30 



H. J. Sears 



THE FORMATION BY BACTERIA OF UREA, URIC ACID, ALLANTOIN, 

 CREATIN, AND CREATININ 



Urea and Uric Acid. — All the peptone cultures described thus far 

 in this paper were examined in several stages of their growth for urea 

 and uric acid. Neither of these compounds was found in any case. 



The urease method originated by Van Slyke" was used for the detection of 

 the former, and the colorimetric method used by Folin and Denis," for the 

 latter. Both these methods were proved to be efficient by determinations made 

 on cuhures to which weighed amounts of the pure chemicals had been added. 

 The medium used in the case of uric acid was a solution containing 10 gm. 

 asparagin, 2.5 gm. NaiCOa, 2 gm. Na2HP04, traces of MgSO* and CaCU and 

 0.902 gm. of uric acid per liter. The time of incubation was 15 days. The 

 medium used in the case of urea was a 2% peptone solution containing about 

 10 gm. of urea per liter. The cultures were incubated for 7 days. 



TABLE 18 

 Decomposition of Uric Acid by Bacteria 



Organism 



Sterile control.... 

 B. coli-communis 



B. acidi-laetici 



B. pyocyaneus.. . 



B. smegmae 



Sp. choleras 



Ammonia Nitro- 

 gen per 100 c.c. 

 Culture Medium 



5.3 mgm. 

 112.0 mgm. 

 102.6 mgm. 



39.1 mgm. 



43.2 mgm. 

 41.5 mgm. 



Amino-acid Nitro- 

 gen per 100 c.c. 

 Culture Medium 



94.5 mgm. 



36.0 mgm. 



7.3 mgm. 



22.5 mgm. 

 68.0 mgm. 



32.6 mgm. 



Uric Acid 



per 100 c.c. 



Culture Medium 



65.7 mgm. 

 7.5 mgm. 

 None 

 None 

 None 

 None 



TABLE 19 

 Decomposition of Urea by Bacteria* 



* In this test inoculations were made into 5-c.c. portions of the culture medium, and the 

 tubes were incubated tor 7 days. 



It is not surprising that uric acid and urea are not to be found in 

 bacterial cultures when it is considered how easily and completely both 

 are decomposed by bacteria. Tables 18 and 19 give the results of brief 

 tests designed to show this. 



Allantoin. — Numerous attempts were made to prove the presence 

 of allantoin in cultures on pure peptone solutions as well as in those 

 on peptone solutions containing uric acid, but it was impossible to find 



" Van Slyke and Cullen: Proc. Soc. Exper. Biol, and Med., 1913, 11, p. 56. 

 " Jour. Biol. Chem., 1913, 14, p. 95. 



