The integration of the λ phage genome in the absence of site specific recombination was investigated. An
int through
red gene deleted λ
gal bio transducing phage was infected onto
gal through
uvrB gene deleted
E. coli cells of
rec+ or
recA. Rare lysogens were selected as the
gal+ transductants on minimal agar which contains galactose as a sole carbon source. All of the
gal+immλ
+ transductants examined carried prophage genomes within the host chromosomes. The integration of λ
gal bio phage genome into the
rec+ host seemed to occur about 300 times more efficiently than in the
recA strain. Approximate chromosomal locations of these prophage genomes were mapped by mating experiments. Eight independently isolated
gal+rec+ lysogens were all found to have the prophage genomes near the
nalA gene. Among nine independently isolated
gal+recA lysogens, eight lysogens had the prophage genomes near the
lac gene and the remaining one near the
rac gene. The prophage gene order was examined in the three
rec+ and four
recA lysogens by deletion mapping and all of the λ
gal bio genomes present within these lysogens were found to have been integrated by the crossover occurring somewhere between J and
gal of the transducing phage genome. General properties of these lysogens were examined.
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