Work

Species-dependent susceptibility of enterococci to bovine cathelicidin BMAP-28 and its relationship to membrane fatty acid composition

Year: 2026

Type: article

Abstract: Antimicrobial peptides (AMPs) are promising agents against multidrug-resistant bacteria. The bovine cathelicidin BMAP-28 is a cationic α-helical AMP with broad-spectrum activity, but its effects on enterococci and determinants of susceptibility remain unclear. Here, we compared the activity of BMAP-28 and four analogs against Enterococcus faecalis and Enterococcus faecium . E. fecium ATCC49533 and E. faecium ATCC6059 were used as reference strains. E. fecium and E. faecium isolates were obtained from the cattle feces. Synthesized BMAP-28 and four analog peptides were used for MIC assay. Killing assays, scanning electron microscopy, LIVE/DEAD staining, fatty acid analysis about membrane composition, and potassium leakage assay were done in this study. In silico structural analysis of BMAP-28 was performed for understanding the characteristics of the peptide. E. faecium were markedly more susceptible (MIC 520 μg/mL), whereas E. faecalis showed high level tolerance (MIC ≥ 80 μg/mL). Killing assays, scanning electron microscopy, and LIVE/DEAD staining consistently showed rapid membrane damage in E. faecium but minimal effects in E. faecalis . Fatty acid analysis revealed significant differences in membrane composition with E. faecium enriched in unsaturated lipids. In contrast, BMAP-28 induced similar potassium leakage from model membranes with different lipid compositions, indicating that lipid differences alone are insufficient to explain the observed species-dependent susceptibility. Together, these results demonstrate pronounced species dependent activity of BMAP against enterococci and suggest that additional cell envelope features beyond lipid composition contribute to the differential response.

Source: Frontiers in Microbiology

DOI: 10.3389/fmicb.2026.1826834