Label-free quantitative proteomics reveals the antibacterial mechanism of rosemary essential oil against Salmonella enterica serovar Typhimurium

Abstract

Rosemary essential oil (REO) shows various biological functions and is widely used in the cosmetic and pharmaceutical industries. Salmonella enterica serovar Typhimurium infection treated by antibiotics leads to serious drug resistance and public health hazard . REO as an antibiotic alternative has become the focus of considerable research efforts. However, knowledge regarding the S. Typhimurium growth characteristics and proteomic responses to REO exposure remains unclear. Here, we evaluated the commonalities and differences in chemical compositions of REOs extracted from Salvia rosmarinus cultivars, ‘Algarve’ (AL), ‘Dutch Mill’ (DM), and ‘Majorca Pink’ (MP) using gas chromatography-mass spectrometry. The three REOs displayed distinct chemical composition profiles, and the DM-REO, predominantly composed of 1,8-cineole and α-pinene, had the highest antibacterial activity. Sublethal levels of DM-REO caused irreversible cell membrane damage, longer lag phases, decreased growth rates, and lower maximum optical densities of S. Typhimurium. The underlying molecular regulatory mechanisms of S. Typhimurium under sublethal DM-REO treatment were investigated using label-free quantitative proteomics. Four hundred thirty-six differentially expressed proteins mainly involved in metabolism, ABC transporters , two-component system, quorum sensing , bacterial chemotaxis, and flagellar assembly were identified. The phenotypic observation test showed that DM-REO significantly inhibited S. Typhimurium motility and quorum sensing. These results increase our understanding of the antibacterial mechanism of REO inhibition in S. Typhimurium. • The chemical compositions and antibacterial properties of three REOs were assessed. • The 1/2MIC REO caused longer lag phases and lower growth rates of S. Typhimurium. • The REO was found to damage the cell membrane integrity of S. Typhimurium. • The antibacterial mechanism of REO was explored by Laber-free quantitative proteomics. • The REO inhibited S. Typhimurium motility and quorum sensing.