{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T09:05:09Z","timestamp":1780304709470,"version":"3.54.0"},"reference-count":45,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,5,30]],"date-time":"2026-05-30T00:00:00Z","timestamp":1780099200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministerio de Ciencia, Tecnolog\u00eda e Conflict of Interest Innovaci\u00f3n","award":["129980763392 CT-760-2018"],"award-info":[{"award-number":["129980763392 CT-760-2018"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>The Ib-M1 peptide exhibits bactericidal activity against Escherichia coli O157:H7 and low toxicity in mammalian cells. The present study aimed to evaluate the effect of Ib-M1 on E. coli O157:H7 membrane permeabilization. For this purpose, the minimum inhibitory concentrations of Ib-M1 for E. coli O157:H7 and ML35 were measured. The permeability of the E. coli outer and inner membranes was determined by measuring N-phenyl-1-naphthylamine and O-nitrophenyl-\u03b2-galactosidase hydrolysis, respectively after bacterial exposure to antimicrobial peptides and control antibiotics. Morphological changes in antimicrobial-exposed E. coli O157:H7 were evaluated by scanning electron microscopy following treatment with antimicrobial peptides. Ib-M1 expressed activity against E. coli O157:H7 and ML35 at minimal inhibitory concentrations (MIC) of 2.9 \u00b1 1.7 and 6.3 \u00b1 0 \u03bcM, respectively. The peptide induced permeabilization of the outer membrane of E. coli O157:H7 at all concentrations evaluated and permeabilization of the inner membrane after 50 min at concentrations between 1\u00d7 MIC and 8\u00d7 MIC. The morphological changes induced by Ib-M1 led to significant alterations in bacterial shape including collapsed cells and pronounced surface roughness and invaginations. In conclusion, physiological and morphological evidence indicates that the Ib-M1 antimicrobial effect against E. coli O157:H7 is mediated by its permeabilizing action on the outer and inner bacterial membranes.<\/jats:p>","DOI":"10.3390\/microorganisms14061237","type":"journal-article","created":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T08:09:16Z","timestamp":1780301356000},"page":"1237","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Ib-M1 Antimicrobial Peptide Alters Membrane Permeability and Disrupts Escherichia\u00a0coli O157:H7 Bacillar Morphology"],"prefix":"10.3390","volume":"14","author":[{"given":"M\u00f3nica Liliana","family":"P\u00e9rez-Rivera","sequence":"first","affiliation":[{"name":"Facultad de Ciencias M\u00e9dicas y de la Salud, Instituto de Investigaci\u00f3n Masira, Universidad de Santander, Bucaramanga 680003, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9691-0759","authenticated-orcid":false,"given":"Ana Elvira","family":"Farf\u00e1n-Garc\u00eda","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias M\u00e9dicas y de la Salud, Instituto de Investigaci\u00f3n Masira, Universidad de Santander, Bucaramanga 680003, Colombia"},{"name":"Corporaci\u00f3n de Ciencias B\u00e1sicas Biom\u00e9dicas, Universidad de Antioquia, Medell\u00edn 050010, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1347-171X","authenticated-orcid":false,"given":"Edgar Javier","family":"Rinc\u00f3n-Baron","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias Naturales, Universidad de Santander, Bucaramanga 680003, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5321-553X","authenticated-orcid":false,"given":"Johanna Marcela","family":"Fl\u00f3rez-Castillo","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias Agr\u00edcolas y Veterinarias, Universidad de Santander, Bucaramanga 680003, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5628-5760","authenticated-orcid":false,"given":"Oscar Gilberto","family":"G\u00f3mez-Duarte","sequence":"additional","affiliation":[{"name":"Division of Pediatric Infectious Diseases and Immunology, Department of Pediatrics, Levine Children\u2019s Hospital, Charlotte, NC 28203, USA"},{"name":"Department of Pediatrics, School of Medicine, Wake Forest University, Charlotte, NC 28203, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Indira Paola","family":"Hern\u00e1ndez-Pe\u00f1aranda","sequence":"additional","affiliation":[{"name":"Facultad de Ciencias Agr\u00edcolas y Veterinarias, Universidad de Santander, Bucaramanga 680003, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"e216","DOI":"10.1016\/S1473-3099(20)30327-3","article-title":"The Value of Antimicrobial Peptides in the Age of Resistance","volume":"20","author":"Magana","year":"2020","journal-title":"Lancet Infect. 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