Abstract
As a result of studies carried out by one of us 1 on the chemical nature of the substances required by the bacillus of diphtheria for growth, and by another of us 2 on the factors underlying toxin-production by this organism, it is now possible for the first time to produce toxin of high titer on a medium of known composition. A qualification of the word “known” is admitted in that certain of the components are obtained from natural sources and may contain traces of impurity, and further, that the extremely important traces of certain inorganic elements are beyond control due to the effect of components from the type of glass containers used. The complete absence of peptone, formerly believed to be the sine qua non for toxin-formation, appears to be assured.
The composition and method of preparation of the medium is as follows: The glycine, valine, leucine, glutamic acid, methionine and tyrosine, sodium chloride and potassium phosphate are weighed out and dissolved in about 500 cc. of distilled water. The cystine is dissolved in a minimal amount of 1:1 HCl and added to the main lot. The pimelic acid, beta alanine and nicotinic acid are now added and the solution adjusted to pH 7.8; 0.3 cc. of a 33% solution of calcium chloride is added and the medium boiled gently for 10 minutes. The precipitated calcium phosphate which carries down any inhibitory excess of iron is now filtered off. Finally the magnesium sulphate, copper sulphate and tryptophane are added and the medium made up to 1000 cc, dispensed and autoclaved. Before inoculation, 2 cc. of a sterile solution containing 37% Merck's U.S.P. sodium lactate, 7.5% Merck's c.p. glucose, 15% purified maltose and 0.3% calcium chloride are added per 100 cc. of medium.
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