Antimicrobial Properties of Averrhoa bilimbi Extracts at DifferentMaturity Stages

In the present study, the water extracts of Averrhoa bilimbi at different maturity stages were evaluated to investigate antimicrobial activity against two Gram positive and three Gram negative bacteria by disc diffusion and broth dilution assays. All of the bacterial isolates showed varying degrees of sensitivity towards A. bilimbi extracts. For disc diffusion assay, Gram positive bacterium, Staphylococcus aureus was more sensitive to the extract than Bacillus cereus with inhibition zone of 9.3 mm (young fruit), 12.3 mm (mature fruit) and 10 mm (ripe fruit). The findings also demonstrated that the extracts have stronger antimicrobial effects against Gram negative bacteria, Salmonella spp. with inhibition zone of 12 mm at young fruit, 11 mm at mature fruit and 9.3 mm at ripe fruit than Escherichia coli and Pseudomonas aeruginosa. From broth dilution method, the MIC of extracts were 0.125 gml-1 at young stage, 0.25 gml-1 at mature stage and 0.5 gml-1 at ripe stage against Escherichia coli while 0.25 gml-1 at either young or ripe stage and 0.125 gml-1 at mature stage for S. aureus. The results suggested that the antimicrobial properties are influenced by the maturity stages of the fruit especially at early stage of maturity.