268 AZOF I CAT ION 



This he finds corresponds remarkably closely with that of legumin. 

 Kxperiments with plants indicate that the nitrogen of the Aznto- 

 Ixirter cells is not readily assimilated. 



Stoklasa found the Azotobacter cells to contain 10.2 per cent, ot 

 total nitrogen and S.6 per cent, of ash. The ash contained from 58 

 to 62.35 per cent, of phosphoric acid. Nitrogen and phosphorus 

 were mainly in the form of nucleo-proteins and lecithin. The per- 

 centage of both nitrogen and phosphorus in the cell increase with 

 age. 



The most complete analyses of the Azotobacter cells, so far reported, 

 show them to contain when grown on dextrin agar and rapidly 

 dried at 30 C., 6.63 per cent, of water, 4.12 per cent, of ash, and 

 12.92 per cent, of protein. The protein is similar to other plant 

 proteins. It contains 10 per cent, of ammonia nitrogen, 26.5 per 

 cent of diamino-nitrogen, and 60 per cent, of monoamino- nitrogen. 

 The quantity of lysin present is very high, but the histidin is present 

 only in traces. 



Krzemieniewski states that Azotobacter produces no hydrogen or 

 other combustible gases in its metabolism, but according to Stoklasa 

 it does, and in the presence of nitrates it produces ammonia and 

 nitrites. Moler claims that during its life, A. chroococcum separates 

 no soluble compounds, and it is only after death that it furnishes 

 nitrogen to higher plants. Nor are their bodies readily broken 

 down by proteolytic enzymes. Both A. agilis and A. vinelandii 

 separate a soluble compound. The protein compounds so formed 

 in soil are quickly broken down by other bacteria. Remy considers 

 the nitrogen fixed by Azotobacter in a readily available form for 

 plant assimilation. Beijerinck found that 50 per cent, of the total 

 nitrogen in Azotobacter cells when supplied to the soil is nitrified in 

 about seven weeks. None of the Azotobacter so far studied produce 

 nitrates in the media. 



Turning now to the breaking down of the carbohydrates, we find 

 that the organisms produce ethyl alcohol, glycocoll, acetic acid, 

 butyric acid, lactic acid, carbon dioxid and hydrogen. The quantity 

 and quality of the different products vary with the species and with 

 the carbohydrate used. 



It is likely that many of the end-products have not been deter- 

 mined, for Stoklasa starting with 15.9 gin. of dextrose recovered 

 7.9 as carbon dioxid, 0.3 as ethyl alcohol, 0.2 as formic acid, 0.7 as 

 acetic acid, 0.2 as lactic acid, but could not trace the remaining 6.6 

 gm. The organisms are extremely active when growing under 

 appropriate conditions, for 1 gm. weight of Azotobacter has evolved 

 no less than 1.3 gm. of carbon dioxid in twenty-four hours. A great 

 distinction between the Azotobacter and the other species is that the 

 former decompose their sugar with carbon dioxid as the chief 



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