期刊
PROCESS BIOCHEMISTRY
卷 45, 期 1, 页码 75-80出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.procbio.2009.08.009
关键词
Xylanase; Aspergillus niger; Site-directed mutagenesis; Pichia pastoris; Thermostability; Bioreactor
资金
- National Natural Science Foundation of China [30870186]
- National Basic Research Program (973) of China [2009CB724700, 2010CB126502]
Xylanase is an important industrial enzyme. In this research, to improve the thermostability and biochemical properties of a xylanase from Aspergillus niger F19, five arginine substitutions and a disulfide bond were introduced by site-directed mutagenesis. The wild-type gene xylB and the mutant gene xylCX8 were expressed in Pichia pastoris. Compare to those of the wild-type enzyme, the optimal reaction temperature for the mutant enzyme increased from 45 degrees C to 50 degrees C, the half-life of the mutant enzyme extended from 10 min to 180 min, and the specific activity increased from 2127 U/mg to 3330 U/mg. However, the V-max and K-m of the mutant xylanase decreased. The enzyme activity in broth obtained from shake flask cultures could be induced to 1850 U/mL in 7 days, which is higher than results reported previously. Furthermore, the highest achievable enzyme activity was 7340 U/mL from 140 g/L of biomass in a 3 L fermentor used in our study. (C) 2009 Elsevier Ltd. All rights reserved.
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