Research
High yield recombinant thermostable α-amylase production using an improved Bacillus licheniformis system
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* Corresponding author: Zheng-Xiang Wang zxwang@jiangnan.edu.cn
1 Center for Bioresource and Bioenergy, School of Biotechnology & Culture and Information Center of Industrial Microorganisms of China Universities, Jiangnan University, Wuxi 214122, PR China
2 The Key Laboratory of Industrial Biotechnology, Ministry of Education, Wuxi 214122, PR China
3 Institute for Wine Biotechnology, University of Stellenbosch, Matieland 7602, South Africa
Microbial Cell Factories 2009, 8:58 doi:10.1186/1475-2859-8-58
Published: 31 October 2009Abstract
Background
Some strains of Bacillus licheniformis have been improved by target-directed screening as well as by classical genetic manipulation and used in commercial thermostable α-amylase and alkaline protease production for over 40 years. Further improvements in production of these enzymes are desirable.
Results
A new strain of B. licheniformis CBBD302 carrying a recombinant plasmid pHY-amyL for Bacillus licheniformis α-amylase (BLA) production was constructed. The combination of target-directed screening and genetic recombination led to an approximately 26-fold improvement of BLA production and export in B. licheniformis. Furthermore, a low-cost fermentation medium containing soybean meal and cottonseed meal for BLA production in shake-flasks and in a 15 liter bioreactor was developed and a BLA concentration of up to 17.6 mg per ml growth medium was attained.
Conclusion
This production level of BLA by B. licheniformis CBBD302(pHY-amyL) is amongst the highest levels in Gram-positive bacteria reported so far.