Production of dextran from Saccharomyces boulardii and its inhibitory effect against MDR-Pseudomonas aeruginosa

Background and Objectives: The goal of the current study is to purify and characterize the dextran from Saccharomyces boulardii and investigated the antibacterial and inhibitory effect against pyocyanin and elastase production from MDR-Pseudomonas aeruginosa. Methods: The optimal production for dextran was determined at different temperature including (32℃, 37℃ and 42℃), at incubation time (24h, 48h, 72h), pH (6, 7, 8), sucrose concentration (10%, 15% and 20%) and inoculum size (1%, 2%, 4%, and 6%), purification and characterization using High performance liquid chromatography (HPLC), Fourier Transform Infrared Spectroscopy (FTIR), and Field Emission Scanning Electron Microscopy (FE-SEM). The anti-bacterial activity of dextran was evaluated by viable count method. Results: The optimum conditions for dextran production were 72 hours of incubation at 32 °C, pH=6, 15% sucrose concentration and 4% inoculum size. Characterization proved that pure polysaccharide was dextran with nano-sphere structure contained each of α (1-6) glycosidic bond and (1-3) α-D-glucan. The highest inhibitory effect was recorded as 98.60% at 100 mg/ml of dextran, while the lowest was 32.06% at 6.25 mg/ml. Anti-elastase production effect of purified dextran was detected against P. aeruginosa, the highest inhibition ratio was (60%) while the lowest ratio was (19.02%). dextran activity on pyocyanin production was detected qualitatively and noticed all isolates lose the distinctive color of pyocyanin. Conclusion: Saccharomyces boulardii produce dextran, the best conditions for production dextran were 72h of incubation at 32 °C, pH=6, 15% sucrose concentration, and 4% inoculum size. Dextran has anti-bacterial and anti-virulence activity against MDR-Pseudomonas aeruginosa isolates.