Process for the biobleaching of eucalyptus kraft pulp with xylanases from Aspergillus niger and isolation of this strain

This invention relates to the process of isolating the strain of Aspergillus niger par usamii, designated as Aspergillus niger CCMI 850. Identification of the strain was confirmed using microbiological methods and electron scanning microscopy. The scope of the invention also includes the process of fermenting the said strain at a temperature of 30 degree C and a pH of 5.0. This new strain can utilize an extensive range of substrates, including complex organic sources of carbon and/or nitrogen, as well as clearly-specified chemically synthesized means to produce high concentrations of xylanolytic enzymes. More specifically, this new strain produces the highest quantity of xylanase ever found in a strain of A. niger. Xylanolytic enzymes from the said xylanolytic product which accumulate outside the cells in the fermentation broth can be applied directly under specified conditions to the biobleaching of kraft pulp. Its application results in a fall in the kappa index and simultaneously an increase in the gloss of the paper obtained using these biocatalysts.