676 ARTHUR ISAAC KEKDALL 



in man and in bacteria, is "bacterial urea," and as such it is the best 

 available measure of nitrogenous metabolism. 



The "endogenous" ammonia is recognizable when bacteria derive their 

 energy solely from carbohydrates, in a protein-carbohydrate* medium. It 

 is of course masked in a purely protein medium where deamination of 

 protein occurs prior to the combustion of the protein for energy, as well 

 as from the structural nitrogenous changes. 



The following analytical data are illustrative of the nitrogenous metab- 

 olism of several saprophytic, parasitic, and pathogenic bacteria, under 

 parallel conditions: 



Briefly, the conditions of experiment are as follows: Plain, nutrient, 

 sugar-free broth, and glucose broth respectively, which differ only in 

 that the latter is reenforced with one per cent of glucose, are inocu- 

 lated with the same organism under exactly similar conditions, incubated 

 side by side, and examined at the same time for changes in titratable 

 acidity and nitrogenous changes, particularly ammonia formation. Am- 

 monia formation is an index of deamination, associated chiefly with the 

 iitilization of the non-nitrogenous residue of the amino acid complex for 

 energy. In media containing glucose in addition to the protein derivatives, 

 the energy requirement is obtained largely at the expense of the non- 

 nitrogenous carbohydrate, which of course does not undergo deamination 

 prior to its energy transformation. Under these conditions the sparing 

 action of glucose [carbohydrate] for protein is obviously manifested by 

 a greater or lesser reduction in the amount of ammonia formed [deamina- 

 tion] in contrast to the amount observed in the corresponding glucose- 

 free medium. - 



The table on following page also shows the relatively lesser nitrogen 

 change in media induced by pathogenic bacteria than that characteristic of 

 the saprophytic types as, for example, between Bacillus dysenteric and 

 Bacillus mesentoricus. This is in harmony with the observation cited 

 above that pathogenic organisms, generally speaking, are less active chemi- 

 cally than the ordinary saprophytic types (Kendall, Sears). 



Explanation : In general, it will be seen that all the bacteria studied 

 become alkaline in reaction and form considerable amounts of ammonia 

 in sugar-free broth. Among the products formed, but not indicated in 

 the table, are diphtheria toxin by the diphtheria bacillus, indol by 

 Bacillus proteus and Bacillus coli, a soluble proteolytic enzyme by Bacillus 

 mesentericus, Bacillus proteus and Staphylococcus aureus, and a soluble 

 hemolysin by Streptococcus hemolyticus. 



In the glucose medium, all the bacteria produce a relatively strong 

 acid reaction [chiefly lactic and acetic acids] and relative! y slight amounts 

 of ammonia, indicating that the major reaction is upon the glucose in 

 place of the protein. Neither toxin, enzyme, hemolysin nor indol is 

 to be found among the products produced from glucose by the organisms. 



