Enhanced production of a novel dextran from Leuconostoc mesenteroides NRRL B-640 by Response Surface Methodology

In our earlier study dextran produced by Leuconostoc mesenteroides NRRL B-640 was reported to possess novel food gelling and thickening properties (Purama et al., 2009). In the present study response surface methodology based experimental designs were applied to enhance the production of this novel dextran by Leuconostoc mesenteroides NRRL B-640. Eleven medium components were examined for their significance on dextran production using Plackett-Burman factorial design. Sucrose, peptone and beef extract were found to have significant effect on the dextran production. The combined effect of these nutrients on dextran production were studied using a 23 full-factorial central composite design, a second-order polynomial was established to identify the relationship between the output i.e. dextran produced and the three medium components. The optimal concentration of variables for maximum dextran production were 5%, w/v sucrose, 2.5%, w/v peptone, and 2.5%, w/v beef extract. The maximum concentration of dextran obtained by predicted model was 12.0 mg/ml that was in perfect agreement with the experimental determined value (12.2 +/- 0.2 mg/ml). This value of dextran concentration was over 70 percent higher as compared to un-optimized medium that gave 7.0 +/- 0.2 mg/ml of dextran.