ANTIBACTERIAL EFFECTS OF SEVEN ESSENTIAL PLANT OILS ON FISH PATHOGENS

Abstract

The use of natural products which have the least harmful effects on the environment has recently been taken as a novel approach against fish diseases. References on in vitro studies have demonstrated antibacterial activity of essential oils (EOs) against certain fish pathogens. The aim of this study was to evaluate the antibacterial effect of some plant essential oils against fish pathogenic bacteria in vitro conditions. Seven plant EOs: lavender (Lavandula angustifolia), clove (Eugenia caryophyllus), peppermint (Mentha piperitae), basil (Ocimum sanctum), rosemary (Rosmarinus officinalis), cinnamon (Cinnamomum zeylanicum) and black cumin (Nigella sativa) were used to identify their antibacterial properties against Yersinia ruckeri, Aeromonas hydrophila, Vibrio anguillarum, Vibrio alginolyticus, Lactococcus garvieae and Vagococcus salmoninarum at five concentrations using disc diffusion method. Especially the EOs of clove, cinnamon and rosemary showed the strongest antibacterial activities than other oils against the three most susceptible bacterial strains (Y. ruckeri, A. hydrophila and V. salmoninarum). Besides, the EOs of clove, rosemary, cinnamon and black cumin showed similar inhibition zones with OTC against A. hydrophila. The minimum inhibitory concentrations of the used EOs found between 500 and 62.5 µl mL-1. As a result, three of the EOs used in this study were effective on both Gr (-) and Gr (+) bacteria.