The Isolation of Type B Botulinum Toxin

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Abstract
A method for the purification of the type B toxin from the proteolytic "okra" strain of Clostridium botulinum is described. The toxin in the mother culture is precipitated by adjusting the acidity to pH 4. The toxin in this precipitate is extracted in dist. water acidified to pH 2. Reprecipitation of the toxin from the extract at pH 5 followed by a wash in a salt soln. and reprecipitation results in a highly toxic product (5-9 X 10-9 mg N per mouse LD50). The purified toxin is a slightly colored simple protein soluble on the acid side of the isoelec-tric range and relatively insoluble on the alkaline side and within the isoelectric range. Slight additions of salt do not favor solubility. Electrophoretically only one component is observed. Serologically, chemically and physically the purified B toxin differed from type A crystalline toxin. The diffusion constant of the B toxin is 7.22 X 10-7 cm2 sec-1 at 20[degree] C as detd. by diffusion through a sintered glass membrane. By the intraperit. route the guinea pig is about 3 times more susceptible to the toxin than is the white mouse.