Practical Media and Control Measures for Producing Highly Toxic Cultures ofClostridium botulinum, Type A

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Abstract
Practical liquid media, composed of 2% powdered milk (or 0.3% casein), 0.5-0.6% commercial glucose, and 0.2-0.4% corn steep liquor, have been developed for production of highly toxic cultures of the "Hall" strain of C. botulinum, type A. These media yield 500,000 to 1,000,000 mouse intraperitoneal M.L.D. of toxin per ml. of culture when inoculated with 2-5% by volume of an actively growing culture and incubated in a quiescent state at 34[degree]C for 24-48 hrs. Although small inocula or mild agitation tend to retard toxin production, no special procedures are required to insure anaerobiosis if culture vessels are used that provide a low exposed surface area per unit volume. Characteristic changes in pH, conc. of reducing substances, and levels of non-protein N occur during incubation of the cultures. The relationships of pH and reducing substances to rapidity of accumulation and stability of toxin provide useful control measures for securing the maximum yield of active toxin.