Comparison of the inhibitory potential of benzyl isothiocyanate and phenethyl isothiocyanate on Shiga toxin-producing and enterotoxigenic Escherichia coli

Abstract

The aim of this study was to investigate the inhibitory effects of benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) against Shiga toxin-producing Escherichia coli (STEC) and enterotoxigenic E. coli (ETEC). Compared with that of PEITC, the antibacterial effect of BITC was more obvious. The minimal inhibitory concentration (MIC) of BITC was 60 and 160 μmol/L for STEC and ETEC, while that of PEITC was 400 μmol/L for both strains. Scanning electron microscopy (SEM) images indicated that treatment with BITC severely affected the cell integrity and led to partly sunken. Incubation of STEC and ETEC with BITC and PEITC for 1 and 4 h decreased total ATP level, while increased extracellular ATP level. Virulence genes were downregulated in dose-dependent fashion upon treatment with subinhibitory concentration of BITC and PEITC, as determined by real-time quantitative polymerase chain reaction (RT-qPCR). The expressions of stx2, eaeA and ehxA, was significantly lower in STEC treated with 1/4 MIC of PEITC than that of BITC. The inhibitory effects of BITC and PEITC on virulence genes were more obvious in STEC than ETEC. These results suggest that BITC and PEITC affect the strains growth, biological structure and expression of virulence genes of both strains.