Inhibitory effect of skatole (3-methylindole) on enterohemorrhagic Escherichia coli O157: H7 ATCC 43894 biofilm formation mediated by elevated endogenous oxidative stress

We investigated the effects of skatole (3-methylindole), which is one of the indole derivatives on the biofilm formation of EHEC O157:H7. Notably, skatole (100 μg ml^-1) significantly reduced EHEC O157:H7 ATCC 43894 biofilm formation by 52% in 96-well polystyrene plates under quiescent conditions, with no effect on planktonic cell growth. The skatole sample was maintained in stable conditions for 24 h without degradation or evaporation via EHEC O157:H7 ATCC 43894. Importantly, skatole negatively triggered the expression of catalase in EHEC strains, as well as altered EHEC surface morphology. Our finding indicated that suppressed catalase activity via skatole might have been responsible for elevated endogenous oxidative stress and increment in oxidative metabolites might have led to damaged cell surfaces and a reduction in biofilm formation of EHEC O157:H7 ATCC 43894.