Properties of polylysogens containing derepressed λN^- prophages : III. A large number of intergrated λ prophages

Abstract

Stable λN^-cI^- lysogens contain 20-25 copies of the λ genome per bacterial genome. Less than 10% of the λ genomes occur as closed circular plasmids. The remaining λ genomes can not be separated from the bacterial DNA by centrifugation in neutral sucrose. We suggest that the bacterial chromosome contains several tandemly integrated prophages which replicate at a higher rate than the remainder of the chromosome.