Testing the Minimum Inhibitory Concentration of Xylopia aethiopica Aqueous Fruit Extract on Bacteria.

Name: Shepherd Coron

Mentor: Christine Priano

Abstract: Xylopia aethiopica is an aromatic tree found across wide areas of Africa and its fruit is commonly used in traditional medicines. It was previously shown that an aqueous X. aethiopica fruit extract completely inhibited the growth of gram-positive Bacillus subtilis but had only minimal effect on growth of gram-negative Escherichia coli. Because inhibition of B. subtilis was complete, it was hypothesized that dilutions of the extract would also confer antibacterial activity against gram-positive bacteria. Experiments were performed to find the minimum concentration needed for inhibition. An aqueous extract of the X. aethiopica fruit was prepared in distilled water by boiling, centrifugation, and sterile filtration. The extract was then serially diluted in fractional increments. Liquid cultures of E. coli and B. subtilis were prepared in a 96 well microplate along with the appropriate bacterial controls. Growth was monitored for eight hours by measuring optical density in a BioTek microplate reader. Results showed that the X. aethiopica extract inhibited growth of B. subtilis at the initial concentration and at a 2-fold dilution, but it did not inhibit at lower concentrations. It was concluded that the active components of the X. aethiopica extract need to be present in relatively high concentrations for maximal effect. Further experiments will include investigating the types of phenolic compounds present in these plant extracts that might be responsible for bacterial inhibition. The inhibitory potential of X. aethiopica extracts against gram positive bacteria might have important implications in the development of alternative antibacterial medications.