Effects of Antibacterial Activities Methanol Ofextract and Lemon Grass Essence on Pathogenic Bacteria

3 Abstract: Background: Including common problems in themedical world, the issue is resistance of bacteria antibiotics, so finding new antimicrobial compounds with minimal side effects is necessary. According to presence of biological active compounds in plant lemon grass and use of this plant that was made in traditional medicine, it seems that this plant contain capacity considerable antibacterial. Objective: The purpose of this study is investigation antibacterial methanol extract and essential oil of lemon grass on the four reference strains of Staphylococcus aureus (ATCC:25923), Bacillus cereus (ATCC:1247), Escherichia coli (ATCC:25922), Pseudomonas aeruginosa (ATCC: 27853). Methods: This study was designed in vitro and antimicrobial effects of methanolic extract lemon grass after extraction were examined with soxhlet method on 4 bacteri, Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa. 20 mg/ml, 30 mg/ml, 50mg/ml and 400 mg/ml concentrations was prepared of methanol extract by the solvent DMSO. Then their antimicrobial effects were assessed with Agar Well Diffusion and dilution test method. Analysis obtained data was done using ANOVA test and chi-square in p<0/01 level. Results: Findings showed that methanol extract of lemon grass plant prevent of bacterial growth of Staphylococcus aureus, Bacillus cereus and Escherichia coli which with increasing concentration, their antibacterial effect also increases, addition 1000 mg/ml concentration leaves of this plant essential oil indicated inhibitory effect on Staphylococcus aureus, Bacillus cereus and Escherichia coli. In this study no inhibitory effect of growth on Pseudomonas aeruginosa bacteria were observed. Conclusion: Despite the effects of concentrations of methanol extracts and essential oil this plant on the growth of pathogenic bacteria especially kind of gram-positive, to introduce it as an alternative to chemical antimicrobial drugs, is required wider investigation.