In vitro Antimicrobial Effect of Oregano, Garlic, and Rosemary Essential Oil Combinations Against Fish Pathogens

Authors : Öznur Özil, Ergi Bahrioğlu

Pages : 1053-1061

Doi:10.35229/jaes.1813438

View : 61 | Download : 215

Publication Date : 2025-11-30

Article Type : Research Paper

Abstract :In this study, the antibacterial effects of single and combined applications of Origanum onites (oregano), Allium sativum (garlic), and Rosmarinus officinalis (rosemary) essential oils on four important fish pathogens (Yersinia ruckeri, Vibrio anguillarum, Vagococcus salmoninarum, and Lactococcus garvieae) were evaluated in vitro by disk diffusion method. Pure oregano oil showed the highest inhibition against all bacteria, with minimum inhibitory concentrations (MICs) ranging from 0.98 to 31.25 µL/mL. Garlic and rosemary oils alone did not create an inhibition zone. Mixing oregano oil with garlic or rosemary oil in a 1:1 ratio significantly reduced the inhibition zones. According to the fractional inhibitory concentration index (FIC), mostly antagonistic or indifferent interactions were observed. The effect was further weakened in the triple mixture. The findings indicate that the antibacterial activity of essential oils depends not only on the potency of the individual components but also on the chemical interactions of these components and the target bacterial species. While oregano oil, rich in phenolic compounds, exhibits particularly high activity, its effectiveness may be diminished when mixed with oils low in phenolic compounds. Consequently, it is emphasized that instead of using random essential oil mixtures for fish disease control, natural formulations with optimized ingredient ratios and standardized chemical profiles should be developed.
Keywords : Uçucu yağ, Antagonizm, Lactococcus garvieae, Vagococcus salmoninarum, Vibrio anguillarum, Yersinia ruckeri

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