Changes in membrane fatty acids composition of microbial cells induced by addiction of thymol, carvacrol, limonene, cinnamaldehyde, and eugenol in the growing media

Major active compounds from essential oils are well known to possess antimicrobial activity against both pathogen and spoilage microorganisms. The aim of this work was to determinate the alteration of the membrane fatty acid profile as an adaptive mechanism of the cells in presence of a sublethal concentration of antimicrobial compound in response to a stress condition. Methanolic solutions of Thymol, Carvacrol, Limonen, Cinnamaldehyde and Eugenol were added into growing media of Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, Pseudomonas fluorescens, Brochothrix thermosphacta and Staphylococcus aureus strains. Fatty acid extraction and their gas-chromatographic analysis were performed to assess changing in membrane fatty acid composition. Substantial changes were observed on the long chain unsaturated fatty acids when the E. coli and Salmonella strains grew in presence of limonene and cinnamaldehyde and carvacrol and eugenol respectively. All compounds influenced the fatty acid profile of Brochothrix thermosphacta, while Pseudomonas and S. aureus strains didn’t show substantial changes in their fatty acids composition.