Optimization of salts supplementation on xylitol production by Debaryomyces hansenii using synthetic medium or corncob hemicellulosic hydrolyzates and further scaled up

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.Spanish Ministry of Economy and Competitiveness for the financial support of this work (project CTQ2015-71436-C2-1-R), which has partial financial support from the FEDER funds of the European Union; to the Spanish Ministry of Education, Culture and Sports for N.P.-R.’s FPU; and to CAPES (Coordination of High-Level Personnel Training, Brazil) for J.M.D.’s fellowship as a Special Visiting Researcher (Science without Borders Program, project no. 88881.062223/ 2014-01).