BACTERIAL NUTRITION 



373 



as seen in table 2, is of special interest, and would indicate that 

 even strongly proteolytic organisms utilize the simpler nitrog- 

 enous substances during their earlier development, thus sparing 

 the more complex substances until the former are exhausted and 

 until abundant enzyme production has taken place. 



The formol titration results are of much interest in connection 

 with the other figures. It is quite apparent that an increase in 



TABLE 3 



Showing utilization of Witte's peptone with and without the addition of certain 



inorganic salts. 



ORQANISMS 



Control 



B. subtilis 



P. vulgaris 



Staph, aureus, average 3 strains. 



B. cloacae 



B. typhi 



B. paratyphi A 



B. paratyphi B 



B. bronchi septicus 



B. coli, average 4 strains. 



B. diphtheriae, average 2 strains. 



MEDIUM A' 



Biiiret test 



1.0 



0.0 



0.0 



0.65 



0.5 



0.75 



0.7 



0.85 



0.85 



0.75 



0.7 



Sorensen 

 test 



10.0 

 52.0 

 58.0 

 35.0 

 46.0 

 22.0 

 22.0 

 20.0 

 12.0 

 22.0 

 23.0 



MEDIUM Bf 



Biuret test 



1.0 



0.0 



0.0 



0.65 



0.5 



0.7 



0.7 



0.9 



0.9 



0.75 



0.75 



Sorensen 

 test 



14.0 

 48.0 

 46.0 

 37.0 

 50.0 

 22.0 

 30.0 

 24.0 

 14.0 

 27.0 

 28.0 



* Medium A: 0.5 per cent peptone, 0.25 per cent Liebig's beef extract and 

 0.5 per cent NaCl. 



t Medium B: Same as A plus 0.1 per cent K2HPO4, 0.02 per cent MgS04 and 

 0.01 per cent CaCl2. 



Note: Incubation at 30°C. for three weeks. 



the titration value does not necessarily run parallel with the 

 results of the biuret tests. 



Other brands of commercial peptone 



The other peptones tested were all of American manufacture, 

 namely the Digestive Ferments Company, Parke, Davis and 

 Company, Armour, Eimer and Amend, and the Arlington 

 Chemical Company (aminoids) brands. The results of these 

 experiments are given in tables 4, 5, 6, 7, and 8. 



THE JOURNAL OF BACTERIOLOGY, VOL. Ill, NO. 4 



