The inhibitory effect of fourteen plant extracts on the growth and development of biofilms of pathogenic micro-organisms namely, Listeria monocytogenes, Pseudomonas aeruginosa and Candida albicans will be investigated. Both aqueous extracts and dichloromethane: methanol (1:1, v/v) extracts will be used. The antimicrobial activity of these plant extracts will be investigated using a 96 well microplate method to determine the MIC on planktonic bacteria. The extracts exhibiting good antimicrobial activity will be selected to investigate their activity in combination using the sum of fractional inhibitory concentration (sum FIC). The most promising solvent extracts and selected combinations of plants will be further investigated for inhibition of biofilm formation and development. Two assays will be used to assess the growth of the biofilm and these include the crystal violet (CV) assay, which is an indirect assessment of biofilm biomass and the 2, 3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay which assesses the metabolic activity of the biofilm. Confocal scanning laser microscopy (CSLM) will also be used to visually assess the morphological changes and composition of the biofilm.
Principal supervisor: Mrs C Leonard
Co-supervisor: Prof AM Viljoen