Dual antibacterial action of ethyl ferulate as antibiofilm molecule and antibiotic synergist against Escherichia coli.

The biofilm formed by Escherichia coli enhances its pathogenicity and antibiotic resistance, posing a serious threat to human and animal health. This study evaluated the anti-biofilm and synergistic antibacterial effects of ethyl ferulate (EF) on E. coli using crystal violet (CV) staining and Alamar Blue (AB) assay. The expression levels of biofilm-related genes were analyzed by qRT-PCR. The results demonstrated that EF effectively inhibited the formation of E. coli biofilm and the production of exopolysaccharides (EPS), while enhancing bacterial motility without affecting bacterial growth and metabolic activity. qRT-PCR analysis revealed that EF treatment significantly downregulated the expression of curli-related gene csgD and c-di-GMP-related genes (pdeR and dgcM), while upregulating the expression of flagella-related genes (fliC, fliM, and motB). Notably, EF exhibited significant antimicrobial synergistic effects when combined with commercially available antibiotics (fosfomycin sodium, cefquinome, gentamicin, tetracycline, and azithromycin), markedly enhancing their antibacterial efficacy. These findings demonstrate that EF possesses potent anti-biofilm activity and holds promise as an antibacterial synergist, offering a promising strategy for the treatment of E. coli infections.