Non-Cytoplasmic Membrane Damage Antimicrobial Mechanism of Metal Antimicrobial Peptide SIF4 Against Escherichia coli Based on Cell Wall Target

Abstract:

To elucidate the non-cytoplasmic membrane damage antimicrobial mechanism of metal antimicrobial peptide SIF₄ against foodborne Escherichia coli(E. coli) based on cell wall target, the effect of SIF₄ on cell wall damage, the competitive binding mechanism of SIF₄ with cell wall lipopolysaccharide (LPS), and the effect of SIF₄ on cell wall membrane components were investigated, and the changes in cell morphology of strain were analyzed using scanning electron microscopy. Results displayed that SIF₄ could destroy the bacterial cell wall. Within a certain concentration range, the damage to the cell wall was positively correlated with the treatment time and treatment dose of SIF₄, and the difference between groups was significant (P<0.05). SIF₄could competitively bind with lipopolysaccharides(LPS), however, no antibacterial activity was observed when the binding amount exceeded 256 mg/L. Fourier transform infrared spectroscopy (FT-IR) analysis revealed that SIF₄ had a significant impact on cell wall polysaccharide information area, as well as the mixed information area of protein and fatty acid, indicating that cell wall was the potential antimicrobial targets. Scanning electron microscope (SEM) analysis showed that SIF₄ could destroy the cell wall membrane structure and alter strain morphology. This study suggests that SIF4 can exert efficient antimicrobial activity against E. coli based on cell wall damage target. Research results could provide supports for elucidating the mechanism of non-cytoplasmic membrane damage based on cell wall targets and biological control of foodborne E. coli.