Sulfur-containing Flavors Inhibit The Expression Virulence Genes Of Enterotoxigenic Escherichia Coli And Inhibitory Mechanism

As the increase in the number of food poisoning caused by enterotoxigenic Escherichia coli and the emergence of a large number of drug-resistant bacteria,the development of new and safe preservatives is a hot issue at home and abroad.Heat-resistant enterotoxin(st)and heat-labile enterotoxin(lt)are the major virulence factors.Sulfocompound are widely concerned due to their anti-cancer,anti-tumor,and anti-microbial properties.In this paper,three kinds of sulfur-containing spices,namely benzyl isothiocyanate(BITC),diallyl disulfide(DADS)and phenylethyl isothiocyanate(PEITC),were selected to explore their antibacterial activity against enterotoxigenic Escherichia coli.The effects of sulfocompound on the expression of virulence factors,the relative activity of signal molecule AI-2,and the expression of quorum-sensing genes were investigated by RT-PCR.To investigate the effect of sulfur-containing flavors on the pathogenic mechanism of enterotoxigenic Escherichia coli,the effect of sulfur-containing flavors on total cell ATP and extracellular ATP was measured using an ATP kit.Sulfur-containing flavors were observed on the cells morphological by scanning electron microscopy.The results showed that the minimum inhibitory concentrations of three kinds of sulfocompound were 160μmol/L,2mmol/L and 400μmol/L,respectively.Three kinds of sulfocompound can down-regulate the expression of virulence factors,and showed a certain concentration dependence.In addition,BITC and DADS can inhibit the expression of AI-2relative activity,and show a concentration-dependent manner.BITC and DADS can down-regulate the expression of quorum-sensing genes LuxS and SdiA.The total ATP content of the cells decreased,and the extracellular ATP content increased.Sulfur-containing flavors by observing scanning electron microscopy can cause cell surface shrinkage,collapse,and even rupture,which lead to leakage of cell contents.Sulfocompound can not only inhibit the effects of virulence genes,signal molecules and quorum-sensing genes in enterotoxigenic Escherichia coli,but also affect the morphology of the bacteria.Description of potential applications of sulfocompound as novel food preservatives to inhibit enterotoxigenic Escherichia coli.