Treatment of cellulosic material and enzymes useful therein
The present invention relates to the production of sugar hydrolysates from cellulosic material. The method may be used e.g. for producing fermentable sugars for the production of bioethanol from lignocellulosic material. Cellulolytic enzymes and their production by recombinant technology is described, as well as uses of the enzymes and enzyme preparations.
1. A cellobiohydrolase fusion protein comprising a cellobiohydrolase core region having at least 95% sequence identity to SEQ ID NO:2, to which a cellulose binding domain obtained from Trichoderma reesei or Chaetomium thermophilum has been genetically attached, wherein the cellobiohydrolase fusion protein displays enhanced crystalline cellulose hydrolysis at temperatures of 45° C. and 70° C. as compared to the cellobiohydrolase T. reesei Cel7A.
2. The cellobiohydrolase fusion protein of claim 1 , wherein the cellulose binding domain is obtained from T. reesei CBHI/Cel7A.
3. The cellobiohydrolase fusion protein of claim 1 , comprising an amino acid sequence having at least 80% identity to SEQ ID NO:28 or SEQ ID NO:30.
4. The cellobiohydrolase fusion protein of claim 1 , comprising the amino acid sequence of SEQ ID NO:28 or SEQ ID NO:30.
5. An enzyme preparation comprising cellobiohydrolase, endoglucanase and beta-glucosidase, wherein said cellobiohydrolase comprises the fusion protein of any one of claims 1 - 2 and 3 - 4 .
6. The enzyme preparation of claim 5 , wherein the endoglucanase comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 10, 12, 14 or 16, or to an enzymatically active fragment thereof.
7. The enzyme preparation of claim 5 , wherein the beta-glucosidase comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 22, 24 or 26, or to an enzymatically active fragment thereof.
8. The enzyme preparation of claim 5 , further comprising a xylanase.
9. The enzyme preparation of claim 8 , wherein the xylanase comprises an amino acid sequence having at least 80% identity to SEQ ID NO: 18 or 20, or to an enzymatically active fragment thereof.
10. The enzyme preparation of claim 5 , which is in the form of spent culture medium, powder, granules, or liquid.
11. A method for treating cellulosic material with cellobiohydrolase, endoglucanase and beta-glucosidase, whereby said cellobiohydrolase comprises the fusion protein of any one of claims 1 - 2 and 4 - 5 .
12. The method of claim 11 , wherein the cellulosic material is lignocellulosic material.
13. The method of claim 11 , comprising further treating lignocellulosic material with a xylanase.
14. The method of claim 11 , wherein the cellulosic material is selected from the group consisting of corn stover, switchgrass, cereal straw, sugarcane bagasse and wood derived materials.
15. The method of claim 11 , wherein the cellulosic material is reacted with said enzymes to obtain hydrolysed cellulosic material, which is used in a process for preparing ethanol from cellulosic material.