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BioMed Research International
Volume 2016 (2016), Article ID 3265895, 9 pages
http://dx.doi.org/10.1155/2016/3265895
Research Article

Improved Production of Aspergillus usamii endo-β-1,4-Xylanase in Pichia pastoris via Combined Strategies

Guangdong VTR Bio-Tech Co., Ltd., Zhuhai, Guangdong 519060, China

Received 11 November 2015; Accepted 24 January 2016

Academic Editor: Bidur P. Chaulagain

Copyright © 2016 Jianrong Wang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A series of strategies were applied to improve expression level of recombinant endo-β-1,4-xylanase from Aspergillus usamii (A. usamii) in Pichia pastoris (P. pastoris). Firstly, the endo-β-1,4-xylanase (xynB) gene from A. usamii was optimized for P. pastoris and expressed in P. pastoris. The maximum xylanase activity of optimized (xynB-opt) gene was 33500 U/mL after methanol induction for 144 h in 50 L bioreactor, which was 59% higher than that by wild-type (xynB) gene. To further increase the expression of xynB-opt, the Vitreoscilla hemoglobin (VHb) gene was transformed to the recombinant strain containing xynB-opt. The results showed that recombinant strain harboring the xynB-opt and VHb (named X33/xynB-opt-VHb) displayed higher biomass, cell viability, and xylanase activity. The maximum xylanase activity of X33/xynB-opt-VHb in 50 L bioreactor was 45225 U/mL, which was 35% and 115% higher than that by optimized (xynB-opt) gene and wild-type (xynB) gene. Finally, the induction temperature of X33/xynB-opt-VHb was optimized in 50 L bioreactor. The maximum xylanase activity of X33/xynB-opt-VHb reached 58792 U/mL when the induction temperature was 22°C. The results presented here will greatly contribute to improving the production of recombinant proteins in P. pastoris.