Antibacterial Activity of Thyme (Thymus vulgaris L.), Laurel (Lauris nobilis L.), Rosemary (Rosmarinus officinalis L.) and Parsley (Petroselinum crispum L.) Essential Oils against Some Fish Pathogenic Bacteria

Abstract

In this study, the antibacterial activity of thyme (TEO), laurel (LEO), rosemary (REO) and parsley essential oils (POE) against different fish pathogens such as Yersinia ruckeri (a, b), Lactococcus garvieae, Pseudomonas fluorescens, Aeromonas sobria, Aeromonas salmonicida and Aeromonas veronii was investigated. The essential oils were extracted by hydro-distillation using a Clevenger apparatus, and their antibacterial activities were measured by paper disk diffusion method. Significant differences in the antibacterial activity of essential oils, depending on plant source and on bacterial strain, were detected. All essential oils showed inhibitory effect against fish pathogenic bacteria (except PEO against Y. ruckeri (b)), and the inhibition zones ranged from 6.00 to 36.00 mm. The highest antibacterial activity against all tested bacteria was determined in TEO with a diameter of inhibition zone ranging from 26.50 to 36.0 mm, while LEO and REO showed a moderate activity with a diameter of inhibition zone ranging from 9.50 to 18.50 mm. The PEO illustrated the lowest diameter of inhibition zone against all the test bacteria. Among the tested bacteria, A. veronii was the most sensitive to the inhibitory activity of TEO, LEO and REO, while P. fluorescens was the most resistant. The results suggested that essential oils from thyme, laurel and rosemary can be used as natural antibacterial agents against fish pathogenic bacteria.