Toxin production by Clostridium botulinum type A under various fermentation conditions

The time of appearance and the quantity of toxin produced by the Hall strain of Clostridium botulinum type A were examined under various conditions. A 70-liter fermentor and a complex medium consisting of 2% casein hydrolysate and 1% yeast extract plus an appropriate concentration of glucose were employed. Optimal conditions for toxin production were as follows: a nitrogen overlay at a rate of 5 liters/min, an agitation rate of 50 rpm, a temperature of 35 degrees C, and an initial glucose concentration of 1.0% with the pH uncontrolled. Under these conditions, the maximum toxin concentration (6.3 x 10(5) mouse median lethal doses/ml) was attained within 24 h. Cell lysis was apparently not required to obtain maximum toxin concentrations under the fermentation conditions described.