Transcriptome Analysis and Weighted Gene Co-expression Network Reveal Multitarget-Directed Antibacterial Mechanisms of Benzyl Isothiocyanate against Staphylococcus aureus

Staphylococcus aureus can cause many diseases and has a strong tendency to develop resistance to multiple antibiotics. In this study, benzyl isothiocyanate (BITC) was shown to have an excellent inhibitory effect on S. aureus ATCC25923 and methicillin-resistant S. aureus strains, with a minimum inhibitory concentration of 10 μg/mL. Under a scanning electron microscope, shrinkage and lysis of the cellular envelope were observed when exposed to BITC, and a bactericidal mode of BITC against S. aureus was further confirmed through flow cytometry. Additionally, the RNA profiles of S. aureus cells exposed to BITC indicated a violent transcriptional response to BITC. Through Kyoto Encyclopedia of Genes and Genomes analysis, it was found that many pathways involving bacterial survival were significantly affected, such as RNA degradation, oxidative phosphorylation, arginine biosynthesis, and so forth. A gene co-expression network was constructed using weighted gene co-expression network analysis, and six biologically meaningful co-expression modules and 125 hub genes were identified from the network. Among them, EfeB, GroES, SmpB, and Lsp were possibly targeted by BITC, leading to the death of S. aureus. Our results indicated a great potential of BITC to be applied in food safety and pharmaceuticals, highlighting its multitarget-directed bactericidal effects on S. aureus.