512 



SELMAN A. WAKSMAN 



A number of organisms were grown on Czapek's solution, for 

 a period of eighteen to sixty days, the slower growing organisms, 

 such as the actinomycetes, requiring a longer incubation period. 

 At the end of that period, the cultures were filtered and the myce- 

 lium treated by the acetone method. This method consists in 

 washing the mycelium a few times with distilled water, then 

 drying it between filter paper, cutting it into fine pieces, and 

 covering it for ten minutes with acetone; the mycelium is then 

 dried again and covered for three minutes with ether, and 

 finally dried over sulfuric acid at 35 to 40°C. One per cent pep- 



TABLE 1 

 Action of exo- and endoenz^jmes of microorganisms upon casein and peptone 



OBGANISMS XrSED 



Control 



A. niger 



A. ochraceus 



Citr. glaber 



P. chrysogenum 



P. chrysogenum. . . . 



Act. griseus 



Act. sp. 101 



Act. violaceus-ruber 

 Trypsin: 200 mgm. 



AGE OF 

 CULTURE 



18 

 18 

 18 

 8 

 60 

 60 

 60 

 60 



MILLIGRAMS OF NHt=N PER 100 CC. 

 OF SOLUTION 



1 per cent peptone 



Exoenzyme 



21.36 

 22.11 

 26.19 

 24.44 

 50.40 

 59.36 

 37.25 

 50.63 

 20.95 

 47.12 



Endoen- 

 zyme 



20.26 

 41.32 

 47.72 

 47.14 



62.27 

 27.35 

 37.25 

 38.76 



1 per cent casein 



Exoenzyme 



7.26 

 10.48 

 19.20 

 17.46 

 16.90 

 70.42 

 52.38 

 52.38 

 55.29 

 62.12 



Endoen- 



6.20 

 29.10 

 37.83 

 55.29 



68.09 

 34.92 

 75.66 

 43.65 



tone and casein solutions, neutral to litmus, were used as sub- 

 strata. Fifty milligrams of treated actinomyces mycelium and 

 800 mgm. of fungus mycelium were taken for the inoculation of 

 each flask for the study of the endoenzymes. Determinations 

 of the amino nitrogen formed as a result of the action of the 

 enzyme upon the substratum were made at the end of four 

 days. The blank was subtracted from each determination. 



It is seen from table I that both the exo- and endoenzymes of 

 the microorganisms studied, when these organisms have been 

 grown on a non-protein medium, can split casein and peptone 



