Determination of the in vitro effect of lemongrass (cymbopogon flexuosus) oil against fish pathogenic bacteria isolated from cultured olive flounder (paralichthys olivaceus)

Abstract

The antibacterial activity of essential oil from lemongrass (Cymbopogon flexuosus) (LGO) was tested against strains of Edwardsiella tarda (n=4), Photobacterium damselae (n=1), Lactococcus garvieae (n=1), Streptococcus iniae (n=4) and S. parauberis (n=4) isolated from cultured olive flounders in Korea. Disk diffusion assay, MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) tests showed the strains of Streptococcus spp. were the most sensitive. LGO was bactericidal (MBC/MIC=1-4) for all strains of L. garvieae, S. iniae and the FP5060 strain of E. tarda, and the FP5228, S527 and S1466 strains of S. parauberis suggesting sensitivity to LGO. Gram-negative bacteria were less sensitive than Gram-positive bacteria. Since antibacterial activity of LGO was effective against fish pathogenic bacteria tested in this study, the use of LGO could be helpful in treating such bacterial infections in fish.