DETAILS OF PRODUCTION OF TOXINS AND TOXOIDS
Stock cultures of the five toxigenic strains used were
prepared in Robertson's cooked meat broth containing ox muscle with tryptic digest meat broth. After incuba- -
tion for 48 hours at 350C (at 28oC for Type E) stock cul-
tures were stored in the dark at 0°Cor freeze-driedadded;
Basic media for bulk toxin production
TypesA andB. Themediumwasprepared by dissolving 25.0% (w/v) tryptic digest of casein and 10.0% (w/v) yeast extract in water (Gladstone &Fildes, 1940). With pH adjusted to 7.6 the medium was dispensed in volumes of about 950 ml in I-litre bottles and autoclaved at
15 p.s.i. (1.05 kg/cm2) for 20 minutes. Types C, DandE. The medium selected was the com
steep liquor medium recommended by Sterne &Wentzel
(1950). Crude corn-steep liquor, containing approximately 50% total solids, was diluted with tap water to contain 3 %-5% total solids and the pH adjusted to 8.8
with 40%sodium hydroxide. After boiling and filtering,
the pH was readjusted to 7.2 and tap water added to
restore the original volume; the medium was dispensed
in volumes of about 950 ml in 1-litre bottles and auto- -
claved at 15 p.s.i. (1.05 kg/cm2) for 15 minutes.