Characterization of the nar promoter to use as an inducible promoter

초록

The nar promoter of Escherichia coil was characterized, which is maximally induced under anaerobic conditions in the presence of nitrate. The following results were obtained; Expression of β-galactosidase was optimal at 1% of nitrate and was not affected much by molybdate; the amount of β-galactosidase per unit volume was maximal when the nar promoter was induced at OD <inf>600</inf> = 1.7, and when anaerobic condition was made by supplying nitrogen gas. At the optimal condition, the ratio of β-galactosidase between before and after induction was approximately 250 and Miller units were approximately 7,500. The results showed that the nar promoter can be used as an inducible promoter.