Γ-polyglutamic acid (γ-PGA) is a bio-safe hydrophilic macromolecular polymer with emulsification, thickening, film formation, moisturizing, flocculation, adhesion, non-toxic properties, etc. In the fields of daily necessities, environmental management, and biomedicine, it has good commercial value. In terms of food, it was first discovered in the Japanese fermented food natto, which has food safety, can be used as a lyoprotectant for the preparation of probiotic powder or starter, oil suppressant in fried pasta, mineral adsorbent, Thickener, bitter masking agent, etc. γ-PGA is a high molecular polymer synthesized by microorganisms. It is formed by condensation of γ-carboxyl and α-amino with amide bond by D-Glu and L-Glu. The possible synthesis mechanism is as follows: Stage (A Phosphorylation, transfer of the phosphate group of ATP to the C-terminal carboxyl group on the polymer chain to form ADP; stage (B), forming an amide bond by attacking the amino group on the D- or L-glutamic acid of the phosphorylated carboxyl group Stage (C), after polymerization by stage (A) and stage (B), output DL-PGA. In principle, PGA does not bind to membrane-associated enzymes at various stages. The current study suggests that DL-PGA synthase is a membrane-associated protein complex (viz, PgsBCA) containing the typical Rossmann-type amide bond synthetase component PgsB. In this experiment, the γ-PGA synthase gene cluster PgsBCA of Bacillus subtilis was cloned, and its bioinformatics was analyzed by related software to understand the function of related genes, and to carry out the key enzyme gene PgsB of amide bond formation. Prokaryotic heterologous expression provides a reference and theoretical basis for the development of new enzyme preparations and extracellular synthesis of related polymers. 
Cloning and expression of a novel food additive γ-polyglutamate synthase gene