Nitrogen Metabolism of Bacteria 7 



follows as a matter of course when we say that growth is supported by them. 

 That proteins other than those of the bacterial bodies are formed seems to be 

 true also."* Moreover, it has been shown by Frankel'" and others'" that the 

 characteristic toxins of diphtheria and tetanus are formed in media containing 

 only amino-acids as a source of nitrogen. 



The fraction of the nitrogen of the amino-acid that is used in synthesis is 

 always very small. The greater portion is found in the form of simpler com- 

 pounds. Frouin and Ledebt" grew several species on the amino-acids resulting 

 from the hydrolysis of serum proteins and observed that in all cases a primary 

 acidity was produced which was followed later by strong alkalinity. Rivas*" 

 found that a short digestion of peptone with trypsin made it a much better 

 culture medium than the undigested peptone. On such a medium he obtained 

 indol reactions in from 5 to 6 hours. 



Of the amino-acids which have been used alone as a source of nitrogen 

 for micro-organisms, asparagin has been most studied. A very large number 

 of organisms are capable of utilizing this compound. The main manner of 

 decomposition is deaminization with formation of aspartic acid and a subsequent 

 production of ammonia from the latter. That nitrogenous products other than 

 ammonia are usually formed also is probable. Nawiasky'"* made a rather 

 exhaustive study of the action of B. proteus on asparagin when large quantities 

 of the organisms are added to pure asparagin solutions. The most of the 

 nitrogen was recovered in the form of ammonia. About 5% of the asparagin 

 which disappeared was not accounted for by the ammonia recovered. 



Tyrosin is broken down by B. coli and yields 78.7% of the theoretical amount 

 of p-oxyphenylethylamin.'" Traetla Mosca" found another organism which 

 decomposed this acid with the formation of p-hydrocoumaric acid and ammonia. 



Of the nitrogenous compounds other than amino-acids, special interest 

 attaches to those found in more or less abundance in the urine of man and 

 animals. That urea, uric acid, and hippuric acid are attacked by a number of 

 species of bacteria has long been known. Kossiwicz"" showed that a number 

 of molds were capable of utilizing these substances also. Liebert" found sev- 

 eral varieties of bacteria that decompose uric acid to ammonia, and he stated 

 that allantoin and urea were intermediary products. Certain other organisms 

 have been isolated" which yield only urea from uric acid, no ammonia being 

 formed. 



That a very large number of species exist capable of converting urea to 

 ammonium carbonate is evident from the researches of Miquel." It is prob- 

 able also that many of the common laboratory forms show this property.' 



" Muller: Pfliiger's Arch., 1906, 112, p. 245. 



» Hyg. Rundschau, 1894, 4, p. 769. 



■•'• Uschinsky: Centralbl. f. Bakteriol., 1893, 14, p. 316. Arch, de nied. exper. et d'anat. 



path., 1893, 5, p. 293. 



" Compt. rend. Soc. de biol., 1911, 70, p. 24. 



» Centralbl. f. Bakteriol., I, O., 1912, 63, p. 547. 



-• Arch. f. Hyg., 1908, 66, p. 209. 



•0 Sasaki: Biochem. Ztschr., 1914, 59, p. 429. 



« Gazz. chim. Ital., 1910, 40, p. 86. 



" Ztschr. Gahrungsphysiol., I, 60, and II, 51. 



» Botan. Centralbl., 1910, 114, p. 361. 



" Ulpiani: Jahrb. f. Tierchem., 1903, 33, p. 1034. Gerard: Compt. rend., 1896, 122, 

 p. 1019; 123, p. 185. 



'' Lafar's Handbuch der technischen Mykologie, 1904-1906, 3, p. 71. 



