Assembling new Escherichia coli strains by transduction using phage P1.

A protocol is described that allows the transfer of genetic material from one Escherichia coli strain to another using bacteriophage P1. P1 transduction can be used to construct new bacterial strains containing multiple alleles, to restore a locus to wild type, to move specific genetic markers from one strain to another, to relocate different mutant genes to a common genetic background, and to evaluate second-site suppression of a mutant allele. Because of these abilities, P1 transduction remains a staple in the arsenal of genetic tools that have kept E. coli at the forefront of model bacterial systems. The protocol incorporates some updated steps and discusses general principles of bacteriophage handling and the infection process.