Artificially Induced Loss of Theta-Toxin Production by Clostridium welchii Types A and C

Abstract

Macfarlane and Knight¹ having shown fairly conclusively that the alpha toxin of Cl. welchii Type A is a lecithinase, we considered it possible that repeated passage through media containing lecithin might enhance the capacity to produce alpha toxin. However, we found that after a dozen rapid passages through Hall's cooked-brain medium, strains showed no loss of capacity to produce alpha toxin when grown in 'test medium' (V. F. broth plus 0.25 percent glucose), as compared with the same strains after similar passaging through test medium, but that they unexpectedly lost the capacity to produce theta toxin. It would thus appear possible to produce large quantities of Cl. welchii toxins free from theta toxin, much more simply than by the procedures described by van Heyningen². Strains of Cl. welchii Type C, which normally produce considerable amounts of theta toxin (up to 1,000 H. U. per ml.), behaved in the same way.