초록
<P>The effect of NADP<SUP>+</SUP> and glucose-6-phosphate (G6P) on the biotransformation of D-xylose to xylitol by cells of <I>Candida guilliermondii</I> permeabilized with surfactant Triton X-100 was evaluated. The experimental runs were performed with 12 g L<SUP>−1</SUP> of permeabilized cells and a reaction medium composed of Tris-HCl buffer (0.1 M pH 7), D-xylose (57 g L<SUP>−1</SUP>), and MgCl<SUB>2</SUB>.6H<SUB>2</SUB>O (5 mM). The levels of NADP<SUP>+</SUP> (from 0.0 to 1.7 mM) and G6P (from 0.00 to 0.17 M) were varied according a 2<SUP>2</SUP>-full factorial composed design. Under optimized conditions (NADP<SUP>+</SUP> 0.5 mM and 0.05 M G6P), the xylitol volumetric productivity (Q<SUB>P</SUB>) and yield factor (Y<SUB>P/S</SUB>) predicted were 1.86 ± 0.03 g L<SUP>−1</SUP> h<SUP>− 1</SUP> and 0.64 ± 0.03 g g<SUP>−1</SUP>, respectively. These values were 94% and 19% higher than those obtained with unpermeabilized cells under fermentation conditions (0.97 g L<SUP>−1</SUP> h<SUP>−1</SUP> and 0.53 g g<SUP>−1</SUP>, respectively). On the basis of the results, it can be concluded that xylitol production by biotransformation with cells of <I>C. guilliermondii</I> permeabilized with Triton X-100 is a promising alternative to the fermentative process.</P>