Assessing of the antibacterial properties of thyme (Thymus vulgaris) essential oil against streptococcus spp. isolated from clinical cases in Nile tilapia: an in vitro study

Abstract

Keywords In the current study, an agar disc diffusion test was used to determine whether or not the thyme essential oil (TEO) had antibacterial properties against pathogenic fish Streptococcus spp. Using gas chromatography-mass spectrometry (GC-MS), the analyzed essential oil of thyme showed a total of 47 different chemical components. Thymol, P-cymene, terpinene, linalool, and endo-borneol were the most abundant active components that were quantified. Three bacterial strains (Streptococcus agalactiae, Streptococcus iniae, and Streptococcus faecalis) that cause streptococcosis in tilapia were chosen for the purpose of invitro evaluation of the antimicrobial activity of TEO at different concentrations against gentamycin which served as the control positive. The results showed that the zone of inhibition for Streptococcus agalactiae was greatest at concentrations of 1:1 and 1:2. However, when compared to gentamycin, the zone of inhibition for concentrations of 1:3 was not significant. Compared to gentamycin, the inhibitory zones produced by TEO against Streptococcus iniae and Streptococcus faecalis were not significant. In overall, TEO showed efficacy in suppressing the growth of the three strains of Streptococcus, with the most successful outcomes shown in inhibiting the growth of Streptococcus agalactiae. Thyme essential oil Streptococcus spp, Agar disc diffusion test Tilapia Medicinal herbs