Mentha longifolia belongs to the family of Laminaceae and is one of the medicinal plants that has a protective effect against bacteria. Aeromonas hydrophila is a Gram-negative, rod-shaped, facultative anaerobic bacterium from the Aeromonadaceae family. In this study, the effect of aqueous and alcoholic extracts of M. longifolia on A. hydrophila has been investigated. For this purpose, alcoholic and aqueous extracts of M. longifolia were prepared. Then, bacterial suspension equal to the turbidity of half McFarland was prepared and cultured on Mueller Hilton agar. Dilutions of ۱۰, ۲۵, ۵۰ and ۱۰۰ mg/ml were prepared from each of the aqueous and alcoholic extracts. Then they were placed on the culture medium by disk diffusion method. After being in the incubator for ۲۴ hours, the inhibition zone diameter of each dilution was measured. The highest and lowest inhibition zone diameter were observed in concentration of ۱۰۰ mg/ml alcoholic extract with a diameter of ۱۴ mm, and in concentration of ۱۰ mg/ml aqueous extract with a diameter of ۳ mm, respectively. The result of this study showed that the alcoholic and aqueous extracts of M. longifolia in different dilutions have different effects on A. Hydrophila.
