(623k) Optimization of Growth Medium and Bioprocessing Condition in Pilot Scale Stirred Tank Bioreactors for Production of Levan By Bacillus Subtilis (Rapid Fire)

Levan is extracellular polysaccharides of fructose and it can be found in plants and microbial products. Recent studies of levan were motivated for its role as antitumor, antioxidants, antiviral and anticancer agents with fibrinolytic action and were produced from various types of microorganisms. This study focused on cultivation of Bacillus subtilis  to  optimize production medium to produce levan in the shake flask levels including effect of bioprocessing parameters when cultivation in the semi-industrial scale 16L- bioreactor.  Recent studies reported that the highest amounts of levans are produced from the production medium with commercial sucrose as the carbon source with minor quantity of alcohol precipitate. The un-optimized medium yielded the cell mass of 1.945 gL^-1 and 13.5 gL^-1 of levan from the shake flasks studies. and after medium optimization using statistical approach  the cell mass increased to 2.26 gL^-1 and the production of levan also increased to 22.1 gL^-1. This showed   increment of levan production up to 38.07% from statistical optimized medium compared to un-optimized medium. Batch cultivations in 16-L stirred tank bioreactors were carried out under uncontrolled pH and controlled pH condition by using the new optimized production medium generated from statistical tool. The new formulations were composed of (g L^-1): Sucrose, 130.0, Yeast extract, 6.3, K₂HPO₄, 5.0, and MgSO₄.7H₂O, 0.2. The result showed that bioreactor under uncontrolled pH was favorable compared to controlled pH condition in obtaining the highest amount of cell mass and levan production which gave about 5.06 gL^-1 and 26.65 gL^-1, respectively. This was almost 49.34% higher than those obtained in shake flask culture. However the yield of levan per cell mass was 5.64g L^-1 compared to 11.54 g L^-1from batch cultivation in the bioreactor due to the low cell mass production of B. subtilis. In conclusion, this study proposed a reliable industrial production medium and aneffective cultivation strategy for the cell mass and levan production in semi- industrial scale bioreactor.