DNA sequence of the insertional hot spot of Tn916 in the Clostridium difficile genome and discovery of a Tn916-like element in an environmental isolate integrated in the same hot spot.

Tn916 is a broad host range tetracycline resistance conjugative transposon. In most bacteria, this element enters the bacterial genome at multiple sites. However, in Clostridium difficile, the element has a strong hot spot when introduced by filter mating from Bacillus subtilis. In this work, the DNA sequence of the preferred insertion site (att916) was obtained. An environmental isolate of C. difficile was also discovered which contained an element indistinguishable from Tn916, Tn916CD. Tn916CD was found integrated at att916.