Abstract: Production and characteristics of twoβ-glucosidase strains,Aspergillus niger M85 and its mutant obtained by soft X-ray Nk,synchrotron irradiation were studied.The results showed that the nutrient demands,culture condition,β-glucosidase production kinetics and properties of the mutant strain are distinctively changed in comparison with the original strain M85.The spectrum of nitrogen sources of the mutant has been broadened and the demand of KH2PO4 reduced from 0.2% to 0.1%.The mutant was addicted to enough oxygen.The fermentation kinetics test showed that fermentation cycle of the mutant is shortened by 16 hours and the β-glucosidase activity is raised about 80%.The optimal temperature and pH for the mutant β-glucosidase reaction are shifted from 60 ℃ to 50 ℃ and from 4.0 to 5.0,respectively.

Key words: Aspergillus niger； &beta, -glucosidase； soft X-ray； enzymatic properties；