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The production of the alpha toxin of Clostridium perfringens in a chemically reproducible medium Costerton, John William Fisher

Abstract

Boyd, Logan and Tytell (1948) have shown that Clostridium perfringens BP6K will grow in a chemically reproducible medium. They recorded no lecithinase (∝toxin) production under the conditions of their experiment. This thesis reports conditions under which lecithinase is produced in the above medium. Time studies Involving hourly sampling proved to be the most satisfactory method of studying the production of the enzyme. The pH of each sample was determined, the bacterial density was recorded turbidimetrically, and the lecithinase was estimated by a modification of the egg yolk suspension method. Lecithinase was found to be produced during the logarithmic phase of growth, after which it rapidly diminished in quantity, disappearing at approximately twelve hours growth. The amount of the enzyme produced is relatively small compared with yields from complex organic media. However, the characteristics of the lecithinase appear identical with those of the lecithinase produced in complex media. Since the medium contains no lecithin, and the enzyme is produced during the logarithmic growth phase, it would appear that the enzyme is essentially constitutive and extracellular. Phase variation as indicated by colonial morphology has been shown to be of considerable importance in lecithinase production in the chemically reproducible medium. The observation of a peculiar colonial morphology designated as a "halo" colony is reported. This morphological type is seen to be closely related to high toxigenic activity in G.P.B.I. In the reproducible medium acid production during growth (pH 7.2 to 4.8) is closely related to enzyme destruction. Adjustment of the pH during growth does not greatly enhance lecithihase production but does markedly slow its destruction. The substitution of dextrin for glucose in the reproducible medium delays but does not reduce growth and lecithinase production. The destruction of the enzyme is slowed by the addition of proteinaceous material. The concentrations of cystine and of iron are also seen to affect the rate of destruction of lecithinase.

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