Temperature-sensitive conjugation-defective F factor in Escherichia coli.

A mutant strain of Escherichia coli K-12 which is unable to transfer genetic material at 42 C has been isolated. Although transfer is inhibited at this temperature, the formation of specific pairs is unaffected. This strain and its derivatives also show an altered sensitivity to certain ribonucleic acid-containing male specific phages at 42 C. Both phenotypic changes are reversed when a derepressed fi(+) R factor is present in the same cell and a revertant which has regained both activities has been obtained. The nature of the temperature-sensitive defect and its effect on the conjugation process are discussed.