Antibacterial Activity of Zingiber officinale on Escherichia coli and Staphylococcus aureus

Aims: The aim of this study was to investigate the antibacterial activity of extracts of fresh, dried and oil of Zinginber officinale on Escherichia coli and Staphylococcus aureus. Minimum inhibitory concentrations of the extracts against test organisms were determined and their inhibitory effects were compared with commercially available antibiotics.

Study Design: Laboratory based controlled experiment.

Place and Duration of Study: The research was conducted at the Molecular Biology Laboratory, Department of Biotechnology, Modibbo Adamawa University of Technology, Yola, Nigeria between January and May, 2014.

Methodology: Extracts from fresh and dried rhizomes of Z. officinale as well as ginger oil, which was extracted with the aid soxhlet extraction apparatus using n-hexane as the solvent were tested on isolates of E. coli and S. aureus using the agar well diffusion method. Both bacterial isolates were also subjected to standard antibiotic susceptibility test for comparison. Broth dilution method was used to determine the minimum inhibitory concentrations of the extracts on the test organisms.

Results: At concentrations of 10 mg/mL, 20 mg/mL, 30 mg/mL, and 40 mg/mL the zones of inhibition of dried Z. officinale extracts on S. aureus were 11.00 ±1.41 mm, 13.5 ± 0.71 mm, 14.00± 2.66 mm and 17.5 ± 0.87 mm respectively and on E. coli were 6.00 ± 2.83 mm, 7.5 ± 2.12 mm, 8.00 ± 2.83 mm and 14.5± 6.08 mm respectively. Fresh ginger showed 15.00±1.40 mm and 12.00±2.83 mm at 100%, 50% concentrations respectively on S. aureus and 15.00±3.54 mm and 13.00±2.66 mm on E. coli respectively but has no effect at 25% and 12.5% on both organisms. The oil extract showed zones of inhibition of 12.00±2.83 mm and 7.00±4.24 mm at 100% and 50% concentrations on S. aureus respectively, while it showed no activity on E. coli. Minimum Inhibitory Concentration (MIC) of dried and fresh Z. officinale extracts on both isolates at 2.5 mg/ml. Oil extract did not exhibit inhibitory effect in broth even at concentration of 10 mg/ml.

Conclusion: The study indicated that both fresh and dried Z. officinale extracts inhibit the growth of S. aureus and E. coli similar to some standard antibiotics. This suggests that the plant is a potential source of antibacterial drug.