516 



SELMAN A. WAKSMAN 



this solution being termed ''neutral;" to the third portion 5 cc. 

 of O.In HCl were added for each gram of casein and peptone, 

 this solution being termed "acid." A.niger and -4. ochraceus grown 

 for fourteen days on Czapek's and Peptone-Czapek solutions 

 were used. The enzyme cultures were incubated for four days. 



TABLE 3 



The influence of composition of medium and reaction upon the production of amino 

 nitrogen from proteins by the exoenzymes of microorganisms 



ORGANISMS USED 



Control 



A. niger 



A . niger 



A . ochraceus 



A. ochraceus 



A. ochraceus 



A . fuscus 



A . fuscii,s 



P. chrysogenum 



Citr. glaber 



Act. calif ornicus. . . . 



Act. sp. 101 



Act. sp. 101 



Act. sp. 101 



Act. violaceus-ruber 

 Trypsin: 200 mgm.. 

 Pepsin : 200 mgm. . . 



CCLTCRE MEDIUM 



Czapek's 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Czapek's 



Czapek's 



Czapek's 



Peptone-Czapek 



Peptone-Czapek 



Czapek's 



AGE 



OF CUI/- 



TURE 



days 



5 

 14 



5 

 14 

 14 

 14 

 14 



8 



5 

 15 

 15 

 15 

 38 

 90 



MILLIGRAMS OF NH2=N PER 

 100 CC. OF SOLUTION 



1 per cent 

 peptone 



1 OS 



©■5 





21.24 



21.46 



21.30 



21. 



22.62 



39.44 



21.40 



41.56 



28.12 



39.44 



33.06 



23.78 



33.06 



70.38 



28.71 



60.90 



22.62 



21.24 



34.16 



22.20 



33.64 



23. 



45.24 



23.56 



50.76 



62.48 



33.06 



47.56 



27.04 



30.16 



52.17 



28.71 



45.24 



26.68 



1 per cent 

 casein 



7.26 

 23.78 

 38.88 

 30.60 



9.86 

 41.76 

 20.30 



19.71 

 31.90 

 31.32 



7.54 

 45.82 

 75.02 

 17.25 

 81.20 

 13.92 



7.26 

 26.10 

 19.44 

 34.80 

 16.82 

 50.76 



7.54 



19.71 

 39.44 

 52.20 

 7.40 

 45.24 

 53.50 

 23.64 

 56.26 

 39.44 



* Phenolphthalein = neutral to phenolphthalein, litmus = neutral to litmus. 



The data presented in table 4 confirm the previous observa- 

 tions concerning the nature of the exoenzymes produced by 

 microorganisms. In this case also the peptone containing media 

 contained a more active enzjone or a stronger concentration of 

 proteolytic enzymes than the non-protein media. As to the 



