Haemolytic activity of the alpha and theta toxins ofClostridium welchii

Abstract

SUMMARYThe lecithinase and haemolytic activity of thirty strains ofCl. welchiiisolated from food, faeces, and soil, was studied. The strains from foods produced smaller amounts of lecithinase and were, in general, less haemolytic than the strains isolated from soil and faeces.The haemolytic activity ofCl. welchiion erythrocytes from different animal species displayed considerable variation. Sheep erythrocytes were the most sensitive to the action of alpha toxin, whereas rabbit blood was most sensitive to haemolysis by theta toxin. The degree of haemolysis was also dependent upon the concentration of the enzyme, and temperature and length of incubation.The haemolytic activity of commercial lecithinase was observed to be similar to the haemolytic activity of the alpha toxin ofCl. welchii. This finding provides further evidence that the haemolytic and lecithinase activities ofCl. welchiiare due to one substance, the alpha toxin. Exposure of commercial lecithinase to heat resulted in the destruction of its haemolytic properties.