XYLANOLYTIC ENZYME-PRODUCTION BY AN ASPERGILLUS-NIGER ISOLATE

Production of xylanolytic enzymes by an Aspergillus niger CCMI 850 iso late was investigated in batch cultures. The effect of the composition of a fermentation medium that did not include chemical inducers, on b eta-xylanase, beta-xylosidase, alpha-L-arabinofuranosidase, and total cellulase activity was studied. With 4% xylan as the carbon source, ab out 65 U/mL of beta-xylanase was obtained, whereas the total cellulase activity was undetectable, under the specified conditions. This beta- xylanase activity represents the highest reported for a wild-type stra in of A. niger. The effect of pH and temperature on the activity of be ta-xylanase was studied. Partial characterization of the beta-xylanase showed that with insoluble birchwood as substrate the K-m and Vmax we re 0.3 mM and 19 mu mol/min, respectively. Aspects of using the crude beta-xylanase preparation for applications in the pulp and paper indus try were discussed.