chiB组成型启动子的获得及工程菌株构建

In this paper, a high constitutive expression promoter was obtained through deletion mutation and Bti engineering strains that enhanced bacteriostatic activity in the use of this promoter was constructed. The full length and series of deletion promoter fragments of chitinase gene B of Bacillus thuringiensis were cloned into a shuttle promoter-probe vector pCB, and all of the constructed plasmids were transformed into Bti75 strain. A 190bp-length high constitutive expression promoter was determined according to the results of β-galactosidase activity and the type of expression. Bti engineering strain was constructed by using this promoter to express chitinase gene chiMY of Bacillus licheniformis in Bti strain. The β-galactosidase activity of 190bp-length promoter is about 7 times higher than the full-length promoter without inducer and the chitinase activity is about 3.5 times in engineered Bti strain. Real-time fluorescence quantitative analysis results showed that the promoter efficiency changes occurred at the transcriptional level. Compared with the parent strain, Bti75 engineering strain has a significant improvement in enzymatic activity and antibacterial activity. This 190bp-length promoter would express different chitinase genes constitutively and efficiently, which provides an example of molecular breeding methods for deinducible synthetase.