Bilayer pellet containing immobilized xylose isomerase and urease for the simultaneous isomerization and fermentation of xylose to ethanol

摘要

A bilayered immobilized enzyme pellet and a process to manufacture this pellet are provided for use in a process involving the simultaneous isomerization of xylose to xylulose and fermentation of xylulose to ethanol. The bilayered pellet is able to maintain the environment where the isomerization reaction occurs within its optimum pH of 7.0 to 8.0 while the fermentation reaction occurs within its optimum pH range of 4.0 to 5.0. This process allows both xylose and glucose sugars to be effectively used as a feedstock for ethanol production by isomerizing the xylose to xylulose and then making the xylulose immediately available for the fermentation process. Because the xylose has been converted to its ketose isomer, xylulose, yeasts which can ferment glucose and xylulose can be used in this process.