@article{mbs:/content/journal/micro/10.1099/00221287-36-2-311, author = "De Zwaig, Rosa Nagel and Puig, J.", title = "The Genetic Behaviour of Colicinogenic Factor E1", journal= "Microbiology", year = "1964", volume = "36", number = "2", pages = "311-321", doi = "https://doi.org/10.1099/00221287-36-2-311", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-36-2-311", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "Summary: Analysis of the genetic behaviour of the colicinogenic factor E1 (colEj) 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.", }