Transcriptomic analysis of Staphylococcus aureus under the stress condition of antibacterial erythorbyl laurate by RNA sequencing

Abstract

Erythorbyl laurate (EL) is a novel multi-functional emulsifier with antibacterial activity against Gram-positive bacteria. The objective of this study was to find genetic evidences of the antibacterial mechanism of EL against food-borne pathogenic Staphylococcus aureus Newman by transcriptomic analysis. Total RNA samples were extracted from non-treated and 0.1 mM (sublethal concentration) EL-treated S. aureus Newman, and then transcriptional profiling was performed by RNA sequencing (RNA-Seq). In EL-treated S. aureus Newman, 242 and 225 genes out of the 2687 genes, were up-regulated and down-regulated greater than 2-fold change, respectively. The majority of up-regulated genes in EL-treated S. aureus Newman were cell wall stress stimulon including genes related to VraSR two-component regulatory system (vraS, vraR, and vraT), cell envelopment (mur, sgt, fmt, and etc.) and L-lysine biosynthesis (lys, dap, and etc.), and there were significant differences in the regulation of peptidoglycan biosynthesis between EL-treated and control samples (p < 0.01). On the other hand, genes involved in energy metabolism, nucleic acid metabolism, translation, cell division, and transporter were down-regulated. Finally, these results of the transcriptional profiling from RNA-Seq were validated by quantitative real-time PCR. This transcriptomic study could provide the genetic evidence of the EL stress response, which suggests that EL act as a cell wall-active (cell membrane targeting) agent.