STUDIES ON AZOTOBACTER CHROOCOCCUM BEIJ. 



359 



After eight days' incubation at 25°C. the cultures were ana- 

 lyzed and found to give the values shown in table 19. 



Here Azotobacter is found to break down the nitrate and 

 actually change it into the organic form with a resultant loss 

 from solution. 



Experiment 46. When the mannitol is replaced by glucose in 

 a solution of the following composition the nitrogen balances 

 vary only with regard to the quantity of nitrogen lost from 

 solution. 



Glucose ." 5 . 00 grams 



K2HPO4 0.05 gram 



Ca(N03)2 + 4H2O 0.316 gram 



Deep well water 250.0 cc. 



One hundred cubic centimeters of this solution pipetted into 

 large Fernbach flasks received 0.5 gram CaCOa. After inocu- 

 lation of one with a very small quantity of a pure culture of 

 Azotobacter chroococcum, the flasks were incubated for fifty-two 

 days at 25°C. Table 20 summarizes the results obtained. 



TABLE 20 

 Attack of nitrates by Azotobacter chroococcum 



Here again nearly the whole of the nitrate nitrogen reduced is 

 to be found in the organic form. As the loss of nitrogen from 

 solution is in this case negligible we may only draw attention 

 to it now and reserve discussion to a later page. 



To estabhsh with certainty the fact of nitrate nitrogen attack 

 and consumption another series of experiments may be cited 

 which is typical of all the results obtained in this connection. 



JOURNAL OF BACTERIOLOGY, VOL. VI, NO. 3 



