BACKGROUND: Corynebacterium ulcerans can cause a diphtheria-like illness, 
especially when the bacterium is lysogenized with a tox gene-carrying 
bacteriophage that produces diphtheria toxin. Acquisition of toxigenicity upon 
phage lysogenization is a common feature of C. ulcerans and C. diphtheriae. 
However, because of a lack of C. ulcerans genome information, a detailed 
comparison of prophages has not been possible between these two clinically 
important and closely related bacterial species.
RESULTS: We determined the whole genome sequence of the toxigenic C. ulcerans 
0102 isolated in Japan. The genomic sequence showed a striking similarity with 
that of Corynebacterium pseudotuberculosis and, to a lesser extent, with that of 
C. diphtheriae. The 0102 genome contained three distinct prophages. One of 
these, ΦCULC0102-I, was a tox-positive prophage containing genes in the same 
structural order as for tox-positive C. diphtheriae prophages. However, the 
primary structures of the individual genes involved in the phage machinery 
showed little homology between the two counterparts.
CONCLUSION: Taken together, these results suggest that the tox-positive prophage 
in this strain of C. ulcerans has a distinct origin from that of C. diphtheriae 
NCTC 13129.