Optimization of Salts Supplementation on Xylitol Production by Debaryomyces hansenii Using a Synthetic Medium or Corncob Hemicellulosic Hydrolyzates and Further Scaled Up

Abstract

The synergic effect of eight salts on D-xylose to xylitol bioconversion by Debaryomyces hansenii NRRL Y-7426 was optimized through a central composite design (CCD) in shaker flasks. Optima conditions were then assayed using detoxified corncob hemicellulosic hydrolyzates as the carbon source, increasing the fermentative parameters to Q P = 0.118 g/L•h and Y P/S = 0.45 g/g from Q P = 0.101 g/L•h and Y P/S = 0.39 g/g (without supplementation). Finally, the process was successfully scaled up to a 50 L Braun Biostat D50 fermenter, since the time of fermentation was reduced from 103 h to 42.8 h and the fermentation parameters increased to Q P = 0.395 g/L•h and Y P/S = 0.59 g/g using a synthetic medium and Q P = 0.236 g/L•h and Y P/S = 0.39 g/g with detoxified hydrolyzates. All the results confirmed the positive influence of supplementing synthetic culture media or detoxified corncob hydrolyzates with salts for the development of D. hansenii.

Bioprocess optimization for enhanced xylitol synthesis by new isolate Meyerozyma caribbica CP02 using rice straw

“…The F-value (Fischer variance ratio) of the computed model was 122.15 and the p-value of < 0.0001, which implies p < 0.05 for regression model equation confirmed that the quadratic model fit well to the experimental results. The lack of fit value of 3.27 implied that the model’s variables significantly correlated with process response which was xylitol production [ 42 ]. Also, the difference between adjusted R 2 (0.9838) and predicted R 2 (0.9569) in the current study was less than 0.20, indicating that the model was reliable (Additional file 2 : Table S2).…”