Expression and secretion of a single-chain sweet protein monellin in Bacillus subtilis by sacB promoter and signal peptide.

The sweet protein monellin gene was expressed in Bacillus subtilis under the control of the Bacillus subtilis sacB promoter and signal peptide sequence. A 294-bp DNA fragment, coding for sweet protein monellin, was ligated into the Escherichia coli/B. subtilis shuttle vector pHPC, producing pHPMS, which was subsequently transformed into B. subtilis QB1098, DB104, and DB403. The peptide efficiently directed the secretion of monellin from the recombinant B. subtilis cells. A maximum yield of monellin of 0.29 g protein l(-1) was obtained from the supernatant of B. subtilis DB403 harboring pHPMS. SDS-PAGE confirmed the purity of the recombinant product.