Abstract

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.

Document Type

Patent

Primary Class

435/41

Secondary Class

435/94; 435/161; 435/162; 435/175; 435/180; 435/182

Application Number

08/125546

Filing Date

September 1993

Patent Number

US5397700

Assignee(s)

The University of Toledo

Publication Date

3-14-1995

Patent Country

US

Language

en_US

Institution

The University of Toledo

Repository

University of Toledo Libraries

Digital Publisher

Digital Initiatives

Rights

These materials are free of copyright restrictions and are in the public domain within the United States only. The USPTO reserves the right to assert copyright protection internationally.

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Rights Statement

No Copyright - United States. URI: http://rightsstatements.org/vocab/NoC-US/1.0/
The organization that has made the Item available believes that the Item is in the Public Domain under the laws of the United States, but a determination was not made as to its copyright status under the copyright laws of other countries. The Item may not be in the Public Domain under the laws of other countries. Please refer to the organization that has made the Item available for more information.