Effect of Integrated Sex Factor on Transduction of Chromosomal Genes in Escherichia coli

Abstract

Pittard, James (Yale University, New Haven, Conn.). Effect of integrated sex factor on the transduction of chromosomal genes in Escherichia coli . J. Bacteriol. 89: 680–686. 1965.—Generalized transducing phage P1kc can contransduce the markers tna and ilv in Escherichia coli K-12 at a frequency of approximately 25%. When sex factor is integrated into the donor chromosome between tna and ilv , as in Hfr AB313, the entire sequence tna F ilv is not cotransduced at a detectable frequency, nor is F cotransduced with either tna or ilv . The frequency with which ilv is transduced from Hfr AB313 to female recipients is approximately one-eighth the frequency obtained when either F + or female strains are used as donors. This reduction of transduction frequency does not occur if the recipient is an Hfr male similar to AB313. The reduction is attributed to pairing difficulties which occur when the transduced fragment carrying the ilv genes also carries sex-factor material. When ilv + is transduced from a female to an ilv − derivative of AB313, 70% of the transductants are converted to F + males. A model is proposed to account for all of these observations.