Mode of action of Lippia graveolens essential oil on Salmonellaenterica subsp. enterica serovar Typhimurium

Abstract

The essential oils are a powerful natural resource with antibacterial activity. This work aims at the mode of action of Lippia graveolens Kunth essential oil of plants growing in Cuba on Salmonella enterica subsp. enterica serovar Typhimurium. The effects of this oil on cell integrity were determined by time-kill, bacteriolysis and loss of 260 and 280-nm-absorbing material assays and total proteins leakage. Also, depolarization of the membrane by essential oil was monitored and intracellular and extracellular ATP was measured. The transmission electron microscopy (TEM) was used for observed morphologic change. Minimum inhibitory concentration (MIC) of L. graveolens essential oil and minimum bactericide concentration (MBC) were 0.4 and 0.8 mg/mL respectively. This essential oil showed a bactericidal action against over S . Typhimurium in a few minutes. After treatment, the cell lysis was not occurred, but little intracellular material and total proteins leakage were observed. This essential oil depolarizes the cell membrane, disturb metabolic processes and changes the structure of cytoplasmic membrane. These results suggest as primary mode of action of L. graveolens essential oil over S . Typhimurium an increased permeability of the membrane and depolarization of inside membrane, inhibition of ATPase or disturbance in proton motive force that finally provokes death of cells. L. graveolens essential oil is a botanic resource can be used for the control of the salmonellosis, foodborne disease.