J Vet Sci.  2021 Sep;22(5):e59. 10.4142/jvs.2021.22.e59.

Investigation of morphological changes of HPS membrane caused by cecropin B through scanning electron microscopy and atomic force microscopy

• Hu H
• Jiang C
• Zhang B
• Guo N
• Li Z
• Guo X
• Wang Y
• Liu B
• He Q

• KMID: 2520763
• DOI: http://doi.org/10.4142/jvs.2021.22.e59

Abstract

Background
Antimicrobial peptides (AMPs) have been identified as promising compounds for consideration as novel antimicrobial agents.
Objectives
This study analyzed the efficacy of cecropin B against Haemophilus parasuis isolates through scanning electron microscopy (SEM) and atomic force microscopy (AFM) experiments.
Results
Cecropin B exhibited broad inhibition activity against 15 standard Haemophilus parasuis (HPS) strains and 5 of the clinical isolates had minimum inhibition concentrations (MICs) ranging from 2 to 16 μg/mL. Microelectrophoresis and hexadecane adsorption assays indicated that the more hydrophobic and the higher the isoelectric point (IEP) of the strain, the more sensitive it was to cecropin B. Through SEM, multiple blisters of various shapes and dents on the cell surface were observed. Protrusions and leakage were detected by AFM.
Conclusions
Based on the results, cecropin B could inhibit HPS via a pore-forming mechanism by interacting with the cytoplasmic membrane of bacteria. Moreover, as cecropin B concentration increased, the bacteria membrane was more seriously damaged. Thus, cecropin B could be developed as an effective anti-HPS agent for use in clinical applications.

Keyword

Antimicrobial peptide; atomic force microscopy; scanning electron microscopy; Haemophilus parasuis