Abstract

Rosmarinus officinalis L., Laurus nobilis L. and Ocimum basilicum L. are widespread herbs in Algeria. The essential oils of the three species were extracted from leaves by hydrodistillation. The yields were respectively 0.36, 0.6 and 0.71%. The aim of this study was to evaluate the antibacterial activity of these essential oils against twenty bacterial strains: Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, MRSA ATCC 31 (Méthicilino), Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus avium, Escherichia coli ATCC 25922, Salmonella OMA 04, E. coli, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter sp.,Citrobacter freundii, Pseudomonas aeruginosa, Acinetobacter baumanii, Serratia marcescens, Salmonella sp., Shigella sp. and Providencia alcalifaciens. The essential oils were used in different concentrations. The diffusion tests on solid medium were efficient in all tested bacterial strains except Pseudomonas aeruginosa. The activity was more pronounced with the essential oil of Laurel. Indeed, the results of diffusion tests showed zones of inhibition as follows: Laurel, 8.4 to 22.4 mm; Rosemary, 8.4 to 16.4 mm and Basil, 7 to 19.9 mm. This study shows bacteriostatic effect of the three oils on all tested bacteria. The minimum inhibitory concentration (MIC) was determined by the dilution on solid medium method.

Key words: Rosmarinus officinalis L., Laurus nobilis L., Ocimum basilicum L., essential oils, antibacterial activity, minimum inhibitory concentration (MIC), Algeria.