Antibacterial Activitiesof Lemon Grass Methanol Extract and Essence on Pathogenic Bacteria

3 Abstract: According to presence of biological active compounds in lemon grass plant and use of this plant in traditional medicine, it seems that this plant possesses considerable antibacterial activity. The purpose of this study was investigatingthe antibacterial activity of lemon grass methanol extract and essential oil on the four reference strains of Staphylococcus aureus (ATCC:25923), Bacillus cereus (ATCC:1247), Escherichia coli (ATCC:25922) and Pseudomonas aeruginosa (ATCC: 27853). 20, 30, 50 and 400 mg/ml concentrations of plant methanol extract were prepared. Then their antimicrobial effects were assessed with agar well diffusion and dilution test methods. Results showed that methanol extract of lemon grass plant prevented bacterial growth of Staphylococcus aureus, Bacillus cereus and Escherichia coli which with increasing concentration, their antibacterial effect also increased. 1000 mg/ml concentration of this plant leaf essential oil indicated inhibitory effect on Staphylococcus aureus, Bacillus cereus and Escherichia coli. In this study no inhibitory effect of growth ofPseudomonas aeruginosawas observed. It can be concluded that despite the inhibitory effects of concentrations of methanol extracts and essential oil of this plant on the growth of pathogenic bacteria especially Gram-positive, to introduce it as an alternative to chemical antimicrobial drugs, wider investigation is required.