Nitrogen Metabolism of Bacteria 



11 



finding of Sperry and Rettger*^ that pure proteins are not attacked by 

 micro-organisms in the entire absence of simpler nitrogenous com- 

 pounds. 



Simultaneously with the foregoing experiment another was made 

 using the same two organisms and also B. coli-communis, but employ- 

 ing a peptone solution containing meat juice instead of the pure peptone 

 media. The medium contained in 1 liter the juice from 1 lb. of finely 

 ground lean beef, 10 gm. of Witte's peptone, and 5 gm. of sodium 

 chlorid. The reaction was made neutral to phenolphthalein. The 

 technic of the experiment was exactly similar to that described. Table 

 2 and Chart 2 give the analytical results of the test. As in Table 1 

 the values are given in milligrams per 100 c.c. of the culture fluid. 



TABLE 1 

 The Production of Amino-acid and Ammonia by Bacteria in a 2% Peptone Solution 



Ttie figures represent the amount in milligrams of the substance mentioned at the bead 

 of the column, that is present in 100 c.c. on the corresponding day. 



The chief differences between the data of Table 2 and those of 

 Table 1 are to be seen in the case of the cultures of B. pyocyaneus. 

 In the presence of the muscle extractives this organism shows a con- 

 siderably higher production of ammonia and a much lower production 

 of amino-acid. There is no tendency at all toward an accumulation of 

 the latter in the medium. Evidently in the case of this bacillus the 

 constituents of the meat juice have a marked protein-sparing effect. 

 The rapidly decreasing figures for creatinin indicate that this compound, 

 at least, is easily utilized. 



'» Jour. Biol. Chem., 1915, 20, p. 445. 



