Clostridium welchii Iota Toxin: Its Activation by Trypsin

SUmmary: The isolation, from sheep, of strains of the Bosworth type of Clostridium welchii is recorded; it is proposed to designate this type as Cl. welchii type E.

The toxicity of culture filtrates of Cl. welchii type E after short growth periods is increased by treatment with crude trypsin preparations; no such increase can be demonstrated when the filtrates are from growths older than 5–7 hr. The toxin which is activated in these filtrates is the toxin iota. It appears that Cl. welchii type E strains elaborate prototoxin convertible by enzymes into iota toxin proper.