Study of inhibitory effects of Satureja bachtiarica and Satureja khuzestanica essential oils against expression of capsule gene (epsD) of Lactococcus garvieae by Real Time PCR

Lactococcus garvieae, the causative agent of lactococcosis, is one of the most important fish pathogens all around the world. The aim of this study was to investigate the inhibitory effects of Satureja bachtiarica and Satureja khuzestanica essential oils against the expression of capsule gene (epsD) of L. garvieae. Bacterial isolates containing epsD gene were exposed to the minimum inhibitory concentrations of the essential oils (0.12 μl/ml) and the expression of epsD gene was investigated by real-time PCR. The results showed that the expression of epsD gene was suppressed in the studied bacterial isolates under MIC concentration of the essential oils. The results also revealed that the gene expression was decreased by increasing the essential oil concentration. However, S. khuzestanica was more effective on the expression of epsD gene than S. khuzestanica. Therefore, the use of S. bachtiarica and S. khuzestanica essential oils can be recommended to prevent lactococcosis in aquaculture via suppression of capsule gene.