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

ABSTRACT: Poly-?-glutamic acid (?-PGA) is an important biochemical product with a variety of applications. This work reports a novel approach to improve ?-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 ?-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 ?-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 ?-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 ?-PGA production in B. licheniformis.

SUBMITTER: Cai D 

PROVIDER: S-EPMC5322528 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature