A novel approach to improve poly-gamma-glutamic acid production by NADPH Regeneration in Bacillus licheniformis WX-02

作者：Cai, Dongbo; He, Penghui; Lu, Xingcheng; Zhu, Chengjun; Zhu, Jiang; Zhan, Yangyang; Wang, Qin; Wen, Zhiyou; Chen, Shouwen^*

来源：Scientific Reports, 2017, 7(1): 43404.

DOI：10.1038/srep43404

• PENTOSE-PHOSPHATE PATHWAY
• ESCHERICHIA-COLI
• SIGNAL PEPTIDE
• SUBTILIS
• BIOSYNTHESIS
• MESO-2,3-BUTANEDIOL
• AMYLOLIQUEFACIENS
• OPTIMIZATION
• NATTOKINASE
• METABOLISM

Poly-gamma-glutamic acid (gamma-PGA) is an important biochemical product with a variety of applications. This work reports a novel approach to improve gamma-PGA through over expression of key enzymes in cofactor NADPH generating process for NADPH pool. Six genes encoding the key enzymes in NADPH generation were over-expressed in the gamma-PGA producing strain B. licheniformis WX-02. Among various recombinants, the strain over-expressing zwf gene (coding for glucose-6-phosphate dehydrogenase), WX-zwf, produced the highest gamma-PGA concentration (9.13 g/L), 35% improvement compared to the control strain WX-pHY300. However, the growth rates and glucose uptake rates of the mutant WX-zwf were decreased. The transcriptional levels of the genes pgsB and pgsC responsible for gamma-PGA biosynthesis were increased by 8.21- and 5.26-fold, respectively. The Zwf activity of the zwf over expression strain increased by 9.28-fold, which led to the improvement of the NADPH generation, and decrease of accumulation of by-products acetoin and 2,3-butanediol. Collectively, these results demonstrated that NADPH generation via over-expression of Zwf is as an effective strategy to improve the gamma-PGA production in B. licheniformis.

• 出版日期2017-2-23
• 单位华中农业大学; 湖北大学