An Alternative Bacterial Expression System Using Bacillus pumilus SG2 Chitinase Promoter

Area of Science:

• Molecular Biology
• Microbial Biotechnology
• Gene Expression Systems

Background:

• Chitin, a natural polysaccharide, is utilized by various bacteria, including Bacillus species, which produce chitinases for its degradation.
• The chitinase genes (chiSL) in Bacillus pumilus SG2 are regulated by carbon catabolite repression (CCR) via a catabolite responsive element (cre).

Purpose of the Study:

• To investigate the utility of the Bacillus pumilus SG2 chitinase promoter (P chiSL) for constructing an inducible expression system in Bacillus subtilis.
• To evaluate chitin as an inducer for this novel expression system.

Main Methods:

• Cloning of complete and shortened versions of the P chiSL into a pBS72/pUC18 shuttle plasmid upstream of the lacZ gene.
• Transformation of Bacillus subtilis with the constructed plasmids.
• Measurement of beta-galactosidase activity in the presence of various carbon sources to assess promoter function and induction.

Main Results:

• Successful establishment of an inducible expression system in Bacillus subtilis utilizing the B. pumilus SG2 chitinase promoter.
• Optimization of the promoter and culture medium led to significant beta-galactosidase production, reaching up to 1,800 Miller units (MU).

Conclusions:

• The developed chitinase promoter system shows potential for use in expression vectors inducible by chitin.
• Chitin serves as a cost-effective and readily available inducer, offering advantages over IPTG and lactose for gene expression applications.