Experiments with Bacterial Enzymes 139 



at 37° C. carbol gelatin originally 0.05 per cent alkaline was made 

 acid as follows: 



S% Trypsin Sol. Carbol Gelatin 



0.003 c.c 0.1% acid 



0.03 i.o " 



01 2.3 



All the bacterial gclatinascs tested are able to manifest their activity 

 in a medium more or less acid. It is further evident from the experi- 

 ments cited above that the initial reaction of the gelatin is not a matter 

 of indifference, that the gelatinases derived from several bacterial 

 species are not alike in this respect, and that it is certainly not true 

 that an initial alkaline reaction presents in all cases the most favorable 

 conditions for the gelatinolytic process. 



Temperature. — The temperatures at which the enzymes manifest 

 their maximum activity have been approximately determined in several 

 cases. In every instance the enzymes have produced greater lique- 

 faction at 37.5° than at lower temperatures. This is true even 

 when the microorganism forming the enzyme grows better at a lower 

 temperature. A strain of Sp. Finkler- Prior, for example, that grew 

 well at 20° C, but refused to grow at 37° C, gave rise to an enzyme that 

 liquefied more rapidly at 37° than at 20°, more rapidly at 45° than at 

 37°, more rapidly at 56° than at 45°, and even at 60° liquefied better 

 than at 37°, though not so well as at 56°. 



The following results were obtained with a B. pyocyaneus culture 

 (M. L. D. at 37° C, 20 hours was o.oi c.c): 



Amount of Filtrate 



0.1 c.c. 



0.08 



COS 



0.03 



0.01 



-O 



Another test with a pyocyaneus gelatinase showed that, as in the 

 experiment just cited, slightly more liquefaction was produced at 45 

 than at 37°; at 65°, however, the activity of the enzyme was distinctly 

 checked but not altogether inhibited. 



The gelatinase of B. prodigiosus behaved in a similar fasliion (M. 

 L. D. 20 hours at 37° was o . 02 c.c.) : 



