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. Key words: lemongrass oil; olive flounders; fish pathogenic bacteria; antimicrobial activity IN VITRO UČINEK OLJA LIMONSKE TRAVE (Cymbopogon flexuosus) PROTI RIBJI PATOGENI BAKTERIJI, IZOLIRANI IZ GOJENEGA MORSKEGA LISTA (Paralichthys olivaceus) Povzetek: Protibakterijsko delovanje eteričnega olja limonske trave (Cymbopogon flexuosus; LGO) je bilo preizkušeno glede njihovega delovanja proti sevom bakterij Edwardsiella tarda (n = 4), Photobacterium damselae (n = 1), Lactococcus garvieae (n = 1), Streptococcus iniae (n = 4) in S. parauberis (n = 4) pridobljenih iz gojenih morskih listov v Koreji. Difuzijska metoda z diskom ter testi MIC (najmanjša zaviralna koncentracija) in MBC (najmanjša baktericidna koncentracija) so pokazali, da so bili sevi Streptococcus spp. najbolj občutljivi. LGO je imel baktericidno delovanje (MBC / MIC = 1-4) na vse seve L. Garvieae in S. Iniae ter na seva FP5060 in FP5228 E. Tarda in seva S527 in S1466 S. parauberis. Gram-negativne bakterije so bile manj občutljive od gram-pozitivnih bakterij. Ker je bilo antibakterijsko delovanje LGO učinkovito proti ribjim patogenim bakterijam, preizkušenim v tej študiji, bi lahko uporaba LGO pomagala pri zdravljenju tovrstnih bakterijskih okužb pri ribah. Ključne besede: olje limonske trave; morski list; patogene bakterije rib; protimikrobno delovanje