Controlled gene expression systems for Lactococcus lactis with the food-grade inducer nisin.

摘要: The kinetics, control, and efficiency of nisin-induced expression directed by the nisA promoter region were studied in Lactococcus lactis with transcriptional translational fusions to gusA reporter genes. In nisin-producing L. strain NZ9700, specific beta-glucuronidase activity increased very rapidly after mid-exponential growth until maximum level at start stationary phase was reached. Expression gene also NZ9800, an NZ9700 derivative carrying a deletion structural that abolishes nisin production, NZ3900, MG1363 containing regulatory nisRK genes integrated chromosome. both strains, linearly dependent on amount added medium. Without nisin, no production observed. To optimize translation initiation, vector constructed fusing translationally codon gene. Use fusion yielded up six times more than these strains induction nisin. this way, can be achieved dynamic range 1,000-fold. found 25-fold higher extracts NZ3900 NZ9800. This used for high-level aminopeptidase N, 47% total intracellular protein. These results clearly illustrate potential nisin-inducible system overproduction desired proteins.