Study On Scale-Up Experiment Of Producing Neokestose By Xanthophyllomyces Dendrorhous

In this work, neokestose produced using free-whole-cell biotransformation byXanthophyllomyces dendrorhous as the starting strain was investigated.Firstly, the effect of culture pH and VC (ventilatory capacity) and sugar-feedingstrategies on biomass and6G-fructofuranosidase activity of Xanthophyllomyces dendrorhouswhich were using in the free-whole-cell biotransformation were investigated in batchfermentation of5L. And the optimal fermentation conditions for pH and VC were8.0and5~8L/min respectively, the maximum biomass and6G-ftuctofuranosidase activity were11.46g/L and0.34mol/L/min respectively.Secondly, the effects of production parameters on the biotransformation wereinvestigated to enhance the yield of neokestose and sucrose conversion by Xanthophyllomycesdendrorhous cells, and the optimal biotransformation conditions were cell concentration of100g/L, sucrose concentration of400g/L and temperature of20℃for4h, and theneokestose concentration and sucrose conversion finally reached250.37g/L and85%respectively.Then batch fermentation was carried out in a mechanically stirred fermentor of50Lusing free-whole-cell biotransformation. The medium consisting of: sucrose50g/L and45ml/L corn steep liquor, fermentation conditions for pH and temperature was controlled at8.0with3mol/L NaOH and2mol/L HCl and20℃respectively, and the VC (ventilatorycapacity) was controlled for5L/min for24h and then shifted to8L/min until thefermentation was finished, the agitation speed was controlled at350r/min. Then the cellswere collected after36h for biotransformation for4h at30℃, the cell and sucroseconcentration was100g/L and400g/L respectively. The average neo-FOS concentrationfinally reached256.64g/L and when three batches fermentations was carried out in amechanically stirred fermentor of500L, the average neokestose concentration was260.52g/L.