Towards Single-Copy Gene Expression Systems Making Gene Cloning Physiologically Relevant: Lambda InCh, a Simple Escherichia coli Plasmid-Chromosome Shuttle System

We describe a simple system for reversible, stable integration of plasmid-borne genes into the Escherichia coli chromosome. Most ordinary E. coli strains and a variety of pBR322-derived ampicillin-resistant plasmids can be used. A single genetic element, a lambda phage, is the only specialized vector required. The resultant strains have a single copy of the plasmid fragment inserted stably at the lambda attachment site on the chromosome, with nearly the entire lambda genome deleted.