Antibacterial Activity of Allium sativum L. on Pathogenic Bacterial Strains

Allium sativum L; commonly known as garlic, is a species in the onion family Alliaceae. The aqueous extract and methanol extract of garlic were tested against two Gram positive and three Gram negative bacterial cultures. Of the different extracts tested, the aqueous extract of garlic showed increased inhibitoiy effect. The maximum antibacterial activity was observed in garlic aqueous extract against Klebsiella pneumoniae (8mm) and minimum activity against Salmonella typhi (4mm). The growth curve analysis of the test pathogens showed slight reduction on growth compared to control cultures. The percentage reduction of the test cultures were found to be less in 4th hour whereas their activity was effectively reduced on 14th hour. Further separation of active fractions from garlic methanol extract by column chromatography was carried out using Silica gel (Si02) as adsorbent and subjected to antibacterial assay using agar well diffusion method. The zone of inhibition was compared. Maximum antibacterial activity observed from the crude methanol extract in the column fraction at random number was detected by Thin layer chromatography. These results suggest that Allium sativum is a potential plant for controlling pathogenic bacterial strains.