Evaluation of the antibacterial activity of turkish gall extract against Staphylococcus aureus ATCC 6538

Abstract

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. The minimum inhibitory concentration (MIC) of the extract was 56.25 µg/mL, and the minimum bactericidal concentration (MBC) was 112.5 µg/mL. Following treatment with the extract, extracellular AKP and nucleic acid content significantly increased, indicating disruption of bacterial cell wall membrane integrity. qRT-PCR analysis revealed that sarA gene expression was significantly downregulated during the initial biofilm adhesion stage; and during the biofilm aggregation and maturation phase, the icaADB gene cluster expression was significantly downregulated, while the expression of the negative regulator icaR was upregulated. The Turkish gall extract exhibits significant antibacterial activity against S. aureus and effectively suppresses its biofilm formation. This extract may directly cause bacterial death by disrupting cell wall membrane integrity. Simultaneously, it may interfere with initial bacterial adhesion and intercellular aggregation by affecting the transcriptional levels of sarA and ica operon-related genes, thereby inhibiting biofilm development at multiple stages. This study provides new strategies and theoretical basis for developing plant-derived anti-biofilm agents.