The Genetic Behaviour of Colicinogenic Factor E1

Abstract

SUMMARY: Analysis of the genetic behaviour of the colicinogenic factor E1 (colE 1) in crosses involving Hfr or F+ and F- strains of Escherichia coli k12 shows: (1) this factor is transferred with very high frequency from different donor bacteria; (2) its transfer begins to take place early whatever the type of donor cell; (3) it is not linked with chromosomal markers; (4) it multiplies autonomously in the zygote at such a rate that its passage to all descendent cells is assured; (5) the non-colicinogenic character of the donor parent does not appear among recombinant or recipient cells; (6) no lethal zygosis occurs related to the transfer of a presumptive colE 1 - locus. All these facts suggest that colE 1 exists in an extra-chromosomal state in Hfr, F+ and F- bacteria. No transfer of colE 1 from F- to F- or Hfr bacteria was observed.