Abstract:The broth microdilution method was used to evaluate the antibacterial activity of Ferula essential oil (FEO), and the quorum sensing (QS) inhibitory activity of FEO was evaluated using Chromobacterium violaceum as a bacterial model. The results revealed that FEO could be used as a food antimicrobial agent and quorum sensing inhibitor. FEO showed a strong inhibitory effect on bacterial growth at minimum inhibitory concentration (MIC) of 0.25 mg/mL for all tested bacteria. Additionally, the minimum bactericidal concentration (MBC) values of FEO against Cronobacter sakazakii, Escherichia coli, Salmonella typhimurium, and Listeria monocytogenes were 0.25, 0.50, and 0.48 mg/mL, respectively. Additionally, the paper disks containing FEO at 6.25 and 12.5 mg/mL significantly inhibited the pigment produced by C. violaceum, but did not affect the growth of C. violaceum CVO26. However, when the concentration was increased to 25 mg/mL, both bacterial growth and the pigment production were inhibited. The FEO samples at all tested concentrations inhibited violacein production by C. violaceum ATCC 12472, and even FEO at the lowest concentration (0.13 mg/mL) reduced pigment production by more than 38%. In addition, the viability of C. violaceum was not affected when the concentrations of FEO samples were 0.13, 0.50, and 1.0 mg/mL, and only the FEO at the highest concentration (2.0 mg/mL) inhibited the bacterial growth and reduced bacterial counts by 1.37 log CFU/mL after incubation. These results show that FEO can effectively affect the quorum sensing system in Chromobacterium violaceum as a novel QS inhibitor.
