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BioMed Research International
Volume 2017 (2017), Article ID 5479762, 11 pages
Research Article

Efficient Expression of Maltohexaose-Forming α-Amylase from Bacillus stearothermophilus in Brevibacillus choshinensis SP3 and Its Use in Maltose Production

Zhu Li,1,2 Lingqia Su,1,2 Xuguo Duan,1,2,3 Dan Wu,1,2 and Jing Wu1,2

1State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
2School of Biotechnology and Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, China
3Department of Food Science and Engineering, College of Light Industry Science and Engineering, Nanjing Forestry University, Nanjing 210037, China

Correspondence should be addressed to Jing Wu

Received 13 June 2017; Revised 23 August 2017; Accepted 10 October 2017; Published 9 November 2017

Academic Editor: Wen-Jun Li

Copyright © 2017 Zhu Li 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.


The maltohexaose-forming, Ca2+-independent α-amylase gene from Bacillus stearothermophilus (AmyMH) was efficiently expressed in Brevibacillus choshinensis SP3. To improve the production of AmyMH in B. choshinensis SP3, the temperature and initial pH of culture medium were optimized. In addition, single-factor and response surface methodologies were pursued to optimize culture medium. Addition of proline to the culture medium significantly improved the production of recombinant α-amylase in B. choshinensis SP3. This improvement may result from improved cellular integrity of recombinant B. choshinensis SP3 in existence of proline. Culture medium optimization resulted in an 8-fold improvement in α-amylase yield, which reached 1.72 × 104 U·mL−1. The recombinant α-amylase was applied to the production of maltose on a laboratory scale. A maltose content of 90.72%, which could be classified as an extremely high maltose syrup, could be achieved using 15% (m/v) corn starch as the substrate. This study demonstrated that the B. choshinensis SP3 expression system was able to produce substantial quantities of recombinant α-amylase that has potential application in the starch industry.