Characterization of the antimicrobial activity and mechanism of the peptide Squ8 isolated from fermented mulberry leaves.

This study identifies a novel antimicrobial peptide, Squ8, from fermented mulberry leaves via LC-MS. The peptide (amino acid sequence RMGAGMAK, 820 Da) features an α-helical structure, +2 net charge, 50 % hydrophobicity, and antibacterial activity against Gram-negative/positive bacteria. Unlike many antimicrobial peptides that are easily inactivated under extreme temperatures or pH conditions, Squ8 retains its activity under such circumstances and has a low hemolysis rate, thus demonstrating excellent stability and safety. Additionally, it can target the genomic DNA of E.coli, exerting a unique multi-target mechanism that reduces the risk of drug resistance. These findings highlight Squ8 as a promising candidate for the development of antimicrobial drugs or novel food/feed additives, and provide a strategy to mitigate antibiotic abuse and drug resistance.