University of Toledo

James P Byers

Sasidhar Varanasi

Ronald L Fournier

Shirley Byers

A method of providing and sustaining a difference in pH of a first reaction of an immobilized enzyme and a second reaction in a bulk liquid surrounding the immobilized enzyme is carried out with a bilayer pellet containing coimmobilized enzymes. The pellet can contain an enzyme that produces a desired product immobilized in an inner core and urease immobilized in an outer layer. The bulk liquid contains urea and a substrate for the enzyme in the core, and has an acidic pH. The urease reacts with urea diffusing into the outer layer from the bulk liquid to produce ammonia. The ammonia consumes hydrogen ions diffusing into the inner core from the acidic bulk liquid. This provides the enzyme in the inner core with a pH higher than the acidic pH of the bulk liquid suitable for the enzyme to react with the substrate as it diffuses into the inner core. In a preferred embodiment, simultaneous isomerization of xylose to xylulose and fermentation of xylulose to ethanol is carried out with a bilayer pellet containing xylose isomerase in the core and yeast in the bulk liquid. The isomerization occurs at an optimum pH of 7.0 to 8.0 and the fermentation occurs at an optimum pH of 4.0 to 5.0.

Method of producing products with a bilayer pellet containing a

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.

Growing community of inventors

Toledo, OH, United States of America

James P Byers