116 CHEMISTRY OF BACTERIA AND THEIR PRODUCTS 



Ptomains 



Ptomains, the soluble basic nitrogenous substances that are found 

 in the medium in which bacteria have been growing, were the first 

 bacterial products that were recognized, and for some time it was 

 believed that it was through the production of such alkaloid-like sub- 

 stances that bacteria caused disease, just as poisonous plants owe 

 their effects to poisonous alkaloids. It was soon found, however, that 

 the ptomains that could be isolated from cultures of pathogenic bac- 

 teria were insufficient by themselves to cause the poisonous effects 

 that such cultures produced when injected into animals. The isolated 

 ptomains were not onlj^ far less poisonous than the original culture, 

 but furthermore they did not produce the symptoms and anatomical 

 changes characteristic of the diseases that the pathogenic organism 

 caused. Moreover, the majority of ptomains are not very poisonous, 

 and highly poisonous ptomains may be produced by non-pathogenic 

 bacteria. As a result, the work on ptomains, which once occupied 

 many laboratories and promised to reveal the entire chemistrj^ of bac- 

 terial intoxication, has now been almost completely dropped. The 

 interest in ptomains is by no means entirely historical, however, for it 

 is possible that poisonous ptomains at times do enter the body and 

 cause illness, perhaps even death. The close chemical resemblance to 

 vegetable alkaloids of some of the ptomains that may arise in decom- 

 posing corpses, makes them of great importance to chemists searching 

 for the cause of death in cases of supposed poisoning. Therefore the 

 most essential features of the ptomains and their chief known rela- 

 tions to intoxications will be briefly discussed, referring the reader 

 for a full consideration to Vaughan and Novy's "Cellular Toxins" 

 and Barger's "The Simpler Natural Bases." 



The ptomains owe their basic character to nitrogen-containing 

 radicals, principally amino-groups, and hence arc formed from ni- 

 trogenous substances, chiefly proteins, which contain their nitrogen 

 in the amino form. Probably most ptomains arise from the decompo- 

 sition of the protein medium upon which the bacteria grow, although 

 undoubtedly part of the ptomains is also formed from the destruc- 

 tion of the bacterial cells themselves; how large a i)art of the pto- 

 mains is formed by intracellular bacterial processes and how much 

 by cleavage of the proteins of the media by extracellular bacterial 

 enzymes is unknown. The structure of the ptomains shows them to 

 be V(!ry closely related to the amino-acids obtained ])y cleavage of the 

 prot(;in molecule by enzymes antl other hj'drolytic agencies; and the 

 determination of the composition of the several amino-acids of the 

 proteins lias quite cleared up the problem of the origin of the pto- 

 mains. Presumably these secondary changes result from the action 

 of special enzynu^s upon th(> aniiiio-acids. Most of the jitomains are 

 fre(! from or ]nn)v in oxygen, lieiicc^ rcihiction processes, or lack of sufli- 

 ciciit oxygen foi- oxidation, are prob;il>ly ini|)ortaiit in t heir proihiction. 



