Abstract

Lactococcus garvieae is one of the most important bacterial pathogens that affect different farmed fish species in many countries. Some of the medicinal plants and their extracts have an antibacterial activity. In this study, antibacterial activity of ethanol extracts and essential oils of fifteen Iranian medicinal plants including, Satureja bachtiarica Bunge.,Thymus daenensis Celak., Stachys lavandulifolia Vahl., Zataria multifora Boiss., Thymbra spicata L., Teucrium polium L. (Lamiaceae); Myrtus communis L. (Myrtaceae); Heracleumlasiopetalum Boiss., Kelussia odoratissima Mozaff., Bunium persicum (Boiss.) K.-Pol., Echiophora platyloba L. (Apiaceae); Punica granatum L. (Punicaceae); Qurcus branti Lindle (Fagaceae); Glycyrrhiza glabra L., Alhagi maurorum L. (Fabaceae) were investigated against Lactococcus garvieae isolated from rainbow trout (Oncorhynchus mykiss) by agar disc diffusion and serial dilution assays. Just the extracts of M. communis and T. daenensis showed relatively antibacterial activity against L. garvieae. Almost the essential oils showed strong antibacterial activity against fish pathogen. The results obtained appeared to confirm the antibacterial potential of the essential oils of B. persicum, Z. multifora, T. daenensis, S. bachtiarica and T. spicata against L. garvieae isolated from rainbow trout. The MICs and MLCs of Z. multifora essential oil against L. garvieae were found as 4-8 µl/ml.

Key words: Lactococcus garvieae, medicinal plants, ethanol extract, antibacterial activity, essential oil.