Evaluation of Antibacterial and Antibiofilm Activity of Turkish Gall Extract against Staphylococcus aureus

Background Staphylococcus aureus is a common foodborne pathogen and a frequent cause of clinical infections. It forms dense biofilms by adhering to surfaces of objects or the human body, thereby reducing the bactericidal efficacy of antibiotics and disinfectants. This study aimed to investigate the inhibitory effect of Turkish gall extract on S. aureus biofilm formation and its potential molecular mechanisms. Results The study found that the minimum inhibitory concentration of this extract was 56.25 µg/mL and the minimum bactericidal concentration was 112.5 µg/mL. It induced bacterial death by disrupting cell wall membrane system permeability, leading to the leakage of intracellular macromolecules. qRT-PCR analysis revealed that during the initial biofilm stage, the extract suppressed sarA expression levels, reducing the amount of cell wall-anchored protein, thereby diminishing bacterial adhesion. During the aggregation and maturation stages, it downregulated icaABD and negatively regulated icaR , inhibiting the synthesis of the polysaccharide intercellular adhesin and reducing extracellular polymer secretion, thus suppressing S. aureus biofilm formation. Gallic acid, a key component in the Turkish gall extract, was clearly observed via confocal laser scanning microscopy to inhibit S. aureus biofilm development. Conclusions The Turkish gall extract exerts inhibitory effects on the entire biofilm development process of S. aureus through multi-target regulatory networks, providing new strategies and theoretical basis for developing plant-derived anti-biofilm agents.