Expression of Plant Monellin in Escherichia coli Induced by Lactose

According to the amino acid sequence of Monellin and the bias in coden choice in Escheria coli,a single chain monellin gene was synthesized and subcloned into a Escheria coli expression vector pET-28a. The recombined plasmid pET28a-mon was then transformed into Escheria coli BL21(DE3).Lactose was used as an inducer instead of IPTG. Through proper optimization of induction conditions,an expression level 33.09% of total cellular protein was achieved.The expression level of recombinant protein induced by lactose was basically the same as that induced by IPTG. The result indicated that lactose could be used as a promising inducer in the production of recombined sweet protein Monellin.