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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    posed indifferently, in which case there remains an excess of racemic lactic acid; or that the cell only decomposes the ^-com- ponent when the d-lactic acid (or, in certain cases, also the 2-lactic acid) is left as a decomposition-product which can no longer be attacked. Under favourable conditions of vitality, the micro-organisms appear rather to be capable of further decomposing both constituents, so that racemic lactic acid invariably is left; if their vitality be weakened, their power of assimilating one or other of the components, according to the circumstances, becomes less, and this conclusion receives support from the experiments of Pere 1 on Coli bacilli. But that, in any case, lactic acid is not to be regarded as the final metabolic 'product of the organisms is clear from the in- variable presence of by-products, even in the case of pure cultivations, and to the significance of these in differentiating fermentation from vital metabolism we shall again refer when discussing alcoholic fermentation. In the first place, carbonic acid is naturally produced as a purely vital respiration product of the organisms, and has no connection with the fermentation as such; the fact of its production has been asserted by Hueppe2 and by Adametz,3 and denied by Leichmann,4 though with reference, it is true, to other micro-organisms. In addition to this, other products are also formed—e.g., traces of alcohol (Leichmann4), &c. Subsequently Kuprianow5 also showed that the consumption of sugar did not run absolutely parallel with the formation of lactic acid, and this we may interpret as indicating that the actual metabolism of the micro-organisms, which depends upon their nature and vital conditions, proceeds simultaneously with the typical fermentative process. Moreover, there are means of checking the power of development of the micro-organisms without interfering with the fermentation, viz., metallic salts in very slight degrees of concentration (Chassevant and Richet6); this fact admits of the same interpretation. We shall deal more fully with this question as a whole in discussing the very much more important alcoholic fermentation. Substratum of Lactic Acid Fermentation.—All simple hexoses undergo the typical lactic acid fermentation under the influence of the ferment, notably glucose, fructose, and galactose. Mannite, 1 Pere, Ann. Inst. Pasteur, vi., 528, 1892 ; vii., 737, 1893. 2 Hueppe, Mitth. a. d. kaiserl. Gesundh. Amt., ii., 309, 1884. 3 Adametz, C. f. Bakt. [II.], i., 465, 1895. 4 Leichmann, C.f. Bakt., xvi., 826; through Milchzeitg.,33, 1894. 6 Kuprianow, Arch. f. Hyg., xix., 282, 1893. 6 Chassevant and Richet, Comptes Rendus, cxvii., 673, 1893.