A novel endogenous antimicrobial peptide targeting Candida albicans from Huangshui: Isolation and characterization

This study aimed to explore Huangshui , a byproduct of Baijiu fermentation, as a novel source of antimicrobial peptides (AMPs). Through ultrafiltration, semi-preparative high-performance liquid chromatography (HPLC), and reversed-phase (RP-HPLC), a fraction with potent antimicrobial activity was isolated. Liquid chromatography-mass spectrometry (LC-MS/MS) analysis identified 27 peptide sequences, among which only the heptapeptide HS-4 (sequence: ALTNPTT) exhibited significant activity against Candida albicans . HS-4, characterized by a net charge of zero and a disordered random-coil conformation, demonstrated a minimum inhibitory concentration (MIC) of 64 μmol/L and a minimum fungicidal concentration (MFC) of 256 μmol/L against C. albicans . It showed excellent biocompatibility (negligible hemolysis and cytotoxicity) and stability under various pH, salt, and serum conditions, though its activity was reduced by high temperatures (>100 °C), divalent metal ions, and enzymatic treatment. Mechanistic studies using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and nucleic acid leakage assays revealed that HS-4 exerts its fungicidal effect by disrupting the cell wall and membrane integrity of C. albicans , leading to content leakage and cell death. These findings highlight the uniqueness of HS-4 as a food-derived AMP and its potential as a natural biopreservative against C. albicans contamination in the food industry.