Correlation of physical maps and some genetic functions in the genomes of the kappa-theta phage family of Bacillus licheniformis.

Natural recombinant genomes between several, phenotypically distinct forms of phages kappa and theta were isolated and characterized by DNA restriction fragment mapping and electron microscopic heteroduplex analysis. The phenotypes of the recombinants were correlated with the physical maps of the genomes, and several genetic functions were therefore defined and mapped. All genes necessary for the assembly of infectious virus particles map in a contiguous tract of DNA comprising about 20 kb, or nearly one third of the genome length. No DNA homology occurs within these domains of the two genomes, so that homologous recombination does not take place here and phenotypic mixing of the phages is eo ipso excluded. Other regions of heterology contain regulatory genes responsible for the lytic or temperature character of the phages, and for exclusion of phage kappa by 9.