Efficacy and mechanisms of antimicrobial peptide BP15 and its lipopeptides against citrus blue mold

Abstract

This study explored the antimicrobial peptide BP15 and its lipopeptides HBP15 and LBP15, with a focus on their efficacy and mechanisms against Penicillium italicum, the blue mold causative agent in citrus fruits. The antimicrobial peptides significantly inhibited P. italicum growth, with minimum inhibitory concentrations (MICs) of 1.56 μM for BP15 and HBP15, and 3.12 μM for LBP15. These peptides altered hyphal morphology and increased intracellular SYTOX Green (SG) fluorescence signals, indicating enhanced cell membrane permeability and disruption. Membrane damage was further evident from increased extracellular conductivity, intracellular nucleic acid, and protein release. Gel retardation assay showed that the peptides bound and affected P. italicum DNA, thereby inhibiting fungal growth. Therefore, the antimicrobial peptide BP15 and its lipopeptides represent potential agents for preventing blue mold in citrus fruits.