Abstract
A temperate phage φ 170 which is dismune to lambda, attaches to the chromosome of Escherichia coli K 12 at a site adjacent to the galactose locus, and can transduce the galactose markers specifically. When a nonlysogenic recipient is used for transduction, a heterogenote (lysogenic syngenote) is isolated. The heterogenote produces a HFT lysate after the induction by UV irradiation. When lambda-lysogenic strains are used as recipients the resulted doubly lysogenic transductants are unstable and segregate Gal- progenies. Preferential elimination of exogenote and transducing phage is observed in this segregation. The unstable lysogeny is also observed in doubly lysogenic strains of non transductant type. In this case, elimination of prophage is not preferential; the segregants are singly lysogenic of each parental type and a small number of doubly lysogenic and nonlysogenic. The segregation of non lysogenic strain from the unstable doubly lysogenic strain is a useful method for the isolation of nonlysogenic derivatives from various K 12 strains.
