Protein Decomposition 175 



When the protein is the oiih' souree of earbon avaihible for fungi, 

 a definite parallehsm is found between the grovvtli of the mycehum 

 and the produetion of ammonia. Different protein derivatives are 

 not utiHzed aHke, and their nitrogen is not hberated ahke in the 

 form of ammonia. As))crgiIUis ni'^cr grows best with leucine, fol- 

 lowed by peptone, asparagine, and glycocoll. The difference in the 

 nature of the carbon compounds accompanying the proteins or of 

 the protein carbon itself accounts for the difference in the amount of 

 fungus growth and ammonia formation, because, in the absence of 

 a\ ailable carboln drates, the fungus uses the protein both as a source 

 of energy and as a source of nitrogen. The amount of nitrogen lib- 

 erated as ammonia depends not only upon the nitrogen content of 

 the protein, but also largely upon the availability of other sources of 

 earbon. The nitrogen is then either liberated as a waste product, 

 ammonia, or reassimilated and changed into microbial protein (Table 

 36). 



Table 36. Influence of Composition of Amino Acid upon Ammonia Production 

 BY Microorganisms (from Waksman and Lomanitz) 



Nitrogen Transformation in Decomposition of Organic Matter 



When nitrogenous organic substances are added to the soil, a group 

 of complex reactions result, so far as the nitrogen is concerned: 



(1) Hydrolysis of the proteins into polypeptides and amino acids, 

 with liberation of some ammonia, takes place. (2) This is followed 

 by the decomposition of the amino acids and other products of pro- 

 tein hydrolysis, with a further liberation of ammonia. (3) Synthesis 

 of microbial protoplasm leads to a storing away of a part or the 

 whole of the ammonia nitrogen; the greater the quantity of available 

 non-nitrogenous organic matter accompanying the nitrogenous sub- 



