Cellulose degrading enzymes of aspergillus

Abstract

Two cellobiohydrolase polypeptides (CBHA and CBHB) derived from Aspergillus are described and can be used to degrade cellulose. Variants of these peptides are described as well as DNA encoding the peptides, vectors and host cells. The peptides can be used to produce or process food, animal feed, wood pulp, paper and textiles.

1 . A polypeptide which comprises the sequence of SEQ ID No: 8 (CBH A) or SEQ ID No:10 (CBH B), a sequence substantially homologous to either sequence, or a fragment of any of these sequences.  
     
     
         2 . A polypeptide from Aspergillus which is a CBH or has CBH activity.  
     
     
         3 . A polypeptide which: 
 (i) has CBH activity;    (ii) has an activity of at least 50% of the maximum activity over the pH range from 3 to 5;    (iii) has an optimum activity at a temperature is greater than 50° C.; and optionally    (iv) does not have a cellulose binding domain or a linker peptide.    
     
     
         4 . A polypeptide according to any one of the preceding claims which has CBHI activity.  
     
     
         5 . A polypeptide according to any of the preceding claims which is obtainable from or produced by a fungus.  
     
     
         6  A polypeptide according to  claim 4  which is obtainable from or produced by Aspergillus.  
     
     
         7 . A polypeptide according to  claim 5  which is obtainable from or produced by  Aspergillus niger.    
     
     
         8 . A polynucleotide comprising a sequence encoding a polypeptide according to any one of the preceding claims.  
     
     
         9 . A polynucleotide capable of selectively hybridising to SEQ ID No: 5 or SEQ ID No:9 or a complement thereof.  
     
     
         10 . A polynucleotide according to  claim 8  or  9  which is a DNA sequence.  
     
     
         11 . A vector which comprises a polynucleotide according to any one of  claims 8  to  10 .  
     
     
         12 . A host cell which: 
 (i) comprises a polynucleotide or vector according to any one of  claims 8  to  11 , which host cell does not naturally comprise such a polynucleotide or vector; and/or    (ii) expresses a polypeptide according to any one of  claims 1  to  7 , which host cell does not naturally express such a polypeptide;    (iii) expresses a polypeptide of the invention at a higher level than naturally expressed by the host cell; and/or    (iv) has been transformed or transected by a polynucleotide or vector according to any one of  claims 8  to  11 .    
     
     
         13 . A process for producing a host cell according to  claim 12 , the process comprising transforming or transfecting a host cell with a polynucleotide or vector according to any one of  claims 8  to  11 .  
     
     
         14 . A method for producing a polypeptide according to any one of  claims 1  to  7  comprising culturing a host cell according to  claim 11  under conditions in which it expresses the polypeptide and optionally recovering the expressed polypeptide.  
     
     
         15 . A polypeptide preparable or prepared by a process according to  claim 14 .  
     
     
         16 . A composition comprising a polypeptide according to any one of  claims 1  to  7  or  15  and optionally one or more enzymes.  
     
     
         17 . A composition comprising a host cell according to  claim 12  or prepared by a process according to  claim 13 .  
     
     
         18 . Use of a polypeptide, host cell or composition according to any one of  claims 1  to  7 ,  12  or  15  to  17  to degrade cellulose.  
     
     
         19 . A method of degrading cellulose comprising contacting a polypeptide, host cell or composition according to any one of  claims 1  to  7 ,  12 , or  15  to  17  with the cellulose.  
     
     
         20 . The use according to  claim 18  in, or in a process for, producing food or beverages, animal feed, pulp, paper or textiles.  
     
     
         21 . A method according to  claim 19  which is part of a method for producing or processing food or beverages, animal feed, pulp, paper or textiles.  
     
     
         22 . A method according to  claim 21  wherein: 
 (i) the cellulose is contained in a material which after degradation of all or part of the cellulose within it is used to make a food or beverage for a human or animal, and/or  
 (ii) all or part of the cellulose is degraded after the food is ingested by a human or animal.  
 
     
     
         23 . A bakery product or ingredient, or a baked product obtainable or obtained by a method according to  claim 22 .  
     
     
         24 . A human food or beverage, or animal feed comprising a polypeptide, host cell or composition according to any one of  claims 1  to  7 ,  12 , or  15  to  17 .  
     
     
         25 . The use according to  claim 20  to degrade cellulose during wood pulp processing or during the manufacture of paper.