EXPERIMENTS WITH BACTERIAL ENZYMES 129 



produce any enzyme upon a medium containing glycerin without 

 peptone. More recently Abbott and Gildersleeve 1 have expressed 

 the same conviction as Fermi regarding the production of proteolytic 

 enzymes in non-proteid media. They state that in their experiments 

 the minimum evidence of digestion was given by nitrates from non- 

 proteid culture media. Details of these experiments are not recorded. 

 Experiments made by me show that under proper conditions a 

 large amount of gelatinase is formed by some bacteria in non-proteid 

 media. The following solutions were employed. 



A. Asparagin -2g. 



Na 2 HPO 4 0.2 



H 2 O (redistilled) . . . loo.oc.c. 



In this very simple medium B. subtilis grows well and produces gelat- 

 inase slowly, but so abundantly that o . 3 c.c. of the filtrate of a 90 day 

 culture at 20, o. i c.c. of a 120 day culture, and 0.05 c.c. of a 150 day 

 culture brought about complete liquefaction of the standard amount 

 of gelatin (p. 125). The use of the same medium plus magnesium 

 sulphate 



B. Asparagin o . 2g. 



Na 2 HP0 4 o.i 



MgSO 4 o.i 



H 2 O (redistilled) . . . loo.oc.c. 



gave very similar results, but the substitution of a potassium for the 

 sodium salt 



C. Asparagin o.2g. 



K 2 HPO o.i 



MgSO 4 o.i 



H 2 O (redistilled) . . . loo.oc.c. 



led to a negative result, as shown by tests made with o . 5 c.c. of the 

 filtrate of a 150 day culture. 



D. Asparagin o.2g. E. Asparagin . . . . o.2g. 



Na 2 HPO 4 . . . . o.i Na 2 HPO 4 .... o.i 



MgSO 4 o.i MgSO 4 o.i 



Dextrose i.o Lactose i.o 



H 2 O (redistilled) . . 100.0 c.c. H 2 O (redistilled) . 100.0 c.c. 



The addition of dextrose had little effect in increasing the gelat- 

 inase production in the organisms studied, B. subtilis in fact yielding 

 much less in D than in A. 



*Loc. cit 



