Genetic studies of coliphage P1. II. Relatedness to P7.

Using semiquantitative spot tests, 107 independently isolated amber mutants of P1 were shown to be rescued by a nonpermissive strain of Escherichia coli lysogenic for P7 (previously called phiamp), indicating extensive genetic relatedness between P1 and P7. The amount of rescue observed varied with mutants from different genetic linkage clusters of P1. Although these rescue tests cannot distinguish between recombination, complementation, transactivation, or combinations thereof, a major role is indicated for recombination.