Variations in cellular membrane fatty acid composition of Escherichia coli in resistance to pulsed electric fields induced by eugenol

Eugenol (EUG; 4-allyl-2-methoxyphenol) is a natural antibacterial component from essential oil. The effects of EUG on cell membrane fatty acid composition, membrane fluidity and resistance to pulsed electric field (PEF) of Escherichia coli ATCC 8,739 (E. coli) were investigated. Results indicated that the PEF resistance of E. coli decreased as EUG concentration increased, which may be related to the alterations in membrane fatty acid composition and fluidity. Gas chromatography−mass spectrometry and micro-Raman spectroscopy showed that EUG increased membrane fluidity by notably increasing the proportion of unsaturation fatty acids and simultaneously decreasing the content of cyclic fatty acids. These results revealed that PEF resistance of E. coli was influenced by EUG due to alterations of fatty acid composition and membrane fluidity. Practical applications: Pulsed electric field (PEF), as a widely used non-thermal sterilization technology, has gained much attention and increasingly focused on improving the efficiency to inactivate micro-organisms. Eugenol (EUG; 4-allyl-2-methoxyphenol) derived from cloves is a natural phenol essential oil and exhibits several pharmacological properties such as being an antimicrobial. Our results revealed the underlying mechanism that EUG reduced PEF resistance of E. coli cells and contributed to achieve better understanding of microbial inactivation by PEF. Therefore, a new route for the application of eugenol to improve the efficiency of PEF in the food industry was created.