FIG 1.

spoVAD and spoVAE are required for DPA uptake into the spore. (A) Equal amounts of spores purified from C. difficile strains RS19 (wild type [WT]), MB03 (ΔspoVAD), and MB04 (ΔspoVAE), containing an empty vector (pEV) or a complementing plasmid, were boiled for 20 min and DPA amounts quantified by Tb³⁺ fluorescence. Values are reported as percentage of the WT DPA content. (B) We serially diluted and plated 1 × 10⁸ spores on BHIS plates supplemented with TA before and after heating at 65°C for 30 min. The values are reported as percentage of heated spores that formed colonies compared to unheated spores. The data represent results from 3 independent assays, and the error bars represent the standard errors of the mean. **, P < 0.001; ***, P < 0.0001 as determined by one-way ANOVA using Tukey’s multiple-comparison test.