Antibacterial Activity and Mechanism of Ginger Essential Oil againstEscherichia coliandStaphylococcus aureus

Though essential oils exhibit antibacterial activity against food pathogens, their underlying mechanism is understudied. We extracted ginger essential oil (GEO) using supercritical CO(2)and steam distillation. A chemical composition comparison by GC-MS showed that the main components of the extracted GEOs were zingiberene and alpha-curcumene. Their antibacterial activity and associated mechanism againstStaphylococcus aureusandEscherichia coliwere investigated. The diameter of inhibition zone (DIZ) of GEO againstS. aureuswas 17.1 mm, with a minimum inhibition concentration (MIC) of 1.0 mg/mL, and minimum bactericide concentration (MBC) of 2.0 mg/mL. ForE. coli,the DIZ was 12.3 mm with MIC and MBC values of 2.0 mg/mL and 4.0 mg/mL, respectively. The SDS-PAGE analysis revealed that some of the electrophoretic bacterial cell proteins bands disappeared with the increase in GEO concentration. Consequently, the nucleic acids content of bacterial suspension was raised significantly and the metabolic activity of bacteria was markedly decreased. GEO could thus inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism. Our findings speculate the bactericidal effects of GEO primarily through disruption of the bacterial cell membrane indicating its suitability in food perseveration.