Unraveling the mechanism of the synergistic antimicrobial effect of cineole and carvacrol on Escherichia coli O157:H7 inhibition and its application on fresh-cut cucumbers

The objective of this study was to evaluate the mechanism of the synergistic antimicrobial effect of cineole (CN) and carvacrol (CR) on E. coli and its application on fresh-cut cucumbers. Herein, the CN/CR synergy could effectively inhibit E. coli by destroying its bacterial cell structure and causing the leakage of intracellular organic matters. For the first time, CN/CR synergy interaction on E. coli DNA and the possible mechanism of action on bacterial genetic material was revealed at the molecular level by molecular docking technology. Furthermore, CN/CR could significantly inhibit E. coli biofilm, mobility, and exopolysaccharides (EPS) production ( p < 0.05). Supporting these findings, CN/CR suppressed E coli virulence genes shiga toxin ( stx 1), intimin ( eae ), flagella regulation ( flh D), and AI-2 quorum-sensing gene ( lux S) at transcriptional levels. Finally, CN/CR application at 1MIC+1MIC was satisfactory in significantly inhibiting E. coli on fresh-cut cucumbers but had a sensorial defect. Moreover, CN/CR at ½MIC+½MIC were generally acceptable with a better sensorial score. This study thus confirmed the CN/CR antimicrobial efficacy and maybe used as an alternative natural food sanitizer of fresh produce. • Cineole and carvacrol synergy significantly inhibited E. coli O157:H7. • The synergy disrupts membrane permeability and increases leakage of cellular matters. • Docked pose of CN and CR interacted with E. coli O157:H7 at similar binding sites. • The cineole-carvacrol synergy suppresses E. coli O157:H7 virulence genes. • The CN/CR synergy demonstrated the potential as a natural food sanitizer.