Mutants of bacteriophage lambda able to grow on the restricting host Escherichia coli strain W

Abstract

Escherichia coli strain W adsorbs phage λ very efficiently but the phage does not form plaques on this strain because the DNA of λ is broken down in a majority of the infected cells shortly after adsorption. In a 10⁻³ to 10⁻⁴ fraction of the infected cells λ grows and small bursts of phage are produced. This phage does not carry the W-specific host modification and is unable to complete a second round of infection in W (Kerszman, Glover & Aronovitch, 1967). λω mutants have been isolated which are able to escape this restriction process and which plate on W with an efficiency of 1·0 and when grown in W these mutants carry a W-specific host modification.