Engineering Expression Cassette of pgdS for Efficient Production of Poly-?-Glutamic Acids With Specific Molecular Weights in Bacillus licheniformis.

ABSTRACT: Poly-?-glutamic acid (?-PGA) is an emerging biopolymer with various applications and ?-PGAs with different molecular weights exhibit distinctive properties. However, studies on the controllable molecular weights of biopolymers are limited. The purpose of this study is to achieve production of ?-PGAs with a wide range of molecular weights through manipulating the expression of ?-PGA depolymerase (PgdS) in Bacillus licheniformis WX-02. Firstly, the expression and secretion of PgdS were regulated through engineering its expression elements (four promoters and eight signal peptides), which generated ?-PGAs with molecular weights ranging from 6.82 × 104 to 1.78 × 106 Da. Subsequently, through combination of promoters with signal peptides, the production of ?-PGAs with a specific molecular weight could be efficiently obtained. Interestingly, the ?-PGA yield increased with the reduced molecular weight in flask cultures (Pearson correlation coefficient of -0.968, P < 0.01). Finally, in batch fermentation, the highest yield of ?-PGA with a weight-average molecular weight of 7.80 × 104 Da reached 39.13 g/L under glutamate-free medium. Collectively, we developed an efficient strategy for one-step production of ?-PGAs with specific molecular weights, which have potential application for industrial production of desirable ?-PGAs.

SUBMITTER: Wang D 

PROVIDER: S-EPMC7381323 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature