FURTHER STUDIES ON BACTERIAL NUTRITION: 



THE UTILIZATION OF PROTEID AND 



NON-PROTEID NITROGEN 



LEO F. RETTGER, NATHAN BERMAN and WILLIAM S. STURGES 

 From the Sheffield Laboratory of Bacteriology and Hygiene, Yale University 



The highly interesting observation of Bainbridge (1911) that 

 certain aerobic and facultative anaerobic bacteria of the gelatin- 

 liquefying and non-hquefying types are of themselves unable to 

 initiate decomposition of purified native proteins has been fully 

 corroborated by Sperry and Rettger (1915). The last-named 

 authors have shown further that the putrefactive anaerobes B. 

 putrificus, B. oedematis (B. oedematis-rnaligni, Zopf) and B. 

 Feseri {B. anthracis-symptomatici, Kruse) are likewise devoid of 

 this property; and that the vegetable protein edestin, like egg 

 and serum albumin, does not undergo disintegration by direct 

 bacterial action. It was but natural to assume, therefore, that 

 the protein nitrogen cannot be utilized by bacteria unless it is 

 first simplified and made available for cell nutrition through the 

 action of a proteolytic enzyme, strong acid or alkali, or some other 

 cleavage-producing agent. 



Solutions of purified proteins were prepared by the methods 

 now used in all biochemical laboratories and involving the crystal- 

 lization of the proteins. The test media were usually the same 

 as those employed by Bainbridge, and contained the following 

 ingredients, besides the protein; sodium chloride 0.5 per cent, 

 sodium sulphate 0.2 per cent, calcium chloride 0.1 per cent and 

 acid potassium phosphate 0.1 per cent. The only possible source 

 of nitrogen was the protein, except in certain check tests in 

 which small amounts of peptone were employed. The solutions 

 containing the purified proteins were steriUzed by filtration 

 through the laboratory Berkefeld. 



The test media were inoculated from 24 hour slant agar cul- 

 tures of the various organisms, with the special precaution of 



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