP analogs and secondary metabolites in the formulation suggests the potential for complementary or multi-modal bactericidal effects, positioning these compounds as promising eco-friendly alternatives for combating MDR pathogens.<\/jats:p>","DOI":"10.3390\/antibiotics14090851","type":"journal-article","created":{"date-parts":[[2025,8,22]],"date-time":"2025-08-22T12:31:26Z","timestamp":1755865886000},"page":"851","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Exometabolite-Based Antimicrobial Formulations from Lactic Acid Bacteria as a Multi-Target Strategy Against Multidrug-Resistant Escherichia coli"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-7819-9679","authenticated-orcid":false,"given":"Gabriela N.","family":"Tenea","sequence":"first","affiliation":[{"name":"Biofood and Nutraceutics Research and Development Group, Faculty of Engineering in Agricultural and Environmental Sciences, Universidad Tecnica del Norte, Av. 17 de Julio s-21, Barrio El Olivo, Ibarra 100150, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diana","family":"Molina","sequence":"additional","affiliation":[{"name":"Biofood and Nutraceutics Research and Development Group, Faculty of Engineering in Agricultural and Environmental Sciences, Universidad Tecnica del Norte, Av. 17 de Julio s-21, Barrio El Olivo, Ibarra 100150, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuleissy","family":"Cuamacas","sequence":"additional","affiliation":[{"name":"Biofood and Nutraceutics Research and Development Group, Faculty of Engineering in Agricultural and Environmental Sciences, Universidad Tecnica del Norte, Av. 17 de Julio s-21, Barrio El Olivo, Ibarra 100150, Ecuador"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9429-4502","authenticated-orcid":false,"given":"George C\u0103t\u0103lin","family":"Marinescu","sequence":"additional","affiliation":[{"name":"Independent Research Association, 58 Timi\u0219ului, Sector 1, 012416 Bucharest, Romania"},{"name":"Blue Screen SRL, 58 Timi\u0219ului, Sector 1, 012416 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Roua Gabriela","family":"Popescu","sequence":"additional","affiliation":[{"name":"Independent Research Association, 58 Timi\u0219ului, Sector 1, 012416 Bucharest, Romania"},{"name":"Blue Screen SRL, 58 Timi\u0219ului, Sector 1, 012416 Bucharest, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Zapa\u015bnik, A., Soko\u0142owska, B., and Bry\u0142a, M. 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