ABSTRACT
The genus Clostridium comprises a highly heterogeneous group of gram-positive, endospore-producing, rod-shaped anaerobes, showing diverse physiology, and genetics.1 For instance, the optimal growth temperature for clostridia varies from 34°C to 37°C for C. beijerinckii to 75°C-78°C for C. thermohydrosulfuricum. The guanosine and cytosine content (GC composition) of Clostridium DNA also varies from 24% in C. pasterianum to 55% in C. barkeri.1 This genus currently contains 146 validly species, which are grouped into 19 clusters.2,3 Cluster I consists of the majority of pathogenic species that have been regarded as the true representatives of the genus (i.e., Clostridium sensu stricto). It has been shown recently that the species of Clostridium cluster I are not only phylogenetically distinct from the remaining cluster of clostridia but also share many unique molecular characteristics.4
