Purpose: The purpose of this study was to evaluate the antimicrobial property of HT and OP against growth and virulent gene expression of major foodborne pathogens.
Methods: The minimum bactericidal/inhibitory concentration (MBC/MIC) of HT and OP on enterohemorrhagic E. coli EDL933 (EHEC) and Salmonella Typhimurium LT2 (ST) were determined by broth micro-dilution method. The inhibitory effects of HT and OP against EHEC and ST were investigated in liquid culture condition. Several invasion-related virulence genes of ST and EHEC under stress of HT and OP were also evaluated by qPCR.
Results: The MBC/MIC of HT on EHEC and ST was found as 0.1% (w/v)/0.075% and 0.075%/0.05%, and it was 1.9%/1.7% and 1.1%/0.8% for OP, both of which were bactericidal. Following a dose-dependent manner, 0.05%, 0.1%, and 0.2% HT reduced 2.8, 3.3, and 4.9 log CFU/ml ST and 2.9, 3.1, and 3.4 log CFU/ml EHEC at 24 hours. Moreover, in mixed-culture with LC, ST and EHEC were excluded quickly by 0.05% and 0.2% HT, respectively, at 24 hours, whereas growth of LC was not affected. Further, HT significantly (P<0.05) down-regulated the expression of multiple invasion-related virulence genes such as hilA/C/D, invA/C/F/G/H, sipA, and sirA/B for ST and eaeA, espA/B/D, ler, and tirfor EHEC by 1.5-6 fold.
Significance: HT in olive might be applied as a strong alternative antimicrobial; OP, both showed antimicrobial effect and in favor of Lactobacillus growth, may serve as gut microbiome modulator for prevention of gut foodborne infections.