Effect of Zn2+ on bacterial conjugation: inhibition of mating pair formation.

Zn(2+) at 10(-3)m has been found to block the formation of mating pairs between Hfr and F(-) strains of Escherichia coli as observed both by light microscopy and by Coulter counter measurements. Kinetic studies show that Zn(2+) reduces the fertility of the male and that its effect disappears within 2 min after Zn(2+) has been removed from the medium. Short treatments of female cells with Zn(2+) have no detectable effect on their ability to form mating pairs. Later steps in the mating process such as mobilization of the male chromosome, transfer of the chromosome to the female, or its integration into the female chromosome seem not to be affected by 10(-3)m Zn(2+).