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Updated: Jun 27, 2026

Production and Visualization of Bacterial Spheroplasts and Protoplasts to Characterize Antimicrobial Peptide Localization
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Published on: August 11, 2018

Ib-M1 Antimicrobial Peptide Alters Membrane Permeability and Disrupts Escherichia coli O157:H7 Bacillar Morphology

Mónica Liliana Pérez-Rivera1, Ana Elvira Farfán-García1,2, Edgar Javier Rincón-Baron3

  • 1Facultad de Ciencias Médicas y de la Salud, Instituto de Investigación Masira, Universidad de Santander, Bucaramanga 680003, Colombia.

Microorganisms
|June 26, 2026
PubMed

Insights

The Ib-M1 peptide effectively targets and permeabilizes both the outer and inner membranes of Escherichia coli O157:H7, leading to bacterial cell death. This study reveals Ib-M1

Area of Science:

  • Antimicrobial Peptides
  • Bacteriology
  • Molecular Biology

Background:

  • The emergence of antibiotic-resistant bacteria necessitates novel therapeutic strategies.
  • Escherichia coli O157:H7 poses a significant public health threat due to its pathogenicity.
  • Antimicrobial peptides (AMPs) represent a promising class of compounds with bactericidal properties.

Purpose of the Study:

  • To investigate the mechanism of action of the Ib-M1 peptide against Escherichia coli O157:H7.
  • To evaluate the impact of Ib-M1 on bacterial membrane integrity and morphology.

Main Methods:

  • Determination of minimum inhibitory concentrations (MIC) for Ib-M1 against E. coli O157:H7 and ML35.
  • Assessing outer and inner membrane permeabilization using N-phenyl-1-naphthylamine and O-nitrophenyl-β-galactosidase hydrolysis assays.
  • Scanning electron microscopy (SEM) to visualize morphological changes in treated bacteria.

Main Results:

  • Ib-M1 demonstrated potent activity against E. coli O157:H7 (MIC: 2.9 ± 1.7 μM) and ML35 (MIC: 6.3 ± 0 μM).
  • The peptide induced significant outer membrane permeabilization at all tested concentrations and inner membrane permeabilization at concentrations ≥1× MIC.
  • SEM analysis revealed substantial morphological alterations, including cell collapse and surface irregularities, in Ib-M1-treated E. coli O157:H7.

Conclusions:

  • Ib-M1 exerts its bactericidal effect against E. coli O157:H7 primarily through the disruption of both outer and inner bacterial membranes.
  • The findings support Ib-M1 as a potential therapeutic agent for combating E. coli O157:H7 infections.
Keywords:
Escherichia coli O157:H7Ib-M1 antimicrobial peptidebacterial membrane permeabilitymorphological alterations cell surface

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