Utilization of xylitol dehydrogenase in a combined microbial/enzymatic process for production of xylitol from D-glucose

Appl Biochem Biotechnol. 2002 Spring;98-100:577-89. doi: 10.1385/abab:98-100:1-9:577.

Abstract

The production of xylitol from D-glucose occurs through a three-step process in which D-arabitol and D-xylulose are formed as the first and second intermediate product, respectively, and both are obtained via microbial bioconversion reactions. Catalytic hydrogenation of D-xylulose yields xylitol; however, it is contaminated with D-arabitol. The aim of this study was to increase the stereoselectivity of the D-xylulose reduction step by using enzymatic catalysis. Recombinant xylitol dehydrogenase from the yeast Galactocandida mastotermitis was employed to catalyze xylitol formation from D-xylulose in an NADH-dependent reaction, and coenzyme regeneration was achieved by means of formate dehydrogenase-catalyzed oxidation of formate into carbon dioxide. The xylitol yield from D-xylulose was close to 100%. Optimal productivity was found for initial coenzyme concentrations of between 0.5 and 0.75 mM. In the presence of 0.30 M (45 g/L) D-xylulose and 2000 U/L of both dehydrogenases, exhaustive substrate turnover was achieved typically in a 4-h reaction time. The enzymes were recovered after the reaction in yields of approx 90% by means of ultrafiltration and could be reused for up to six cycles of D-xylulose reduction. The advantages of incorporating the enzyme-catalyzed step in a process for producing xylitol from D-glucose are discussed, and strategies for downstream processing are proposed by which the observed coenzyme turnover number of approx 600 could be increased significantly.

MeSH terms

  • Arthrobacter / enzymology
  • D-Xylulose Reductase
  • Gluconobacter / metabolism
  • Glucose / metabolism*
  • Kinetics
  • Microbiological Techniques / methods
  • NAD / metabolism
  • Oxidation-Reduction
  • Recombinant Proteins / metabolism
  • Saccharomycetales / metabolism
  • Sugar Alcohol Dehydrogenases / metabolism*
  • Sugar Alcohols / metabolism
  • Xylitol / metabolism*
  • Xylulose / metabolism

Substances

  • Recombinant Proteins
  • Sugar Alcohols
  • NAD
  • Xylulose
  • Sugar Alcohol Dehydrogenases
  • D-Xylulose Reductase
  • Glucose
  • Xylitol
  • arabitol