An assessment of antibacterial effect of alcoholic and aquatic extracts of Eucalyptus leaves on Pseudomonas aeruginosa

In this study the inhibitory effect of Eucalyptus extracts as a natural and herbal antibacterial substance was evaluated against Pseudomonas aeruginosa strains (8821M and ATCC27853). The MIC (Minimal Inhibitory Concentration) of alcoholic and aquatic extracts of Eucalyptus was determined using the tube and agar dilution methods. The growth rate of Pseudomonas aeruginosa in sub-MIC concentration of extracts was compared with the controls. Phenol coefficients of extracts were determined by the Ridal- Walker method. The MIC was 1:8(3.2 mg/ml) fold of the alcoholic extracts and 1:4(17.5 mg/ml) fold of the aquatic extracts. In the sub-MIC concentration of extracts, by increasing the Eucalyptus extract concentration, the growth rate was decreased. Phenol coefficients of the alcoholic and aquatic extracts were evaluated to be 0.0381 and 0.019, respectively. Results of this study indicated that crude aquatic and alcoholic extracts of Eucalyptus have inhibitory effects on the growth of Pseudomonas aeruginosa and in the sub- MIC concentration of extracts this value decreases. Overall, the plants indicated a wide range of antimicrobial activities which can lead to the detection of new antibiotics against resistant bacteria.