Ferments and their actions / by Carl Oppenheimer ; Translated from the German by C. Ainsworth Mitchell.

Date:
1901
Catalogue details

Licence: In copyright

Credit: Ferments and their actions / by Carl Oppenheimer ; Translated from the German by C. Ainsworth Mitchell. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    the fermentative energy. Thus Effront1 found that sodium fluoride and other fluorine compounds when present in slight con- centration checked the reproduction of the yeast-cells, but, on the other hand, not only did not have any prejudicial activity on the action of the ferment, but even stimulated it. According to Foth,2 yeast behaves in a similar manner in an atmosphere of carbon dioxide. An analogous instance of the fact that it is possible under certain conditions to preserve the fermentative activity whilst destroying the vital activity, is furnished by the experiments of Fiechter,3 who found that hydrocyanic acid, even in very slight quantities, destroyed the vital activity of the yeast without immediately putting an end to the fermentation. The question so often raised in discussing the enzymes, and not answered with complete unanimity, as to how far the products of the decomposition have an injurious action, receives the simple answer in the case of alcoholic fermentation, that here one of the decomposition-products—viz., alcohol—is poisonous to the protoplasm in certain degrees of concentration, and thus injures both the yeast and the fermentation. 12 per cent, of alcohol prevents the growth of saccharomycetes, and 14 per cent, destroys all manifestation of energy. Mucor yeasts terminate their activity when the alcohol is as little as 34 to 4 per cent., Jtf. stolonifer even with 1*3 per cent.4 There are, however, also saccharomycetes which are very sensitive towards alcohol, as, for example, a beer-yeast of the Saaz type, examined by Prior,5 and the alcohol-producing mould-fungi of koji-yeast (vide supra). The Significance of Oxygen and Pasteur’s Theory of Fermenta- tion.—The study of the fermentative and vital processes of yeast under the influence of the admission of a greater or smaller a mount of oxygen has furnished further proofs in support of the view that the alcoholic fermentation of sugar is not under all conditions inseparably connected with the vital process. The discussion of this question appears the more important, inasmuch as it was on the ground of this influence of oxygen that the only real theory of alcoholic fermentation was based by Pasteur and upheld by the supporters of the vitalistic view. We must, therefore, deal with this point more fully. In the first place we can admit as an uncontested fact that the yeast-fungus requires 1 Effront, Bull. Soc. Chim. [3], v., 148, 476, 731 ; vi., 7S6, 1891. 2 Foth, C.f. Bakt., i., 502, 1885. 3 Fiechter, Ueb. d. Wirkg. der Blausdure, Diss. Basle, 1875. 4 Quoted by Fltigge, Micro-organ., 229, 1896. 5 Prior, Centralbl. f. Bakteriol. [II.], i., 432, 1895.