M13 Phage Growth and Single-Stranded DNA Preparation

M13 bacteriophage has a single-stranded DNA (ssDNA) genome, and has proven an extremely useful vector from which to derive single-stranded templates for sequencing and site-directed mutagenesis. During infection of its host cell, the phage DNA replicates as a double-stranded intermediate from which the ssDNA containing phage particles are produced. Infected cells do not lyse, but instead phage particles are continuously released. Cells infected with M13 phage, however, have a longer replication cycle, which means that as the infection proceeds, the areas of slower-growing cells can be visualized as turbid plaques on the lawn of unaffected E. coli (1 ). Recombinant M13 phage can be cloned from well-separated plaques and used as a source of SSDNA.