Lambda red-dependent growth and recombination of phage P22.

Plasmids that express lambda recombination functions singly and in combinations, at controllable levels, have been constructed. These plasmids were placed in Escherichia coli and Salmonella strains, and their ability to complement lambda and P22 strains lacking recombination functions was examined. The combination of lambda bet and exo constitutes a minimal system that can substitute for the recombination system of P22 in allowing efficient growth and recombination in a recA- host.