Fig. 22.—Bacillus e.
Bacillus ureaæ, B. prodigiosus, and B. fluorescens putridus, evolve trimethylamine (Herfeldt), and, as the writer has shown, this amine has an important action in the puering process. In combination with organic acids, it removes lime from the skin, and in addition it favours the growth of bacteria, such as bacillus d and e (Figs. 21 and 22) and B. coli.
The albumens and peptones of the dung are pretty well decomposed and absorbed before evacuation; the bacteria subsequently split up the amido acids into fatty acids and ammonia. The fatty acids are then decomposed generally in the form of the calcium salts, in the manner shown in the table (p. 108), for which I am indebted to Dr. E. Herfeldt, of Bonn.
We have already treated of the action of these various products in Chapter [II]., but it will be seen from what has been said in the present chapter that the chemistry and bacteriology of the puer overlap, and that it is difficult, if not impossible, to separate them entirely. The bacteria are continually manufacturing chemical compounds, and decomposing others.
In this respect it is interesting and instructive to note that Nencki, in his classical work “The Chemical Mechanism of Putrefaction,”[85] considers the processes by which the putrefaction of proteids is brought about by bacteria, to be analogous to those taking place by melting the bodies with potash, and he holds the view that in the hydration processes brought about by bacteria, the water plays the same part as the potash.
| No. | Fermenting Substance. | Cause of Fermentation. | Fermentation Product. | Authors. |
|---|---|---|---|---|
| 1 | Calcium formate | Bacteria from sewer slime. | Calcium carbonate, CO2 and H | Hoppe-Seyler, Archiv f. d. g. Physiol. xii. |
| 2 | Calcium acetate | " " | Calcium carbonate, CO2 and CH4 | " " |
| 3 | Calcium lactate Undergoes four different fermentations | Thin bacillus | 1. Propionic acid, and, as by-products, acetic acid, succinic acid and alcohol. | Fitz, nine papers in the “Berichte der Deutsch. Chem. Gesellschaft,” 1876–1884. |
| Other species of bacteria: short aerobic, butyric bacteria (Fitz). | 2. Propionic acid and valerianic acid. | |||
| 3. Butyric acid and propionic acid. | ||||
| 4. Butyric acid, according to Pasteur (Comptes rend. 1861) | ||||
| 4 | Calcium malate | Bacteria (not described). Thin bacilli. | 1. Chief product, propionic acid; and, as by-product, acetic acid. | Schützenberger, “Fermentation,” 1876. |
| 2. Chief product, succinic acid; and, as by-product, some acetic acid. | ||||
| 3. Butyric acid and H. | ||||
| Bacteria | 4. Lactic acid and CO2. | |||
| 5 | Calcium tartrate | Different species of bacteria. | 1. Chief product, propionic acid; by-product, acetic acid. | " " |
| 2. Butyric acid. | ||||
| 3. Chief product, calcium acetate; by-products, ethyl alcohol, butyric and succinic acids. | ||||
| 6 | Calcium citrate | Small, thin bacilli | Acetic acid in large quantities, along with small quantities of ethyl alcohol and succinic acid. | Fitz. |
| 7 | Calcium glycerate | Micrococci | 1. Calcium acetate, along with small quantities of succinic acid and ethyl alcohol. | " " |
| Medium-sized bacilli | 2. Formic acid, with some methyl alcohol and acetic acid. |
Nencki explains, for example, the metamorphosis of leucin by putrefaction in this way: The bacteria decompose the water into hydrogen and hydroxyl, which act upon the leucin as follows:—