Combined enzyme mediated fermentation of cellulous and xylose to ethanol by Schizosaccharoyces pombe, cellulase, .beta.-glucosidase, and xylose isomerase

• US 5,372,939 A
• Filed: 03/08/1993
• Issued: 12/13/1994
• Est. Priority Date: 03/21/1991
• Status: Expired due to Fees

• Current Assignee: United States Department of Energy
• Original Assignee: United States Department of Energy
• Inventors: Mohagheghi, Ali, Lastick, Stanley M., Grohmann, Karel, Tucker, Melvin P.
• Primary Examiner(s): KNODE, MARIAN C
• Application Number:
  US08/028,592
• Time in Patent Office: 645 Days
• Field of Search: 426/11, 426/18, 426/20, 426/21, 435/161, 435/163, 435/165, 435/162
• US Class Current: 435/165
• CPC Class Codes: C12P 7/06 Ethanol, i.e. non-beverage
• CPC Class Codes: C12P 7/10 substrate containing cellulosic material
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

A process for producing ethanol from mixed sugar streams from pretreated biomass comprising xylose and cellulose using enzymes to convert these substrates to fermentable sugars; selecting and isolating a yeast Schizosaccharomyces pombe ATCC No. 2476, having the ability to ferment these sugars as they are being formed to produce ethanol; loading the substrates with the fermentation mix composed of yeast, enzymes and substrates; fermenting the loaded substrates and enzymes under anaerobic conditions at a pH range of between about 5.0 to about 6.0 and at a temperature range of between about 35° C. to about 40° C. until the fermentation is completed, the xylose being isomerized to xylulose, the cellulose being converted to glucose, and these sugars being concurrently converted to ethanol by yeast through means of the anaerobic fermentation; and recovering the ethanol.

Claims

1. A process for producing ethanol from mixed streams from biomass comprising:

selecting as substrates either xylose and cellulose or xylan and cellulose;

selecting a plural ferment comprising a mixture of Schizosaccharomyces pombe ATCC No. 2476, cellulase, betaglucosidase and xylose isomerase wherein said plural ferment can isomerize xylose and ferment xylulose as it is being formed to ethanol and simultaneously saccharily cellulose to glucose and ferment glucose to ethanol;

loading said substrates with said plural ferment;

fermenting said loaded substrate under anaerobic conditions at a pH range of between about 5.5 to about 6.0 and at a temperature range of between about 30°

C. to about 45°

C., until any xylose in the mixture is isomerized to xylulose as it is produced, and any xylulose is fermented as it is produced to ethanol, while in the same fermentation, glucose is fermented to ethanol; and

recovering the ethanol.

2. The process of claim 1, wherein said substrates are cellulose and xylose.

3. The process of claim 2, wherein said temperature is between 35°

C. and 40°

C.

4. The process of claim 3, wherein said enzymes are in amounts of about 2,000 IFPU/L cellulase, 2,000 IU/L betaglucosidase and 25 IU/L xylose isomerase.