Mechanically caused damage to Hfr cells of Escherichia coli K12

When mating pairs of Escherichia coli K12 are separated by physical means, e.g. by violent agitation, the Hfr cell is unable to mate with a second F− cell. This effect can be simulated by agitation of the Hfr cells prior to mating and, in addition, such cells can be shown to have an impaired ability to adsorb the male-specific coliphage μ2. Inhibitory concentrations of chloramphenicol block the repair of the damage.