ABSTRACT
The clostridia are anaerobic, Gram-positive, endospore-forming bacilli and are comprised of a large number of species, most of which were originally assigned to this group because they exhibit these three characteristics. This method of strain classification has resulted in the assignation of a heterogenous group of bacteria to the genus Clostridium. Bacteria from this group are therefore capable of degrading a large range of carbohydrate substrates and of exhibiting a wide variety of metabolic activities [1]. The classification of this genus is still under review, particularly since molecular taxonomic techniques have been used to re-examine the status of some of these strains [2]. The saccharolytic clostridia are a good example of recent, more rational reorganization of species assignment, and the group of bacteria previously designated as Clostridium acetobutylicum has now been divided into four different taxonomic clusters [3-5]. Although studies on clostridia have contributed greatly to our understanding of many metabolic pathways [6], knowledge of these activities is far from complete. However, as more molecular data regarding these processes become available, it is useful to compare the genetic structure and organization of the pathways found in different Clostridium species, so that common regulatory patterns become more apparent and evolutionary history can be deduced.
