BACTERIOPHAGE-T5 GROWTH IN ESCHERICHIA-COLI CONTAINING CLONED PSTI FRAGMENTS OF THE COLICIN IB PLASMID

PstI restriction fragments of the colicin Ib (ColIb) plasmid were cloned into the Apr (ampicillin resistance) gene of the plasmid pBR322 vector. Colicin-producing clones (Col+) all contained 2 common PstI (L and U) fragments, 2000 and 800 bp (base pairs) long, respectively. All of these colicin producers permitted the normal growth of bacteriophage T5; the presence of the whole ColIb plasmid causes an abortive phage T5 or phage BF23 infection. None of the other clones selected for their inability to propagate T5 produced colicin. The clones (Abi+) that permitted only an abortive infection by T5 contained a single restriction fragment, O (1600 bp), which was not found in any of the colicin producers. The specific fragments (L and U) found in the Col+ clones were not found in the Abi+ clones. These data are difficult to reconcile with the hypothesis of a colicin-induced cell deterioration after T5 phage infection.