Optimization of salts supplementation on xylitol production by Debaryomyces hansenii using 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 carbon source, increasing the fermentative parameters to QP = 0.118 g/L·h and YP/S = 0.45 g/g from QP = 0.101 g/L·h and YP/S = 0.39 g/g (without supplementation). Finally, the process was successfully scaled up to a 50L Braun Biostat D50 fermentor, since the time of fermentation was reduced from 103h to 42.8h and the fermentation parameters increased to QP = 0.395 g/L·h and YP/S = 0.59 g/g using synthetic medium and QP = 0.236 g/L·h and YP/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.