Enzymatic bleaching of paper pulp

Abstract

The use of a GH78 enzyme in the bleaching of pulp for preparing paper materials, such as paper, linerboard, corrugated paperboard, tissue, towels, corrugated containers and boxes.

1 . A method for increasing the brightness and/or decreasing the kappa number of a paper pulp, comprising contacting the paper pulp with a GH78 enzyme, wherein the GH78 enzyme
 a) belongs to glycoside hydrolase family 78,   b) exhibits esterase and rhamnosidase activities and   c) consists or comprises an amino acid sequence with at least 60% identity to the amino acid sequence of SEQ ID NO: 1.   
     
     
         2 . The method of  claim 1 , wherein the GH78 enzyme is a glycoside hydrolase exhibiting feruloyl esterase and α-L-rhamnosidase activities. 
     
     
         3 . The method of  claim 1 , wherein the amino acid sequence of the GH78 enzyme has at least 65% identity, more preferably at least 70% identity, more preferably at least 75% identity, more preferably at least 80% identity, more preferably at least 85% identity, more preferably at least 90% identity, more preferably at least 95%, 96%, 97%, 98%, 99%, and most preferably 100% identity to the amino acid sequence of SEQ ID NO: 1. 
     
     
         4 . The method of  claim 1 , wherein the GH78 enzyme is derived from a  Xylaria  sp., such as  Xylaria polymorpha.    
     
     
         5 . The method of  claim 1 , wherein the pulp is wood pulp. 
     
     
         6 . The method of  claim 1 , wherein the pulp is a chemical pulp, such as kraft pulp. 
     
     
         7 . The method of  claim 1 , which further comprises a step of chlorine dioxide treatment (D stage) and/or alkaline peroxide treatment (E stage). 
     
     
         8 . The method of  claim 1 , which further comprises contacting the pulp with one or more additional enzyme(s), such as a lipase. 
     
     
         9 . A bleaching composition, comprising a paper pulp and a GH78 enzyme, wherein the GH78 enzyme
 a) belongs to glycoside hydrolase family 78,   b) exhibits esterase and rhamnosidase activities and   c) consists or comprises an amino acid sequence with at least 60% identity to the amino acid sequence of SEQ ID NO: 1.   
     
     
         10 . The composition of  claim 9 , wherein the GH78 enzyme belongs to glycoside hydrolase family 78 and exhibits feruloyl esterase and α-L-rhamnosidase activities. 
     
     
         11 . The composition of  claim 9 , wherein the amino acid sequence of the GH78 enzyme has at least 65% identity, more preferably at least 70% identity, more preferably at least 75% identity, more preferably at least 80% identity, more preferably at least 85% identity, more preferably at least 90% identity, more preferably at least 95%, 96%, 97%, 98%, 99%, and most preferably 100% identity to the amino acid sequence of SEQ ID NO: 1. 
     
     
         12 . The composition of  claim 9 , wherein the pulp is wood pulp. 
     
     
         13 . The composition of  claim 9 , wherein the pulp is a chemical pulp, such as kraft pulp. 
     
     
         14 . (canceled)