Enhancing poly-γ-glutamic acid production in Bacillus amyloliquefaciens by introducing the glutamate synthesis features from Corynebacterium glutamicum

Microbial Cell Factories

Research

Yi Wang¹  Mingfeng Cao²  Xiaoyun Lu³  Xiaozhong Huang⁴  Cunjiang Song⁴  Haosheng Shen⁴  Yulei Dang⁴  Weixia Gao⁴  Yufen Quan⁴  Fenghong Liu⁴  Yanyan Gu⁵  Jun Feng⁶  Shufang Wang⁷ 

[1] Department of Biosystems Engineering, Auburn University, 36849, Auburn, AL, USA;Department of Chemical and Biological Engineering, Iowa State University, 50011, Ames, IA, USA;Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, 710049, Xi’an, Shaanxi, China;Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, 300071, Tianjin, China;Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, 300071, Tianjin, China;Department of Biosystems Engineering, Auburn University, 36849, Auburn, AL, USA;Key Laboratory of Molecular Microbiology and Technology for Ministry of Education, Nankai University, 300071, Tianjin, China;Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi’an Jiaotong University, 710049, Xi’an, Shaanxi, China;Department of Biosystems Engineering, Auburn University, 36849, Auburn, AL, USA;State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, 300071, Tianjin, China;State Key Laboratory of Medicinal Chemical Biology, Nankai University, 94 Weijin Road, 300071, Tianjin, China;

关键词: Poly-γ-glutamic acid;    NADPH-dependent glutamate dehydrogenase;    Metabolic toggle switch;   

DOI  :  10.1186/s12934-017-0704-y

 received in 2016-12-27, accepted in 2017-05-15,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundPoly-γ-glutamic acid (γ-PGA) is a valuable polymer with glutamate as its sole precursor. Enhancement of the intracellular glutamate synthesis is a very important strategy for the improvement of γ-PGA production, especially for those glutamate-independent γ-PGA producing strains. Corynebacterium glutamicum has long been used for industrial glutamate production and it exhibits some unique features for glutamate synthesis; therefore introduction of these metabolic characters into the γ-PGA producing strain might lead to increased intracellular glutamate availability, and thus ultimate γ-PGA production.ResultsIn this study, the unique glutamate synthesis features from C. glutamicum was introduced into the glutamate-independent γ-PGA producing Bacillus amyloliquefaciens NK-1 strain. After introducing the energy-saving NADPH-dependent glutamate dehydrogenase (NADPH-GDH) pathway, the NK-1 (pHT315-gdh) strain showed slightly increase (by 9.1%) in γ-PGA production. Moreover, an optimized metabolic toggle switch for controlling the expression of ɑ-oxoglutarate dehydrogenase complex (ODHC) was introduced into the NK-1 strain, because it was previously shown that the ODHC in C. glutamicum was completely inhibited when glutamate was actively produced. The obtained NK-PO1 (pHT01-xylR) strain showed 66.2% higher γ-PGA production than the NK-1 strain. However, the further combination of these two strategies (introducing both NADPH-GDH pathway and the metabolic toggle switch) did not lead to further increase of γ-PGA production but rather the resultant γ-PGA production was even lower than that in the NK-1 strain.ConclusionsWe proposed new metabolic engineering strategies to improve the γ-PGA production in B. amyloliquefaciens. The NK-1 (pHT315-gdh) strain with the introduction of NADPH-GDH pathway showed 9.1% improvement in γ-PGA production. The NK-PO1 (pHT01-xylR) strain with the introduction of a metabolic toggle switch for controlling the expression of ODHC showed 66.2% higher γ-PGA production than the NK-1 strain. This work proposed a new strategy for improving the target product in microbial cell factories.

【 授权许可】

CC BY   
© The Author(s) 2017