A Mutant of Escherichia coli with a New, Highly Efficient Promoter for the Lactose Operon

We have isolated a mutant of E. coli whose maximal rate of synthesis of lac mRNA is 25-fold greater than that of its parental wild-type strain. The mutant also shows alterations in the kinetics of beta-galactosidase synthesis, the functional half-life of beta-galactosidase mRNA, and the properties of lac repressor.