Antibiofilm mechanism of 2R,3R-dihydromyricetin by targeting sortase A and its application against Staphylococcus aureus adhesion on eggshell

Abstract

Biofilm formation of Staphylococcus aureus in food processing environments raises significant safety concerns, necessitating the development of new antibiofilm approaches for controlling S. aureus contamination. This study aimed to elucidate the antibiofilm mechanism of 2R,3R-dihydromyricetin (DMY), a natural flavonoid, against S. aureus and evaluate its efficacy in reducing bacterial adhesion to eggshell. The results revealed that DMY was a potent inhibitor of S. aureus sortase A (SrtA) with an IC₅₀ of 73.43 μM, preventing bacterial adhesion to fibrinogen and subsequent biofilm formation. Fluorescence quenching assay and surface plasmon resonance analysis confirmed that DMY could directly bind to S. aureus SrtA. Notably, circular dichroism spectra demonstrated a conformational change in SrtA from α-helical to β-sheet structure upon DMY binding. Molecular dynamics simulation suggested that DMY bound to the catalytic pocket of S. aureus SrtA via hydrophobic interactions and hydrogen bonds. Furthermore, fluorescence microscopic observations further revealed that DMY attenuated the biofilm-related phenotype of SrtA by decreasing the anchoring of S. aureus protein A (SpA) onto cell wall. Importantly, pretreatment with 125 μg/mL DMY significantly reduced 1.14–1.75 log CFU/cm² of S. aureus adhered on eggshells. Overall, these findings highlight how specific targeting of SrtA by DMY inhibits the attachment stages of biofilm development in S. aureus, making it a promising candidate for a novel disinfectant against this pathogen in the food industry.