Abstract
The present study investigated the antimicrobial effect and mechanism of ultrasound (US) with thyme essential oil nanoemulsions (TEON) on the inactivation of Staphylococcus aureus (S. aureus) cells. A remarkable increase in reducing the population of S. aureus was observed when cells were subjected to combined US (3.33 W/mL, 3 min) and TEON (0.375 mg/mL) treatment, which exhibited synergistic inactivation efficiency and caused a 3.21-log reduction in viability. The most severe damage to cell morphology was visualized in US + TEON group using scanning electron microscopy. Other proposed mechanisms involved that ultrasound reduced the membrane hydrophobicity, which increased the exposure of cell membrane to TEON. Moreover, the greatest degree of membrane permeabilization was evaluated, along with the massive leakage of intracellular contents. Depolarization in membrane potential was also observed and confirmed by the excessive outflow of K+ and influx of Ca2+. On the other hand, a significant decrease in membrane fluidity was monitored and further verified by the modifications in bacterial membrane fatty acid profile. This study also highlighted the impact of US + TEON treatment on bacterial membrane compositions involving proteins, nucleic acids, and phospholipids by infrared spectroscopy. Current study provides a proof-of-concept into the synergistic mechanisms of the integrated technology for enhancing S. aureus inactivation.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
