The value of Douglas's medium for the production of diphtheria toxin / by Percival Hartley.

  • Percival Horton-Smith Hartley
Date:
[1922?]
Catalogue details

Licence: In copyright

Credit: The value of Douglas's medium for the production of diphtheria toxin / by Percival Hartley. Source: Wellcome Collection.

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    DOUGLASES MEDIUM FOR DIPHTHERIA TOXIN 481 Altlioiigli tliG gGiiGicil GxpGriGiiCG lias bGGii tliat niGclia prGparGcl iii thG laboratory by tliG action of enzymes on proteins have given disappointing results as far as toxin production is concerned, yet the earlier experiments of Harden and the writer, to which reference is made above, encouraged the belief that a satisfactory medium could be made provided that proper working conditions could be discovered. Other considerations which stimulated this research were those of economy and convenience. In the ordinary methods of making media for toxin production, '^peptone” is dissolved in an infusion of beef or veal. The present cost of “pep^one” and butcher’s meat is high and makes this an expensive process. How by the modified method of Douglas described below, the peptone ” and the essential constituents of the infusion are brought into solution together, and are both provided by the same muscle. Since it has been found possible to substitute horse flesh for veal or beef, the dual object of preparing a satisfactory medium in a convenient way at a much reduced cost has been attained. During this work, media have been made by the action of pepsin (four different preparations) and trypsin (six different preparations) on horse muscle, serum albumin, egg albumin, minced liver tissue, minced kidney tissue, and casein. The most satisfactory results have been obtained by the action of trypsin on minced horse muscle, and of the samples of trypsin used, one made in the laboratory according to the method of Cole and Onslow has given the best and most consistent results. A preparation of this pancreatic extract made in September 1919 appeared to have lost none of its activity in Hovember 1921, and yielded media at this latter date from which high-grade toxin was obtained (M.L.D. = O'OOIS c.c.). An interesting fact emerged from a study of the comparative value of a number of different samples of trypsin. Included in the series was Allen and Hanbury’s Liquor Trypsin Co., the preparation originally used by Douglas (1914). This proved to be very active and when the resulting broth was sown with the strain of B. diplitlierim used for toxin-making in these laboratories, a heavy typical film was rapidly formed. The filtrate from this growth, however, was very acid (P^ = 5 A), and contained no toxin. This was repeated with the same result on two other occasions, and further experiments showed that the acid production, and consequent absence of toxin in the filtrate, was due to the fact that the Liquor Trypsin Co. contained glycerol. Other experiments were performed in which definite amounts of glycerol were added to media which had been adjusted to a suitable hydrogen- ion concentration. Growth on such media was rapid and prolific, and in a certain number of cases in which the final reaction was alkaline, the toxin produced was as great as, and sometimes even greater than, the toxin produced on the control. This, however, was not the usual result. In the majority of instances the reaction of the medium containing glycerol became acid and remained acid, and no toxin was
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