Development of expression vector with the Pgrac100 promoter induced by IPTG and integrated gfp+ gene into Bacillus subtilisgenome at lacA locus

Bacillus subtilis is a prospective gram - positive bacterium that offers an opportunity for the production of recombinant proteins in the pharmaceutical, agricultural, industrial, and food industries.The goal of this study was to develop an integrative inducible expression system by incorporating the Pgrac100 promoter into the lacA locus of the B. subtilis genome. The results showed that the Pgrac100 promoter was able to strictly control the expression of the target protein, with induction factors of 3.3, 7.6, and 10.8 after 4 hours under induction with 0.01, 0.1, and 1 mM Isopropulβ-D-1-thiogalactopyranoside (IPTG), respectively. The duration of induction and the concentration of IPTG had significant effects on the efficacy of target protein expression. Specifically, when induced with 0.1 mM IPTG after 4 hours, there was a significant rise in GFP expression, accounting for 13% of the total cellular protein. Our new vector system provided more options for the production of recombinant proteins in basic research and industrial applications.