A mutant of bacteriophage phiX174 which infects E. coli K12 strains. I. Isolation and partial characterization of phiXtB.

A mutant of bacteriophage phiX174 has been isolated which infects K12 strains of E. coli. This mutant, phiXtB, also infects strains C and B, though at reduced efficiencies. phiXtB's properties are summarized as follows: (1) phiXtB has an altered plating temperature range; (2) phiXtB particles sediment slightly faster and are slightly more dense than phiX174 particles; (3) phiXtB's replication involves intracellular DNA forms like those found in phiX-infected cells and a possible new species not previously seen in phiX-infected cells.