PROTEOLYTIC ENZYMES OF SOIL FUNGI 



517 



influence of reaction, the highest production of amino nitrogen 

 took place, in most instances, when the reaction was almost 

 neutral to litmus. All the three reactions proved to be more or 

 less favorable to the enzyme action, but the medium reaction 

 which was not too acid nor too alkaline gave the best" results. 

 The enzymes of the fungi studied seem to have a wider range 

 of reaction than the animal enzymes. 



To obtain further information on the influence of the reaction 

 upon the activities of the enzymes studied and also to throw 

 some light upon the possibility of their being a mixture of two 



TABLE 4 

 Influence of reaction upon the enzyme activities of microorganisms 



ORGANISMS USED 



Control 



A. niger 



A. niger 



A. niger 



A. niger 



A. niger 



A. niger 



A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 



CULTURE MEDIUM 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



REACTION OF 

 SOLUTION 



Alkaline 



Neutral 



Acid 



Alkaline 



Neutral 



Acid 



Alkaline 



Neutral 



Acid 



Alkaline 



Neutral 



Acid 



MILLIGRAMS OF NHj=N 

 PER 100 CC. OF SOLUTION 



1 per cent 

 peptone 



21.40 

 23.00 

 23.60 

 21.44 

 37.18 

 64.90 

 25.00 

 24.92 

 30.70 

 21.26 

 44.88 

 55.14 

 32.50 



1 per cent 

 casein 



7.28 

 12.40 

 25.60 

 13.44 

 19.44 

 39.56 

 24.80 

 53.34 

 38.96 

 27.36 

 69.32 

 73.76 

 74.84 



kinds of enzymes, one acting best in a slightly acid and the 

 other in an alkaline reaction, the following experiment was made. 

 Exo- and endoenzymes of A. niger were obtained by the pre- 

 viously described methods from eight-day-old cultures grown on 

 the Peptone-Czapek solution. Twenty cubic centimeters of the 

 filtrate containmg the exoenzyme and 800 mgm. of the mycelium 

 containing the endoenzyme were added to 1 per cent peptone 

 and casein solutions. The reaction of the substrata was made 

 neutral to litmus, which was found in the previous experiments 

 to be the best reaction for the activity of these enzymes. The 



