Antimicrobial activity of various extracts of Ocimum basilicum l. and observation of the inhibition effect on bacterial cells by use of scanning electron microscopy

Abstract

The antimicrobial activities of chloroform, acetone and two different concentrations of methanol extracts of Ocimum basilicum L. were studied. These extracts were tested in vitro against 10 bacteria and 4 yeasts strains by the disc diffusion method. The results indicated that the methanol extracts of O. basilicum exhibited the antimicrobial activity against tested microorganisms. While the chloroform and acetone extracts had no effect, the methanol extracts showed inhibition zones against strains of Pseudomonas aeruginosa, Shigella sp., Listeria monocytogenes, Staphylococcus aureus and two different strains of Escherichia coli. The cells of microorganisms, which were treated and untreated with plant extracts, were observed by using the scanning electron microscope. It was observed that the treated cells were damaged. Keywords: Antimicrobial activity, Disc diffusion method, Ocimum basilicum, Plant extract, SEM, Spices.African Journal of Trad, Comp and Alternative Medicine Vol. 5 (4) 2008: pp. 363-369