Antibacterial Activity of Organically Grown Vegetables

In recent years many antimicrobial agents became ineffective against bacteria. This lead to many studies of the antimicrobial effects among plants. Bulgarian vegetables are ingredients in many traditional Bulgarian foods. The aim of the study was to compare the antibacterial activity of organically grown parsley, tomatoes, cayenne peppers, onions and garlic against referent test bacteria - Bacillus subtilis No8751 and Escherichia coli No8752, supplied by the National Bank for Microorganisms and Cell Cultures. Sixteen vegetable samples were analyzed. Petri dishes were cultivated at 37oC for 24 hours. Our results demonstrated low antibacterial activity of tomato and parsley samples against the Gram(+) B. subtilis and from weak to no activity against the Gram (-) E. coli.Fresh garlic samples showed low antibacterial activity against Gram (+) bacteria with only fresh garlic leaves displaying wider sterile zones. No antibacterial activity was demonstrated by the fresh onion bulbs and leaves. In contrast, the mature garlic bulbs showed pronounced activity against the Gram (-) E. coli (30 mm zone d). Cayenne pepper tissue and seeds possess antibacterial properties against both Escherichia coli and Bacillus subtilis.Strong antimicrobial activity against B. subtilis was shown by the mature onion samples with 25 mm zone diameter for the red onion bulbs and 27 mm zone diameter for the white onion bulbs. Both mature onion samples demonstrated low activity towards E. coli.