PROTEOLYTIC ENZYMES OF SOIL FUNGI 



519 



action. Long alid Hull (1917) have recently shown that trypsin 

 acts on fibrin and fibrin-peptone most energetically at an H-ion 

 concentration between 10~^ and 5.10~^ and on casein at 3.10~^ 

 to 5.10"^ The enzyme of A. niger, although acting on casein 

 at a reaction similar to the one found to be optimum for trypsin 



TABLE 6 \ 



Influence of age of culture upon the activities of proteolytic exo- and endoenzym.es of 



microorganisms 



ORGANISMS USED 



Control 



A. niger 



A. niger 



A . niger 



A . niger 



A . niger 



A. niger 



A. niger 



A. niger 



A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 

 A. ochraceus 



CULTURE MEDIUM 



Czapek's 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



Czapek's 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



Peptone-Czapek 



INCU- 

 BATION 



days 



3 

 10 

 18 

 35 



3 

 10 

 18 

 35 



3 

 10 

 18 

 35 



3 

 10 

 18 

 22 



MILLIGRAMS OF NH2=N PER 

 100 CC. OP SOLUTION 



1 per cent 

 peptone 



Exoen- 

 zyme 



21.24 

 26.30 

 21.64 

 21.84 

 21.76 

 28.67 

 24.26 

 29.12 

 46.74 

 26.32 

 31.86 

 34.72 

 22.46 

 26.91 

 62.59 

 42.56 

 62.70 



Endo- 

 enzyme 



20.35 

 53.41 

 36.42 

 39.76 

 34.77 

 84.82 

 59.75 

 64.40 

 43.89 

 47.97 

 68.28 

 71.68 

 57.00 

 49.14 

 80.80 

 93.52 

 64.26 



1 per cent 

 casein 



Exoen- 

 zyme 



7.18 

 12.27 

 11.38 

 10.64 



7.84 

 19.89 

 25.71 

 21.28 

 18.24 

 19.31 

 43.87 

 50.40 

 20.32 

 53.24 

 58.03 

 64.40 

 68.40 



Endo- 

 enzyme 



6.22 

 90.60 

 33.00 

 28.00 

 15.39 



125.77 

 80.80 

 92.40 

 22.33 

 38.02 

 73.97 

 82.88 

 76.95 

 55.58 

 79.66 



115.92 

 74.10 



by Long and Hull, acts on peptone and on fibrin (as will be seen 

 later) at a higher H-ion concentration. 



To throw more light upon the influence of the age of the cul- 

 ture on the proteolytic activities of both kinds of enzymes, it 

 was thought advisable to grow A. niger and A. ochraceus on both 

 media, in a large number of flasks. At the end of the proper 

 incubation period, single flasks containing each organism were 

 taken out of the incubator and filtered. The mycelium was 



