Abstract
We examined production of ADP-ribosyltransferase C3 in 11 strains of Clostridium botulinum type C and D and their nontoxigenic derivatives. Antisera to C3 proteins of type C organisms divided C3 proteins roughly into at least two groups, bearing no relation to their bacterial types. The C3 gene of type D strain South African was isolated from a toxigenic phage library, and the complete sequence of the C3 gene was determined. The C3 protein of type D strain South African had 98% homology to the C3 protein of type C strain 003-9 and 66% homology to that of type D strain 1873. These results indicate that there are two types of C3 protein in type D organisms, as there are in type C organisms.