The concentration of diphtheria toxin by acid precipitation / by A.F. Watson and U. Wallace.

  • Watson, A. F.
Date:
[1924?]
Catalogue details

Licence: In copyright

Credit: The concentration of diphtheria toxin by acid precipitation / by A.F. Watson and U. Wallace. Source: Wellcome Collection.

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    the ordinary hand or motor driven Sharpies centrifuge has been employed and has proved very satisfactory. Formation of precipitate.—It has been shown in a former com¬ munication (1924) that during the growth of P.W. 8 strain of B. diphtherias, in addition to hydrogen ion concentration changes, several interesting changes in nitrogen metabolism take place in the culture medium. Of these the most important are the increase in the amount of nitrogenous material precipitable by glacial acetic acid, and the amount of amino-nitrogen as determined by the Yan Slyke method. Table I. No. Type of medium. Milligrams Van Slyke N. per 10 c.c. Milligrams Precipitable N. per 300 c.c. Toxicity. Strain. Before growth. After growth. Before growth. After growth. Lr/500 doses per c.c. 1766 Tryptic digest of horse muscle. 9-62 16-62 8-71 12-2 2500 ... 1767 5 5 5 5 9-60 15-67 10-95 12-12 2000 . . . 1771 5 5 5 5 12-59 18-06 3-25 17-11 4000 79 1771 5 5 5 5 12-59 20-34 3-25 29-04 5000 103 1771 5 5 5 5 12-59 17-26 3-25 23-88 3333 106 1769 Witte peptone broth 5-54 9-25 13-33 ... 5000 .. • 1773 5 5 5 5 5-07 6-13 12-89 17-08 200 79 1777 5 5 5 5 5-17 6-49 13-1 12-4 1250 103 1775 5 5 5 5 4-05 7-80 12-24 16-10 less than 100 106 1780 5 5 5 5 5-33 5-49 17-28 • • • 100* , . , 1783 Abt and Loiseau broth . 5-23 7-69 4-76 7-72 1666 79 1786 Difco peptone broth 4-98 5 94 5-52 13-36 less than 100 106 1787 Parke - Davis peptone broth. 7-40 8-7 • • • 6-5 • • • 106 * This filtrate on concentration by the method outlined to one-twentieth of the original volume gave a solution of very high Ramon value suggesting that the original filtrate might have been of high combining value but of low toxicity. Table I. shows the analysis of various culture media made by different methods, and brings into prominence these typical changes which are found during the growth of the powerfully toxin-producing strain of B. diphtherias. It will be seen that parallel with the pro¬ duction of amino-nitrogen as growth progresses we get an increasing amount of nitrogen which is precipitable by glacial acetic acid. It must be emphasised at this point that the production of this “pre¬ cipitable nitrogen” is a function of the growth and the particular strain of the bacillus rather than of toxin production. When the various factors which influence toxin production are working smoothly, we find that this precipitable nitrogen contains most of the toxin, if precautions are taken regarding its separation and recovery. It will be seen also from the above table that toxins made from “digest” media (Watson and Wallace, 1923) contain a comparatively large