6 H. J. Sears 



respect to the extent to which they break down peptones prepared from pure 

 proteins, and compared the results with the effect on the proteins themselves. 

 Kendall and his co-workers""" recently studied the production of ammonia by a 

 large number of species, using in some cases Witte's peptone and in others a pep- 

 tone solution containing meat juice. Their aim was mainly to investigate the effect 

 that carbohydrates have on the decomposition of the nitrogenous substances. 

 They took the ammonia-production as a measure of proteolysis. Their data 

 show interesting exceptions to the general rule that carbohydrates have a 

 protein-sparing effect. 



The investigation by Glenn^' of the inhibition of indol-formation by members 

 of the proteus group grown in a peptone-carbohydrate solution also indicates 

 that these compounds materially lessen proteolysis. The author attributes this 

 effect, however, to the inactivation of the tryptic enzymes of the bacteria by the 

 acid products of sugar-fermentation. The decreased gelatin-liquefaction by this 

 group in the presence of sugars fermentable by them he explains in the 

 same way. 



Berghaus'" also published extensive data on the subject of ammonia-formation 

 by bacteria. He furthermore drew curves representing the production of this 

 compound after chemical inhibition of growth. 



Kendall and Farmer" attempted also to measure the rate of the production 

 of amino-acid, but were unable with the method used (formol titration) to 

 get results of any value. 



Kendall and Walker" claimed the production of minute quantities of urea 

 from meat-juice peptone solutions, and further stated that the amounts formed 

 day by day were about proportional to the ammonia produced. 



Antonoff,** using Weyl's test, and German," using Salkowski's method, claimed 

 creatinin-production from Witte's peptone for a large number of species. Both 

 investigators believed the tests to have differentiating value. Fitzgerald and 

 Schmidt^ repeated these tests, but could find appreciable amounts of creatinin 

 only in cultures of B. proteus. They employed both Weyl's method and 

 Jaffe's picric-acid test. 



That polypeptids are produced by bacteria has not been established as far 

 as I know. That they may be utilized, however, as a source of nitrogen is 

 known. Sasaki^ demonstrated the ability of a variety of species to split some 

 of the simpler peptids into their constituent amino-acids. 



A study of the metabolism of bacteria grown on media containing nitrogen 

 only in the form of amino-acids has been productive of much information that 

 is interesting and valuable. We may deal here with synthetic as well as analytic 

 products. That proteins are synthesized from amino-acids by micro-organisms 



" Kendall and Farmer: Jour. Biol. Chem., 1912, 12, pp. 13, 19, 21, 465, 469. 

 »* Kendall, Farmer, Bagg, and Day: Ibid., p. 219. 

 i» Kendall and Farmer: Ibid., 1912, 13, p. 64. 



'« Kendall, Day, and Walker: Jour. Infect. Dis., 1913, 13, p. 425. 

 •» Kendall and Walker: Jour. Biol. Chem., 1913, IS, p. 277. 

 '" Kendall, Day, and Walker: Jour. Med. Research, 1913, 28, p. 465. 



«' Kendall. Day, and Walker: Jour. Am. Chem. Soc, 1913, 35, pp. 1201, 1208, 1211, 

 1217, 1225, 1237. 



'» Centralbl. f. Bakteriol., I, O., 1911, 58, p. 481. 



'» Arch. f. Hyg., 1908, 64, p. 1. 



•-» Centralbl. f. Bakteriol., I, O., 1906, 43, p. 209. 



=> Ibid., 1912, 63, p. 545. 



=2 Proc. Soc. Exper. Biol, and Med., 1912, 10, p. 55. 



-' Biochem. Ztschr., 1912, 41, p. 174; 1913, 47, pp. 462. 472. 



