Assessment of the Antimicrobial Effects of Some Ethiopian Aromatic Spice and Herb Hydrosols

The objective of the present study was to evaluate the in vitro antimicrobial effects of the hydrosols of basil (O. basilicum), thyme (T. schimperi), cardamon (E. cardamom), cinnamon (C. Zeylanicum), mustard (B. nigra) and clove (S. aromaticum) against S. aureus, E. coli, S. typhi, P. aerugenosa and Candida albicans. Hydrosols were obtained from the selected plant species after hydro distillation using Clevenger type apparatus. The antimicrobial effects of the hydrosols were determined by measuring the zone of microbial growth on agar plates treated with hydrosol and control agar (hydrosol untreated agar) plates and then the percentage of growth inhibition was determined. Accordingly, the percent inhibition of the hydrosols were found to range from 20 to 100% (against S. aureus, p = 0.005), 10 to 100% (against E. coli, p = 0.005), 0 to 35% (against P. aerugenosa, p = 0.069) and 15 to 100% S. typhi, p = 0.00). Complete (100%) growth inhibition was demonstrated at 15% hydrosol concentration of cardamom and thyme (against E. coli), cardamon and cinnamon (against S. aureus) and cardamom, thyme and cinnamon (against S. typhi). Candida albicans were inactive to the test hydrosols. From this study, it can be concluded that the hydrosols of basil, cardamom, clove, cinnamon and thyme were effective to elicit inhibitory effect against S. typhi, S. aureus and E. coli. Further study is recommended to verify the activity of the plant hydrosols against wide range of microbial strains, characterize the chemical constituents of the hydrosols and see if the biological property can be correlated to the constituents.