Nitrogen Metabolism of Bacteria 29 



solution were placed in each of 6 tubes, sterilized, and inoculated sev- 

 erally with the organisms as indicated in Table 17. After 15 days' 

 incubation at Z7 C. the tubes were again sterilized and the whole 

 contents of each submitted to a total nitrogen-determination. The 

 results are given in Table 17. The figures represent the total nitrogen 

 in milligrams in the 5 c.c. of the corresponding culture. 



TABLE 17 

 Nitrogen Lost from Bacterial Cultures by Volatilization 



Organism 



Milligrams of Total 



Nitrogen in 5 c.c. of 



Culture Medium After 



15 Days' Incubation 



Sterile control 



B. coli-communis 



B. typhosus 



B. pyoeyaneus 



B. faecalis-alkaligenes. 

 B. subtilis 



15.95 

 15.64 

 15.94 

 15.61 

 15.72 

 14.39 



It is seen that B. subtilis is the only one of the organisms investi- 

 gated in this respect which lost any appreciable quantity of nitrogen 

 during the 15 days' incubation. Even its loss could by no means 

 account for the differences mentioned. Berghaus*^ also gives data on 

 the loss of ammonia through volatilization. Tho ammonia is undoubt- 

 edly utilized to a certain, extent by most of the species studied, the 

 amount utilized must necessarily be small. That part of it which 

 is used for the synthesis of bacterial protein or the metabolism of 

 which results in compounds which are not volatile could not be great 

 enough to be considered in the present connection. 



The only conclusion which can be drawn from the facts in the 

 case, therefore, is that the greater part of the reported losses in amino- 

 acid nitrogen which take place from time to time is due to the con- 

 version of this nitrogen into compounds other than ammonia. Further, 

 the continued low concentration or the entire absence of the latter, as 

 seen particularly in the gelatin cultures, during the first days of the 

 experiments, points to the conclusion that ammonia arises from the 

 decomposition of these other compounds, and that the latter are there- 

 fore to be regarded as important stages in the complete decomposition 

 of protein. That some of them are true end products, and undergo 

 no further change through the action of the micro-organism concerned 

 is evidenced by the slight extent to which creatin is attacked by B. 

 proteus (Table 5), which, as seen in Table 1, is capable of forming 

 this substance from peptone. 



*- Arch. f. Hyg., 1907, 64, p. 1. 



