Experiments with Bacterial Enzymes 129 



produce any enzyme upon a medium containing glycerin without 

 peptone. More recently Abbott and Gildersleeve' 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 filtrates from non- 

 protcid 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 o-2g. 



Na,HP04 0.2 



H2O (redistilled) . . . loo.oc.c. 



In this very simple medium B. suhtilis 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. 



Na2HP04 0.1 



MgS04 o.r 



H2O (redistilled) . . . loo.oc.c. 



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

 sodium salt 



C. Asparagin o ■ 2g. 



K2HPO 0.1 



MgS04 0.1 



H2O (redistilled) . . . loo.o c.c. 



led to a negative result, as shown by tests made with 0.5 c.c. of the 

 filtrate of a 150 day culture. 



D. Asparagin 



Na2HP04 . . 

 MgS04 . . . 

 Dextrose . 

 H,0 (redistilled) 



o . 2 g. R. .\sparagin o • 2 g. 



0.1 NajHP04 .... 0.1 



. I MgS04 0.1 



1 . o Lactose 10 



100. o c.c. HjO (redistilled) 100. o c.c. 



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

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

 much less in D than in A. 



■ Loc, cit 



