Improved xylitol production in media containing phenolic aldehydes: application of response surface methodology for optimization and modeling of bioprocess

BACKGROUND: The combined effects of vanillin and syringaldehyde on xylitol production by Candida guilliermondii using response surface methodology (RSM) have been studied. A 2² full-factorial central composite design was employed for experimental design and analysis of the results.RESULTS: Maximum xylitol productivities (QP = 0.74 g L⁻¹h⁻¹) and yields (YP/S = 0.81 g g⁻¹) can be attained by adding only vanillin at 2.0 g L⁻¹ to the fermentation medium. These data were closely correlated with the experimental results obtained (0.69 ± 0.04 g L⁻¹ h⁻¹ and 0.77 ± 0.01 g g⁻¹) indicating a good agreement with the predicted value. C. guilliermondii was able to convert vanillin completely after 24 h of fermentation with 94% yield of vanillyl alcohol.CONCLUSIONS: The bioconversion of xylose into xylitol by C. guilliermondii is strongly dependent on the combination of aldehydes and phenolics in the fermentation medium. Vanillin is a source of phenolic compound able to improve xylitol production by yeast. The conversion of vanillin to alcohol vanilyl reveals the potential of this yeast for medium detoxification. Copyright