Improved endoxylanase production and colony morphology of Aspergillus niger DSM 26641 by gamma-ray induced mutagenesis

摘要

Aspergillus niger DSM 26641 was exposed to Co-60 gamma-radiation to enhance the beta-1,4-endoxylanase activity, restrict colony growth and improve robustness of pellets. The first promising mutant obtained after gamma-radiation of the fungal spores at 50-2000 Gy showed a restricted colony growth and an 82% enhancement in beta-1,4-endoxylanase activity. The mutant was subjected to a second round of gamma-radiation at 1400 Gy generating a mutant with double the beta-1,4-endoxylanase activity compared to the native strain. The selected final mutant, deposited as A. niger DSM 28712, showed a maximal saccharification activity of 26 U ml(-1) on xylan based broth, 48 U ml(-1) on lignocellulose hydrolysate and 375 U ml(-1) on lignocellulose hydrolysate supplemented with yeast extract and mineral salts. (C) 2014 Elsevier B.V. All rights reserved.