FIG 4.

The chemical composition of the mating support affects conjugation. Standard filter matings were performed on supports with different chemical compositions. Donor and recipient cells were mixed in equal numbers and then collected on a filter that was placed on a mating support with the indicated composition. KCl was added to 125 mM. Mixed salts contained 106 mM sodium phosphate, 14 mM sodium sulfate, and 3 mM trisodium citrate. The dashed horizontal line in each panel marks the value for mating on TSS. The mean and standard deviation from ≥3 experiments for each condition are shown. Asterisks indicate that the difference in conjugation frequency on the given support compared to conjugation frequency on TSS is statistically significant (P < 0.05, t test). (A and B) The conjugation frequency is shown as transconjugants per donor for a wild-type donor (CMJ348) and recipient (CMJ161) (A) and for an mprF null mutant donor (CMJ476) and recipient (CMJ162) (B). (C) The conjugation frequencies obtained from panels A and B are directly compared. The ratio of the conjugation frequencies of the mprF mutant (B) and the wild-type strain (A) under each of the indicated conditions is shown.