Complementation of TcdE mutant.

<p><b>A</b> Growth curve of parent, the TcdE mutant and the complemented TcdE mutant strains. A. The inducer ATc (20 ng/ml) was added to bacterial cultures at 4 hrs after inoculation, indicated by an arrow. The star * indicates the time point when the cultures were harvested for toxin release analysis. <b>B.</b> Toxins were quantified by ELISA from supernatants of bacterial cultures induced by 20 ng/ml ATc for 2 hours. The signal from the test was recorded as absorbance at 450 nm. The data shown are the mean +/− standard error of three replicative samples. <b>C.</b> Dot blots of culture supernatants of the parental, the TcdE mutant and the complemented TcdE mutant, induced or not induced by ATc (0 and 20 ng/ml), with monoclonal anti-TcdA. <b>D.</b> Dot blots of samples in B with monoclonal antibodies against L7/L12 ribosomal subunits.