Gas-Gangrene-Toxin Production

Abstract

Since Bull's original demonstration that Cl. welchii is toxigenic it has been customary to cultivate this and other gas-gangrene anaerobes for toxin-production in chopped-meat media, rich infusion-broths or serum-broths. It seems evident from the literature that many workers have found these methods to give highly variable yields of toxin. In our experience different batches of such media made in an apparently similar manner, inoculated with the same strain of organism and handled in as nearly as possible an identical manner, give very different yields of toxin. The recent experience with the production of diphtheria toxin has indicated that more consistent yields may be obtained by substituting for complex infusions, media of known, or for the most part known, chemical composition.

After several preliminary trials the following medium was found to give fairly high yields of toxin which are consistent from batch to batch with all the toxin-producing members of the gas-gangrene group of organisms:

The most consistent results have been obtained with freshly prepared and autoclaved media. While small inocula give good growths, more uniform toxin-yields have followed the use of inocula consisting of 3% of a 5 to 6 hour culture in the same medium.

Many modifications of this medium have been tried, particularly various proportions of gelatin and peptone. Variations of 1 to 10% of gelatin and 0.1 to 10% of peptone give fair yields of toxin but with a maximum at about 5% gelatin and 1% of peptone. Bacto peptone is slightly superior to several others tested. Fair yields of toxin are obtained with 5% of gelatin and no peptone. Larger concentrations of glucose and other sugars, fermentable by the organism in question, give somewhat more rapid growth but the yield of toxin is conspicuously lower probably due to the greater acid-production.