Optimization of D-xylose to xylitol biotransformation by Candida guilliermondii cells permeabilized with Triton X-100

Abstract

The effect of NADP⁺ and glucose-6-phosphate (G6P) on the biotransformation of D-xylose to xylitol by cells of Candida guilliermondii permeabilized with surfactant Triton X-100 was evaluated. The experimental runs were performed with 12 g L⁻¹ of permeabilized cells and a reaction medium composed of Tris–HCl buffer (0.1 M pH 7), D-xylose (57 g L⁻¹), and MgCl₂.6H₂O (5 mM). The levels of NADP⁺ (from 0.0 to 1.7 mM) and G6P (from 0.00 to 0.17 M) were varied according a 2²-full factorial composed design. Under optimized conditions (NADP⁺ 0.5 mM and 0.05 M G6P), the xylitol volumetric productivity (Q_P) and yield factor (Y_P/S) predicted were 1.86 ± 0.03 g L⁻¹ h^{− 1} and 0.64 ± 0.03 g g⁻¹, respectively. These values were 94% and 19% higher than those obtained with unpermeabilized cells under fermentation conditions (0.97 g L⁻¹ h⁻¹ and 0.53 g g⁻¹, respectively). On the basis of the results, it can be concluded that xylitol production by biotransformation with cells of C. guilliermondii permeabilized with Triton X-100 is a promising alternative to the fermentative process.

Keywords::

• Candida guilliermondii permeabilized
• Triton X-100
• biotransformation
• D-xylose
• xylitol
• glucose-6-phosphate
• NADP⁺

Acknowledgements

The authors gratefully acknowledge financial support of Conselho Nacional de desenvolvimento Científico e Tecnológico (CNPq).

Declaration of interest: The authors report no declarations of interest. The authors alone are responsible for the content and writing of the paper.