Fig. 4.

Comparative efficiencies of conjugative plasmid transfer of various vectors from the E. coli donors CA434 and sExpress into the recipient strain C. difficile R20291. The indicated plasmids, along with a control pMTL80000 plasmid lacking a functional Gram-positive replicon, were transferred from either donor using the conjugation method outlined in the materials and methods section. Conjugation efficiency was calculated as the proportion of putative transconjugant thiamphenicol resistant colonies divided by the CFU of recipient cells. Bars represent the means of three separate conjugations with error bars representing standard deviation. Statistical significance was determined using multiple unpaired t-tests, with one asterisk denoting a (p < 0.05 *, n = 3).