Abstract: A process for the production and use of a xylanase enzyme, having a high specific activity, of use in the treatment and/or biobleaching of chemical pulps is described. The enzyme provides for a more commercially feasible process for the treatment of pulps, and lignocellulosic materials in general, which process provides improved results in delignification and brightening over conventional bleaching process, together with reduced bleaching chemical consumption and environmental impact.

Abstract: A method of treating lignocellulosic material with a cellulase-free endo-xylanase for delignification, brightening and viscosity improvement. The endo-xylanase is obtained by the overexpression of the xylanase gene using a cellulase-negative recombinant microorganism of the genus Streptomyces. The recombinant microorganism is produced in a homologous cloning system in which the xylanase gene is inserted into a vector plasmid to provide the hybrid plasmid that is introduced into a host cellulase-negative mutant strain and said xylanase gene, said vector plasmid and said host mutant strain are obtained from microorganisms of the genus Streptomyces.