Vimolmas Lipipun, Nantawan Nantawanit, and Sunanta Pongsamart

pp. 31 - 38

Abstract

In vitro activity study of polysaccharide gel (PG) extracted from fruit-hulls of durian (Durio zibethinus L.) was performed to evaluate the activities against microorganisms. Inhibitory activity of PG against two bacterial strains, Staphylococcus aureus and Escherichia coli, and two yeast strains, Candida albicans and Saccharomyces cerevisiae, were determined by microbiological assay techniques using a simple agar diffusion and broth dilution method. PG at the concentration 0.32% in distilled water showed inhibition zone on TSA medium against S. aureus, and MIC of PG in TSB medium against S. aureus was 0.64 mg/ml. However, the lowest concentration of PG in distilled water at 1.25% and 2.50% produced inhibitory activity on MNG agar medium against S. aureus and E. coli, respectively, and an inhibition zone with sharp and clear delineated zone margins was obtained. Inhibitory activity of PG at the lowest concentration of 1% in peptone broth medium against E. coli and S. aureus was demonstrated: the colony count at 24 hours declined to zero and to 15%, respectively. However, both strains of test bacteria in NSS were inhibited in the presence of 0.1% PG: the colony count at 24 hours declined to zero. PG showed no inhibitory activity against two strains of test yeast in this study.