An Alternative Bacterial Expression System Using SG2 Chitinase Promoter.

Background: Chitin is an abundant natural polysaccharide found in fungi, algae, and exoskeleton of insects. Several bacterial species are capable of utilizing chitin as their carbon source. These bacteria produce chitinases for degradation of chitin into -acetyl-D-glucosamine. So far, regulation of the chitinase encoding genes has been studied in different bacterial species. Among species, strain SG2 encodes two chitinases, ChiS and ChiL. The promoter region of SL genes (P ) is mainly regulated by the general carbon catabolite repression (CCR) system in due to the presence of a catabolite responsive element ().

Objectives: Use of P in constructing an inducible expression system in was investigated.

Materials And Methods: In the first step, complete and shortened versions of P were inserted upstream of the lacZ on a pBS72/pUC18 shuttle plasmid. The β-galactosidase activity of carrying one of the relevant plasmids was measured in the presence of different carbon sources.

Results: An expression system based on the chitinase promoter of SG2 was established. Modification of P and the culture medium resulted in production of β-galactosidase in up to 1,800 Miller unit (MU) activity.

Conclusions: The chitinase promoter developed in this study, has potential to be used in an expression vector that could be induced by chitin. In addition, compared to the other inducers like IPTG and lactose, chitin is definitely cheaper and more available as an inducer.