The Clostridia are a class of Firmicutes, including Clostridium and other similar genera. They're distinguished from the Bacilli by lacking aerobic respiration. Studies show they aren't a monophyletic group, and their relationships aren't entirely certain. Currently most are placed in a single order called Clostridiales, but this isn't a natural group and's likely to be redefined in the future. Notable species of this Class include; Clostridium perfringens (Gangrene,Food Poisoning) Clostridium… (More on Clostridia)