Construction of the expression vector based on the growth phase- and growth rate-dependent rmf promoter: use of cell growth rate to control the expression of cloned genes in Escherichia coli

A novel expression vector based on the rmf promoter (Wada et al. Proc. Natl . Acad. Sci. USA (1995) 87: 2657-2661) was developed. Using lacZ gene as a model, protein production depending on cell growth phase and growth rate wa s found. In addition, by subjecting the recombinant cells to temperature do wnshift and substrate famine, the strain was capable of producing 35 000-40 000 units of beta -galactosidase. These characteristics indicate the poten tial application of this expression vector to bioprocessing such as protein production in continuous or batch fermentation, biotransformation using en trapped cells, and in situ bioremediation.