AMINO ACIDS AND MICRO-ORGANISMS 
545 
to the alternately occurring carbon atoms, in order to be sub- 
ject to attack by .certain fungi. For example, a and 7 amino- 
butyric acids are utilized while Z 3 amino butyric acid is not. 
The effect of saprophytic mold fungi upon amino acids is 
still more profound. In this case the products are chiefly C0 2 
HoO, NH 3 and oxalic acid. The commonly occurring species of 
Aspergillus and Penicillium are able to utilize the naturally 
occurring amino acids as sources of nitrogen, and as a rule the}^ 
carry oxidation practically to completion. Certain intermediary 
fungi, however, seem content with the initial hydrolysis whereby 
the nitrogen is liberated in a form that meets their require- 
ments, and the remaining hydroxy acid left to accumulate in 
the medium. Thus Oidium lactis converts tyrosine into p-oxy- 
phenyl lactic acid, phenyl-alanine into phenyl-lactic acid, and 
tryptophan into indollactic acid. But the oxidizing fungi are 
present in sufficient abundance in nature to account for the 
continual disappearance of recognizable protein decomposition 
products from such media as the soil where they would other- 
wise tend to accumulate. 
Chemistry Section, 
Iowa State College. 
35 
