Chemical composition and antimicrobial activity of Achillea wilhelmsii C.Koch essential oil against selected bacterial and fungal pathogens of fish

Abstract

Background & Aim: By increasing resistance of fish pathogens to chemical drugs, using herbal plants with antimicrobial properties is necessary.In this study, the composition of the essential oil and antimicrobial activity of aerial parts of <em>Achillea wilhelmsii</em> C.Koch growing wild in Zagross mountain (Southwest of Iran) was analyzed against common bacterial and fungal pathogens of fish. Experimental: In the present study, aerial parts of <em>A. Wilhelmsii</em> were tested against five bacterial strains including <em>Streptococcus iniae</em>, <em>Yersinia ruckeri</em>, <em>Vibrio angularum</em>, <em>Aeromonas</em><em> hydrophila </em>and <em>Pseudomonas aeruginosa</em> and four pathogenic fungi namely <em>Saprolegnia </em>sp., <em>Fusarium solani</em>, <em>Candida albicans</em>and <em>Aspergillus flavus</em>. Also, the oil constituents of <em>A. Wilhelmsii</em> were analyzed by gas chromatography/mass spectrometry (GC/MS). Results & Discussion: The major composition of the essential oil of <em>A. Wilhelmsii</em> was 1.8-cineol (25.2%), Camphor (18.9%), Linalool (6.9%), Borneol (5.7%) and Artemisia alcohol (4.3). All microorganisms showed more sensitivity to essential oil of <em>A. Wilhelmsii</em> than the control antibiotics. Maximum antibacterial and antifungal activity was observed against <em>Y. ruckeri </em>(25.4 mm)and <em>C. albicans </em>(25 mm) respectively, while <em>S. iniae </em>(16.4 mm)and<em> A. flavus</em> (14 mm)exhibited the least sensitivity. In addition, MIC test showed that minimum concentrations of the essential oil ranged from 125 to 800 μg/l were able to inhibit the growth of the selected bacterial and fungal pathogens. Industrial and practical recommendations: The results showed that the essential oil of <em>A. Wilhelmsii</em> could be a potential source of new and effective antibacterial components in aquaculture industry. Although, more study needed to purify, fractional and characterize various antimicrobial compounds from the essential oil of <em>A. Wilhelmsii.</em>