Figure 3.

Elimination of the lethal toxin gene from C. novyi. Following heat shock, PCR was performed on DNA from colonies to identify those which had lost the lethal toxin gene on the phage episome. Agarose gel electrophoresis of the PCR products with two independent primer sets (ToxA and ToxB) shows results from a C. novyi clone (C. novyi-NT) that had lost the gene and another clone (indicated as “C. novyi”) that retained the gene. Controls were provided by primer sets (PlcA and PlcB) specific for the C. novyi phospholipase C gene demonstrating the integrity of the DNA templates in all reactions.