BACTERIAL ENZYMES. 37 



BACTERIAL ENZYMES. The enzymes are, in gen- 

 eral, amorphous products of living protoplasm, that 

 are able to split up large quantities of complex or- 

 ganic and inorganic substances into smaller, simpler, 

 more soluble, and diffusible combinations. Bacteria 

 produce a variety of enzymes, by means of which 

 they are able to derive their nutrition from complex 

 molecular substances. The enzymes are to some extent 

 dialysable. The principal enzymes produced by bacteria 

 are proteolytic, diastatic, inverting, coagulating, and sugar 

 splitting. 



The proteolytic or albumin-dissolving enzymes are 

 formed by a great many bacteria. The most familiar 

 indications of the formation of a proteolytic enzyme are 

 seen in the liquefaction of gelatin, of coagulated blood- 

 serum, and of casein. Most frequently the proteolytic 

 enzyme is allied to trypsin, as shown by Abbott and 

 Gildersleeve, 1 since the liquefaction or digestion pro- 

 ceeds only under an alkaline reaction. Some bacteria, 

 however, produce a proteolytic enzyme analogous to 

 pepsin, and this enzyme is active under an acid reac- 

 tion. The proteolytic enzymes of different bacteria 

 vary considerably with regard to their resistance to 

 heat, some being destroyed in a few minutes when 

 heated to 60 or 70 C., while others may be boiled for 

 a short time without suffering marked deterioration (see 

 Abbott and Gildersleeve, loc. cit.). The proteolytic 

 enzymes also differ in respect to their susceptibility to 

 the action of acids and other chemicals. 



The formation of proteolytic enzymes is one of the 

 functions of bacteria that is easily disturbed by external 

 conditions, for instance, long-continued cultivation on 



i Abbott aud Gildersleeve: Journ. of Med. Research, vol. v. 1903. 



