In-vitro Antibacterial Activity of Allium sativum L. Clove Extract Against Agrobacterium tumefaciens

Agrobacterium tumefaciens is responsible for causing crown gall disease which causes major economic losses and increases the host’s susceptibility to opportunistic pathogens. Although there has been much research on the effectiveness of Allium sativum (garlic) against human pathogenic bacteria, there are very few studies on its effect on plant bacteria, especially Agrobacterium tumefaciens.

Aims: To determine the in-vitro antibacterial activity of A. sativum clove crude extract against Agrobacterium tumefaciens

Study Design: Experimental.

Place and Duration of Study: Department of Parasitology and Microbiology, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University between March and May 2016.

Methodology: Agar disc diffusion method was used to screen for antibiotic susceptibility. Indole test was used for the determination of minimum inhibitory concentration (MIC) of the garlic extracts. The significant antibacterial activity of the active extract was compared with the standard antibiotic, methyl bromide. Thus, methyl bromide was the positive control and distilled water was the negative control.

Results: The garlic extract had a mean inhibition zone of 12 mm and an MIC and MBC of 50 mg/ml. The inhibitory effect of the garlic clove extract was proportional to its concentration thus the higher the concentration of garlic clove extract, the more the inhibitory effects.

Conclusion: The results indicate that garlic clove extract has the ability to both inhibit and kill Agrobacterium tumefaciens in a manner similar to that exhibited in other bacterial pathogens, though at higher concentrations.