Chemical pathology : being a discussion of general pathology from the standpoint of the chemical processes involved / by H. Gideon Wells.

  • Wells, H. Gideon (Harry Gideon), 1875-1943.
Date:
1918
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Licence: In copyright

Credit: Chemical pathology : being a discussion of general pathology from the standpoint of the chemical processes involved / by H. Gideon Wells. Source: Wellcome Collection.

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    most at will, and even to develop races of bacteria that do not produce pigment at all, from races that ordinarily are pigment-producers. Of numerous classifications of pigment-forming bacteria*, all faulty because of our slight knowledge of the chemistry of the process, that of Migula seems the best; it is based on the solubility of the pigments formed, as follbws: (1) Pigments Soluble in Water.—This includes the pigments of all fluorescent bacteria, as well as those giving a red or brown color to gelatin media. Most important among these is Bacillus pyo- cyaneus, whose pigments have been considerably studied. There seem to be two pigments, one, pyocyanin, characteristic for this organism; and a fluorescent pigment which numerous other organisms also pro- duce. Pyocyanin has been analyzed by Ledderhose, who found it to be a ptomain-like body, a derivative of the aromatic series, probably re- lated to the anthracenes. It can be reduced to a colorless leuco-base, in which form it is probably produced by the bacteria, and then is oxidized in the air into the pigment. Its composition is C14H14N20 (the sulphur-containing pyocyanin which has been described is proba- bly impure). The fluorescent pigment is insoluble in alcohol and chloroform, and can thus be separated from pyocyanin, which is solu- ble in chloroform. Although related to the ptomains, pyocyanin seems to be altogether non-poisonous to animals. Jordan 14 and Sullivan 13 have studied the conditions under which pigments are formed, and found that pyocyanin can be produced in protein-free media, and without the presence of either phosphates or sulphates; but both sulphur and phosphorus must be present to pro- duce the fluorescent pigment. As pigments can be produced on media containing only ammonium salts of succinic, lactic, or aspartic acid, or asparagin, they are evidently formed synthetically, and not by cleavage of the media. (2) Pigments Soluble in Alcohol and Insoluble in Water.—The most important bacteria of this group are the Staphylococcus pyogenes aureus and citreus. Their pigment is of a fatty nature, a lipochrome, which lies among the bacteria in the form of dendritic crystals. Be- ing a fat, it can be saponified, and when decomposed it gives the acrolein reactions and odor, from the breaking down of the glycerol of the fat molecule. Acted upon by strong sulphuric acid, the yel- low pigment changes into blue granules and crystals (lipocyanin re- action). The lipochromes are soluble in the usual fat solvents, and form fat spots on paper. (3) Pigments Insoluble in Water and in Alcohol.—The pigment of Micrococcus cereus flavus belongs to this class; its nature is quite un- known. 4 14 Jour. Exper. Med., 1899 (4), 627.